JP5924376B2 - Liquid crystal device and electronic device - Google Patents

Description

  The present invention relates to a liquid crystal device, an electronic apparatus including the liquid crystal device, and a projection display device.

  As the liquid crystal device, a VAN (Vertical Alignment Nematic) liquid crystal in which liquid crystal molecules are aligned substantially perpendicular to the substrate surface when no voltage is applied to the liquid crystal layer is used, and an inorganic material is obliquely deposited. The optical axis is inclined with respect to the element surface, and the direction in which the vapor deposition direction of the inorganic material is orthogonally projected onto the element surface coincides with the direction of the fast axis, and the liquid crystal molecules are inclined with respect to the substrate surface. A reflection type liquid crystal display device having a biaxial birefringent body that compensates for a phase difference caused by this is known (Patent Document 1).

In the above-mentioned Patent Document 1, a uniaxial birefringent body that compensates for a phase difference caused when polarized light transmitted through a liquid crystal layer is transmitted through a biaxial birefringent body is disposed so as to overlap the biaxial birefringent body. Is also disclosed.
By providing such a biaxial birefringent body and a uniaxial birefringent body, the contrast in the front direction and the oblique direction of the reflective liquid crystal display element can be improved.

JP 2008-164754 A

  In the reflection-type liquid crystal display element of Patent Document 1, a biaxial birefringent body and a uniaxial birefringent body are used to compensate for the phase difference between light transmitted vertically through the liquid crystal layer and light transmitted obliquely. Both are necessary. That is, there is a problem that the number of parts increases and it is difficult to reduce the size in terms of structure.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 In the liquid crystal device of this application example, a liquid crystal layer is sandwiched between a pair of substrates, and liquid crystal molecules of the liquid crystal layer are initially aligned substantially perpendicular to the substrate surface. In the liquid crystal device, an inorganic alignment film is formed on the substrate surface on the liquid crystal layer side, and a pretilt in a predetermined azimuth direction is imparted to the liquid crystal molecules on the surface of the inorganic alignment film, The inorganic alignment film has a slow axis substantially orthogonal to the predetermined azimuth angle direction, and the inorganic alignment film optically compensates for a phase difference of the liquid crystal layer as an optical compensation layer. It is characterized by that.

  According to this configuration, the inorganic alignment film provided for each pair of substrates is an optical compensation layer that optically compensates for the phase difference caused by the pretilt of the liquid crystal molecules, so a new optical compensation layer needs to be provided. There can be provided a small liquid crystal device capable of obtaining high contrast.

Application Example 2 In the liquid crystal device according to the application example, the inorganic alignment film is obtained by oblique deposition or oblique sputtering of an inorganic material with respect to the substrate surface.
According to this configuration, since the inorganic alignment film obtained by oblique vapor deposition or oblique sputtering is employed, the phase difference necessary for the optical compensation layer can be ensured by adjusting the film thickness at the time of film formation. Therefore, compared to the case where a member having an optical compensation layer having a predetermined retardation is procured in advance, an inorganic alignment film is formed in accordance with the setting of the retardation of the liquid crystal layer in the course of manufacturing the liquid crystal device. Thus, the optical compensation layer can be provided flexibly.
In addition, since the inorganic alignment film obtained by oblique vapor deposition or oblique sputtering functions as a biaxial birefringent body, optical compensation for light transmitted through the liquid crystal layer in a direction perpendicular to the substrate surface is effective. In particular, the contrast in the front direction of the liquid crystal device is improved.

Application Example 3 In the liquid crystal device according to the application example described above, it is preferable that a uniaxial birefringent body is further provided on one side of the pair of substrates opposite to the liquid crystal layer.
According to this configuration, by providing the uniaxial birefringent body, optical compensation is further made for light that is obliquely transmitted through the liquid crystal layer, and a high contrast can be obtained over a wide viewing angle. Can provide.

Application Example 4 In the liquid crystal device according to the application example, the uniaxial birefringent body has an optical axis in a direction substantially perpendicular to a surface of the uniaxial birefringent body, and the optical axis is It is preferable that the liquid crystal molecules are arranged so as to be inclined with respect to the one substrate so as to approach a state substantially parallel or substantially parallel to the pretilt direction of the liquid crystal molecules.
According to this configuration, more appropriate optical compensation is performed for light that is obliquely transmitted through the liquid crystal layer. That is, high contrast can be obtained over a wider viewing angle.

Application Example 5 In the liquid crystal device according to the application example described above, the inorganic alignment film has an optical phase difference 1 / of an optimum value that compensates for the phase difference of the liquid crystal layer for each pair of substrates. It is preferable that the film thickness is set to be a value smaller than 2, and the uniaxial birefringent body has a phase difference that is insufficient with respect to the optimum value.
The film thickness of the inorganic alignment film on the substrate surface may be difficult to make a certain film thickness depending on conditions during film formation. For example, if the film thickness is partially greater than a predetermined value due to in-plane variations on the substrate surface, there is a possibility that appropriate optical compensation cannot be performed even if a uniaxial birefringent body is provided.
According to this configuration, even if the film thickness of the inorganic alignment film varies at the time of film formation, the original film thickness setting is set to be smaller than a half value of the optimum value. Can be reduced. Further, by adjusting the tilt angle of the uniaxial birefringent body with respect to one of the substrates, the optical compensation can be adjusted to be in an appropriate state.

Application Example 6 In the liquid crystal device according to the application example, it is preferable that the uniaxial birefringent body is an inorganic retardation plate in which a high refractive index layer and a low refractive index layer are alternately stacked.
According to this configuration, it is possible to provide a liquid crystal device having excellent durability such as high temperature and high humidity as compared with a case where an organic retardation plate made of, for example, a resin material is used as the uniaxial birefringent body.

Application Example 7 In the liquid crystal device according to the application example described above, a common electrode having light transmittance is provided on the liquid crystal layer side of the one of the pair of substrates, and the other substrate of the pair of substrates is provided. A pixel electrode having light reflectivity may be provided on the liquid crystal layer side.
According to this configuration, a so-called reflective liquid crystal device including a pixel electrode having light reflectivity originally has a self-compensation property in which the viewing angle characteristics hardly depend on the pretilt of the liquid crystal molecules, and the transmissive liquid crystal device. As compared with the above, the effect of providing an inorganic alignment film that also serves as an optical compensation layer and a uniaxial birefringent body is more effectively reflected. That is, a reflective liquid crystal device having excellent viewing angle characteristics can be provided.

Application Example 8 An electronic apparatus according to this application example includes the liquid crystal device according to the application example described above.
According to this configuration, since the liquid crystal device capable of obtaining high contrast in viewing angle characteristics is provided, it is possible to provide an electronic device that has a good appearance when viewed from at least the front direction.

  Application Example 9 A projection display device according to this application example is provided for each light source, a light separation element that separates light emitted from the light source into red light, green light, and blue light, and each separated color light. A light modulation element that modulates the color light based on image information; and a light synthesis element that synthesizes the modulated color light. The light modulation element includes the liquid crystal device according to the application example. The uniaxial birefringent body is arranged to be inclined with respect to the one substrate on the incident side or the emission side of colored light.

  According to this configuration, the inorganic alignment film that optically compensates for the phase difference caused by the pretilt of the liquid crystal molecules in the liquid crystal layer, and the 1 arranged to be inclined with respect to one of the pair of substrates of the liquid crystal device. By having the axial birefringent body, it is possible to provide a projection display device capable of obtaining high contrast over a wide viewing angle.

Application Example 10 In the projection display device according to the application example described above, it is preferable that the uniaxial birefringent body is disposed to be inclined with respect to the one substrate at a different angle for each color light.
According to this configuration, it is possible to provide a projection display device in which appropriate optical compensation is realized in consideration of wavelength dependency for each of red, green, and blue color lights.

It is the schematic which shows the structure of the liquid crystal device of 1st Embodiment, (a) is a front view, (b) is sectional drawing cut | disconnected by the HH 'line | wire of (a). FIG. 2 is an equivalent circuit diagram illustrating an electrical configuration of the liquid crystal device according to the first embodiment. 2A and 2B are schematic views illustrating a structure of a pixel of the liquid crystal device according to the first embodiment, in which FIG. 2A is a plan view, and FIG. FIG. 3 is a schematic cross-sectional view illustrating a formation state of an inorganic alignment film and an alignment state of liquid crystal molecules in the liquid crystal device of the first embodiment. The graph which shows the relationship between the vapor deposition angle of oblique vapor deposition, and the pretilt angle of a liquid crystal molecule. The graph which shows the relationship between the pretilt angle of the liquid crystal molecule in 1st Embodiment, and the front phase difference of a liquid crystal layer. The graph which shows the relationship between the film thickness of an inorganic alignment film, and front phase difference. (A) And (b) is a figure explaining the optical viewing angle compensation principle of the liquid crystal device of 1st Embodiment. 2 is an isocontrast curve showing the viewing angle characteristics of the liquid crystal device, (a) is an isocontrast curve of Comparative Example 1, (b) is an isocontrast curve of Comparative Example 2, and (c) is an isocontrast curve of the first embodiment. FIG. 5 is a schematic cross-sectional view illustrating a configuration of a liquid crystal device according to a second embodiment. The figure explaining the optical viewing angle compensation principle of the liquid crystal device of 2nd Embodiment. The graph which shows the relationship between the inclination-angle of a uniaxial birefringent body in 2nd Embodiment, and front phase difference. (A) is an iso-contrast curve which shows the viewing angle characteristic of the liquid crystal device of 2nd Embodiment, (b) is an iso-contrast curve when the inclination-angle of an inorganic phase difference plate shall be -2.0 degrees. The figure which shows the structure of the transmissive | pervious liquid crystal projector of 3 plate type which is an example of the projection type display apparatus as an electronic device of 3rd Embodiment. FIG. 6 is a schematic cross-sectional view illustrating a structure of a liquid crystal device according to a fourth embodiment. The graph which shows the relationship between the pretilt angle of the liquid crystal molecule in 4th Embodiment, and the front phase difference of a liquid crystal layer. (A) is an iso-contrast curve which shows the viewing angle characteristic of the liquid crystal device of 4th Embodiment, (b) is an iso-contrast curve which shows the viewing angle characteristic of the reflection type liquid crystal device of a comparative example. FIG. 10 is a schematic cross-sectional view illustrating a structure of a liquid crystal device according to a fifth embodiment. The graph which shows the relationship between the inclination-angle of a uniaxial birefringent body in 5th Embodiment, and front phase difference. An isocontrast curve showing the viewing angle characteristics of the liquid crystal device of the fifth embodiment. The figure which shows the structure of the 3 plate-type reflective liquid crystal projector which is an example of the projection type display apparatus as an electronic device of 6th Embodiment.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings. Note that the drawings to be used are appropriately enlarged or reduced so that the part to be described can be recognized.

(First embodiment)
In the present embodiment, an active matrix liquid crystal device including a thin film transistor (TFT) as a pixel switching element will be described as an example. This liquid crystal device can be suitably used as, for example, a light modulation element (liquid crystal light valve) of a projection type display device (liquid crystal projector) described later.

<Liquid crystal device>
First, the liquid crystal device of the present embodiment will be described with reference to FIGS. 1A and 1B are schematic views showing the configuration of a liquid crystal device. FIG. 1A is a front view, and FIG. 1B is a cross-sectional view taken along the line HH ′ in FIG.

As shown in FIGS. 1A and 1B, the liquid crystal device 100 of this embodiment includes an element substrate 10 and a counter substrate 20 as a pair of substrates, and a liquid crystal layer 50 sandwiched between the pair of substrates. Have.
The element substrate 10 is slightly larger than the counter substrate 20, and both substrates are bonded via a sealing material 52, and liquid crystal having negative dielectric anisotropy is sealed in the gap to form the liquid crystal layer 50. .

  As shown in FIG. 2A, a data line driving circuit 101 is provided along one side portion of the element substrate 10, and a plurality of terminal portions 102 electrically connected thereto are arranged. On the other two sides orthogonal to the one side and facing each other, a scanning line driving circuit 104 is provided along the two sides. A plurality of wirings 105 that connect the two scanning line driving circuits 104 are provided on the other one side facing the one side across the counter substrate 20.

  A parting portion 53 is also provided in a frame shape on the inside of the sealing material 52 arranged in a frame shape. The parting part 53 is made of a light-shielding metal material or resin material, and the inside of the parting part 53 is a display region 10a having a plurality of pixels.

  As shown in FIG. 2B, on the surface of the element substrate 10 on the liquid crystal layer 50 side, a pixel electrode 15 having light transmissivity provided for each pixel, a thin film transistor 30 as a switching element, a signal wiring, An alignment film 18 covering these is formed.

  On the surface of the counter substrate 20 on the liquid crystal layer 50 side, a parting portion 53, a common electrode 23 formed so as to cover it, and an alignment film 29 covering the common electrode 23 are formed.

The alignment film 18 and the alignment film 29 are inorganic alignment films made of an inorganic material, and are obtained by oblique deposition of SiO ₂ (silicon oxide) as an inorganic material. The alignment state of the liquid crystal molecules in the liquid crystal layer 50 sandwiched between the alignment films 18 and 29 will be described later.

  The common electrode 23 provided on the counter substrate 20 is electrically connected to the wiring on the element substrate 10 side by the vertical conduction portions 106 provided at the four corners of the counter substrate 20 as shown in FIG.

  FIG. 2 is an equivalent circuit diagram showing an electrical configuration of the liquid crystal device. As shown in FIG. 2, the liquid crystal device 100 includes a plurality of scanning lines 3a and a plurality of data lines 6a as signal lines that are insulated and orthogonal to each other at least in the display region 10a. In addition, the capacitor line 3b is arranged so as to be parallel to the scanning line 3a at a predetermined interval.

  A pixel electrode 15, a TFT (Thin Film Transistor) 30 as a switching element that controls the switching of the pixel electrode 15, and a holding area in an area partitioned by the scanning line 3 a, the data line 6 a, and the capacitance line 3 b A capacitor 16 is provided, and these constitute pixels. That is, the pixels are arranged in a matrix.

The scanning line 3 a is electrically connected to the gate of the TFT 30, and the data line 6 a is electrically connected to the source of the TFT 30. The pixel electrode 15 is electrically connected to the drain of the TFT 30.
The data line 6a is connected to the data line driving circuit 101 (see FIG. 1), and supplies image signals D1, D2,..., Dn supplied from the data line driving circuit 101 to the pixels. The scanning line 3a is connected to a scanning line driving circuit 104 (see FIG. 1), and supplies scanning signals SC1, SC2,..., SCm supplied from the scanning line driving circuit 104 to each pixel. The image signals D1 to Dn supplied from the data line driving circuit 101 to the data lines 6a may be supplied line-sequentially in this order, or may be supplied for each of a plurality of adjacent data lines 6a for each group. Good. The scanning line driving circuit 104 supplies the scanning signals SC1 to SCm to the scanning line 3a in a pulse-sequential manner at predetermined timing.

In the liquid crystal device 100, the TFT 30 that is a switching element is turned on for a certain period by the input of the scanning signals SC1 to SCm, so that the image signals D1 to Dn supplied from the data line 6a are supplied to the pixel electrode 15 at a predetermined timing. It is the structure written in. The predetermined level of image signals D1 to Dn written to the liquid crystal layer 50 via the pixel electrode 15 is held for a certain period between the pixel electrode 15 and the common electrode 23 arranged to face each other via the liquid crystal layer 50. The
In order to prevent the held image signals D1 to Dn from leaking, the holding capacitor 16 is connected in parallel with the liquid crystal capacitor formed between the pixel electrode 15 and the common electrode 23. The storage capacitor 16 is provided between the drain of the TFT 30 and the capacitor line 3b.

  3A and 3B are schematic views showing the structure of a pixel of the liquid crystal device, where FIG. 3A is a plan view, and FIG. 3B is a cross-sectional view taken along line AA ′ in FIG. is there.

  As shown in FIG. 3A, the pixel of the liquid crystal device 100 has a substantially rectangular pixel electrode 15 in a pixel region defined by a scanning line 3a and a data line 6a that intersect (orthogonal) each other. The pixel electrode 15 is made of a transparent conductive film such as ITO (Indium Tin Oxide), for example, and has light transmittance.

  The TFT 30 is provided on the scanning line 3a in the vicinity of the intersection of the scanning line 3a and the data line 6a. A semiconductor layer 30a is provided along the scanning line 3a, and a source electrode 30s formed integrally with the data line 6a is provided so as to overlap the source side of the semiconductor layer 30a. A drain electrode 30d is provided so as to overlap the drain side of the semiconductor layer 30a.

  The drain electrode 30d extends into the pixel region, and the extended portion is electrically connected to the pixel electrode 15 through the contact hole 15a.

  The capacitance line 3b is provided in parallel with the scanning line 3a, and an extension portion 30e of the drain electrode 30d is provided in a region overlapping the capacitance line 3b in the pixel region.

More specifically, as shown in FIG. 3B, first, a low resistance wiring material such as aluminum is formed on the element substrate 10 and patterned, so that the scanning line 3a and the capacitor line 3b parallel to the scanning line 3a are formed. And form. A gate insulating film 11 made of, for example, silicon oxide is formed so as to cover the scanning line 3a and the capacitor line 3b. A semiconductor layer 30a is formed in an island shape on the gate insulating film 11 at a position overlapping the scanning line 3a. A data line 6a, a source electrode 30s, and a drain electrode 30d are formed by forming and patterning a low-resistance wiring material so as to cover the semiconductor layer 30a. In addition, an extended portion 30e connected to the drain electrode 30d is formed at a position overlapping the capacitor line 3b.
The storage capacitor 16 is configured by the capacitor line 3b and the extending portion 30e arranged to face each other with the gate insulating film 11 interposed therebetween.
An interlayer insulating film 12 made of, for example, silicon oxide or nitride is formed so as to cover the TFT 30 and the storage capacitor 16, and a contact hole 15a is formed at a position overlapping the drain electrode 30d of the interlayer insulating film 12 in a plane. Keep it. By forming and patterning a transparent conductive film so as to cover the interlayer insulating film 12, the pixel electrode 15 electrically connected to the drain electrode 30d through the contact hole 15a is formed.

Subsequently, an alignment film 18 is formed so as to cover the pixel electrode 15. As described above, the alignment film 18 is formed by oblique deposition of SiO ₂ (silicon oxide) as an inorganic material. The planar vapor deposition direction of the oblique vapor deposition is a direction indicated by an arrow in FIG. 3A, has an angle θa with respect to the extending direction of the scanning line 3a, and extends from the upper right to the lower left of the pixel region. ing. In this case, the angle θa in the vapor deposition direction is approximately 45 °. Further, the angle of the vapor deposition direction in the direction perpendicular to the paper surface, that is, the direction perpendicular to the surface of the pixel electrode 15 is about 45 ° (see FIG. 4).

According to such oblique deposition, as shown in FIG. 3B, a columnar body (column) 18c is formed in which a crystal of SiO ₂ as an inorganic material grows obliquely with respect to the substrate surface. The alignment film 18 is made of an aggregate in which such columnar bodies (columns) 18c are erected on the substrate surface.
3A and 3B, the configuration on the element substrate 10 side has been described, but the alignment film 29 in the counter substrate 20 is also formed so as to cover the common electrode 23 using oblique deposition, The planar deposition direction is 180 ° opposite to the deposition direction of the angle θa on the element substrate 10.

  FIG. 4 is a schematic sectional view showing the formation state of the inorganic alignment film and the alignment state of the liquid crystal molecules in the liquid crystal device. Specifically, it is a cross-sectional view taken along the vapor deposition direction of oblique vapor deposition in FIG.

  As shown in FIG. 4, the angle θb of the vapor deposition direction in the alignment films 18 and 29 with respect to the substrate surface facing the liquid crystal layer 50 is about 45 °. The angle θc of the column growth direction with respect to the substrate surface is about 70 °. Hereinafter, the angle θc is referred to as a column angle θc.

  The pretilt angle θp of the liquid crystal molecules LC that are substantially vertically aligned on the surfaces of the alignment films 18 and 29 is about 85 °. Further, the pretilt direction of the liquid crystal molecules LC viewed from the normal direction of the substrate surface, that is, the azimuth angle direction, is the same as the planar deposition direction of the oblique deposition in the alignment films 18 and 29.

  In the liquid crystal device 100 according to the present embodiment, the alignment films 18 and 29 that are aggregates of columns are set to have specific thicknesses, thereby causing a pretilt of the liquid crystal molecules LC on the surfaces of the alignment films 18 and 29. The phase difference was optically compensated. Further, an inorganic retardation plate 42 as a uniaxial birefringent material is disposed on the light emission side that transmits the liquid crystal panel 110 including the liquid crystal layer 50 sandwiched between the element substrate 10 and the counter substrate 20. The phase difference of the light transmitted through the liquid crystal layer 50 obliquely was optically compensated.

The liquid crystal device 100 includes polarizing elements 41 and 43 disposed on the light incident side and the light emitting side of the liquid crystal panel 110, respectively, and the inorganic retardation plate 42 is disposed on the light emitting side. And the liquid crystal panel 110. Further, the polarizing elements 41 and 43 are arranged with respect to the liquid crystal panel 110 so that the absorption axes or transmission axes of the polarizing elements 41 and 43 are orthogonal to each other. More specifically, one absorption axis or transmission axis is arranged in parallel with the scanning line 3a, and the other absorption axis or transmission axis is arranged in parallel with the data line 6a (see FIG. 3A). .
That is, the azimuth direction of the pretilt of the liquid crystal molecules LC intersects with the transmission axis or absorption axis of the polarizing elements 41 and 43 at 45 °, and a drive voltage is applied between the pixel electrode 15 and the common electrode 23. When the liquid crystal layer 50 is driven, the liquid crystal molecules LC are tilted in the pretilt azimuth direction, so that an optical arrangement is obtained in which high transmittance is obtained.

  Next, the deposition conditions of the alignment films 18 and 29, the pretilt angle θp of the liquid crystal molecules LC, and the front phase difference of the liquid crystal layer 50 will be described with reference to FIGS. FIG. 5 is a graph showing the relationship between oblique deposition and the pretilt angle of liquid crystal molecules, and FIG. 6 is a graph showing the relationship between the pretilt angle of liquid crystal molecules and the front phase difference of the liquid crystal layer.

When the alignment films 18 and 29 are formed by obliquely depositing an inorganic material with respect to the substrate surface using a vacuum deposition apparatus, the deposition is performed depending on the size of the substrate and the relative positional relationship between the substrate and the deposition source. The vapor deposition angle θb in the direction may vary. Further, when the deposition angle θb varies, the pretilt angle θp of the liquid crystal molecules LC also varies, and the phase difference value in the liquid crystal layer 50 may vary accordingly. Needless to say, when the phase difference of the liquid crystal layer 50 is to be optically compensated, it is desirable that these parameters vary as little as possible.
In this embodiment, the element substrate 10 and the counter substrate 20 are bonded to each other with an interval of about 2.5 μm, and a liquid crystal having negative dielectric anisotropy and a birefringence Δn of about 0.14 is sandwiched therebetween. The following description is given by taking the configuration as an example.
As the conditions for forming the alignment films 18 and 29, the temperature of the substrate disposed in the vacuum chamber is approximately 100 ° C., and the degree of vacuum at the start of the deposition of SiO ₂ is approximately 5.0 × 10 ⁻³ Pa. Evaporation is performed.

  As shown in FIG. 5, the liquid crystal when the liquid crystal layer 50 is sandwiched between the alignment films 18 and 29 obtained by changing the deposition angle θb of the oblique deposition with respect to the substrate surface in the range of 30 ° to 60 ° in increments of 5 °. The pretilt angle θp of the molecule LC varies between approximately 85 ° and 89 °. The change is a quadratic function having a minimum point. When the oblique deposition is performed with the deposition angle θb being approximately 37.5 ° to 45 °, the pretilt angle θp is within 85 ° ± 1 °. You can see that it is stable. In other words, in order to stably obtain a pretilt angle θp of approximately 85 °, the relative positional relationship between the substrate and the vapor deposition source is adjusted so that the vapor deposition angle θb is between 37.5 ° and 45 °. It is preferable to do.

On the other hand, the relationship between the pretilt angle θp of the liquid crystal molecules LC and the front phase difference of the liquid crystal layer 50 changes substantially linearly as shown in FIG. 6, and the value of the front phase difference ( nm) becomes smaller. Needless to say, it depends on the birefringence Δn of the liquid crystal and the thickness of the liquid crystal layer 50.
When a predetermined drive voltage is applied between the pixel electrode 15 and the common electrode 23 to drive the liquid crystal layer 50, the liquid crystal molecules LC are perpendicular to the direction of the electric field generated between the pixel electrode 15 and the common electrode 23. It collapses in the direction parallel to the substrate surface. When the pretilt angle θp approaches 90 °, the direction in which the liquid crystal molecules LC collapse is not uniform, reverse tilt domains and the like are generated, and the optical characteristics become unstable. In particular, when the distance between adjacent pixel electrodes 15 is narrow, a reverse tilt domain is likely to occur due to an electric field generated between the pixel electrodes 15. Therefore, in order to obtain stable optical characteristics, the pretilt angle θp is set to approximately 85 °. The front phase difference when the pretilt angle θp is 85 ° is approximately 2.4 nm. The pretilt angle θp is not limited to 85 °, and is set in consideration of the stability of alignment in the liquid crystal layer 50 and the optical characteristics.

FIG. 7 is a graph showing the relationship between the thickness of the inorganic alignment film and the front phase difference. FIG. 7 shows the value of the front phase difference when the inorganic alignment film is formed with the deposition angle θb in oblique deposition being 45 °.
As shown in FIG. 7, it can be seen that the value of the front phase difference increases almost linearly as the thickness of the inorganic alignment film increases. From another viewpoint, the front phase difference is hardly generated when the film thickness is about 20 nm. On the other hand, it has been found that if the film thickness is at least 20 nm or more, a substantially stable pretilt can be imparted to the liquid crystal molecules LC.

  Next, the principle of optical viewing angle compensation in the liquid crystal device 100 will be described with reference to FIG. 8A and 8B are diagrams for explaining the optical viewing angle compensation principle of the liquid crystal device.

  As shown in FIG. 8A, each configuration in which a phase difference occurs with respect to light transmitted through the liquid crystal device 100 is shown as a refractive index ellipsoid. The coordinate axes X-axis and Y-axis are axes parallel to the substrate surface, and the Z-axis is an axis perpendicular to the substrate surface. More specifically, the X-axis direction is the extending direction of the scanning line 3a, and the Y-axis is the extending direction of the data line 6a.

  As described above, the liquid crystal molecules LC of the liquid crystal layer 50 are tilted so that a pretilt is given to the substrate surface (alignment film surface) and the major axis indicating the pretilt direction intersects the Z axis. When the liquid crystal molecules LC are cut in a direction perpendicular to the major axis, the relationship between the in-plane refractive index nx, ny and the major axis direction (pretilt direction) refractive index nz is nx = ny <nz. It has become. That is, the in-plane refractive indexes nx and ny in the liquid crystal layer 50 are smaller than the refractive index nz in the thickness direction.

  The alignment films 18 and 29 obtained by oblique deposition have a refractive index nx ″ in the column growth direction of about 1.45, and an in-plane refractive index ny ″ of about 1.5. 41. Similarly, the refractive index nz ″ is 1.40. That is, these relationships are nx ″> ny ″> nz ″, which is a biaxial birefringent body.

The inorganic retardation plate 42 as a uniaxial birefringent body is obtained by alternately laminating a high refractive index layer and a low refractive index layer on a substrate such as transparent glass. Examples of the material constituting the high refractive index layer include TiO ₂ and ZrO ₂ . Examples of the material constituting the low refractive index layer include SiO ₂ and MgF ₂ .

  In order to prevent the light transmitted through the inorganic retardation plate 42 from being reflected and interfered with each layer, the thickness of each refractive index layer is preferably thin, and the product of the film thickness and the refractive index is larger than the wavelength λ of visible light. It is formed so as to be sufficiently small. For example, λ / 100 to λ / 5 is desirable.

  Such an inorganic phase difference plate 42 has an optical axis in a direction perpendicular to the plate surface. The relationship between the refractive index nz ′ at the optical axis and the refractive indexes nx ′ and ny ′ in the plane parallel to the plate surface is nx ′ = ny ′> nz ′. That is, the in-plane refractive indexes nx ′ and ny ′ are larger than the refractive index nz ′ in the thickness direction.

  Since the inorganic phase difference plate 42 is isotropic (in-plane refractive index nx ′ = refractive index ny ′) with respect to light incident perpendicularly to the plate surface, that is, light parallel to the optical axis, the optical axis It is not possible to compensate for the phase difference of light incident in parallel with respect to. On the other hand, the light transmitted obliquely with respect to the plate surface is not isotropic and birefringence is generated, and the phase difference of the light transmitted obliquely through the liquid crystal layer 50 can be compensated. The retardation of the inorganic retardation plate 42 of the present embodiment is given by (nx′−nz ′) × birefringent layer thickness, and is approximately 350 nm. That is, it is set to have the same value as the phase difference of the liquid crystal layer 50 given by the product of the birefringence Δn (0.14) and the layer thickness (2.5 μm).

As described above, the liquid crystal molecules LC are given a pretilt angle θp of 85 ° with respect to the substrate surface (alignment film surface). The front phase difference at that time is approximately 2.4 nm (see FIG. 6). On the other hand, the alignment films 18 and 29 of the present embodiment are formed so as to have a thickness of about 270 nm, respectively. As described above, the column angle θc is 70 ° (see FIG. 4). The axis indicating the reflectance nx ″ is parallel to this column. Therefore, when viewed from the normal direction of the substrate surface, the axis indicating the refractive index ny ″ is the slow axis, and the alignment films 18 and 29 are each − A phase difference of 1.2 nm is shown. The total is -2.4 nm.
When viewed from the normal direction of the substrate surface as shown in FIG. 8B, the azimuthal direction in which the pretilt direction (major axis) of the liquid crystal molecules LC is projected onto the substrate surface is the column of the alignment films 18 and 29. Since the growth direction is parallel to the azimuth angle direction projected on the substrate surface and is orthogonal to the direction of the slow axis of the alignment films 18 and 29, the phase difference between the two is canceled out. That is, the front phase difference of the liquid crystal layer 50 is optically compensated. In other words, the alignment films 18 and 29 also serve as an optical compensation layer that optically compensates for the front phase difference of the liquid crystal layer 50.
In the transmissive liquid crystal device 100, the inorganic retardation plate 42 is not limited to be disposed between the counter substrate 20 on the light emission side and the polarizing element 43, but is incident on the light incident side, that is, the element substrate 10. A similar effect can be obtained even if it is arranged between the polarizing element 41 and the polarizing element 41 (see FIG. 4).

  FIG. 9 is an isocontrast curve showing the viewing angle characteristics of the liquid crystal device. FIG. 9A is an isocontrast curve of Comparative Example 1, FIG. 9B is an isocontrast curve of Comparative Example 2, and FIG. It is an isocontrast curve of this embodiment. The isocontrast curve was measured by arranging the liquid crystal device on the backlight that emits diffused light, displaying all white and all black in order, and changing the luminance of the viewing angle. The center of the figure is the normal direction of the liquid crystal device, and shows the characteristics in the viewing angle direction tilted ± 20 ° in the left-right direction and ± 20 ° in the vertical direction from the normal line.

<Comparative Example 1>
In Comparative Example 1, the thickness of the alignment films 18 and 29 obtained by oblique deposition so that the liquid crystal molecules LC have a pretilt angle θp of 85 ° in the liquid crystal layer 50 is, for example, about 20 nm that does not cause birefringence. It was. According to this, as shown in FIG. 9A, the phase difference (2.4 nm) due to the pretilt of the liquid crystal molecules LC cannot be compensated for viewing angle, so the azimuth angle at which the maximum contrast is obtained is the normal direction of the substrate surface, that is, The directions are shifted by about 5 ° in the X-axis direction and the Y-axis direction from (0 °, 0 °). Incidentally, the contrast ratio (C, R) when this liquid crystal device was projected by a projector was about 1100.

<Comparative Example 2>
In Comparative Example 2, the thickness of the alignment films 18 and 29 obtained by oblique deposition so that the liquid crystal molecules LC have a pretilt angle θp of 85 ° in the liquid crystal layer 50 is, for example, about 20 nm that does not cause birefringence. And an inorganic retardation plate 42 having a retardation of 350 nm. According to this, as shown in FIG. 9B, the provision of the inorganic retardation plate 42 compensates for the phase difference of light obliquely transmitted through the liquid crystal layer 50, thereby forming the shape of the isocontrast curve. However, the azimuth angle at which the maximum contrast is obtained is still deviated from the front position. That is, the phase difference due to the pretilt of the liquid crystal molecules LC cannot be sufficiently compensated. The projection contrast ratio was approximately 1400.

  On the other hand, in the present embodiment, as shown in FIG. 9C, the viewing angle of the phase difference (2.4 nm) due to the pretilt of the liquid crystal molecules LC is compensated, and the azimuth angle at which the maximum contrast is obtained is located in front. ing. The projection contrast ratio was about 2200, which was improved as compared with Comparative Examples 1 and 2. That is, the liquid crystal device 100 having a wide viewing angle characteristic and a high front contrast ratio is realized.

  Even if the inorganic phase difference plate 42 is omitted from the present embodiment, the alignment films 18 and 29 obtained by oblique deposition compensate for the phase difference (2.4 nm) due to the pretilt of the liquid crystal molecules LC. It is known that the contrast ratio is about 1300, which is improved as compared with Comparative Example 1.

  According to such a liquid crystal device 100, the alignment films 18 and 29 also serve as the optical compensator for optically compensating the front phase difference of the liquid crystal layer 50 due to the pretilt of the liquid crystal molecules LC without providing a new optical compensation plate. Yes. That is, it is possible to provide a small liquid crystal device 100 having a wide viewing angle characteristic and a high front contrast ratio by realizing viewing angle compensation without increasing the number of components.

(Second Embodiment)
A liquid crystal device according to a second embodiment will be described with reference to FIGS. 10 is a schematic cross-sectional view showing the configuration of the liquid crystal device of the second embodiment, FIG. 11 is a diagram for explaining the optical viewing angle compensation principle of the liquid crystal device of the second embodiment, and FIG. 12 is a diagram of a uniaxial birefringent body. It is a graph which shows the relationship between an inclination angle and a front phase difference.
The liquid crystal device of the second embodiment is obtained by reviewing the thickness of the inorganic alignment film and the arrangement of the uniaxial birefringent material with respect to the liquid crystal panel 110 with respect to the first embodiment. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals and detailed description thereof is omitted.

As shown in FIG. 10, the liquid crystal device 150 of this embodiment includes a liquid crystal panel 110 including a liquid crystal layer 50 sandwiched between an element substrate 10 and a counter substrate 20. An alignment film 18 covering the pixel electrode 15 provided on the element substrate 10 and an alignment film 29 covering the common electrode 23 provided on the counter substrate 20 are inorganic alignment obtained by obliquely depositing SiO ₂ as an inorganic material. It is a membrane.

The deposition angle θb of oblique deposition with respect to the substrate surface is 45 °. Although not shown in the drawing, the angle θa of the planar deposition direction with respect to the substrate surface is 45 ° with respect to the extending direction of the scanning line 3a. The column angle θc at which the SiO ₂ crystal grows by oblique deposition is 70 ° with respect to the substrate surface.

  The element substrate 10 and the counter substrate 20 are arranged to face each other with an interval of about 2.5 μm, and a liquid crystal having a negative dielectric anisotropy (birefringence index Δn is 0.14) is filled between the element substrate 10 and the counter substrate 20. Is configured.

  The liquid crystal molecules LC are initially aligned with a pretilt applied to the alignment film surfaces of the alignment films 18 and 29, and the pretilt angle θp is approximately 85 °.

  As described in the first embodiment, the optimum film thickness of the alignment films 18 and 29 for optically compensating for the phase difference (2.4 nm) of the liquid crystal layer 50 caused by the pretilt of the liquid crystal molecules LC is approximately 270 nm. . However, in an actual oblique deposition process, it is difficult to form a uniform film with a constant film thickness. For example, a method of slowly forming a film by increasing the distance between the substrate and the vapor deposition source is conceivable, but there is a problem that productivity is lowered.

  Further, if the film thickness of the alignment films 18 and 29 becomes thicker than the optimum value that enables viewing angle compensation due to the film thickness variation, even if the inorganic retardation plate 42 as a uniaxial birefringent body is equipped. Deviation from the appropriate state.

Therefore, in the present embodiment, the film thickness of the alignment films 18 and 29 is set to be smaller than the optimum value, and the inorganic phase difference plate 42 is inclined with respect to the liquid crystal panel 110 to compensate for the insufficient front phase difference. It is a configuration. As shown in FIG. 10, the inclination angle of the inorganic retardation film 42 with respect to the surface of the counter substrate 20 of the liquid crystal panel 110 on the light emission side is referred to as θd.
FIG. 10 corresponds to FIG. 4 of the first embodiment, and is a schematic cross-sectional view of the liquid crystal device 150 cut along the pretilt direction of the liquid crystal molecules LC, that is, the planar oblique vapor deposition direction. It is.

  As shown in FIG. 11, the inorganic retardation plate 42 has a liquid crystal panel 110, that is, a liquid crystal panel 110 so that the optical axis showing the refractive index nz ′ approaches a state substantially parallel to the pretilt direction (long axis) of the liquid crystal molecules LC. Inclined with respect to the layer 50.

  As shown in FIG. 12, when the inclination angle θd of the inorganic retardation plate 42 as a uniaxial birefringent material is changed from 0 ° to 9 °, the front phase difference may change from 0 nm to 3.8 nm. I understood.

  In the present embodiment, the thickness of each of the alignment films 18 and 29 in the liquid crystal panel 110 is about 240 nm. At this time, the front phase difference of the alignment films 18 and 29 is approximately 1.1 nm (see FIG. 7). As described above, since the front phase difference of the liquid crystal layer 50 when the pretilt angle θp of the liquid crystal molecules LC is 85 ° is 2.4 nm, the front phase difference that is insufficient for optically compensating the viewing angle is 2. 4-2 × 1.1 = 0.2 nm. Therefore, the inclination angle θd of the inorganic retardation plate 42 is set to approximately 2.0 °.

Considering the productivity and yield when forming the alignment films 18 and 29 by oblique deposition, the film thickness of the alignment films 18 and 29 is preferably thinner than 240 nm within a range in which a front phase difference is generated. To compensate for the viewing angle compensation of the front phase difference of the liquid crystal layer 50 due to the pretilt of the liquid crystal molecules LC, the inclination angle θd of the inorganic retardation plate 42 may be made larger than 2.0 °. On the other hand, since the space occupied by the liquid crystal device 150 increases as the tilt angle θd of the inorganic retardation plate 42 increases, it is necessary to set the tilt angle θd in consideration of downsizing of the device to which this is applied.
In the transmissive liquid crystal device 150, the inorganic phase difference plate 42 is not limited to be disposed between the counter substrate 20 on the light emission side and the polarizing element 43, but the light incident side, that is, the element substrate 10. A similar effect can be obtained even when the optical element is inclined with respect to the polarizing element 41 (see FIG. 10).

  FIG. 13A is an isocontrast curve showing the viewing angle characteristics of the liquid crystal device of the second embodiment. As shown in FIG. 13A, the liquid crystal device 150 of the present embodiment has an azimuth angle indicating the maximum contrast ratio located in the front direction and a viewing angle range in which a high contrast ratio can be obtained as in the first embodiment. It can be seen that it is wider than the liquid crystal device 100 (comparison with FIG. 9C).

  FIG. 12 shows that the front phase difference is generated when the inorganic retardation plate 42 is tilted with respect to the liquid crystal panel 110. For example, the tilt angle θd of the inorganic retardation plate 42 is set to −2.0 °. . That is, even if the inorganic retardation plate 42 is tilted counterclockwise from the state parallel to the liquid crystal panel 110 in FIG. However, the viewing angle characteristics of the liquid crystal device 150 at that time are as shown in FIG. 13B, and the viewing angle range in which a high contrast ratio is obtained is the first even though the azimuth angle indicating the maximum contrast ratio is located in front. It turns out that it is narrow compared with 1 embodiment. In other words, it is important that the inorganic retardation plate 42 is tilted so that the optical axis approaches a state substantially parallel to the pretilt direction (long axis) of the liquid crystal molecules LC.

  Further, optically, it is ideal to incline so that the optical axis of the inorganic retardation plate 42 is substantially parallel to the pretilt direction (long axis) of the liquid crystal molecules LC. Since it becomes complicated, it is desirable to incline the inorganic retardation plate 42 in a certain direction with respect to the liquid crystal panel 110 from the viewpoint of facilitating relative arrangement as in the present embodiment.

  According to such a liquid crystal device 150, the thickness of the alignment films 18 and 29 in oblique deposition is set to 240 nm, which is approximately 10% smaller than 270 nm where the front phase difference is the optimum value (−1.2 nm). Insufficient front phase difference was compensated by inclining the inorganic phase difference plate 42. Therefore, even if the film thickness of the alignment films 18 and 29 varies somewhat by oblique deposition, the film thickness does not exceed 270 nm, and the effect is reduced and stable viewing angle compensation is realized.

  As shown in FIG. 12, the front phase difference can be set to about 2.4 nm if the inclination angle θd of the inorganic phase difference plate 42 is set to about 7 °. That is, the front phase difference of the liquid crystal layer 50 due to the pretilt of the liquid crystal molecules LC can be optically compensated only by the inorganic phase difference plate 42. However, since the inclination angle θd of the inorganic retardation plate 42 is larger than that of the second embodiment, there arises a problem that it is difficult to reduce the size of the apparatus. In other words, the second embodiment can provide a smaller liquid crystal device 150.

(Third embodiment)
<Electronic equipment>
Next, a projection display device will be described as an example of the electronic apparatus of the present embodiment. FIG. 14 is a diagram illustrating a configuration of a three-plate transmissive liquid crystal projector which is an example of a projection display device as an electronic apparatus according to the third embodiment.

  As shown in FIG. 14, the liquid crystal projector 1000 of the present embodiment includes a polarization illumination device 1100 arranged along the system optical axis L, two dichroic mirrors 1104 and 1105 as light separation elements, and three reflection mirrors. 1106, 1107, 1108, five relay lenses 1201, 1202, 1203, 1204, 1205, liquid crystal light valves 1210, 1220, 1230 as three light modulation elements, a cross dichroic prism 1206 as a light combining element, and projection And a lens 1207.

  The polarized light illumination device 1100 is generally configured by a lamp unit 1101 as a light source composed of a white light source such as a halogen lamp, an integrator lens 1102, and a polarization conversion element 1103.

  The dichroic mirror 1104 reflects red light (R) and transmits green light (G) and blue light (B) among the polarized light beams emitted from the polarization illumination device 1100. Another dichroic mirror 1105 reflects the green light (G) transmitted through the dichroic mirror 1104 and transmits the blue light (B).

The red light (R) reflected by the dichroic mirror 1104 is reflected by the reflection mirror 1106 and then enters the liquid crystal light valve 1210 via the relay lens 1205.
Green light (G) reflected by the dichroic mirror 1105 enters the liquid crystal light valve 1220 via the relay lens 1204.
The blue light (B) transmitted through the dichroic mirror 1105 enters the liquid crystal light valve 1230 via a light guide system including three relay lenses 1201, 1202, 1203 and two reflection mirrors 1107, 1108.

  The liquid crystal light valves 1210, 1220, and 1230 are disposed to face the incident surfaces of the cross dichroic prism 1206 for each color light. The color light incident on the liquid crystal light valves 1210, 1220, and 1230 is modulated based on the image information and is emitted toward the cross dichroic prism 1206. In this prism, four right-angle prisms are bonded together, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in a cross shape on the inner surface thereof. The three color lights are synthesized by these dielectric multilayer films, and the light representing the color image is synthesized. The synthesized light is projected on the screen 1300 by the projection lens 1207 which is a projection optical system, and the image is enlarged and displayed.

  The liquid crystal light valve 1210 is applied with the liquid crystal device 150 of the second embodiment, and includes a pair of polarizing elements arranged in crossed Nicols on the incident side and the emitting side of color light, and a pair of polarizing elements. A liquid crystal panel 1211 and an inorganic retardation plate 1212 as a uniaxial birefringent body. The same applies to the other liquid crystal light valves 1220 and 1230. That is, the liquid crystal panels 1211, 1221, and 1231 are substantially vertically aligned in a state where liquid crystal molecules having negative dielectric anisotropy are given a pretilt with respect to the substrate surface. The pretilt angle θp is approximately 85 °. Moreover, it has the inorganic alignment film formed by oblique vapor deposition facing the liquid crystal layer, and the film thickness of an inorganic alignment film is about 240 nm. The front phase difference of the liquid crystal layer due to the pretilt of the liquid crystal molecules is optically compensated for viewing angle by the inorganic alignment film that also serves as the optical compensation layer.

  The inorganic phase difference plates 1212, 1222, and 1232 each have a phase difference of 350 nm, and are inclined on the surface of the liquid crystal panels 1211, 1221, 1231 on the color light emission side. Since the front phase difference of the liquid crystal layer depends on the wavelength of the color light transmitted through the liquid crystal layer, the inclination angle θd of the inorganic phase difference plates 1212, 1222, and 1232 is set based on the wavelength (550 nm) of the green light (G). In this embodiment, the green light (G) has a wavelength of about 2 °, the red light (R) having a longer wavelength than the green light (G) has a wavelength of about 2.1 °, and the green light (G) has a shorter wavelength. For blue light (B), the angle is set to 1.7 °.

Further, the green light (G) modulated by the liquid crystal light valve 1220 goes straight to the cross dichroic prism 1206, and the red light (R) modulated by the liquid crystal light valve 1210 and the liquid crystal light valve 1230. The modulated blue light (B) is reflected with the left and right sides of the image reversed by the dielectric multilayer film. Therefore, the optical conditions are set corresponding to the color light so that the combined light does not cause coloring due to the viewing angle characteristics of the liquid crystal light valves 1210, 1220, and 1230. Specifically, with respect to the direction of the pretilt of the liquid crystal molecules in the green light (G) liquid crystal panel 1221, the liquid crystal molecules in the other red light (R) liquid crystal panel 1211 and the blue light (B) liquid crystal panel 1231 The inorganic alignment film is formed by reversing the planar vapor deposition direction of oblique vapor deposition by 180 ° so that the pretilt direction is reversed.
Therefore, when the inclination angle θd of the liquid crystal light valve 1220 corresponding to green light (G) with respect to the liquid crystal panel 1221 is 2 °, the inorganic phase difference plate 1212 that apparently transmits red light (R). The tilt angle θd is −2.1 °, and the tilt angle θd of the inorganic retardation plate 1232 through which the blue light (B) is transmitted is −1.7 °.

  According to such a liquid crystal projector 1000, the liquid crystal light valves 1210, 1220, and 1230 provided for each color light are optically corresponding to the wavelength of the color light that transmits the front phase difference of the liquid crystal layer due to the pretilt of the liquid crystal molecules. Since the viewing angle is compensated, an image display with a higher contrast can be obtained over a wider viewing angle than the conventional one.

In this embodiment, the inorganic phase difference plates 1212, 1222, and 1232 are arranged to be inclined on the color light emission side of the liquid crystal panels 1211, 1221, and 1231, respectively, but the present invention is not limited to this. Even if the liquid crystal panels 1211, 1221, and 1231 are arranged to be inclined on the color light incident side, the same effect can be obtained, and the influence of stray light incident at an irregular angle can be reduced.
The liquid crystal device applied to the liquid crystal light valves 1210, 1220, and 1230 of the liquid crystal projector 1000 is not limited to the liquid crystal device 150 of the second embodiment, and the liquid crystal device 100 of the first embodiment is also applied. Good. According to this, since the inorganic retardation plates 1212, 1222, and 1232 are not inclined, a smaller liquid crystal projector 1000 can be realized.

(Fourth embodiment)
The liquid crystal device to which the present invention is applied is not limited to the transmissive type as in the first and second embodiments. In this embodiment, an example of a reflective liquid crystal device to which the present invention is applied will be described with reference to FIGS.
FIG. 15 is a schematic sectional view showing the structure of the liquid crystal device of the fourth embodiment, FIG. 16 is a graph showing the relationship between the pretilt angle of the liquid crystal molecules and the front phase difference of the liquid crystal layer, and FIG. 17A is the fourth embodiment. FIG. 6B is an isocontrast curve showing the viewing angle characteristics of the reflective liquid crystal device of the comparative example. In addition, about the same structure as 1st Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

<Liquid crystal device>
As shown in FIG. 15, the liquid crystal device 200 of this embodiment includes a liquid crystal panel 210 including a liquid crystal layer 50 sandwiched between the element substrate 10 and the counter substrate 20. The liquid crystal panel 210 is a reflection type, and the element substrate 10 is provided with a pixel electrode 15R having light reflectivity.
Other electrical configurations are basically the same as those of the transmissive liquid crystal panel 110. The alignment film 18 covering the pixel electrode 15R provided on the element substrate 10 and the alignment film 29 covering the common electrode 23 provided on the counter substrate 20 are inorganic alignment obtained by oblique deposition of SiO ₂ as an inorganic material. It is a membrane.
The pixel electrode 15R is made of a highly reflective conductive material such as aluminum (Al) or silver (Ag). The alignment film 18 may be formed after the surface of the pixel electrode 15 </ b> R facing the liquid crystal layer 50 is covered with an insulating film in consideration of the influence of the ionic component that the conductive material gives to the liquid crystal layer 50.

The deposition angle θb of oblique deposition with respect to the substrate surface is 45 °. Although not shown in the drawing, the angle θa of the planar deposition direction with respect to the substrate surface is 45 ° with respect to the extending direction of the scanning line 3a. The column angle θc at which the SiO ₂ crystal grows by oblique deposition is 70 ° with respect to the substrate surface.

  The element substrate 10 and the counter substrate 20 are disposed to face each other with an interval of about 1.8 μm, and a liquid crystal having a negative dielectric anisotropy (birefringence index Δn is 0.12) is filled between the element substrate 10 and the counter substrate 20. Is configured.

  The liquid crystal molecules LC are initially aligned with a pretilt applied to the alignment film surfaces of the alignment films 18 and 29, and the pretilt angle θp is approximately 85 °. The azimuth angle direction of the pretilt is the same as the planar deposition direction in the oblique deposition of the alignment films 18 and 29, and is inclined by 45 ° with respect to the scanning line 3a.

  An inorganic phase difference plate 202 as a uniaxial birefringent body and a wire grid polarizing plate 203 as a reflective polarizing element are provided on the light incident side and the light exit side of the reflective liquid crystal panel 210. The inorganic phase difference plate 202 is provided in parallel with the counter substrate 20. The wire grid polarizing plate 203 is provided so as to intersect at a 45 ° angle with respect to a system optical axis L of a liquid crystal projector 1500 to be described later to which the liquid crystal device 200 of the present embodiment is applied (see FIG. 21). The reflective polarizing element may be a polarizing beam splitter.

  As shown in FIG. 16, the front phase difference of the liquid crystal layer 50 in the liquid crystal device 200 of the present embodiment is based on the thickness of the liquid crystal layer 50 and the birefringence of the liquid crystal, and the pretilt angle θp of the liquid crystal molecules LC is 85 °. Since it is set, it is about 1.5 nm.

  Therefore, in this embodiment, the thickness of each of the alignment films 18 and 29 is set to about 170 nm in order to optically compensate the viewing angle of the liquid crystal layer 50 in the viewing angle. When the film thickness is 170 nm, the front phase difference of the alignment films 18 and 29 is approximately 0.75 nm (see FIG. 7). That is, the value is ½ of the front phase difference of the liquid crystal layer 50. As described in the first embodiment, when viewed from the normal direction of the substrate surface, the azimuth direction of the pretilt of the liquid crystal molecules LC is the azimuth angle in which the growth direction of the columns of the alignment films 18 and 29 is projected onto the substrate surface. Since it is parallel to the direction and is orthogonal to the direction of the slow axis of the alignment films 18 and 29, the phase difference between the two is canceled out. That is, the alignment films 18 and 29 also serve as an optical compensation layer that optically compensates for the front phase difference of the liquid crystal layer 50.

  The phase difference of the inorganic phase difference plate 202 is given by (nx′−nz ′) × thickness, and in this case, it is 220 nm. This compensated for the phase difference of the light transmitted obliquely through the liquid crystal layer 50.

As shown in FIG. 17A, in the liquid crystal device 200, the region where the maximum contrast ratio can be obtained is located in the front, and spreads almost evenly in the vertical and horizontal directions with respect to the front. The contrast ratio (C, R) when this liquid crystal device was projected by a projector was approximately 14900.
On the other hand, in the comparative example in which the alignment films 18 and 29 have a thickness of about 20 nm and do not serve as an optical compensation layer, as shown in FIG. It was not located, and its projection contrast ratio (CR) was about 2300.

  The reflective liquid crystal device 200 originally has a self-compensation structure in view angle characteristics because incident light and reflected light are applied to the liquid crystal molecules LC which are pre-tilted and substantially vertically aligned. Therefore, compared with the transmission type liquid crystal device 100 of the first embodiment, the comparative example has a wide viewing angle range in which a high contrast ratio can be obtained. However, by applying the present invention, a higher contrast ratio can be obtained over a wide viewing angle. Is obtained. That is, the application to the reflective liquid crystal device 200 is more effective than the application to the transmissive liquid crystal device 100.

(Fifth embodiment)
Next, another application example of the reflective liquid crystal device of this embodiment will be described with reference to FIGS. 18 is a schematic sectional view showing the structure of the liquid crystal device of the fifth embodiment, FIG. 19 is a graph showing the relationship between the tilt angle of the uniaxial birefringent body and the front phase difference, and FIG. 20 is the liquid crystal of the fifth embodiment. It is an isocontrast curve which shows the viewing angle characteristic of an apparatus.
The liquid crystal device of the fifth embodiment is obtained by reviewing the thickness of the inorganic alignment film and the arrangement of the uniaxial birefringent body with respect to the fourth embodiment. Therefore, the same components as those in the fourth embodiment are denoted by the same reference numerals and detailed description thereof is omitted.

As shown in FIG. 18, the liquid crystal device 250 of the present embodiment includes a reflective liquid crystal panel 210 including a liquid crystal layer 50 sandwiched between the element substrate 10 and the counter substrate 20. The alignment film 18 covering the pixel electrode 15R having light reflectivity provided on the element substrate 10 and the alignment film 29 covering the common electrode 23 provided on the counter substrate 20 are formed by obliquely depositing SiO ₂ as an inorganic material. It is the obtained inorganic alignment film. The film thickness is set to be about 10% thinner than 170 nm of the fourth embodiment, which is 150 nm. The front phase difference of the alignment films 18 and 29 when the film thickness is 150 nm is approximately 0.7 nm (see FIG. 7). That is, with respect to 1.5 nm which is the front phase difference of the liquid crystal layer 50 based on the thickness 1.8 μm of the liquid crystal layer 50, the birefringence Δn = 0.12, and the pretilt angle θp (approximately 85 °) of the liquid crystal molecules LC. There is a shortage of 0.1 nm.

An inorganic phase difference plate 202 and a wire grid polarizer 203 are provided on the light incident side and the light emitting side of the reflective liquid crystal panel 210.
In the present embodiment, the front phase difference that is insufficient in optical viewing angle compensation is compensated by disposing the inorganic retardation plate 202 that is a uniaxial birefringent body so as to be inclined with respect to the liquid crystal panel 210.

  Specifically, as shown in FIG. 19, the front phase difference can be set to 0.1 nm by setting the inclination angle θd of the inorganic phase difference plate 202 to approximately 2 °.

  The film thickness of each of the alignment films 18 and 29 is set to a film thickness (150 nm) smaller than the film thickness value (170 nm) indicating the optimum value in optical viewing angle compensation. It was hard to be influenced by. Specifically, the film thickness during oblique deposition was set not to exceed 170 nm.

  According to such a liquid crystal device 250, as shown in FIG. 20, the region where the maximum contrast ratio can be obtained is located on the front side, and spreads almost evenly vertically and horizontally with respect to the front side. The projection contrast ratio (C, R) was approximately 14800. That is, the same operation and effect as in the fourth embodiment are achieved, and the effect of variations in the thickness of the alignment films 18 and 29 is reduced, thereby realizing stable viewing angle compensation.

  In the liquid crystal device 250 of the present embodiment, even if the inclination angle θd of the inorganic retardation plate 202 is set to −2 °, the projected contrast ratio (C, R) is an isocontrast curve substantially the same as that shown in FIG. 14300 is obtained. This is also considered to be derived from the reflection type self-compensation structure.

(Sixth embodiment)
<Electronic equipment>
Next, an example of another projection type display device as the electronic apparatus of this embodiment will be described. FIG. 21 is a diagram illustrating a configuration of a three-plate reflective liquid crystal projector which is an example of a projection display device as an electronic apparatus according to the sixth embodiment. In addition, the same code | symbol is attached | subjected to the same structure as 3rd Embodiment, and detailed description is abbreviate | omitted.

  As shown in FIG. 21, a liquid crystal projector 1500 which is another projection type display device of the present embodiment includes a polarization illumination device 1100 arranged along the system optical axis L, three dichroic mirrors 1111, 1112 and 1115. Two reflection mirrors 1113, 1114, reflection type liquid crystal light valves 1250, 1260, 1270 as three light modulation elements, a cross dichroic prism 1206, and a projection lens 1207 are provided.

The polarized light beam emitted from the polarization illumination device 1100 is incident on the dichroic mirror 1111 and the dichroic mirror 1112 which are arranged orthogonal to each other. A dichroic mirror 1111 serving as a light separation element reflects red light (R) in the incident polarized light flux. The dichroic mirror 1112 as the other light separation element reflects green light (G) and blue light (B) in the incident polarized light flux.
The reflected red light (R) is reflected again by the reflection mirror 1113 and enters the liquid crystal light valve 1250. On the other hand, the reflected green light (G) and blue light (B) are reflected again by the reflection mirror 1114 and enter the dichroic mirror 1115 as a light separation element. The dichroic mirror 1115 reflects green light (G) and transmits blue light (B). The reflected green light (G) enters the liquid crystal light valve 1260. The transmitted blue light (B) enters the liquid crystal light valve 1270.

The liquid crystal light valve 1250 includes a reflective liquid crystal panel 1251, an inorganic retardation plate 1252 as a uniaxial birefringent body, and a wire grid polarizer 1253 as a reflective polarizing element.
The liquid crystal light valve 1250 is arranged so that the red light (R) reflected by the wire grid polarizer 1253 is perpendicularly incident on the incident surface of the cross dichroic prism 1206. Further, an auxiliary polarizing plate 1254 that compensates for the degree of polarization of the wire grid polarizing plate 1253 is disposed on the red light (R) incident side of the liquid crystal light valve 1250, and another auxiliary polarizing plate 1255 is disposed on the red light (R) emission side. Are arranged along the incident surface of the cross dichroic prism 1206. In the case where a polarizing beam splitter is used as the reflective polarizing element, the pair of auxiliary polarizing plates 1254 and 1255 can be omitted.
The configuration of the reflective liquid crystal light valve 1250 and the arrangement of the components are the same in the other reflective liquid crystal light valves 1260 and 1270.

  Each color light incident on the liquid crystal light valves 1250, 1260, 1270 is modulated based on the image information, and again enters the cross dichroic prism 1206 via the wire grid polarizers 1253, 1263, 1273. In the cross dichroic prism 1206, the color lights are combined, and the combined light is projected onto the screen 1300 by the projection lens 1207, and the image is enlarged and displayed.

  In the present embodiment, the liquid crystal device 250 of the fifth embodiment is applied as the liquid crystal light valves 1250, 1260, 1270. In other words, the liquid crystal panels 1251, 1261, 1271 are substantially vertically aligned in a state where liquid crystal molecules having negative dielectric anisotropy are given a pretilt with respect to the substrate surface. The pretilt angle θp is approximately 85 °. Moreover, it has the inorganic alignment film formed by oblique vapor deposition facing the liquid crystal layer, and the film thickness of an inorganic alignment film is about 150 nm. With the inorganic alignment film that also serves as the optical compensation layer, the front phase difference of the liquid crystal layer due to the pretilt of the liquid crystal molecules is optically compensated for viewing angle.

  The inorganic phase difference plates 1252, 1262, and 1272 each have a phase difference of 220 nm, and are inclined to the surfaces of the liquid crystal panels 1251, 1261, and 1271 on the incident side and the emission side of the colored light. Since the front phase difference of the liquid crystal layer depends on the wavelength of the color light transmitted through the liquid crystal layer, the inclination angle θd of the inorganic phase difference plates 1252, 1262 and 1272 is set based on the wavelength of green light (G) (550 nm). In this embodiment, the green light (G) has a wavelength of about 2 °, the red light (R) having a longer wavelength than the green light (G) has a wavelength of about 2.1 °, and the green light (G) has a shorter wavelength. For blue light (B), the angle is set to 1.7 °.

Further, the green light (G) modulated by the liquid crystal light valve 1260 goes straight to the cross dichroic prism 1206, and the red light (R) modulated by the liquid crystal light valve 1250 and the liquid crystal light valve 1270. The modulated blue light (B) is reflected with the left and right sides of the image reversed by the dielectric multilayer film. Therefore, the optical conditions are set corresponding to the color light so that the combined light does not cause coloring due to the viewing angle characteristics of the liquid crystal light valves 1250, 1260, and 1270. Specifically, with respect to the pretilt direction of the liquid crystal molecules in the green light (G) liquid crystal panel 1261, the liquid crystal molecules in the other red light (R) liquid crystal panel 1251 and the blue light (B) liquid crystal panel 1271 The inorganic alignment film is formed by reversing the planar vapor deposition direction of oblique vapor deposition by 180 ° so that the pretilt direction is reversed.
Therefore, when the inclination angle θd of the liquid crystal light valve 1260 corresponding to green light (G) with respect to the liquid crystal panel 1261 is 2 °, the inorganic phase difference plate 1252 that apparently transmits red light (R). The tilt angle θd is −2.1 °, and the tilt angle θd of the inorganic retardation plate 1272 through which the blue light (B) is transmitted is −1.7 °.

  According to such a liquid crystal projector 1500, the reflective liquid crystal light valves 1250, 1260, and 1270 provided for each color light correspond to the wavelength of the color light that transmits the front phase difference of the liquid crystal layer due to the pretilt of the liquid crystal molecules. Since the viewing angle is optically compensated, a high-contrast image display can be obtained over a wider viewing angle than the conventional one. Compared with the transmissive liquid crystal projector 1000 of the third embodiment described above, high contrast image display is realized.

  The liquid crystal device applied to the liquid crystal light valves 1250, 1260, 1270 of the liquid crystal projector 1500 is not limited to the liquid crystal device 250 of the fifth embodiment, and the liquid crystal device 200 of the fourth embodiment is also applied. Good.

  Various modifications other than the above embodiment are conceivable. Hereinafter, a modification will be described.

  (Modification 1) In the first and second embodiments and the fourth and fifth embodiments, the method of forming the alignment films 18 and 29 is not limited to oblique deposition. For example, even if formed by oblique sputtering, a pretilt can be given to the liquid crystal molecules LC having negative dielectric anisotropy. An example of a more specific method for forming an inorganic alignment film by oblique sputtering is disclosed in Japanese Patent Application Laid-Open No. 2004-170744.

  (Modification 2) In the third embodiment, the inorganic phase difference plates 1212, 1222, and 1232 are not limited to changing the inclination angle θd for each color light. The inclination angle θd of the inorganic phase difference plate 1222 may be set on the basis of the green light (G) having the highest visibility, and the other inorganic phase difference plates 1212 and 1232 may have the same inclination angle θd. This makes it relatively easy to adjust the tilt angle θd. Similarly in the sixth embodiment, the inclination angle θd of the inorganic retardation plates 1252, 1262, 1272 may be constant.

  (Modification 3) The uniaxial birefringent body is not limited to an inorganic retardation plate in which a high refractive index layer and a low refractive index layer are laminated. For example, what was comprised using resin materials, such as a polycarbonate and polyvinyl alcohol, may be used. According to this, the organic phase difference plate as a uniaxial birefringent body cheaper than an inorganic phase difference plate can be provided.

  (Modification 4) The electronic apparatus to which the liquid crystal device 100 and the liquid crystal device 150 are applied is not limited to the liquid crystal projector 1000 of the third embodiment. For example, a projection-type HUD (head-up display), a direct-view HMD (head-mounted display), an electronic book, a personal computer, a digital still camera, an LCD TV, a viewfinder-type or monitor-direct-view video recorder, car navigation It can be suitably used as a display unit of an information terminal device such as a system, electronic notebook, or POS. The same applies to the liquid crystal device 200 and the liquid crystal device 250.

  DESCRIPTION OF SYMBOLS 10 ... Element board | substrate of a pair of board | substrates, 15R ... Pixel electrode which has light reflectivity, 18, 29 ... Alignment film | membrane as an inorganic alignment film, 20 ... Opposite board | substrate as one board | substrate of a pair of board | substrates, 23 ... Common electrode, 42 ... Inorganic retardation plate as uniaxial birefringent body, 50 ... Liquid crystal layer, 100, 150, 200, 250 ... Liquid crystal device, 202 ... Inorganic retardation plate, 1000, 1500 ... Projection type display device Liquid crystal projector as 1101, Lamp unit as light source, 1104, 1105, 1111, 1112, 1115 ... Dichroic mirror as light separating element, 1206 ... Cross dichroic prism as light combining element, 1210, 1220, 1230, 1250, 1260 , 1270 ... Liquid crystal light valves as light modulation elements, 1212, 1222, 1232 1252,1262,1272 ... inorganic phase difference plate.

Claims (7)

A first substrate;
A second substrate disposed to face the first substrate;
A liquid crystal layer disposed between the first substrate and the second substrate and having negative dielectric anisotropy;
A first alignment film disposed between the first substrate and the liquid crystal layer and including a plurality of columns;
A second alignment film that is disposed between the second substrate and the liquid crystal layer and includes a plurality of columns ;
The liquid crystal of the liquid crystal layer is aligned with a pretilt so that the major axis direction is the first direction,
The first substrate and the second substrate, each of the extending direction of the plurality of columns of the first alignment layer, the same second direction and each of the extending direction of the plurality of columns of the second alignment layer Arranged as
The liquid crystal layer is arranged so that a direction of a slow axis that is a direction orthogonal to the second direction and the first direction are orthogonal to each other in a plan view as viewed from the normal direction of the first substrate. A liquid crystal device characterized by that. The liquid crystal device according to claim 1,
An angle formed by the first substrate and the first direction is an angle of 85 ° ± 1 °. The liquid crystal device according to claim 1 or 2,
The liquid crystal device according to claim 1, wherein a thickness of the first alignment film and a thickness of the second alignment film are each 20 nm or more. The liquid crystal device according to any one of claims 1 to 3 ,
A liquid crystal device, wherein a uniaxial birefringent body is further provided on a side of the first substrate opposite to the liquid crystal layer. The liquid crystal device according to claim 4 .
The liquid crystal device according to claim 1, wherein the uniaxial birefringent body is an inorganic retardation plate in which high refractive index layers and low refractive index layers are alternately laminated. The liquid crystal device according to any one of claims 1 to 5 ,
A pixel electrode having light reflectivity disposed between the first substrate and the first alignment layer;
A liquid crystal device comprising: a common electrode having optical transparency disposed between the second substrate and the second alignment film. An electronic apparatus comprising the liquid crystal device according to any one of claims 1 to 6.

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