JP2009128855A - Liquid crystal device, projector, and optical compensation method for liquid crystal device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve, for example, a high-contrast display in a liquid crystal device. <P>SOLUTION: The projector (10 etc.) includes: a liquid crystal panel (15c) modulating light and having a twisted liquid crystal (34) held between a first substrate (92) having a first alignment layer (98) and a second substrate (41) having a second alignment layer (43), the alignment state of the liquid crystal regulated by the first and second alignment layers; a pair of polarizing plates (15b, 15d); a first retardation plate (15a) holding a uniaxial first refractive anisotropy (81a), in which, in a plan view in the normal direction of the polarizing plate, a first optical axis (nz1') of the first refractive index anisotropy is along a first alignment direction (R1) that is the alignment direction of first liquid crystal molecules constituting a portion of the liquid crystal face-contact with the first alignment layer; and a second retardation plate (15e) having a uniaxial second refractive index anisotropy (81e), in which, in a plan view along the normal direction, a second optical axis (ny2') of the second refractive index anisotropy is along a second alignment direction (R2) that is the alignment direction of second liquid crystal constituting a portion of the liquid crystal face-contact with the second alignment layer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal device including a polarizing plate and a retardation plate, a projector including the liquid crystal device, an optical compensation method for the liquid crystal device, and a technical field of a retardation plate used in the liquid crystal device.

  As this type of liquid crystal device, a so-called TN (Twisted Nematic) type liquid crystal panel including a microlens array has been proposed. Here, as a technique for improving the contrast, a technique for arranging a retardation plate has been proposed (see Patent Document 1). On the other hand, as a technique capable of preventing deterioration of the retardation plate, an optical compensation retardation plate composed of an inorganic material including a structural birefringent material has been proposed (see Patent Document 2).

JP 2002-14345 A JP 2004-102200 A

  However, the techniques disclosed in Patent Documents 1 and 2 have a technical problem that they are insufficient to improve contrast while preventing deterioration of the retardation plate.

  The present invention has been made in view of the above-described problems, for example, and a liquid crystal device capable of displaying a high-contrast image with a relatively simple configuration, a projector including the liquid crystal device, and optical compensation of the liquid crystal device It is an object to provide a method.

(Liquid crystal device)
In order to solve the above problems, the liquid crystal device of the present invention has an alignment state between the first substrate having the first alignment film and the second substrate having the second alignment film by the first and second alignment films. A regulated twisted liquid crystal is sandwiched between the liquid crystal panel that modulates light, a pair of polarizing plates that are disposed with the liquid crystal panel interposed therebetween, and a pair of polarizing plates. The first optical axis of the first refractive index anisotropy while maintaining the axial or negative uniaxial first refractive index anisotropy is planarly viewed from the normal direction of the polarizing plate, and A first retardation plate along the first alignment direction, which is the alignment direction of the first liquid crystal molecules constituting the portion of the liquid crystal facing the one alignment film, and the pair of polarizing plates; Second light having the second refractive index anisotropy while maintaining the axial or negative uniaxial second refractive index anisotropy A second retardation plate along a second alignment direction, which is an alignment direction of second liquid crystal molecules constituting the portion of the liquid crystal that faces the second alignment film when viewed in plan from the normal direction; Is provided.

  According to the liquid crystal device of the present invention, for example, light emitted from a light source is color-separated into red light, green light, and blue light by a color separation optical system such as a reflection mirror and a dichroic mirror. The liquid crystal panel is used as a light valve that modulates red light, green light, and blue light, for example. In the liquid crystal panel, for example, the alignment state of the liquid crystal molecules of each pixel is changed according to a data signal (or image signal), and an image corresponding to the data signal is displayed on the display area via the polarizing plate. An image displayed by each liquid crystal panel is synthesized by a color synthesis optical system such as a dichroic prism, and projected onto a projection surface such as a screen as a projection image via a projection lens.

  The liquid crystal panel is formed by sandwiching “twisted liquid crystal” which is liquid crystal in which liquid crystal molecules are sealed in a twisted state between a pair of substrates. In addition, each of the pair of substrates is provided with a first alignment film and a second alignment film. Here, the “twisted liquid crystal” according to the present invention means that the liquid crystal molecules whose alignment (or alignment state) is regulated by the alignment film is larger or smaller in the direction parallel to the substrate surface between the pair of substrates. Means liquid crystal. Typically, the major axis direction of the first liquid crystal molecules whose orientation is regulated by the first alignment film and the major axis direction of the second liquid crystal molecules whose orientation is regulated by the second orientation film are 90 degrees. For example, a twisted nematic (TN) liquid crystal that is twisted only can be cited. Alternatively, a super twisted nematic liquid crystal (STN liquid crystal) or a DSTN liquid crystal in which the major axis direction of the first liquid crystal molecule and the major axis direction of the second liquid crystal molecule are twisted by 270 degrees can be given. Typically, in this twisted liquid crystal, the first liquid crystal molecules that are in contact with the first alignment film among the liquid crystal molecules constituting the liquid crystal are regulated in a certain direction by the first alignment film. The second liquid crystal molecules in contact with the second alignment film among the liquid crystal molecules constituting the liquid crystal are regulated in a certain direction by the second alignment film.

  The liquid crystal molecules maintain the position along the plane direction of the substrate of the liquid crystal panel when no voltage is applied to the liquid crystal panel, and approach the normal direction of the substrate of the liquid crystal panel when a voltage is applied to the liquid crystal panel. To tilt. Thereby, a normally white liquid crystal or a normally black liquid crystal can be easily realized. The liquid crystal panel, the first retardation plate, and the second retardation plate are disposed so as to be sandwiched between a pair of polarizing plates.

  In particular, according to the liquid crystal device of the present invention, the first retardation plate retains negative biaxial or negative uniaxial first refractive index anisotropy and is planar from the normal direction of the polarizing plate. As can be seen, the first optical axis of the first refractive index anisotropy is along the first alignment direction of the first liquid crystal molecules whose alignment is regulated by the first alignment film. As a result, the first liquid crystal molecules in which the first refractive index anisotropy of the first retardation plate is aligned by the first alignment film, in other words, the first liquid crystal existing in the vicinity of the interface with the first alignment film. It is possible to compensate for the optical anisotropy of the molecules toward optical isotropy.

  On the other hand, the second retardation plate retains negative biaxial or negative uniaxial second refractive index anisotropy, and the second refraction when viewed in a plane from the normal direction of the polarizing plate. The second optical axis having a rate anisotropy is along the second alignment direction of the second liquid crystal molecules whose alignment is regulated by the second alignment film. Thereby, the second refractive index anisotropy of the second retardation plate is the second liquid crystal molecule whose alignment is regulated by the second alignment film, in other words, the second liquid crystal existing in the vicinity of the interface with the second alignment film. It is possible to compensate for the optical anisotropy of the molecules toward optical isotropy.

  In general, the major axis direction of the liquid crystal molecules near the interface between the liquid crystal and the first alignment film and the liquid crystal molecules near the interface between the liquid crystal and the second alignment film are orthogonal to the optical axis of the incident light. Or, it remains in an inclined orientation state. Since there are liquid crystal molecules tilted with respect to the optical axis of the incident light in this way, if the first retardation plate and the second retardation plate are not provided, linearly polarized light is parallel to the optical axis of the incident light. When light is incident, a phase difference occurs near the interface due to the birefringence of liquid crystal molecules, and as a result, the light is emitted as elliptically polarized light. Therefore, a residual phase difference is produced during black display, and since the elliptical shape is different when observed from an oblique direction, it has a viewing angle dependent phase difference. This phase difference causes light leakage in black display, and reduces the contrast ratio of the liquid crystal panel.

  On the other hand, according to the liquid crystal device of the present invention, as described above, the first retardation plate retains negative biaxial or negative uniaxial first refractive index anisotropy and polarization. When viewed in plan from the normal direction of the plate, the first optical axis of the first refractive index anisotropy is along the first alignment direction of the first liquid crystal molecules whose alignment is regulated by the first alignment film. As a result, when viewed in a plan view from the normal direction of the polarizing plate, the first biaxial or negative uniaxial optical axis extending direction of the first refractive index anisotropy of the first retardation plate, and the first The positional relationship with the first alignment direction of the first liquid crystal molecules whose alignment is regulated by the alignment film can be made closer to parallel. In other words, when viewed planarly from the normal direction of the polarizing plate, the long axis direction of the first refractive index anisotropy of the first retardation plate and the long axis of the liquid crystal molecules aligned by the first alignment film The angle formed with the direction can be close to 90 degrees.

  Therefore, the first liquid crystal molecules in which the first refractive index anisotropy of the first retardation plate is aligned by the first alignment film, in other words, the first liquid crystal molecules existing in the vicinity of the interface with the first alignment film. The optical anisotropy can be compensated so as to be directed toward optical isotropy.

  On the other hand, as described above, the second retardation plate retains the uniaxial second refractive index anisotropy, and the second refractive index anisotropic when seen in a plane from the normal direction of the polarizing plate. The second optical axis has a second alignment direction of the second liquid crystal molecules whose alignment is regulated by the second alignment film. Accordingly, when viewed in plan from the normal direction of the polarizing plate, the second biaxial or negative uniaxial optical axis extending direction in the second refractive index anisotropy of the second retardation plate is The positional relationship with the second alignment direction of the second liquid crystal molecules whose alignment is regulated by the alignment film can be made closer to parallel. In other words, the major axis direction of the negative biaxial or negative uniaxial second refractive index anisotropy of the second retardation plate and the second alignment film as viewed in plan from the normal direction of the polarizing plate The angle formed by the major axis direction of the liquid crystal molecules aligned by can be brought close to 90 degrees. Therefore, the second liquid crystal molecules in which the second refractive index anisotropy of the second retardation plate is aligned by the second alignment film, in other words, the second liquid crystal molecules existing in the vicinity of the interface with the second alignment film. The optical anisotropy can be compensated so as to be directed toward optical isotropy.

  As a result, the major axis direction of the first liquid crystal molecules in the vicinity of the interface between the liquid crystal and the first alignment film is aligned perpendicular to the optical axis of the incident light, or an alignment state slightly inclined from the orthogonal alignment state. Even in such a case, the phase difference caused by the birefringence of the first liquid crystal molecules can be optically compensated by the first retardation plate. In addition, the major axis direction of the second liquid crystal molecules in the vicinity of the interface between the liquid crystal and the second alignment film is perpendicular to the optical axis of the incident light, or is slightly inclined from the perpendicular orientation state. Even in such a case, the phase difference caused by the birefringence of the second liquid crystal molecules can be optically compensated by the second retardation plate.

  As a result of the above, in the TN liquid crystal device, the first retardation plate cancels the phase difference (in other words, the birefringence effect) generated in the first liquid crystal molecules in the vicinity of the interface between the liquid crystal and the first alignment film (that is, Compensation). In addition, the phase difference generated in the second liquid crystal molecules in the vicinity of the interface between the liquid crystal and the second alignment film can be canceled by the second retardation plate. As a result, during the operation of the liquid crystal device, the phase difference of the light generated by the light emitted from the light source passing through the vicinity of the interface of the liquid crystal composed of the aligned first and second liquid crystal molecules is determined. Compensation can be performed by the first retardation plate and the second retardation plate, respectively. Therefore, it is possible to prevent the light that has passed through the liquid crystal panel from entering the output-side polarizing plate in a phase-shifted state. As a result, for example, in the polarizing plate on the output side, the possibility that light that should not be allowed to leak is reduced, and it is possible to prevent a decrease in contrast and a reduction in viewing angle.

  In one aspect of the liquid crystal device of the present invention, at least one of the first retardation plate and the second retardation plate includes an inorganic material.

  According to this aspect, for example, an inorganic material such as Ta2O5 can effectively prevent the first and second retardation plates from being deteriorated due to light irradiation and accompanying temperature rise, and a liquid crystal device having excellent reliability can be obtained. Can be configured.

  In another aspect of the liquid crystal device of the present invention, when the polarity of the refractive index anisotropy of the first liquid crystal molecule is one of positive and negative, the polarity of the first refractive index anisotropy is the positive and negative. In addition to or instead of being the other, when the polarity of the refractive index anisotropy of the second liquid crystal molecule is one of positive and negative, the polarity of the second refractive index anisotropy is the positive and negative The other.

  According to this aspect, the polarity of the refractive index anisotropy of the liquid crystal molecules, the polarity of the first refractive index anisotropy of the first retardation plate, and the polarity of the second refractive index anisotropy of the second retardation plate Thus, the optical anisotropy of the first and second liquid crystal molecules existing in the vicinity of the interface with the first and second alignment films is more appropriately compensated toward the optical isotropy, and a higher contrast. Higher quality display can be obtained.

  In another aspect of the liquid crystal device of the present invention, in the liquid crystal panel, the light is incident on the first alignment film side, and the light is emitted from the second alignment film side, so that the first position When the retardation film and the second retardation film are disposed on the light incident side of the liquid crystal panel, the first retardation film is closer to the first alignment film than the second retardation film. Placed in.

  According to this aspect, the first retardation plate can remarkably suppress the occurrence of retardation in the first liquid crystal molecules whose alignment is regulated by the first alignment film, and can improve the contrast.

  In another aspect of the liquid crystal device of the present invention, in the liquid crystal panel, the light is incident on the first alignment film side, and the light is emitted from the second alignment film side, so that the first position When the phase difference plate and the second phase difference plate are disposed on the light emitting side of the liquid crystal panel, the second phase difference plate is closer to the second alignment film than the first phase difference plate. Placed in.

  According to this aspect, the second retardation plate can remarkably suppress the occurrence of retardation in the second liquid crystal molecules whose alignment is regulated by the second alignment film, and can improve the contrast.

  In another aspect of the liquid crystal device of the present invention, in the liquid crystal panel, the light is incident on the first alignment film side, and the light is emitted from the second alignment film side, so that the first position When the retardation plate and the second retardation plate are disposed so as to sandwich the liquid crystal panel, the first retardation plate is disposed at a position closer to the first alignment film than the second retardation plate. In addition, the second retardation plate is disposed at a position closer to the second alignment film than the first retardation plate.

  According to this aspect, the first retardation plate can remarkably suppress the occurrence of retardation in the first liquid crystal molecules whose alignment is regulated by the first alignment film, and can improve the contrast. In addition, the second retardation plate can remarkably suppress the occurrence of retardation in the second liquid crystal molecules whose alignment is regulated by the second alignment film, thereby improving the contrast.

  In another aspect of the liquid crystal device of the present invention, when viewed in plan from the normal direction, the major axis direction of the first liquid crystal molecule and the direction of one optical axis of the first refractive index anisotropy (for example, Main refractive index nz1 ′: where nx1 ′ = ny1 ′> nz1 ′), but in addition to or in place of the major axis direction of the second liquid crystal molecules and the second refractive index anisotropy Are aligned with the direction of one optical axis (for example, main refractive index nz2 ′: nx2 ′ = ny2 ′> nz2 ′).

  According to this aspect, in the first retardation plate, typically, the optical axis having the maximum main refractive index of the first refractive index anisotropy (for example, main refractive index nx1 ′ or ny1 ′: where nx1 ′ = Ny1 ′> nz1 ′) can increase the component in the direction orthogonal to the major axis direction of the first liquid crystal molecules whose alignment is regulated by the first alignment film. In addition to or instead of this, in the second retardation plate, the optical axis having the maximum main refractive index of the second refractive index anisotropy (for example, main refractive index nx2 ′ or nz2 ′: where nx2 ′ = nz2 '> Ny2') can increase the component in the direction perpendicular to the major axis direction of the first liquid crystal molecules whose alignment is regulated by the first alignment film. As a result, the refractive index ellipsoid formed by the first retardation plate and the first liquid crystal molecules whose alignment is regulated by the first alignment film can be brought close to the refractive index sphere three-dimensionally accurately. In addition, the refractive index ellipsoid formed by the second retardation plate and the second liquid crystal molecules whose alignment is regulated by the second alignment film can be accurately approximated to the refractive index sphere in a three-dimensional manner.

  In another aspect of the liquid crystal device of the present invention, the short axis direction of the first liquid crystal molecule and the other optical axis direction of the first refractive index anisotropy when viewed in plan from the normal direction. In addition to or instead of being aligned, the minor axis direction of the second liquid crystal molecules and the direction of the other optical axis of the second refractive index anisotropy are aligned.

  According to this aspect, in the first retardation plate, typically, the optical axis (for example, the main refractive index nz1 ′: where nx1 ′ = ny1 ′ is the main refractive index having the minimum first refractive index anisotropy). > Nz1 ′) can increase the component in the direction orthogonal to the minor axis direction of the first liquid crystal molecules whose alignment is regulated by the first alignment film. In addition to or instead of this, in the second retardation plate, the optical axis having the minimum main refractive index of the second refractive index anisotropy (for example, main refractive index ny2 ′: where nx2 ′ = nz2 ′> ny2 However, the component in the direction orthogonal to the minor axis direction of the first liquid crystal molecules whose alignment is regulated by the first alignment film can be made larger. As a result, the refractive index ellipsoid formed by the first retardation plate and the first liquid crystal molecules whose alignment is regulated by the first alignment film can be brought close to the refractive index sphere three-dimensionally accurately. In addition, the refractive index ellipsoid formed by the second retardation plate and the second liquid crystal molecules whose alignment is regulated by the second alignment film can be accurately approximated to the refractive index sphere in a three-dimensional manner.

  In another aspect of the liquid crystal device of the present invention, the first refractive index anisotropy is such that when the first optical axis is the Z axis, the refractive index in the Z axis direction is smaller than the refractive index in the X axis direction, and In addition to or instead of having the magnitude relationship that the refractive index in the X-axis direction is equal to the refractive index in the Y-axis direction, the second refractive index anisotropy is based on the second optical axis as the Y-axis. In this case, the refractive index in the Y-axis direction is smaller than the refractive index in the X-axis direction, and the refractive index in the X-axis direction is equal to the refractive index in the Z-axis direction.

  According to this aspect, the first refractive index anisotropy and the second refractive index anisotropy can be accurately specified, so that the first and second alignment films appropriately correspond to the first alignment film and the second alignment film of the liquid crystal panel. The second retardation plate can be more easily incorporated into the liquid crystal device.

  In another aspect of the liquid crystal device of the present invention, the first transmission axis of the first polarizing plate located on the incident side from the liquid crystal panel of the pair of polarizing plates when viewed in plan from the normal direction, Of the pair of polarizing plates, the second transmission axis of the second polarizing plate located on the emission side from the liquid crystal panel is orthogonal to each other, and when viewed in plan from the normal direction, the direction of the first transmission axis and the The first alignment direction is parallel, and the second transmission axis direction and the second alignment direction are parallel.

According to this aspect, the first and second retardation plates can be more easily combined with the first polarizing plate, the second polarizing plate, and the first alignment film and the second alignment film of the liquid crystal panel in a liquid crystal device more easily. It can be incorporated.
(projector)
In order to solve the above-described problems, a projector according to the present invention includes the above-described liquid crystal device according to the present invention (including various aspects), a light source that emits the light, and a projection optical system that projects the modulated light. And a projector.

  According to the projector of the present invention, the light emitted from the light source is color-separated into red light, green light, and blue light by a color separation optical system such as a reflection mirror and a dichroic mirror. The liquid crystal panel described above is used as a light valve that modulates red light, green light, and blue light, for example. In the liquid crystal panel, for example, the alignment state of liquid crystal molecules of each pixel is regulated according to a data signal (or image signal), and an image corresponding to the data signal is displayed in the display area. An image displayed by each liquid crystal panel is synthesized in a projection optical system by a color synthesis optical system such as a dichroic prism, and projected onto a projection surface such as a screen as a projection image via a projection lens.

  In substantially the same manner as the above-described liquid crystal device of the present invention, in a projector having a twisted liquid crystal, a phase difference (in other words, a phase difference generated in the first liquid crystal molecules near the interface between the liquid crystal and the first alignment film by the first retardation plate For example, the birefringence effect can be canceled (ie, compensated). In addition, the phase difference generated in the second liquid crystal molecules in the vicinity of the interface between the liquid crystal and the second alignment film can be canceled by the second retardation plate. As a result, during the operation of the projector, the phase difference of the light generated by the light emitted from the light source passing through the vicinity of the interface of the liquid crystal composed of the aligned first and second liquid crystal molecules is expressed as the first phase difference. Compensation can be made by the retardation plate and the second retardation plate, respectively. Therefore, it is possible to prevent the light that has passed through the liquid crystal panel from entering the output-side polarizing plate in a phase-shifted state. As a result, for example, in the polarizing plate on the output side, the possibility that light that should not be allowed to leak is reduced, and it is possible to prevent a decrease in contrast and a reduction in viewing angle.

Note that the projector of the present invention can appropriately adopt the same aspects as the various aspects of the liquid crystal device of the present invention described above.
(Optical compensation method for liquid crystal device)
In order to solve the above problems, an optical compensation method for a liquid crystal device according to the present invention is an optical compensation method for performing optical compensation in the above-described first liquid crystal device according to the present invention (including various aspects), An optical adjustment step of rotating at least one of the first retardation plate and the second retardation plate with the normal direction of the one retardation plate as a rotation axis.

  According to the optical compensation method of the liquid crystal device of the present invention, in the step of incorporating the light source, the polarizing plate and the phase difference plate into the liquid crystal device of the present invention described above, the first phase difference plate and the second phase difference in the optical adjustment step. The phase difference plate of at least one of the plates is rotated about the normal direction of the liquid crystal panel, which is the incident direction in which light is incident, as a rotation axis. As a result, the relative positional relationship between the first optical axis of the first retardation plate and the major axis direction of the first liquid crystal molecules can be adjusted with high accuracy, and higher contrast can be realized. In addition to or instead of this, the relative positional relationship between the second optical axis of the second retardation plate and the major axis direction of the second liquid crystal molecules can be adjusted with high accuracy to achieve higher contrast. is there.

  In addition to the optical adjustment step described above, the pair of polarizing plates is rotated with the normal direction of the first and second retardation plates as the rotation axis. Thereby, for example, a normally black liquid crystal or a normally white liquid crystal can be easily realized.

  In the optical compensation method of the liquid crystal device of the present invention, it is possible to appropriately adopt the same aspects as the various aspects of the liquid crystal device of the present invention described above.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

(First embodiment)
FIG. 1 is a schematic configuration diagram of a liquid crystal projector according to an embodiment of the present invention. The projector 10 is a front projection type projector that projects an image on a screen 11 provided in front. The projector 10 includes a light source 12, dichroic mirrors 13 and 14, liquid crystal light valves 15 to 17, a projection optical system 18, a cross dichroic prism 19, and a relay system 20.

  The light source 12 is composed of an ultrahigh pressure mercury lamp that supplies light including red light, green light, and blue light. The dichroic mirror 13 is configured to transmit the red light LR from the light source 12 and reflect the green light LG and the blue light LB. The dichroic mirror 14 is configured to transmit the blue light LB and reflect the green light LG among the green light LG and the blue light LB reflected by the dichroic mirror 13. As described above, the dichroic mirrors 13 and 14 constitute a color separation optical system that separates the light emitted from the light source 12 into the red light LR, the green light LG, and the blue light LB. Between the dichroic mirror 13 and the light source 12, an integrator 21 and a polarization conversion element 22 are sequentially arranged from the light source 12. The integrator 21 makes the illuminance distribution of the light emitted from the light source 12 uniform. The polarization conversion element 22 converts the light from the light source 12 into polarized light having a specific vibration direction such as s-polarized light.

  The liquid crystal light valve 15 is a transmissive liquid crystal device (electro-optical device) that modulates the red light LR transmitted through the dichroic mirror 13 and reflected by the reflection mirror 23 in accordance with an image signal. The liquid crystal light valve 15 includes a first polarizing plate 15b, a liquid crystal panel 15c, a first retardation plate 15a, a second retardation plate 15e, and a second polarizing plate 15d.

  Here, the red light LR incident on the liquid crystal light valve 15 passes through the first polarizing plate 15b and is converted into, for example, s-polarized light. The liquid crystal panel 15c converts the incident s-polarized light into p-polarized light (circularly polarized light or elliptically polarized light in the case of halftone) by modulation according to the image signal. Furthermore, the second polarizing plate 15d is a polarizing plate that blocks s-polarized light and transmits p-polarized light. Therefore, the liquid crystal light valve 15 is configured to modulate the red light LR in accordance with the image signal and to emit the modulated red light LR toward the cross dichroic prism 19.

  The liquid crystal light valve 16 modulates the green light LG reflected by the dichroic mirror 14 after being reflected by the dichroic mirror 13 in accordance with the image signal, and emits the modulated green light LG toward the cross dichroic prism 19. This is a transmissive liquid crystal device. Similarly to the liquid crystal light valve 15, the liquid crystal light valve 16 includes a first polarizing plate 16b, a liquid crystal panel 16c, a first retardation plate 16a, a second retardation plate 16e, and a second polarizing plate 16d. .

  The liquid crystal light valve 17 reflects the blue light LB reflected by the dichroic mirror 13, passes through the dichroic mirror 14 and then passes through the relay system 20 according to the image signal, and directs the modulated blue light LB to the cross dichroic prism 19. A transmissive liquid crystal device that emits light. Similarly to the liquid crystal light valves 15 and 16, the liquid crystal light valve 17 includes a first polarizing plate 17b, a liquid crystal panel 17c, a first retardation plate 17a, a second retardation plate 17e, and a second polarizing plate 17d. ing.

  The relay system 20 includes relay lenses 24a and 24b and reflection mirrors 25a and 25b. The relay lenses 24a and 24b are provided to prevent light loss due to the long optical path of the blue light LB. The relay lens 24a is disposed between the dichroic mirror 14 and the reflection mirror 25a. The relay lens 24b is disposed between the reflection mirrors 25a and 25b. The reflection mirror 25a is disposed so as to reflect the blue light LB transmitted through the dichroic mirror 14 and emitted from the relay lens 24a toward the relay lens 24b. The reflection mirror 25 b is disposed so as to reflect the blue light LB emitted from the relay lens 24 b toward the liquid crystal light valve 17.

  The cross dichroic prism 19 is a color combining optical system in which two dichroic films 19a and 19b are arranged orthogonally in an X shape. The dichroic film 19a reflects the blue light LB and transmits the green light LG. The dichroic film 19b reflects the red light LR and transmits the green light LG. Therefore, the cross dichroic prism 19 is configured to combine the red light LR, the green light LG, and the blue light LB modulated by the liquid crystal light valves 15 to 17 and emit the resultant light toward the projection optical system 18. Yes. The projection optical system 18 has a projection lens (not shown) and is configured to project the light combined by the cross dichroic prism 19 onto the screen 11.

  The liquid crystal light valves 15 and 17 for red and blue are provided with λ / 2 phase difference plates, and light incident on the cross dichroic prism 19 from these liquid crystal light valves 15 and 17 is set as s-polarized light. As the configuration without the λ / 2 retardation plate, a configuration in which the light incident on the cross dichroic prism 19 from the liquid crystal light valve 16 is p-polarized light can be employed. By making the light incident on the cross dichroic prism 19 into different types of polarized light, an optimized color synthesis optical system can be configured in consideration of the reflection characteristics of the dichroic films 19a and 19b. In general, since the dichroic films 19a and 19b are excellent in the reflection characteristics of s-polarized light, as described above, the red light LR and the blue light LB reflected by the dichroic films 19a and 19b are made s-polarized, and the dichroic films 19a and 19b are used. The transmitted green light LG may be p-polarized light.

(LCD light valve)
Next, the liquid crystal light valves (liquid crystal devices) 15 to 17 will be described.

  The liquid crystal light valves 15-17 differ only in the wavelength range of the light to be modulated, and the basic configuration is the same. Therefore, hereinafter, the liquid crystal panel 15c and the liquid crystal light valve 15 including the same will be described as an example.

  FIG. 2 is an overall configuration diagram of the liquid crystal panel according to the present embodiment (FIG. 2A) and a sectional configuration diagram along line HH ′ of FIG. 2A (FIG. 2B). . FIG. 3 is an explanatory diagram showing the configuration of the liquid crystal light valve according to the present embodiment. FIG. 4 is a diagram showing an optical axis arrangement of each component in FIG.

  As shown in FIG. 2, the liquid crystal panel 15 c includes a counter substrate 31 and a TFT array substrate 32 that are disposed so as to face each other, and are bonded to each other via a seal material 33. A liquid crystal layer 34 is sealed in a region surrounded by the counter substrate 31, the TFT array substrate 32, and the sealing material 33.

  The liquid crystal layer 34 is made of liquid crystal having dielectric anisotropy, and the liquid crystal panel 15c of this embodiment has a configuration in which liquid crystal molecules 51 are aligned between alignment films 43 and 98 as shown in FIG.

  The liquid crystal panel 15 c has a liquid crystal layer 34 sealed in a region partitioned by the TFT array substrate 32, the counter substrate 31 and the sealing material 33. In the liquid crystal panel 15c, a light shielding film 35 is formed inside the region where the sealing material 33 is formed. An inter-substrate conductive material 57 for providing electrical continuity between the TFT array substrate 32 and the counter substrate 31 is disposed at a corner on the outer peripheral side of the sealing material 33.

  A data line driving circuit 71, an external circuit mounting terminal 75, and two scanning line driving circuits 73 are formed in a region outside the formation region of the sealing material 33 in a plan view of the TFT array substrate 32. Further, a plurality of wirings 74 for connecting between the scanning line driving circuits 73 provided on both sides of the image display region are also formed in the region of the TFT array substrate 32. Instead of forming the data line driving circuit 71 and the scanning line driving circuit 73 on the TFT array substrate 32, for example, a TAB (TapeAutomatedBonding) substrate on which a driving LSI is mounted and terminals formed on the periphery of the TFT array substrate 32 The group may be electrically and mechanically connected through an anisotropic conductive film.

  The counter substrate 31 is a microlens substrate (light collecting substrate) having a plurality of microlenses arranged in a plane, as shown in FIG. The counter substrate 31 is mainly composed of a substrate 92, a resin layer 93, and a cover glass 94.

  The substrate 92 and the cover glass 94 are transparent substrates made of glass or the like, and substrates made of quartz, borosilicate glass, soda lime glass (blue plate glass), crown glass (white plate glass), or the like can also be used. A plurality of concave portions (microlenses) 95 are formed on the liquid crystal layer 34 side (the lower surface side in the drawing) of the substrate 92. The microlens 95 condenses the light incident on the substrate 92 from the side opposite to the liquid crystal layer 34 and emits it to the liquid crystal layer 34 side.

  The resin layer 93 is a layer made of a resin material filled on the microlens 95 of the substrate 92, and is formed using a resin material that can transmit light, such as an acrylic resin. The resin layer 93 is provided so as to cover one side of the substrate 92 and fill the concave interior of the microlens 95. The upper surface of the resin layer 93 is a flat surface, and a cover glass 94 is attached to the flat surface.

  A light shielding film 35, a common electrode 97, and an alignment film 98 are formed on the surface of the microlens substrate 36 on the liquid crystal layer 34 side. The light shielding film 35 is formed on the cover glass 94 in a substantially lattice shape in plan view. The microlenses 95 are located between the light shielding films 35 and are respectively disposed in regions overlapping the pixel region of the liquid crystal panel 15c (region where the pixel electrode 42 is formed) in plan view. The alignment film 98 is an alignment film that aligns liquid crystal molecules constituting the liquid crystal layer 34 substantially in parallel with the substrate surface. For example, a silicon oxide film formed with a columnar structure by vapor deposition or an alignment treatment is performed. It consists of applied polyimide film or the like.

  The alignment film 98 is disposed so that the surface on the light emission side is in contact with the liquid crystal layer 34. The surface of the alignment film 98 on the side in contact with the liquid crystal layer 34 is subjected to a rubbing treatment in order to align the alignment direction of the liquid crystal molecules existing in the light incident side region (near the interface with the alignment film 98) in the liquid crystal layer 34. ing. The rubbing process is generally performed by rubbing the surface of the alignment film 98 with a roller wound with a cloth. Hereinafter, the direction of the grooves carved by performing the rubbing process is appropriately referred to as “rubbing direction” or “alignment direction”. By subjecting the alignment film 98 to a rubbing process, a plurality of grooves are formed in the same direction on the surface of the alignment film 98. The alignment (or alignment state) of the liquid crystal molecules in the region in contact with the alignment film 98 is regulated in a certain direction along the groove formed on the surface of the alignment film 98. A specific example of the “first liquid crystal molecule” according to the present invention is constituted by liquid crystal molecules whose alignment is regulated by the alignment film 98 or liquid crystal molecules existing in the vicinity of the interface of the alignment film 98.

  The TFT array substrate 32 is mainly composed of a transparent substrate 41 made of glass or quartz, a pixel electrode 42 formed on the side surface of the liquid crystal layer 34 of the substrate 41, a TFT 44 for driving the pixel electrode, and an alignment film 43. Has been.

  The surface of the alignment film 43 on the side in contact with the liquid crystal layer 34 is aligned with the alignment film 98 described above in order to align the alignment direction of the liquid crystal molecules present in the light emission side region of the liquid crystal layer 34 (near the interface with the alignment film 43). The same rubbing treatment is applied. By subjecting the alignment film 43 to a rubbing process, a plurality of grooves are formed in the same direction on the surface of the alignment film 43. The alignment (or alignment state) of the liquid crystal molecules in the region in contact with the alignment film 43 is regulated in a certain direction along the groove formed on the surface of the alignment film 43. A specific example of the “second liquid crystal molecule” according to the present invention is constituted by liquid crystal molecules whose alignment is regulated by the alignment film 43 or liquid crystal molecules existing in the vicinity of the interface of the alignment film 43.

  The pixel electrodes 42 are substantially rectangular conductive films in a plan view made of a transparent conductive material such as ITO, for example, and are arranged in a matrix in a plan view on the substrate 41 as shown in FIG. It is formed in a region overlapping with the microlens 95.

  Although the TFT 44 is simplified in illustration, the TFT 44 is formed on the substrate 41 corresponding to each of the pixel electrodes 42, and usually an area (non-display area, overlapping with the light shielding film 35 on the counter substrate 31 side in a plan view). It is arranged in the light shielding area.

  The alignment film 43 formed so as to cover the pixel electrode 42 is an alignment film made of a silicon oxide film or the like formed by oblique vapor deposition, like the previous alignment film 98.

  The alignment films 43 and 98 are formed so that their alignment directions (alignment directions of the columnar structures) are substantially orthogonal in a plan view, and the liquid crystal molecules constituting the liquid crystal layer 34 are substantially parallel to the substrate surface. It functions to align the liquid crystal molecules and make the tilt direction of the liquid crystal molecules uniform in the substrate surface direction.

  A data line (not shown) and a scanning line (not shown) for connecting the pixel electrode 42 and the TFT 44 are formed in a region on the liquid crystal layer 34 side surface of the substrate 41 that is inside the region where the sealing material 33 is formed in plan view. ) Is formed. The data line and the scanning line are formed in a region overlapping the light shielding film 35 in plan view. A region bordered by the light shielding film 35, the TFT 44, the data line, and the scanning line is a pixel region of the liquid crystal panel 15c. A plurality of pixel areas are arranged in a matrix in plan view to form an image display area.

(Polarizing plate and first and second retardation plates)
As shown in FIG. 3, the liquid crystal light valve 15 includes the above-described liquid crystal panel 15c, a first retardation plate 15a disposed outside the counter substrate 31 of the liquid crystal panel 15c, and an outside of the first retardation plate 15a. The first polarizing plate 15b disposed on the second side, the second retardation plate 15e disposed on the outside of the TFT array substrate 32 of the liquid crystal panel 15c, and the second polarization disposed on the outside of the second retardation plate 15e. It is comprised by the board 15d.

  In the liquid crystal light valve 15 of the present embodiment, the side on which the first polarizing plate 15b is disposed (the upper side in the drawing) is the light incident side, and the side on which the second polarizing plate 15d is disposed is the light emitting side. It is.

  In the liquid crystal panel 15c, the alignment films 43 and 98 facing each other with the liquid crystal layer 34 interposed therebetween are formed by evaporating silicon oxide, for example. The film thickness is about 40 nm in all cases. The rubbing directions R2 and R1 indicated by the arrows attached to the alignment films 43 and 98 in FIG. 3 coincide with the direction in the substrate plane among the vapor deposition directions at the time of formation. The rubbing direction R2 in the alignment film 43 and the rubbing direction R1 in the alignment film 98 are orthogonal to each other.

  Then, due to the alignment regulating force of the alignment films 43 and 98, the liquid crystal molecules 51 are aligned such that the major axis direction of the liquid crystal molecules 51 is the direction along the rubbing directions R2 and R1 in the substrate surface direction.

  In each of the first polarizing plate 15b and the second polarizing plate 15d, a polarizing element 151 made of dyed PVA (polyvinyl alcohol) is sandwiched between two protective films 152 made of TAC (triacetyl cellulose). It has a three-layer structure. Specifically, as shown in FIG. 4, the first polarizing plate 15b and the second polarizing plate 15d are arranged so as to have a so-called orthogonal Nicol relationship in which the transmission axes Pr1 and Pr2 of the light are orthogonal to each other. Has been. Further, as will be described later, the transmission axis Pr1 of the first polarizing plate 15b is set to be in the same direction as the rubbing direction R1 of the alignment film 98 in the liquid crystal panel 15c. On the other hand, the transmission axis Pr2 of the second polarizing plate 15d is set to be in the same direction as the rubbing direction R2 of the alignment film 43 in the liquid crystal panel 15c. That is, the image display method in the liquid crystal light valve has a so-called normally white configuration. As will be described later, the direction of the main refractive index nz1 ′, which is the minor axis direction of the refractive index ellipsoid, is the refractive index in the plane direction of the first retardation plate 15a, and the rubbing direction R2 of the alignment film 43. And are arranged so as to be in substantially the same direction. Further, as will be described later, the direction of the main refractive index ny2 ′, which is the minor axis direction of the refractive index ellipsoid, is the rubbing of the alignment film 98 as well as the refractive index in the plane direction of the second retardation plate 15e. It arrange | positions so that it may become substantially the same direction as direction R1.

  The first retardation plate 15a is composed of a substrate (not shown) and a refractive index anisotropic medium that holds uniaxial refractive index anisotropy. In particular, the first retardation plate 15a may be configured by vapor deposition of a refractive index anisotropic medium containing an inorganic material. Or the 1st phase difference plate 15a may be comprised by the optical film containing an inorganic material.

  An average refractive index ellipsoid 81a of the first retardation plate 15a is schematically shown on the side of the first retardation plate 15a in FIG. In this figure, nx1 ′ and ny1 ′ indicate the main refractive index in the vertical plane direction of the first phase difference plate 15a, and nz1 ′ indicates the main refractive index in the horizontal plane direction of the first phase difference plate 15a. Yes. In the present embodiment, the main refractive indexes nx1 ′, ny1 ′, and nz1 ′ satisfy the relationship nx1 ′ = ny1 ′> nz1 ′. That is, the refractive index nz1 'in the horizontal plane direction is smaller than the refractive index in the other direction, and the refractive index ellipsoid 81a is a spheroid or disk. The refractive index ellipsoid 81a is disposed perpendicular to the plate surface of the first retardation plate 15a, and has a main refractive index nx1 that is one major axis direction of the refractive index ellipsoid of the first retardation plate 15a. The direction of 'is parallel to the normal direction of the plate surface. At the same time, the direction of the main refractive index ny1 ', which is the other major axis direction of the refractive index ellipsoid of the first retardation plate 15a, is orthogonal to the normal direction of the plate surface. In particular, the refractive index in the plane direction of the plate surface of the first retardation plate 15a and the main refractive index nz1 'which is the minor axis direction of the refractive index ellipsoid are parallel to the rubbing direction R1.

  The second retardation plate 15e is composed of a substrate (not shown) and a refractive index anisotropic medium that holds uniaxial refractive index anisotropy. In particular, the second retardation plate 15e may be configured by vapor deposition of a refractive index anisotropic medium containing an inorganic material. Or the 2nd phase difference plate 15e may be comprised by the optical film containing an inorganic material.

  An average refractive index ellipsoid 81e of the second retardation plate 15e is schematically shown on the side of the second retardation plate 15e in FIG. In this figure, nx2 ′ and nz2 ′ indicate the main refractive index in the vertical plane direction of the second phase difference plate 15e, and ny2 ′ indicates the main refractive index in the horizontal plane direction of the second phase difference plate 15e. Yes. In the present embodiment, the main refractive indexes nx2 ', ny2', and nz2 'are configured to satisfy the relationship of nx2' = nz2 '> ny2'. That is, the refractive index ny2 'in the horizontal plane direction is smaller than the refractive index in the other direction, and the refractive index ellipsoid 81e is a spheroid or disk. The refractive index ellipsoid 81e is oriented perpendicular to the plate surface of the second retardation plate 15e, and has a main refractive index nx2 that is one major axis direction of the refractive index ellipsoid of the second retardation plate 15e. The direction of 'is parallel to the normal direction of the plate surface. At the same time, the direction of the main refractive index nz2 'which is the other major axis direction of the refractive index ellipsoid of the second retardation plate 15e is orthogonal to the normal direction of the plate surface. In particular, the refractive index in the plane direction of the plate surface of the second retardation plate 15e and the main refractive index ny2 'that is the minor axis direction of the refractive index ellipsoid are parallel to the rubbing direction R2.

  Typically, a C plate using a discotic liquid crystal may be used as the first retardation plate 15a and the second retardation plate 15e. Alternatively, an optical film using an unstretched cellulose ester film (for example, unstretched triacetyl cellulose (TAC), unstretched cellulose acetate propionate (CAP), etc.), a biaxially stretched norbornene resin, or the like is used. It's okay.

  In particular, the first retardation plate 15a and the second retardation plate 15e typically have a refractive index anisotropic medium having a relatively high refractive index and a refractive index anisotropic having a relatively low refractive index. Alternatively, a C plate configured by alternately arranging a conductive medium in the horizontal direction of the plate surface may be employed. By changing the thickness and angle of the refractive index anisotropic medium arranged in this way, it is possible to realize changes in the characteristics of light such as changes in the direction of travel of light, changes in polarization state, changes in frequency and phase, etc. it can.

  In this embodiment, typically, a uniaxial refractive index ellipsoid will be described as a specific example of the first retardation plate and the second retardation plate, but a biaxial refractive index ellipsoid is used. However, it should be noted that if there is a component orthogonal to the major axis direction of the liquid crystal molecules, a corresponding optical compensation effect can be obtained according to the size of the orthogonal component.

(Detailed configuration of the first and second retardation plates)
Here, in addition to FIGS. 5 to 7, the detailed configuration of the first and second phase difference plates according to the present embodiment will be described with reference to FIG. 4 as appropriate. FIG. 5 conceptually shows the positional relationship between the liquid crystal molecules, the first retardation plate 15 and the second retardation plate in the normal state where no voltage is applied to the liquid crystal according to the present embodiment. It is the one schematic diagram shown. FIG. 6 conceptually shows the major axis direction of the aligned liquid crystal molecules and the direction of the main refractive index that is the major axis direction of the refractive index ellipsoid formed by the first retardation plate according to the present embodiment. Fig. 6 is a schematic diagram (Fig. 6 (a) to Fig. 6 (c)). FIG. 7 is another schematic diagram conceptually showing another positional relationship between the liquid crystal molecules, the first retardation plate 15, and the second retardation plate according to the present embodiment.

  As shown in FIG. 4 described above, the transmission axis Pr1 of the first polarizing plate 15b and the transmission axis Pr2 of the second polarizing plate 15d are arranged orthogonally. The direction of the transmission axis Pr1 of the polarizing plate 15b is parallel to the rubbing direction (evaporation direction) R1 of the alignment film 98 of the liquid crystal panel 15c in plan view. In addition, as described above, the refractive index in the plane direction of the plate surface of the first retardation plate 15a and the main refractive index nz1 ′ that is the minor axis direction of the refractive index ellipsoid are parallel to the rubbing direction R1. ing. On the other hand, the direction of the transmission axis Pr2 of the polarizing plate 15d is parallel to the rubbing direction (evaporation direction) R2 of the alignment film 43 of the liquid crystal panel 15c in plan view. In addition, as described above, the refractive index in the plane direction of the plate surface of the second retardation plate 15e and the main refractive index ny2 ′ that is the minor axis direction of the refractive index ellipsoid are parallel to the rubbing direction R2. ing.

  FIG. 5 shows an alignment state of liquid crystal molecules in a normal state where no voltage is applied to the liquid crystal layer. In FIG. 5, a straight line parallel to the optical axis of the incident light is taken as the x-axis, and two straight lines in a plane orthogonal to the x-axis are taken as the y and z axes. The light incident surface and light exit surface of the liquid crystal layer 34 are parallel to the yz plane. Nematic liquid crystal composed of a plurality of rod-like liquid crystal molecules 51 is sealed in the liquid crystal layer 34. Each liquid crystal molecule 51 is aligned such that its major axis direction is orthogonal to the optical axis of incident light. That is, the major axis direction of each liquid crystal molecule 51 is aligned parallel to the light incident surface and the light emitting surface. The rubbing direction R1 of the alignment film 98 and the rubbing direction R2 of the alignment film 43 are set to be orthogonal to each other. In the example of FIG. 5, the rubbing direction R1 of the alignment film 98 is the z-axis direction, and the rubbing direction R2 of the alignment film 43 is the y-axis direction.

  In the liquid crystal layer 34, the liquid crystal molecules present near the interface with the alignment film 98 are aligned in the same direction as the rubbing direction R <b> 1 of the alignment film 98 by the action of rubbing treatment performed on the surface of the alignment film 98. In substantially the same manner, the liquid crystal molecules existing near the interface with the alignment film 43 are aligned in substantially the same direction as the rubbing direction R 2 of the alignment film 43. Since the rubbing directions R1 and R2 are orthogonal to each other, the liquid crystal molecules 51 move in the major axis direction of the liquid crystal molecules from the alignment film 98 toward the alignment film 43, that is, from the light incident side to the light emission side. The orientation is regulated or oriented so as to be twisted by 90 °. The nematic liquid crystal aligned with the liquid crystal molecules twisted in this way is called a TN liquid crystal. When light enters the TN liquid crystal in a normal state where no voltage is applied, the optical rotation occurs due to the twist of the liquid crystal, and the vibration direction of the light is rotated by 90 ° along the twist direction of the liquid crystal. On the other hand, when a voltage is applied to the liquid crystal layer 34, the liquid crystal molecules 51 stand up, that is, the major axis of the liquid crystal molecules is parallel to the optical axis of incident light (perpendicular to the light incident surface). Thus, the alignment state of the liquid crystal molecules 51 changes. Here, ideally, it is desirable that the orientation state changes so that all the liquid crystal molecules 51 in the liquid crystal layer 34 are parallel to the optical axis of the incident light in a state where a voltage is applied. In such an alignment state, light incident in parallel to the optical axis of incident light can be transmitted while the vibration direction is constant. However, in actuality, the liquid crystal molecules 51 change their alignment state so that the molecular long axis gradually rises from the alignment films 98 and 43 toward the central region of the liquid crystal layer 34 in the energized state.

  In particular, in the present embodiment, as described above, the main refractive index nz1 ′ that is the minor axis direction of the refractive index ellipsoid and the refractive index in the plate surface plane direction of the first retardation plate 15a is in the rubbing direction R1. It is parallel. In other words, the main refractive index ny1 ′ that is the major axis direction of the refractive index ellipsoid is orthogonal to the rubbing direction R1, and the main refractive index nx1 ′ that is the major axis direction of the refractive index ellipsoid is orthogonal to the rubbing direction R1. To do.

  In addition, in the present embodiment, as described above, the refractive index in the plate surface plane direction of the second retardation plate 15e and the main refractive index ny2 ′ that is the minor axis direction of the refractive index ellipsoid are expressed in the rubbing direction. It is parallel to R2. In other words, the main refractive index nz2 ′ that is the major axis direction of the refractive index ellipsoid is orthogonal to the rubbing direction R2, and the main refractive index nx2 ′ that is the major axis direction of the refractive index ellipsoid is orthogonal to the rubbing direction R2. To do.

  The refractive index in the first retardation plate can be uniquely defined by the above-described main refractive indexes nx1 ', ny1', nz1 'and the material of the refractive index anisotropic medium. In substantially the same manner, the refractive index in the second retardation plate can be uniquely defined by the main refractive indexes nx2 ', ny2', nz2 'and the material of the refractive index anisotropic medium.

  Thereby, the liquid crystal molecules in which the direction in which the optical axes of the main refractive indexes ny1 ′ and nx1 ′, which are the major axis directions of the refractive index ellipsoid of the first retardation plate 15a, extend are aligned along the rubbing direction R1 of the alignment film 98. Since the optical axis of the main refractive index ny1 ′ and nx1 ′ of the first retardation plate 15a is orthogonal to the major axis direction of the liquid crystal layer 51, the optical axis of the liquid crystal molecules 51 existing in the vicinity of the interface between the liquid crystal layer and the alignment film 98 is obtained. Compensates for anisotropy towards optical isotropy.

  In addition, the direction in which the optical axes of the main refractive indexes nz2 ′ and nx2 ′, which are the major axis directions of the refractive index ellipsoid of the second retardation plate 15e, are aligned along the rubbing direction R2 of the alignment film 43 is aligned. Since the optical axes of the main refractive indexes nz2 ′ and nx2 ′ of the second retardation plate 15e are orthogonal to the major axis direction of the liquid crystal layer 51, the optical axes of the liquid crystal molecules 51 existing in the vicinity of the interface between the liquid crystal layer and the alignment film 43 are used. Compensates for anisotropy towards optical isotropy.

  More specifically, as shown in FIG. 6A and FIG. 6B, it is formed by the major axis direction of the liquid crystal molecules 51 aligned along the rubbing direction R1 and the first retardation plate 15a. The directions of the main refractive indexes ny1 ′ and nx1 ′, which are the major axis directions of the refractive index ellipsoid, are orthogonal to each other. Accordingly, as shown in FIG. 6C, the refractive index ellipsoid formed by the liquid crystal molecules 51 aligned along the rubbing direction R1 of the alignment film 98 and the first retardation plate 15a is three-dimensionally displayed. Can be close to the refractive index sphere.

  In substantially the same manner, the main refractive indexes nz2 ′ and nx2 ′ that are the major axis direction of the liquid crystal molecules 51 aligned along the rubbing direction R2 and the major axis direction of the refractive index ellipsoid formed by the second retardation plate 15e. And are orthogonal. Thereby, the refractive index ellipsoid formed by the liquid crystal molecules 51 aligned along the rubbing direction R2 of the alignment film 43 and the second retardation plate 15e can be brought close to the refractive index sphere three-dimensionally.

  As a result, the major axis direction of the liquid crystal molecules 51 in the vicinity of the interface between the liquid crystal layer 34 and the alignment film 98 is not parallel to the optical axis of the incident light, but is slightly inclined from the orthogonal alignment state or the orthogonal alignment state. Even in the aligned state, the phase difference caused by the birefringence of the liquid crystal molecules 51 can be optically compensated by the first retardation plate 15a. In addition, the major axis direction of the liquid crystal molecules 51 in the vicinity of the interface between the liquid crystal layer 34 and the alignment film 43 is not parallel to the optical axis of the incident light, but is slightly inclined from the orthogonal alignment state or the orthogonal alignment state. Even in the aligned state, the phase difference caused by the birefringence of the liquid crystal molecules 51 can be optically compensated by the second retardation plate 15e. Note that this optical compensation is performed in substantially the same manner in a normal state in which no voltage is applied to the liquid crystal layer and in an energized state in which a voltage is applied to the liquid crystal layer.

  In general, the liquid crystal molecules 51 in the vicinity of the interface between the liquid crystal layer 34 and the alignment film 98 have their long axes in a normal state where no voltage is applied to the liquid crystal layer and an energized state where a voltage is applied to the liquid crystal layer. The direction is not parallel to the optical axis of the incident light, but remains orthogonal or inclined. As described above, since the liquid crystal molecules 51 are tilted with respect to the optical axis of the incident light, if the first retardation plate 15a and the second retardation plate 15e are not provided, the light of the incident light in the energized state. When linearly polarized light is incident parallel to the axis, a phase difference occurs near the interface due to the birefringence of the liquid crystal molecules 51, and as a result, the light is emitted as elliptically polarized light. Therefore, a residual phase difference is produced during black display, and since the elliptical shape is different when observed from an oblique direction, it has a viewing angle dependent phase difference. This phase difference causes light leakage in black display, and reduces the contrast ratio of the liquid crystal panel.

  On the other hand, according to the present embodiment, the direction in which the optical axes of the main refractive indexes ny1 ′ and nx1 ′ that are the major axis directions of the refractive index ellipsoid of the first retardation plate 15a extend is the rubbing of the alignment film 98. Since it is orthogonal to the major axis direction of the liquid crystal molecules 51 aligned along the direction R1, the optical axes of the main refractive indexes ny1 ′ and nx1 ′ of the first retardation plate 15a are near the interface between the liquid crystal layer and the alignment film 98. The optical anisotropy of the existing liquid crystal molecules 51 is compensated so as to be toward optical isotropy. In addition, the direction in which the optical axes of the main refractive indexes nz2 ′ and nx2 ′, which are the major axis directions of the refractive index ellipsoid of the second retardation plate 15e, are aligned along the rubbing direction R2 of the alignment film 43 is aligned. Since the optical axes of the main refractive indexes nz2 ′ and nx2 ′ of the second retardation plate 15e are orthogonal to the major axis direction of the liquid crystal layer 51, the optical axes of the liquid crystal molecules 51 existing in the vicinity of the interface between the liquid crystal layer and the alignment film 43 are used. Compensates for anisotropy towards optical isotropy.

  As a result, even when the major axis direction of the liquid crystal molecules 51 in the vicinity of the interface between the liquid crystal layer 34 and the alignment film 98 is not parallel to the optical axis of the incident light but is in an orthogonal or inclined alignment state, The phase difference caused by the birefringence of the liquid crystal molecules 51 can be optically compensated by the first retardation plate 15a. In addition, even when the major axis direction of the liquid crystal molecules 51 in the vicinity of the interface between the liquid crystal layer 34 and the alignment film 43 is not parallel to the optical axis of incident light but is in an orthogonal or inclined alignment state, The phase difference caused by the birefringence of the liquid crystal molecules 51 can be optically compensated by the second retardation plate 15e.

  As a result, the phase difference (in other words, the birefringence effect) generated in the liquid crystal by the first phase difference plate 15a and the second phase difference plate 15e can be canceled (that is, compensated). As a result, during the operation of the projector, the phase difference of the light generated when the light emitted from the light source passes near the interface of the liquid crystal composed of the aligned liquid crystal molecules is expressed as the first retardation plate 15a and This can be compensated by the second retardation plate 15e. Therefore, it is possible to prevent the light that has passed through the liquid crystal panel from entering the output-side polarizing plate in a phase-shifted state. As a result, for example, in the polarizing plate on the output side, the possibility that light that should not be allowed to leak is reduced, and it is possible to prevent a decrease in contrast and a reduction in viewing angle.

  In particular, the positional relationship among the first retardation plate 15a, the second retardation plate 15e, the alignment film 98 of the liquid crystal panel 15c, and the alignment film 43 of the liquid crystal panel 15c depends on the liquid crystal molecules to be optically compensated. It is preferable to make them close to each other in terms of remarkably suppressing the occurrence of a phase difference. In other words, the above-described first retardation plate 15a and the alignment film 98 of the liquid crystal panel 15c are brought close to each other, and the above-described second retardation plate 15e and the alignment film 43 of the liquid crystal panel 15c are brought close to each other. The second retardation plate 15e shown in FIG. 5 and the alignment film 98 of the liquid crystal panel 15c are brought close to each other, and the retardation is compared with the case where the first retardation plate 15a and the alignment film 43 of the liquid crystal panel 15c are brought close to each other. Can be remarkably suppressed. A quantitative analysis of this effect will be described later. FIG. 7 shows that the optical compensation according to the present embodiment is performed in the energized state where a voltage is applied to the liquid crystal layer as described above.

  In particular, the use of an inorganic material such as Ta2O5 as the refractive index anisotropic medium constituting the first phase difference plate 15a and the second phase difference plate 15e is caused by light irradiation and the accompanying temperature increase. The retardation plate 15a and the second retardation plate 15e can be effectively prevented from deteriorating, and a projector having excellent reliability can be configured.

(Quantitative analysis of contrast improvement due to arrangement of first and second retardation plates)
Next, with reference to FIG. 8, a quantitative analysis of the improvement in contrast caused by the arrangement of the first and second retardation plates according to the present embodiment will be described. FIG. 8 is a graph quantitatively showing the correlation between the arrangement of the first and second phase difference plates according to the present embodiment and the light contrast. The horizontal axis in FIG. 8 indicates the type of arrangement of the first retardation plate and the second retardation plate, and the vertical axis indicates the magnitude of contrast.

  As shown in FIG. 8, the second phase difference plate 15e and the alignment film 98 of the liquid crystal panel 15c are brought close to each other, and the first phase difference plate 15a and the alignment film 43 of the liquid crystal panel 15c are made close to each other. In the case of a certain positional relationship B, the contrast is approximately level “3.0”.

  On the other hand, the first retardation plate 15a and the alignment film 98 of the liquid crystal panel 15c are brought close to each other, and the second retardation plate 15e and the alignment film 43 of the liquid crystal panel 15c are brought close to each other. In the case of A, the contrast is approximately the level “4.0”.

  As described above, the positional relationship among the first phase difference plate 15a, the second phase difference plate 15e, the alignment film 98 of the liquid crystal panel 15c, and the alignment film 43 of the liquid crystal panel 15c is a liquid crystal to be optically compensated. Making it closer to the molecule can remarkably suppress the occurrence of a phase difference and realize a higher contrast.

(Arrangement of the first to second retardation plates)
Next, with reference to FIG. 9 and FIG. 10, the arrangement of the first and second retardation plates according to the present embodiment will be described. FIG. 9 is a schematic diagram (FIGS. 9A to 9D) showing the arrangement of the constituent members in the liquid crystal light valve 15 according to the present embodiment. FIG. 10 shows one and other graphs (FIGS. 10A and 10B) quantitatively showing the correlation between the arrangement of the first and second retardation plates according to the present embodiment and the contrast of light. )). 10A and 10B, the horizontal axis indicates the type of arrangement of the first phase difference plate and the second phase difference plate, and the vertical axis indicates the magnitude of contrast.

(Incident side retardation plate)
As shown in FIG. 9A, the first retardation plate 15a and the second retardation plate 15e are arranged on the side where the light is incident on the liquid crystal panel 15c, and the first retardation plate 15a is in the second position. Compared to the phase difference plate 15e, it may be arranged at a position far from the alignment film 98. Alternatively, as shown in FIG. 9B, a first retardation plate 15a and a second retardation plate 15e are arranged on the side where light enters the liquid crystal panel 15c, and the first retardation plate 15a You may arrange | position in the position close | similar to the alignment film 98 compared with the two phase difference plate 15e.

  In these cases, in the case of the positional relationship D in which the first retardation plate 15a is arranged at a position far from the alignment film 98 as compared with the second retardation plate 15e, the positional relationship D in FIG. Thus, the contrast is approximately level “3.0”.

  On the other hand, in the case of the positional relationship C in which the first retardation plate 15a is disposed closer to the alignment film 98 than the second retardation plate 15e, the positional relationship C in FIG. As shown, the contrast is approximately level “4.0”.

  As described above, when the first retardation plate 15a and the second retardation plate 15e are arranged on the side where the light is incident on the liquid crystal panel 15c, the first retardation plate 15a is a target for optical compensation. By bringing the liquid crystal molecules close to the alignment film 98 of the liquid crystal panel 15c, the occurrence of the phase difference can be remarkably suppressed and higher contrast can be realized.

(Output side retardation plate)
As shown in FIG. 9C, a first retardation plate 15a and a second retardation plate 15e are arranged on the side from which light is emitted from the liquid crystal panel 15c, and the second retardation plate 15e has a first position. Compared to the phase difference plate 15 a, it may be arranged at a position far from the alignment film 43. Alternatively, as shown in FIG. 9D, a first retardation plate 15a and a second retardation plate 15e are arranged on the side from which light is emitted from the liquid crystal panel 15c, and the second retardation plate 15e You may arrange | position in the position close | similar to the alignment film 43 compared with the 1 phase difference plate 15a.

  In these cases, the second phase difference plate 15e is compared with the first phase difference plate 15a, and in the case of the positional relationship F arranged at a position far from the alignment film 43, the positional relationship F shown in FIG. Thus, the contrast is approximately level “3.0”.

  On the other hand, in the case of the positional relationship E in which the second retardation plate 15e is disposed closer to the alignment film 43 than the first retardation plate 15a, the positional relationship E in FIG. As shown, the contrast is approximately level “4.0”.

  Thus, when the 1st phase difference plate 15a and the 2nd phase difference plate 15e are arrange | positioned at the side from which light is radiate | emitted from the liquid crystal panel 15c, the 2nd phase difference plate 15e becomes an object which performs optical compensation. By bringing the liquid crystal molecules close to the alignment film 43 of the liquid crystal panel 15c, the occurrence of the phase difference can be remarkably suppressed and higher contrast can be realized.

  In the projector according to the present invention, any of the six types shown in FIGS. 4, 7, and 9A to 9D may be adopted.

  If the form of Fig.9 (a) and FIG.9 (b) is employ | adopted, since the 1st phase difference plate 15a and the 2nd phase difference plate 15e are arrange | positioned at the light-incidence side of the liquid crystal panel 15c, it is from a light source. After adjusting the phase difference appropriately for the light, the light can be incident on the liquid crystal panel 15c.

  On the other hand, if the configuration shown in FIGS. 9C and 9D is adopted, the first retardation plate 15a and the second retardation plate 15e are arranged on the light emission side of the liquid crystal panel 15c, so that the liquid crystal Compensation can be performed for the entire light transmitted through the panel 15c, and a better optical compensation effect can be obtained. In addition, since the first retardation plate 15a and the second retardation plate 15e are arranged on the light emission side of the liquid crystal panel 15c, the first retardation plate 15a and the second retardation plate 15e are kept away from the light source. Therefore, it is possible to effectively prevent the first retardation plate 15a and the second retardation plate 15e from being deteriorated due to light irradiation and the accompanying temperature rise, and the projector has excellent reliability.

(Optical adjustment by rotation of the first and second retardation plates)
Next, with reference to FIG. 4 described above, optical adjustment by rotation with the substrate normal in the first and second retardation plates as the rotation axis will be described.

  As shown in FIG. 4, the optical adjustment of the liquid crystal light valve 15 in the projector according to the present embodiment is performed by the first retardation plate provided so as to be movable around an axis whose rotation axis is the substrate normal line of the liquid crystal panel 15 c. In addition to or instead of the first optical adjustment step for adjusting the rotation angle of 15a, the rotation angle of the second retardation plate 15e provided so as to be movable around an axis whose rotation axis is the substrate normal of the liquid crystal panel 15c. The second optical adjustment step can be performed.

  In the first optical adjustment step, as shown in FIG. 4 described above, the rotation axis of the first retardation plate 15a disposed opposite to the liquid crystal panel 15c is the rotation axis of the first retardation plate 15a (and the liquid crystal panel 15c). Set the direction along the normal direction. The major axis of the refractive index ellipsoid formed by the first retardation plate 15a described above is obtained by adjusting the rotation angle θa by rotating the first retardation plate 15a about the rotation axis. The angle between the direction of the optical axis of the main refractive index ny1 ′ which is the direction and the major axis direction of the liquid crystal molecules 51 aligned along the rubbing direction R1 of the alignment film 98 is adjusted with high accuracy. In addition to or instead of this, for the second retardation plate 15e disposed opposite to the liquid crystal panel 15c, the rotation axis is a direction along the normal direction of the second retardation plate 15e (and the liquid crystal panel 15c). Set to. The main refraction in the major axis direction of the refractive index ellipsoid of the second retardation plate 15e described above is obtained by adjusting the rotation angle θe by rotating the second retardation plate 15e around an axis having the rotation axis as a center. The angle between the direction in which the optical axis of the rate nz2 ′ extends and the major axis direction of the liquid crystal molecules 51 aligned along the rubbing direction R2 of the alignment film 43 is adjusted with high accuracy.

  Specifically, the above-described contrast measurement method is performed in the following order. First, a liquid crystal panel is placed, a voltage of 5V is applied, and the projection screen is all displayed in black. Secondly, the first polarizing plate 15b disposed on the incident side of the liquid crystal panel is rotated to adjust the illuminance when displaying all black. Third, the contrast of the liquid crystal panel is measured. Fourth, from this state, when the first retardation plate 15a and the second retardation plate 15e described above are arranged and rotated at the arrangement positions shown in FIG. Adjust so that the illuminance is minimized. Fifth, the contrast of the liquid crystal panel in this state is measured. Sixth, in substantially the same manner, the first retardation plate 15a and the second retardation plate 15e are adapted to the various arrangement positions shown in FIGS. 7 and 9A to 9D described above. Then, the first to fifth processes are repeated.

  As a result, the optical anisotropy of the liquid crystal molecules 51 can be compensated with higher accuracy by adjusting more parameters such as the rotation angles θa and θe.

  In addition, as a specific example of the 1st phase difference plate 15a and the 2nd phase difference plate 15e which concern on this embodiment, it can produce also by extending | stretching a polycarbonate, norbornene resin, etc. by applying shear stress. In this case, the material resin is stretched from two directions while being heated to near the glass transition point, and is sandwiched between a pair of heated substrates. Then, while applying pressure to the material resin from the outside of one substrate, the pair of substrates are shifted in opposite directions. Thereby, shear stress is applied to the upper and lower surfaces of the material resin in opposite directions, and the optical axis direction of the optical body constituting the material resin is inclined obliquely. The tilt angle of the optical axis can be controlled by the magnitude of the shear stress.

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. The optical compensation method of the liquid crystal device is also included in the technical scope of the present invention.

1 is a schematic configuration diagram of a liquid crystal projector according to an embodiment of the present invention. FIG. 2 is an overall configuration diagram (FIG. 2A) of a liquid crystal panel according to the present embodiment and a sectional configuration diagram (FIG. 2B) along line H-H ′ in FIG. 2A. It is explanatory drawing which shows the structure of the liquid crystal light valve which concerns on this embodiment. It is a figure which shows the optical axis arrangement | positioning of each structural member in FIG. 3 which concerns on this embodiment. 1 is a schematic diagram conceptually showing one positional relationship between liquid crystal molecules, a first retardation plate, and a second retardation plate in a normal state where no voltage is applied to the liquid crystal according to the present embodiment. It is. The schematic diagram which showed notionally the major axis direction of the liquid crystal molecule based on this embodiment, and the direction of the main refractive index which is the major axis direction of the refractive index ellipsoid formed by the 1st phase difference plate ( FIG. 6 (a) to FIG. 6 (c)). It is the other schematic diagram which showed notionally the other positional relationship of the liquid crystal molecule based on this embodiment, a 1st phase difference plate, and a 2nd phase difference plate. It is the graph which showed quantitatively the correlation of arrangement | positioning of the 1st and 2nd phase difference plate which concerns on this embodiment, and the contrast of light. It is the schematic (FIG. 9 (a) to FIG.9 (d)) which shows the arrangement | positioning form of the structural member in the liquid crystal light valve 15 which concerns on this embodiment. FIG. 10 is one and other graphs (FIG. 10A and FIG. 10B) that quantitatively show the correlation between the arrangement of the first and second retardation plates according to the present embodiment and the contrast of light. .

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Projector, 11 ... Screen, 12 ... Light source, 15, 16, 17, 215 ... Liquid crystal device, 15a, 16a, 17a ... 1st phase difference plate, 15b, 16b, 17b, 15d, 16d, 17d ... Polarizing plate, 15c, 16c, 17c ... liquid crystal panel, 15e, 16e, 17e ... second retardation plate, 31 ... counter substrate, 32 ... TFT array substrate, R2, R1 ... rubbing direction, 43, 98 ... alignment film, 51 ... liquid crystal molecule 81a: refractive index ellipsoid, 81e: refractive index ellipsoid, LB: blue light, LG: green light, LR: red light

Claims (12)

Between the first substrate having the first alignment film and the second substrate having the second alignment film, a twisted liquid crystal in which the alignment state is regulated by the first and second alignment films is sandwiched between the first substrate and the second substrate. A liquid crystal panel that modulates
A pair of polarizing plates disposed across the liquid crystal panel;
The first optical axis of the first refractive index anisotropy is disposed between the pair of polarizing plates and maintains negative biaxial or negative uniaxial first refractive index anisotropy. A first retardation plate along a first alignment direction, which is an alignment direction of the first liquid crystal molecules constituting the portion of the liquid crystal facing the first alignment film, as viewed in plan from the normal direction of the plate;
The second optical axis of the second refractive index anisotropy is disposed between the pair of polarizing plates and retains a negative biaxial or negative uniaxial second refractive index anisotropy. A second retardation plate along a second alignment direction which is an alignment direction of the second liquid crystal molecules constituting the portion of the liquid crystal facing the second alignment film when viewed in plan from the line direction. A characteristic liquid crystal device.   2. The liquid crystal device according to claim 1, wherein at least one of the first retardation plate and the second retardation plate includes an inorganic material.   The liquid crystal device according to claim 1, wherein the liquid crystal molecules constituting the liquid crystal have positive refractive index anisotropy. In the liquid crystal panel, the light is incident on the first alignment film side, and the light is emitted from the second alignment film side,
When the first retardation plate and the second retardation plate are disposed on the light incident side of the liquid crystal panel, the first retardation plate has the first orientation compared to the second retardation plate. The liquid crystal device according to claim 1, wherein the liquid crystal device is disposed at a position close to the film. In the liquid crystal panel, the light is incident on the first alignment film side, and the light is emitted from the second alignment film side,
When the first retardation plate and the second retardation plate are disposed on the light emission side of the liquid crystal panel, the second retardation plate has the second orientation compared to the first retardation plate. The liquid crystal device according to claim 1, wherein the liquid crystal device is disposed at a position close to the film. In the liquid crystal panel, the light is incident on the first alignment film side, and the light is emitted from the second alignment film side,
When the first retardation plate and the second retardation plate are disposed so as to sandwich the liquid crystal panel, the first retardation plate is closer to the first alignment film than the second retardation plate. The second retardation plate is disposed at a position closer to the second alignment film than the first retardation plate in addition to being disposed at a position. The liquid crystal device according to any one of the above.   In addition to or instead of the major axis direction of the first liquid crystal molecules being aligned with the direction of one optical axis of the first refractive index anisotropy when viewed in plan from the normal direction. The major axis direction of the second liquid crystal molecules is aligned with the direction of one optical axis of the second refractive index anisotropy. The liquid crystal device described.   In addition to or instead of the short axis direction of the first liquid crystal molecules and the direction of the other optical axis of the first refractive index anisotropy being aligned in a plan view from the normal direction. The minor axis direction of the second liquid crystal molecule is aligned with the direction of the other optical axis of the second refractive index anisotropy. The liquid crystal device described.   In the first refractive index anisotropy, when the first optical axis is the Z axis, the refractive index in the Z axis direction is smaller than the refractive index in the X axis direction, and the refractive index in the X axis direction is the Y axis. In addition to or instead of having a magnitude relationship that is equal to the refractive index in the direction, the second refractive index anisotropy is such that when the second optical axis is the Y axis, the refractive index in the Y axis direction is the X axis. 9. The liquid crystal according to claim 1, wherein the liquid crystal has a magnitude relationship that the refractive index is smaller than the refractive index in the direction and the refractive index in the X-axis direction is equal to the refractive index in the Z-axis direction. apparatus. The first transmission axis of the first polarizing plate located on the incident side of the liquid crystal panel in the pair of polarizing plates when viewed in plan from the normal direction, and the light emitted from the liquid crystal panel of the pair of polarizing plates. The second transmission axes of the second polarizing plates located on the side are orthogonal to each other,
The direction of the first transmission axis and the first alignment direction are parallel to each other and the direction of the second transmission axis and the second alignment direction are parallel to each other when viewed in plan from the normal direction. The liquid crystal device according to claim 1, wherein the liquid crystal device is a liquid crystal device. A liquid crystal device according to any one of claims 1 to 10,
A light source that emits the light;
A projector comprising: a projection optical system that projects the modulated light. An optical compensation method for performing optical compensation in the liquid crystal device according to any one of claims 1 to 10,
An optical adjustment step of rotating at least one of the first retardation plate and the second retardation plate with the normal direction of the one retardation plate as a rotation axis. An optical compensation method for a liquid crystal device.