JP2006178302A - Liquid crystal cell driven by lateral electric field - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal cell driven by lateral electric field in which the aperture ratio is more heightened than that in a conventional liquid crystal cell driven by lateral electric field. <P>SOLUTION: The liquid crystal cell driven by lateral electric field is equipped with a pair of transparent substrates 1, 2 placed opposite to each other, a plurality of transparent members 4 arranged between the transparent substrates 1, 2, transparent electrodes 5a, 5b mounted on at least side faces of the transparent members 4, a liquid crystal 3 sandwiched and held between the transparent substrates 1, 2 and the transparent electrodes 5a, 5b, and a sealing materials 6, and has a construction in which each of the transparent members 4 is arranged on a contact face of at least one transparent substrate 1 and has a nearly constant shape of a cross-section in a direction vertical to the transparent member contact face, and the transparent electrodes 5a, 5b are electrically connected so as to apply a lateral electric field to the liquid crystal between mutually adjacent transparent electrodes 5a, 5b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a horizontal electric field drive liquid crystal cell in which an electric field in a direction parallel to a substrate (hereinafter referred to as a horizontal electric field) is applied to liquid crystal in the cell to control the alignment direction of the liquid crystal.

  2. Description of the Related Art Conventionally, a vertical electric field driving liquid crystal cell that controls an alignment direction of liquid crystal by applying an electric field in a direction perpendicular to a substrate (hereinafter referred to as a vertical electric field) to the liquid crystal in the cell is a notebook personal computer, a portable game machine, It is used as a thin and light display unit with low power consumption in various electronic devices such as electronic notebooks. However, in such a vertical electric field drive liquid crystal cell, the optical characteristics change depending on the viewing angle (hereinafter referred to as viewing angle) due to the presence of a state in which the liquid crystal is obliquely oriented with respect to the substrate. There is a problem of causing a decrease in contrast.

  In order to solve such a problem, a lateral electric field drive liquid crystal cell has been developed (see, for example, Patent Document 1 and Patent Document 2). In the method of controlling the alignment direction of the liquid crystal by applying a horizontal electric field to the liquid crystal in the cell, the alignment direction changes in a plane substantially parallel to the substrate by applying the horizontal electric field. There is no problem that the optical characteristics change depending on the viewing angle.

In the so-called IPS (In-Plane Switching) technology, a plurality of electrodes arranged separately for each pixel are provided on one substrate surface of a substrate sandwiching a TN (Twisted Nematic) liquid crystal or the like. In this configuration, a horizontal electric field can be applied to a predetermined portion between the electrodes, and light passing through the electrodes in a direction perpendicular to the substrate is shielded. This is because a vertical electric field component is generated in addition to the horizontal electric field in the direction perpendicular to the substrate on the electrode, and the light to be shielded by the vertical electric field component is prevented from leaking.
JP 2000-27602 A JP 2004-184967 A

  However, such a conventional lateral electric field driving liquid crystal cell has been developed from the viewpoint of improving the viewing angle dependency in the application of the liquid crystal display device, and therefore, the light passing through the region other than the main region is shielded from light. Therefore, there is a problem that an effective ratio (aperture ratio) of a region through which light passes is small. Such a small aperture ratio is a serious problem in optical components such as a wavelength tunable filter using liquid crystal and a diffraction efficiency variable element, leading to a decrease in light use efficiency.

  The present invention has been made to solve such problems, and provides a lateral electric field driving liquid crystal cell capable of improving the aperture ratio as compared with a conventional lateral electric field driving liquid crystal cell.

  In view of the above points, the invention according to claim 1 is provided on a predetermined surface of the transparent member, a pair of transparent substrates opposed to each other, a plurality of transparent members provided between the opposed transparent substrates. A transparent electrode, a pair of the transparent substrates, and a plurality of the transparent members or a liquid crystal sandwiched between the transparent electrodes, each transparent member facing each other of the transparent substrates The at least one of the opposing substrate surfaces is provided on a transparent member contact surface parallel to the opposing substrate surface of the transparent substrate, and has a substantially constant cross-sectional shape in a direction perpendicular to the transparent member contact surface. The transparent electrode is provided on at least the side surface of the transparent member, and is electrically connected so that a lateral electric field can be applied to the liquid crystal between the adjacent transparent electrodes.

  With this configuration, each transparent member has a substantially constant cross-sectional shape in a direction perpendicular to the transparent member contact surface, the transparent electrode is provided on at least the side surface of the transparent member, and the liquid crystal is horizontally disposed between the adjacent transparent electrodes. Since it is electrically connected so that an electric field can be applied, a lateral electric field can be applied effectively, and light passes through a transparent member and a transparent electrode, so that the aperture ratio is improved over conventional lateral electric field drive liquid crystal cells. It is possible to realize a horizontal electric field drive liquid crystal cell that can be formed.

  The invention according to claim 2 is the structure according to claim 1, wherein each of the transparent members has a columnar shape, and a central axis of the columnar shape faces a direction perpendicular to the transparent member contact surface. Have.

  With this configuration, in addition to the effect of claim 1, each transparent member has a columnar shape, so that it can be arranged in a lattice shape having a two-dimensional periodicity, and as a result, the area to which a lateral electric field can be applied is further increased. Therefore, in a predetermined application such as a wavelength tunable filter, a lateral electric field drive liquid crystal cell that can further improve the aperture ratio or the like can be realized.

  According to a third aspect of the present invention, in the first aspect, each of the transparent members has a rectangular parallelepiped shape and is periodically arranged to form a partition-like lattice.

  With this configuration, in addition to the effect of the first aspect, each transparent member has a rectangular parallelepiped shape, and is periodically arranged to form a partition-like grating. Therefore, as a diffraction grating with high light utilization efficiency, A horizontal electric field drive liquid crystal cell can be realized.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein each of the transparent members has a cross section in a direction away from the transparent member contact surface of the transparent substrate on which the transparent member is provided. The structure has a taper so that the area of the shape is small.

  According to this configuration, in addition to the effect of any one of claims 1 to 3, each transparent member has a reduced cross-sectional area in a direction away from the transparent member contact surface of the transparent substrate on which the transparent member is provided. Therefore, it is possible to realize a lateral electric field drive liquid crystal cell capable of facilitating a manufacturing process such as deposition of a conductive film.

  The invention according to claim 5 has a configuration according to any one of claims 1 to 4, wherein at least the refractive index of the transparent member is substantially equal to the ordinary light refractive index or the extraordinary light refractive index of the liquid crystal. ing.

  With this configuration, in addition to the effect of any one of claims 1 to 4, at least the refractive index of the transparent member is substantially equal to the ordinary light refractive index or the extraordinary light refractive index of the liquid crystal. In applications, it is possible to realize a horizontal electric field driving liquid crystal cell capable of ensuring a function of transmitting light or a function of diffracting without applying a horizontal electric field.

  The invention according to claim 6 is the invention according to any one of claims 1 to 4, wherein at least the refractive index of the transparent member is between the ordinary light refractive index and the extraordinary light refractive index of the liquid crystal. The structure has a refractive index of the value.

  With this configuration, in addition to the effect of any one of claims 1 to 4, at least the refractive index of the transparent member has a refractive index of any value between the ordinary light refractive index and the extraordinary light refractive index of the liquid crystal. Therefore, in a predetermined application such as a wavelength tunable filter, it is possible to realize a horizontal electric field drive liquid crystal cell that can suppress stray light, scattered light, and the like when transmitting light and can further improve the light use efficiency. .

  The invention according to claim 7 has a configuration in which the plurality of transparent members are periodically arranged on the transparent member contact surface to form a lattice in any one of claims 1 to 6. Yes.

  According to this configuration, in addition to the effect of any one of claims 1 to 6, a plurality of transparent members are periodically arranged on the transparent member contact surface to form a lattice. It is possible to realize a lateral electric field drive liquid crystal cell capable of performing a wiring process that can apply an electric field to the substrate.

  The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein the plurality of transparent members are distributed on the transparent member contact surfaces of the two transparent substrates. It has a configuration.

  According to this configuration, in addition to the effect of any one of claims 1 to 7, a plurality of transparent members are distributed and formed on the transparent member contact surfaces of the two transparent substrates. The tip and bottom of the formed transparent electrode are opposed to each other, and the relative electrode arrangement is different from the case where the tips are opposed to each other, and the electric field components other than the transverse electric field generated near the tip of the transparent member are A lateral electric field drive liquid crystal cell that can be reduced can be realized.

  The invention according to claim 9 is the structure according to claim 8, wherein the relative arrangement of the plurality of transparent members distributed and formed on each transparent substrate is the same between the two transparent substrates. have.

  According to this configuration, in addition to the effect of the eighth aspect, the relative arrangement of the plurality of transparent members distributed and formed on each transparent substrate is the same between the two transparent substrates. It is possible to realize a lateral electric field drive liquid crystal cell capable of facilitating processes such as formation of electrodes and wiring, alignment processing, and the like.

  In a tenth aspect of the present invention, the liquid crystal is a cholesteric liquid crystal according to any one of the first to ninth aspects, and the spiral axis of the cholesteric liquid crystal is substantially perpendicular to the contact surface of the transparent member. It has the structure which is orientated.

  According to this configuration, in addition to the effect of any one of claims 1 to 9, the helical axis of the cholesteric liquid crystal is aligned in a direction substantially perpendicular to the transparent member contact surface, so that the helical pitch is selected. Accordingly, it is possible to realize a horizontal electric field drive liquid crystal cell capable of selectively reflecting light corresponding to the pitch.

  In an eleventh aspect of the present invention, the cholesteric liquid crystal according to the tenth aspect includes a liquid crystal exhibiting a chiral smectic C phase.

  With this configuration, in addition to the effect of the tenth aspect, since the cholesteric liquid crystal includes a liquid crystal exhibiting a chiral smectic C phase, the helical pitch can be controlled at a high speed and a low voltage by applying a lateral electric field, and the light is transmitted with good controllability. A transverse electric field drive liquid crystal cell capable of changing the wavelength of light can be realized.

  The invention according to claim 12 has a configuration in which a plurality of lateral electric field drive liquid crystal cells according to any one of claims 1 to 11 are stacked.

  According to this configuration, in addition to the effect of any one of claims 1 to 11, a plurality of the transverse electric field drive liquid crystal cells according to any one of claims 1 to 10 are stacked. A lateral electric field drive liquid crystal cell capable of further improving optical performance can be realized.

  According to a thirteenth aspect of the present invention, in the twelfth aspect, the transparent members of the stacked horizontal electric field drive liquid crystal cells are not overlapped with each other of the stacked horizontal electric field drive liquid crystal cells. The lateral electric field driving liquid crystal cells are stacked.

  According to this configuration, in addition to the effect of the twelfth aspect, each horizontal electric field driving liquid crystal is arranged so that the transparent members of the stacked horizontal electric field driving liquid crystal cells do not overlap each other between the stacked horizontal electric field driving liquid crystal cells. Since the cells are stacked, it is possible to realize a lateral electric field drive liquid crystal cell that can reduce unevenness in contrast.

  In the present invention, each transparent member has a substantially constant cross-sectional shape in a direction perpendicular to the contact surface of the transparent member, the transparent electrode is provided on at least the side surface of the transparent member, and the liquid crystal is horizontally disposed between the adjacent transparent electrodes. Since it is electrically connected so that an electric field can be applied, a lateral electric field can be applied effectively, and light passes through a transparent member and a transparent electrode, so that the aperture ratio is improved over conventional lateral electric field drive liquid crystal cells. It is possible to provide a horizontal electric field drive liquid crystal cell having an effect of being able to be made.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
Hereinafter, the case where the lateral electric field drive liquid crystal cell of the present invention is applied to a diffraction efficiency variable element having variable diffraction efficiency will be described. FIG. 1 is a side sectional view showing a conceptual configuration of a lateral electric field drive liquid crystal cell according to a first embodiment of the present invention. In FIG. 1, a horizontal electric field drive liquid crystal cell 100 includes a pair of opposed transparent substrates 1 and 2, a plurality of transparent members 4 provided between the opposed transparent substrates 1 and 2, and a predetermined surface of the transparent member 4. Transparent electrodes 5a and 5b, a pair of transparent substrates 1 and 2 and a plurality of transparent members 4 or transparent electrodes 5a and 5b, and a liquid crystal 3 sandwiched between the transparent electrodes 5a and 5b.

  In FIG. 1, glass substrates are preferable as the transparent substrates 1 and 2 in terms of durability, reliability, and the like. However, since it is lightweight and inexpensive, an organic resin such as an acrylic resin, an epoxy resin, a vinyl chloride resin, or polycarbonate may be used.

  The transparent member 4 is a counter substrate surface of at least one transparent substrate (hereinafter referred to as the transparent substrate 1) of the substrate surfaces (hereinafter referred to as counter substrate surfaces) of the transparent substrates 1 and 2 facing each other. Is an optical member having a substantially constant cross-sectional shape in a direction perpendicular to the transparent member contact surface. Here, when the transparent substrates 1 and 2 are partially removed by etching or the like when the transparent member 4 is formed, the transparent member contact surface is located on the inner side of the transparent substrates 1 and 2 than the counter substrate surface and is transparent. When a thin film or the like for the transparent member 4 remains between the counter substrate surface and the transparent member after the member 4 is formed, the transparent member contact surface is positioned inside the transparent substrates 1 and 2 with respect to the counter substrate surface.

  Hereinafter, in order to ensure the function as a diffraction element, the transparent member 4 has a rectangular cross-sectional shape provided in a direction substantially perpendicular to the transparent member contact surface as shown in FIG. And a rectangular parallelepiped structure extending in a direction perpendicular to the longitudinal direction (hereinafter referred to as a longitudinal direction). The transparent member 4 is periodically arranged on the transparent member contact surface of the transparent substrate 1 in a direction perpendicular to the longitudinal direction of the transparent member 4 to form a stripe-like lattice. Hereinafter, the length of the transparent member 4 in the direction parallel to the transparent member contact surface of the transparent substrate 1 is referred to as the width of the transparent member 4, and the length of the transparent member 4 in the direction perpendicular to the transparent member contact surface is the length of the transparent member 4. The height is referred to as a direction perpendicular to the longitudinal direction of the transparent member 4 and parallel to the transparent member contact surface.

For the transparent member 4, for example, inorganic materials such as SiO ₂ , SiO _x N _y , Al ₂ O ₃ , Ta ₂ O ₅ , or organic materials such as polyimide are used. The transparent member 4 is formed by etching a thin film such as SiO ₂ or SiO _x N _y formed on the transparent substrate 1, but Al ₂ is formed on the resist pattern or the like formed on the transparent substrate 1. It may be formed by depositing and lifting off a thin film such as O ₃ .

Here, it is preferable to use the inorganic material as the material of the transparent member 4 from the viewpoints of heat resistance, reliability, and the like. In particular, the etching can be appropriately performed using the difference in etching rate with glass, and the deposition of a thin film with a uniform thickness is easy, so that the height of the transparent member 4 can be made uniform. In particular, using SiO ₂ or SiO _x N _y makes it easy to form a desired shape because etching is easy. In addition, it is preferable to use the above organic material as the material of the transparent member 4 because the film can be easily formed at low cost.

  Here, the ratio of the width of the transparent member 4 to one period of the lattice (hereinafter referred to as the transparent member width ratio) is preferably 0.5 or less, particularly in the range of 0.25 to 0.5. It is preferable to be within. In the vicinity of the surface of the transparent member 4 facing the transparent member contact surface of the transparent substrate 1 provided with the transparent member 4 (hereinafter referred to as an end surface of the transparent member 4), the effects of the transparent member 4 and the transparent electrodes 5a and 5b are affected. Accordingly, it is difficult to control the alignment direction of the liquid crystal in a desired direction. Therefore, in order to appropriately change the diffraction efficiency, the transparent member width ratio is preferably set to 0.5 or less. On the other hand, if the transparent member width ratio is too small, the ratio of the change in diffraction efficiency with respect to the change in the alignment direction of the liquid crystal is lowered. As a result, the transparent member width ratio is preferably in the range of 0.25 to 0.5.

  Making the height of the transparent member 4 approximately the same as the cell gap of the lateral electric field driving liquid crystal cell 100 means a gap between the end surface of the transparent member 4 and the opposite substrate surface of the transparent substrate 2 (hereinafter referred to as a substrate transparent member gap). Since the liquid crystal 3 entering can be reduced, the ratio of the liquid crystal in the portion where the electric field having the vertical electric field component is generated in the optically effective region can be reduced, and the lateral electric field can be efficiently applied to the liquid crystal.

  The transparent electrodes 5a and 5b are formed on at least a surface (hereinafter referred to as a side surface of the transparent member) substantially perpendicular to the transparent member contact surface of the transparent substrate 1 of the transparent member 4. Further, the transparent electrodes 5a and 5b formed on the two opposing side surfaces of the same transparent member 4 are electrically connected by the conductive material provided on the end surface of the transparent member 4 or the transparent member contact surface of the transparent substrate 1. It is connected. Moreover, as shown in FIG. 1, the transparent electrode 5a and the transparent electrode 5b have a configuration in which every other transparent electrode is placed between each other, and the transparent electrode 5a and the transparent electrode 5b are transparent between the transparent electrode 5a and the transparent electrode 5b. A lateral electric field parallel to the member contact surface is applied. Such a configuration eliminates the need for alignment between the opposing transparent substrates, thereby improving productivity.

With this configuration, since the transparent electrodes 5a and 5b to which the horizontal electric field is applied are opposed to each other, the horizontal electric field can be effectively applied to all the liquid crystals 3 positioned between the transparent electrodes 5a and 5b. Here, it is preferable to use a conductive oxide such as ITO or SnO ₂ as the material of the transparent member 4, and the use of ITO is particularly easy because pattern formation by etching is easy, and transmittance and electrical conductivity are high. It is suitable because it is high.

  The transparent electrodes 5a and 5b are formed by a method in which a transparent conductive film is formed on the transparent member 4 and unnecessary portions are removed. Here, the transparent conductive film can be formed by a sputtering method, a vacuum vapor deposition method, or the like. In particular, the sputtering method is preferable because it tends to cause the deposition object to wrap around the side surface of the transparent member 4. It is. This is because sputtering can be performed in an atmosphere at a higher pressure than vapor deposition.

  The patterning of the transparent electrodes 5a and 5b is performed using a lithography technique and an etching technique. Here, since the transparent conductive film is also formed on the transparent member contact surface of the transparent substrate 1 before patterning, the transparent conductive film on the transparent member contact surface of the transparent substrate 1 is used as the transparent electrode to be at the same potential. The transparent electrodes 5a and 5b are patterned so as to be connected. That is, patterning is performed so that the transparent electrodes on the same transparent member 4 are electrically connected and the transparent electrodes on every other transparent member 4 are electrically connected. By patterning in this way, a separate step for connecting the transparent electrodes 5a and 5b as described above can be omitted, which is preferable.

A liquid crystal having a positive dielectric anisotropy Δε (= ε _// −ε _⊥ ) that is aligned in the electric field direction when an electric field is applied is parallel to each transparent electrode, that is, parallel to the electric field direction of the applied electric field. It can be used in such an orientation. On the other hand, a liquid crystal having a negative dielectric anisotropy Δε that is aligned in a direction perpendicular to the electric field direction when an electric field is applied can be used by being aligned so as to be perpendicular to each transparent electrode.

  Among the liquid crystals, a liquid crystal having a positive dielectric anisotropy Δε and oriented in a direction parallel to the surfaces of the transparent electrodes 5a and 5b when no electric field is applied is preferable from the following points. Since the liquid crystal is usually easily oriented in parallel to the surfaces of the transparent electrodes 5a and 5b when no electric field is applied, a liquid crystal having a positive dielectric anisotropy Δε is used to change the orientation direction when an electric field is applied. It is easy to change.

  Hereinafter, when the electric field is not applied to the liquid crystal 3 by an alignment film or the like provided on the transparent member contact surface of the transparent substrate 1 and the opposite substrate surface of the transparent substrate 2 facing the transparent member contact surface of the transparent substrate 1. It is assumed that it is oriented in a direction parallel to the surfaces of the transparent electrodes 5a and 5b. The alignment direction of the liquid crystal 3 can be set by adjusting the rubbing of the alignment film, and can also be set by obliquely depositing SiO or the like, or irradiating an ion beam. Hereinafter, it is assumed that a rubbing-treated alignment film is formed at the interfaces between the transparent electrodes 5 a and 5 b and the transparent member 4 and the liquid crystal 3.

  Further, in order to facilitate orientation in the same direction when an electric field is applied, the rubbing process is performed in a direction inclined by a predetermined tilt angle (hereinafter referred to as a pretilt angle) in the orientation direction at the time of electric field application. Like that. Since the rubbing process for providing the pretilt angle is well known, the description thereof is omitted. By giving a pretilt angle as described above, the occurrence of so-called multi-domains can be suppressed, and uniform liquid crystals aligned in the same direction can be obtained, so that the generation of scattered light is suppressed and uniform optical characteristics are obtained. This is preferable.

  Here, when a cholesteric liquid crystal is used as the liquid crystal 3, it is preferable to use a material having a refractive index that is an intermediate value between the ordinary light refractive index and the extraordinary light refractive index of the cholesteric liquid crystal to be used as the material of the transparent member 4. Use of the material as described above as the material of the transparent member 4 reduces the transmission loss due to diffraction and scattering because the refractive index of the transparent member 4 is close to the effective refractive index of the cholesteric liquid crystal that the incident light senses. This is preferable.

  The sealing material 6 is formed by printing outside the optically effective area of the opposing substrate surface of the transparent substrate 2, and the interval between the transparent substrates 1 and 2 is made constant by bonding the transparent substrate 1 and the transparent substrate 2 together. A liquid crystal cell that holds and seals the liquid crystal 3 between the transparent substrates 1 and 2 is provided. As the sealing material 6, a thermosetting polymer such as an epoxy resin, an ultraviolet curable resin, or the like can be used, and in order to obtain a desired cell interval, a spacer such as a glass fiber is mixed into the sealing material 6 by several percent. Good.

  Further, as shown in FIG. 1, a step (hereinafter referred to as a seal contact portion) where the sealing material 6 outside the optically effective area of the transparent substrate 2 is provided is provided with a step so that the seal contact of the transparent substrate 2 is achieved. It is preferable that the interval between the portion and the transparent member contact surface of the transparent substrate 1 is larger than the interval between the substrate transparent member gaps. By configuring as described above, the control of the gap of the liquid crystal cell can be controlled independently of the height of the transparent member 4, so that the degree of freedom in processing and the controllability of the gap are improved. Further, by adjusting the level difference of the seal contact portion according to the diameter of the spacer to be used, a liquid crystal cell having a narrow substrate transparent member gap can be produced without damaging the transparent electrodes 5a and 5b during thermocompression bonding.

  Hereinafter, an example of the operation of the horizontal electric field drive liquid crystal cell 100 according to the first embodiment of the present invention will be described. FIG. 2 is an explanatory diagram for explaining the operation of the horizontal electric field drive liquid crystal cell 100 according to the first embodiment of the present invention. FIG. 2A is a diagram showing the alignment state of the liquid crystal molecules 31 when no lateral electric field is applied to the liquid crystal 3. In FIG. 2A, the liquid crystal molecules 31 are aligned in a direction parallel to the surfaces of the transparent electrodes 5 a and 5 b, the transparent member contact surface of the transparent substrate 1, and the counter substrate surface of the transparent substrate 2.

  Hereinafter, it is assumed that the refractive index of the transparent member 4 and the ordinary light refractive index of the liquid crystal 3 are substantially the same. When a lateral electric field is not applied to the liquid crystal 3, when linearly polarized light polarized in the lattice orthogonal direction (hereinafter referred to as lattice orthogonally polarized light) enters the lateral electric field driving liquid crystal cell 100, the refractive index of the transparent member 4 and the liquid crystal 3. Therefore, the lattice-polarized light passes through the transverse electric field drive liquid crystal cell 100.

  Next, when a lateral electric field is applied to the liquid crystal 3, the alignment direction of the liquid crystal 3 starts to change toward the lattice orthogonal direction in accordance with the applied lateral electric field, and the lattice orthogonal polarized light incident on the liquid crystal 3 is ordinary light. It begins to diffract, feeling the refractive index changing from the refractive index to the extraordinary light refractive index. When the lateral electric field applied to the liquid crystal 3 is increased, the refractive index approaches the extraordinary light refractive index in accordance with the lateral electric field applied to the liquid crystal 3, so that the diffraction of the lattice-polarized light is applied to the liquid crystal 3. It becomes stronger according to the electric field.

  When the lateral electric field applied to the liquid crystal 3 is further strengthened and the liquid crystal 3 is oriented in the lattice orthogonal direction as shown in FIG. 2B, the lattice orthogonal polarized light is diffracted and substantially not transmitted. In the above, the operation of causing the transverse electric field drive liquid crystal cell 100 to function as a diffraction grating for grating orthogonal polarization light has been described. The lateral electric field driving liquid crystal cell 100 also functions as a diffraction grating for light polarized in the longitudinal direction (hereinafter referred to as longitudinally polarized light). However, the lateral electric field driving liquid crystal cell 100 functions to transmit the longitudinally polarized light when the lateral electric field applied to the liquid crystal 3 is increased, contrary to the lateral electric field dependency on the lattice orthogonally polarized light. As described above, in the above configuration, the transverse electric field drive liquid crystal cell 100 can function as a diffraction element, a blocking filter, or the like with respect to grating orthogonal polarization light and longitudinal polarization light.

  In the above description, the liquid crystal molecules 31 are aligned in a direction parallel to the surfaces of the transparent electrodes 5a and 5b, the transparent member contact surface of the transparent substrate 1, and the opposite substrate surface of the transparent substrate 2 without applying a lateral electric field. However, the present invention is not necessarily limited to such a configuration, and the liquid crystal molecules 31 are not applied to the surface of the transparent electrodes 5a and 5b without applying a lateral electric field. The transparent substrate 1 may be oriented parallel to the transparent member contact surface of the transparent substrate 1 and the opposite substrate surface of the transparent substrate 2.

  In this case, the liquid crystal molecules 31 are applied to the surfaces of the transparent electrodes 5 a and 5 b, the transparent member contact surface of the transparent substrate 1, and the counter substrate surface of the transparent substrate 2 with no lateral electric field applied to the lattice orthogonal polarization light. This works in the same manner as the configuration oriented in the parallel direction, but when the longitudinally polarized light is incident on the transverse electric field driving liquid crystal cell 100, the longitudinally polarized light is transmitted regardless of whether or not the transverse electric field is applied to the liquid crystal 3. Therefore, it can function as an element filter or the like that blocks grating orthogonal polarization light.

  As described above, in the horizontal electric field drive liquid crystal cell according to the first embodiment of the present invention, each transparent member has a substantially constant cross-sectional shape in a direction perpendicular to the transparent member contact surface. Is provided on at least the side surface of the transparent member, and is electrically connected so that a lateral electric field can be applied to the liquid crystal between the adjacent transparent electrodes, so that the lateral electric field can be effectively applied and light is transparent to the transparent member. Since the light is transmitted through the electrodes, the aperture ratio can be improved as compared with the conventional lateral electric field drive liquid crystal cell.

  Moreover, since each transparent member has a rectangular parallelepiped shape and is periodically arranged to form a partition-like grating, a lateral electric field driving liquid crystal cell as a diffraction grating with high light use efficiency can be realized.

  In addition, since at least the refractive index of the transparent member is approximately equal to the ordinary or extraordinary refractive index of the liquid crystal, in applications such as electric field control diffraction gratings, the function of transmitting light without applying a lateral electric field or diffracting is performed. Function can be secured.

  Further, since the plurality of transparent members are periodically arranged on the transparent member contact surface to form a lattice, wiring processing that can apply an electric field between the electrodes can be performed without using a TFT substrate.

  In the above description, an example in which the present invention is applied to a transmissive diffraction element has been described. However, the present invention may be applied to a reflective diffraction element. Such a reflection type diffractive element can be realized by providing a reflection surface in a lateral electric field drive liquid crystal cell so that, in addition to incident light, light reflected by the reflection surface is transmitted through the liquid crystal 3 in a reciprocating manner.

  Further, the lateral electric field drive liquid crystal cell of the present invention may be laminated with a wave plate, a polarizing plate or the like. With this configuration, the polarization direction of incident light can be adjusted by a polarizing plate, a half-wave plate, a quarter-wave plate, and the like, and high contrast can be obtained.

  In addition, the lateral electric field drive liquid crystal cell of the present invention may be configured by stacking a plurality of liquid crystal cells. With this configuration, when the lateral electric field drive liquid crystal cell of the present invention is applied to a diffraction efficiency variable element, a diffraction efficiency variable element having high contrast can be obtained.

  Furthermore, in the above description, the configuration in which the horizontal electric field is directed to the transparent electrode 5a or the transparent electrode 5b has been described. However, the transparent electrodes 5a and 5b are connected to the two transparent members 4 facing each other. It may be separated into portions on the side surfaces and electrically insulated, and wired so that a horizontal electric field in a certain direction can be applied regardless of the type of transparent electrode.

(Second Embodiment)
FIG. 3 is a side sectional view showing a conceptual configuration of a horizontal electric field drive liquid crystal cell according to the second embodiment of the present invention. In FIG. 3, the transparent member constituting the horizontal electric field driving liquid crystal cell 300 is the transparent member 4 constituting the horizontal electric field driving liquid crystal cell according to the first embodiment of the present invention. It has the same configuration as that provided separately on the member contact surface. Hereinafter, among the components of the horizontal electric field drive liquid crystal cell 300 according to the second embodiment of the present invention, the same components as those of the horizontal electric field drive liquid crystal cell 100 according to the first embodiment of the present invention are described. Are given the same reference numerals and their explanation is omitted.

  As shown in FIG. 3, the transparent member 4 a according to the second embodiment of the present invention is provided on the transparent member contact surface of the transparent substrate 1, and the transparent member 4 b is provided on the transparent member contact surface of the transparent substrate 2. . The transparent members 4a and 4b according to the second embodiment of the present invention have the same shape and arrangement as the transparent member 4 according to the first embodiment of the present invention as shown in FIG. Made of materials. That is, the transparent members 4a and 4b according to the second embodiment of the present invention have a rectangular cross-sectional shape provided in a direction substantially perpendicular to the transparent member contact surface, and extend in the longitudinal direction. It is a transparent member having a rectangular parallelepiped structure. The transparent member 4a and the transparent member 4b form a striped lattice.

  However, the transparent members 4a and 4b according to the second embodiment of the present invention may be different in width and height from the transparent member 4 according to the first embodiment of the present invention. In addition, the lattice formed by the transparent members 4a and 4b according to the second embodiment of the present invention includes the lattice formed by the transparent member 4 according to the first embodiment of the present invention, the pitch, the longitudinal direction, and The lengths in the longitudinal direction may be different.

  Here, in order to make the horizontal electric field drive liquid crystal cell 300 according to the second embodiment of the present invention similar to the horizontal electric field drive liquid crystal cell 100 according to the first embodiment of the present invention, a transparent The pitch of each grid formed by the members 4a and 4b needs to be twice the pitch of the grid formed by the transparent member 4.

  The transparent electrode 35a is formed at least on the side surface of the transparent member 4a provided on the transparent substrate 1, and the transparent electrode 35b is formed at least on the side surface of the transparent member 4b provided on the transparent substrate 2. Moreover, the transparent electrode formed on the transparent member provided on the same substrate is electrically connected by the conductive material provided on the end surface of the transparent member or the transparent member contact surface of the transparent substrate.

  In this way, a transparent electrode is formed and electrically connected using a conductive material on the transparent member contact surface of each transparent substrate, whereby the transparent substrate 1 and the transparent substrate 2 are combined to form a lateral electric field drive liquid crystal cell 300. Sometimes a lateral electric field can be applied between the transparent electrode 35a and the transparent electrode 35b. Further, with this configuration, the wiring can be easily formed and the period of the lattice can be doubled, so that it is easy to perform an alignment process such as rubbing.

  FIG. 4 is an explanatory diagram for explaining the operation of the horizontal electric field drive liquid crystal cell 300 according to the second embodiment of the present invention. The lateral electric field according to the first embodiment of the present invention shown in FIG. 2 is the same as that shown in FIG. 4 except that the transparent electrode 35a and the transparent electrode 35b are provided on separate transparent substrates 1 and 2, respectively. Since the configuration is the same as that of the driving liquid crystal cell 100, the operation of the horizontal electric field driving liquid crystal cell 300 according to the second embodiment of the present invention is the same as that of the horizontal electric field driving liquid crystal cell 100 according to the first embodiment of the present invention. This is the same as the operation.

  However, since the transparent electrodes 35a and 35b can be expanded in the vicinity of the transparent members 4a and 4b on the transparent member contact surfaces of the transparent substrates 1 and 2, the end effect that occurs in the vicinity of the end surface of the transparent member as shown in FIG. Can be relaxed. FIG. 5 shows that the edge effect generated in the vicinity of the end face of the transparent member 4 of the horizontal electric field drive liquid crystal cell 100 according to the first embodiment of the present invention is the horizontal electric field drive liquid crystal according to the second embodiment of the present invention. It is a figure which shows notionally a mode that it suppresses in the end surface vicinity of the transparent members 4a and 4b of the cell 300. FIG.

  As described above, the horizontal electric field drive liquid crystal cell according to the second embodiment of the present invention has a plurality of distributed and formed on each transparent substrate in addition to the effects of the first embodiment of the present invention. Since the relative arrangement of the transparent members is the same between the two transparent substrates, the interval between the transparent members can be widened, and the steps such as the formation of electrodes and wiring and the orientation treatment can be facilitated. .

  In addition, since the plurality of transparent members are distributed and formed on the transparent member contact surfaces of the two transparent substrates, the tip and the bottom of the transparent electrode formed on the transparent member are opposed to each other. The relative electrode arrangement is different from the case where the portions face each other, and electric field components other than the transverse electric field generated near the tip of the transparent member can be reduced.

(Third embodiment)
Hereinafter, the case where the lateral electric field drive liquid crystal cell of the present invention is applied to a wavelength tunable filter element in which the wavelength of transmitted light is variable will be described. FIG. 6 is a side sectional view showing a conceptual configuration of a horizontal electric field drive liquid crystal cell according to a third embodiment of the present invention. Hereinafter, among the components of the horizontal electric field drive liquid crystal cell 600 according to the third embodiment of the present invention, the same components as those of the horizontal electric field drive liquid crystal cell 100 according to the first embodiment of the present invention are described. Are given the same reference numerals and their explanation is omitted.

  A lateral electric field drive liquid crystal cell 600 according to the third embodiment of the present invention has a configuration in which a first liquid crystal cell 60 and a second liquid crystal cell 70 are bonded together by an adhesive 7. The first liquid crystal cell 60 includes transparent substrates 1 and 2, a liquid crystal 63, a transparent member 64, transparent electrodes 65 a and 65 b, and a sealing material 6. Similarly, the second liquid crystal cell 70 includes transparent substrates 1 and 2, a liquid crystal 73, a transparent member 74, transparent electrodes 75 a and 75 b, and a sealing material 6.

  The transparent member 64 constituting the first liquid crystal cell 60 has a central axis in the direction perpendicular to the striped lattice and the transparent member contact surface, like the transparent member 4 according to the first embodiment of the present invention. The cross-sectional shape is a shape that can effectively apply a lateral electric field to the liquid crystal 63, such as a circle, polygon, or other cross-sectional columnar shape. Moreover, as a material of the transparent member 64, the material similar to the transparent member 4 which concerns on the 1st Embodiment of this invention can be used. Hereinafter, it is assumed that the transparent member 64 has a columnar shape and is arranged to form a lattice having symmetry of a two-dimensional face-centered structure.

  Here, when the transparent member 64 has, for example, a cylindrical shape, the ratio of the cross-sectional diameter of the transparent member 64 to the shortest period of the lattice is preferably 0.3 or less, and particularly preferably 0.1 or less. Since the transmittance of the portion where the transparent member 64 is formed cannot be changed even when an electric field is applied, the transparent member 64 having such a shape and arrangement can increase the area of the transparent member 64 in the optically effective area. The ratio can be reduced as compared to a striped lattice. Since the transparent member 64 part transmits light in the entire wavelength region, the smaller the proportion of the transparent member 64 part, the better the contrast. In particular, when the above ratio is 0.1 or less, transmission loss due to diffraction and scattering can be reduced even when there is a mismatch in refractive index between the transparent member 64 and the liquid crystal 63.

  The transparent electrodes 65a and 65b constituting the first liquid crystal cell 60 are formed on the side surface of the transparent member 64, and are arranged so as to have, for example, a two-dimensional face-centered square lattice symmetry. That is, when one transparent electrode (hereinafter referred to as transparent electrode 65a) is positioned at the center of the square lattice, the other transparent electrode 65b is positioned at each corner point of the square lattice. The transparent electrode 65a is disposed so as to be surrounded by the transparent electrode 65b at each corner point.

  With this configuration, a lateral electric field can be effectively applied to the liquid crystal 63 by applying an electric field between the transparent electrodes 65a and 65b. Moreover, since the transparent electrodes 65a and 65b are periodically arranged in a lattice, the same kind of transparent electrodes 65a or 65b are arranged in a specific direction, and wiring of the same kind of transparent electrodes can be easily performed. It is not necessary to use a complicated TFT substrate.

  As described in the second embodiment of the present invention, the transparent member 64 and the transparent electrodes 65a and 65b may be distributed and provided on the transparent member contact surfaces of the two transparent substrates 1 and 2 to be opposed. In this case, for example, the transparent member 64 and the transparent electrode 65a at the face center position are provided on the transparent substrate 1 side, and the transparent member 64 and the transparent electrode 65b at the corner position are provided on the transparent substrate 2 side. The transparent electrode may be wired so as to have the same potential every time.

  The second liquid crystal cell 70 has a configuration similar to that of the first liquid crystal cell 60, but when the first liquid crystal cell 60 and the second liquid crystal cell 70 are bonded together, The positions of the transparent member 64 and the transparent electrodes 65a and 65b are arranged so as not to overlap the positions of the transparent member 74 and the transparent electrodes 75a and 75b. By sticking together in this way, the light transmitted through the transparent electrodes 65a and 65b of the first liquid crystal cell 60 can be reflected by the liquid crystal 73 of the first liquid crystal cell 60, and unevenness in the transmission intensity can be reduced. it can.

  The transparent members 64 and 74 are tapered so that the cross-sectional shape becomes smaller in the direction away from the transparent member contact surface of the transparent substrates 1 and 2 on which the transparent members 64 and 74 are provided so that the end surfaces are narrowed. The shape is suitable. By configuring in this way, it becomes easy to deposit thin films of the transparent electrodes 65a, 65b, 75a, 75b on the transparent members 64, 74.

  In the wavelength tunable filter element, unlike the diffraction grating, the transparent members 64 and 74 and the transparent electrodes 65a, 65b, 75a, and 75b only serve as electrodes through which light passes, and have a tapered shape. This is because there is little deterioration of the optical characteristics due to the attachment. Here, it is preferable to set the taper angle to about 5 degrees because the influence on the optical characteristics can be suppressed and deposition of the thin films of the transparent electrodes 65a, 65b, 75a, 75b can be facilitated.

  A cholesteric liquid crystal may be used for the liquid crystals 63 and 73, but a cholesteric liquid crystal including a liquid crystal exhibiting a chiral smectic C phase (hereinafter referred to as a chiral smectic C liquid crystal) changes the helical pitch in accordance with the applied lateral electric field. It is preferable because the wavelength of transmitted light can be easily controlled. Further, the chiral smectic C liquid crystal is preferable because the helical pitch, that is, the wavelength of transmitted light can be controlled by adjusting the amount of the chiral material to be mixed. In addition, since it is a liquid crystal exhibiting a chiral smectic C phase that changes the helical pitch according to the applied lateral electric field, the liquid crystal exhibiting the chiral smectic C phase is contained in applications where the wavelength range of light to be transmitted is wide. It is preferable to increase the amount.

  When cholesteric liquid crystal is used, as the transparent members 64 and 74 and the transparent electrodes 65a, 65b, 75a, and 75b, the refractive index is any value between the ordinary light refractive index and the extraordinary light refractive index of the liquid crystals 63 and 73. In particular, it is preferable to use a material having a value approximately halfway between the ordinary light refractive index and the extraordinary light refractive index of the liquid crystals 63 and 73. By using such a material, since the refractive index is close to the average refractive index of the liquid crystals 63 and 73, transmission loss due to diffraction and scattering can be reduced. Hereinafter, it is assumed that the spiral axis of the chiral smectic C liquid crystal is oriented in the direction perpendicular to the transparent member contact surface of the transparent substrates 1 and 2.

  Further, the spiral directions of the liquid crystals 63 and 73 may be the same. This is because when the first liquid crystal cell 60 and the second liquid crystal cell 70 are bonded together as shown in FIG. 6, the transparent member 64 and the transparent electrode of the light source side liquid crystal cell (referred to as the first liquid crystal cell). This is because the light transmitted through 65a and 65b is blocked by the liquid crystal 73 of the second liquid crystal cell 70 and cannot be transmitted, so that unevenness in the transmission intensity can be reduced.

  Further, the rotational directions of the spirals of the liquid crystals 63 and 73 may be opposite to each other. When the first liquid crystal cell 60 and the second liquid crystal cell 70 are bonded together as shown in FIG. 6, one liquid crystal cell reflects clockwise polarized light and the other liquid crystal cell reflects counterclockwise polarized light. The light can be reflected. As a result, a wavelength tunable filter that does not depend on the incident polarization state can be realized, and the light utilization efficiency can be improved.

  The operation of the lateral electric field drive liquid crystal cell 600 according to the third embodiment of the present invention will be described below. FIG. 7 is an explanatory diagram for explaining the operation of the horizontal electric field drive liquid crystal cell 600 according to the third embodiment of the present invention. In FIG. 7, a chiral smectic C liquid crystal is used as the liquid crystal 63 in one liquid crystal cell (hereinafter referred to as the first liquid crystal cell 60) constituting the horizontal electric field drive liquid crystal cell 600, depending on the presence or absence of an applied electric field. It is a figure which shows notionally the mode of the spiral of the liquid crystal molecule 32 which changes in a row. Here, FIG. 7A and FIG. 7B are diagrams conceptually showing the spiral state of the liquid crystal molecules 32 when no electric field is applied and when an electric field is applied.

  The liquid crystal molecules 32 act to Bragg-reflect incident light according to the helical pitch. And the helical pitch of the liquid crystal molecules 32 becomes longer as the applied lateral electric field increases. Therefore, the lateral electric field driving liquid crystal cell 600 functions as a wavelength variable filter element that reflects incident light having a wavelength determined according to the lateral electric field applied through the transparent electrodes 65a and 65b.

  As described above, in the horizontal electric field drive liquid crystal cell according to the third embodiment of the present invention, each transparent member has a substantially constant cross-sectional shape in a direction perpendicular to the transparent member contact surface. Is provided on at least the side surface of the transparent member, and is electrically connected so that a lateral electric field can be applied to the liquid crystal between the adjacent transparent electrodes, so that the lateral electric field can be effectively applied and light is transparent to the transparent member. Since the light is transmitted through the electrodes, the aperture ratio can be improved as compared with the conventional lateral electric field drive liquid crystal cell.

  In addition, since each transparent member has a columnar shape, it can be arranged in a lattice shape having a two-dimensional periodicity, and as a result, it is possible to further increase the region to which a lateral electric field can be applied. In certain applications, the aperture ratio and the like can be further improved.

  In addition, since each transparent member is tapered so that the cross-sectional shape becomes smaller in the direction away from the transparent member contact surface of the transparent substrate provided with the transparent member, the manufacturing process such as deposition of the conductive film is facilitated. Can do.

  In addition, since at least the refractive index of the transparent member is a refractive index of any value between the ordinary light refractive index and the extraordinary light refractive index of the liquid crystal, it transmits light in a predetermined application such as a wavelength tunable filter. Stray light, scattered light, and the like can be suppressed, and the light utilization efficiency can be further improved.

  Further, since the plurality of transparent members are periodically arranged on the transparent member contact surface to form a lattice, wiring processing that can apply an electric field between the electrodes can be performed without using a TFT substrate.

  Moreover, since the relative arrangement of the plurality of transparent members distributed and formed on each transparent substrate is the same between the two transparent substrates, the interval between the transparent members can be widened, and electrodes, wiring, etc. Steps such as forming and alignment treatment can be facilitated.

  Further, since the spiral axis of the cholesteric liquid crystal is oriented in a direction substantially perpendicular to the contact surface of the transparent member, the light corresponding to this pitch can be selectively reflected by selecting the pitch of the spiral. .

  In addition, since the cholesteric liquid crystal includes a liquid crystal exhibiting a chiral smectic C phase, the helical pitch can be controlled at a high speed and a low voltage by applying a lateral electric field, and the wavelength of light transmitted with good controllability can be changed.

  In addition, since a plurality of liquid crystal cells are stacked, optical performance such as contrast can be further improved.

  In addition, since each horizontal electric field drive liquid crystal cell is laminated so that each transparent member of each horizontal electric field drive liquid crystal cell to be laminated does not overlap each other between each of the horizontal electric field drive liquid crystal cells to be laminated, unevenness in contrast is caused. Can be reduced.

  In the above description, a configuration in which a plurality of lateral electric field drive liquid crystal cells are stacked has been described. However, for example, a configuration including the first liquid crystal cell 60 may be used. In this case, the lateral electric field drive liquid crystal cell of the present invention may be a reflective element. Such a reflection type lateral electric field drive liquid crystal cell is realized by providing a reflection surface in the horizontal electric field drive liquid crystal cell so that light reflected by the reflection surface in addition to incident light is transmitted through the liquid crystal 63 in a reciprocating manner. it can.

  Further, the lateral electric field drive liquid crystal cell of the present invention may be laminated with a wave plate, a polarizing plate or the like. By comprising in this way, the polarization direction of incident light can be adjusted with a polarizing plate, a half-wave plate, a quarter-wave plate, etc., and high utilization efficiency is obtained.

(First embodiment)
A first embodiment in which the lateral electric field drive liquid crystal cell of the present invention is applied to a diffraction efficiency variable element will be described below. FIG. 1 is a sectional view showing a conceptual configuration of a horizontal electric field drive liquid crystal cell according to a first embodiment of the present invention. A quartz glass substrate having a refractive index of 1.46 is used as the transparent substrates 1 and 2 and the transparent substrate 1 is processed to form the transparent member 4. The transparent member 4 has the shape and arrangement described in the first embodiment of the present invention, and the transparent member 4 is formed using a photolithography technique and a dry etching technique.

  The period of the grating formed by the transparent member 4 (hereinafter referred to as the grating period) is 10 μm, the width of the transparent member 4 is about 4 μm, and the height of the transparent member is about 2.7 μm. Next, an ITO film having a thickness of 30 nm is deposited on the surface of the transparent substrate 1 on which the transparent member 4 is formed by sputtering, leaving the ITO film on the transparent member 4 as transparent electrodes 5a and 5b. Conductivity is obtained between 5a and between the transparent electrodes 5b, and the ITO film on the substrate surface is left so that an electric field can be applied between the transparent electrodes 5a and 5b, and the other part of the ITO film is removed. The removal of the ITO film is performed using a photolithography technique and a dry etching technique.

  On the other hand, with respect to the transparent substrate 2, a portion where the sealing material 6 on the opposite substrate surface of the transparent substrate 2 is provided is removed by etching to a depth of 8 μm from the substrate surface to form a seal contact portion. Next, a vertical alignment film is applied to the substrate surface side of the transparent substrate 1 where the transparent electrodes 5a and 5b are formed and the substrate surface side of the transparent substrate 2 where the seal contact portion is formed and baked to perform alignment treatment. Apply.

  Next, a sealing material 6 mixed with a spacer having a diameter of 8.2 μm for holding the gap is printed on the sealing contact portion of the transparent substrate 2, and the transparent substrate 1 and the transparent substrate 2 are thermocompression bonded to form a liquid crystal cell. Form. By doing as described above, a narrow liquid crystal cell having a substrate transparent member gap between the transparent electrodes 5a, 5b and the transparent substrate 2 of about 0.2 μm, which is not more than 1/10 of the height of the transparent member 4 Can be formed.

  A liquid crystal having positive dielectric anisotropy having an ordinary light refractive index of 1.482 and an extraordinary light refractive index of 1.582 is injected into the liquid crystal cell formed as described above and sealed. Next, an electric signal for controlling the alignment of the liquid crystal by forming an electrode pad on each ITO film left on the substrate surface so that an electric field can be applied between the transparent electrode 5a and the transparent electrode 5b. The terminal to which is applied. By applying an electric signal to this terminal, a horizontal electric field parallel to the substrate surface of the transparent substrate can be applied to the liquid crystal 3.

In the diffraction efficiency variable element 100 manufactured as described above, the incident light with wavelengths of about 470 nm (blue), about 550 nm (green), and about 630 nm (red) depends on the polarization direction when no electric field is applied. The transmittance is 85% or more. When an electric field is applied between the transparent electrodes 5a and 5b and the electric field is gradually increased, the refractive index of the liquid crystal with respect to the lattice-polarized light gradually changes from the ordinary light refractive index to the extraordinary light refractive index. For this reason, the transmittance gradually decreases, and the transmittance when the applied electric field is about 7 V is 10% or less for all wavelengths of about 470 nm (blue), about 550 nm (green), and about 630 nm (red). Become.
(Second embodiment)
Hereinafter, a second embodiment in which the lateral electric field drive liquid crystal cell of the present invention is applied to a diffraction efficiency variable element will be described. FIG. 3 is a sectional view showing a conceptual configuration of a horizontal electric field drive liquid crystal cell according to a second embodiment of the present invention. The transparent member constituting the horizontal electric field drive liquid crystal cell 300 is the transparent member 4 constituting the horizontal electric field drive liquid crystal cell according to the first embodiment of the present invention on the transparent member contact surfaces of both transparent substrates 1 and 2. It has the same configuration as that provided separately.

  First, a SiON film having a refractive index of 1.51 and a thickness of about 2.4 μm is formed on the surfaces of the transparent substrates 1 and 2 using the CVD method. The transparent members 4a and 4b have the shape and arrangement described in the second embodiment of the present invention, and the transparent members 4a and 4b are formed by using a photolithography technique and a dry etching technique. The grating period of the grating formed by the transparent member 4 is 30 μm, the width of the transparent member 4 is approximately 6 μm, and the height of the transparent member is approximately 2.4 μm. Here, a seal contact portion having a step of about 2.4 μm is formed at the same time.

  Next, an ITO film having a thickness of 30 nm is deposited by sputtering on the substrate surface side where the transparent members 4a and 4b of the transparent substrates 1 and 2 are formed, and on the transparent members 4a and 4b of the transparent substrates 1 and 2 Of the ITO film on the substrate surface so that electrical conduction can be obtained between the transparent electrodes 35a and 35b, and an electric field can be applied between the transparent electrodes 35a and 35b. The other part of the ITO film is removed. The removal of the ITO film is performed using a photolithography technique and a dry etching technique.

  Next, an alignment film is applied and baked on the substrate surface side of the transparent substrates 1 and 2 on which the transparent members 4a and 4b are formed, and an alignment process is performed. As the alignment process, a rubbing process is performed so that the liquid crystal 3 is aligned in the longitudinal direction of the transparent members 4a and 4b.

  Next, a sealing material 6 mixed with a spacer having a diameter of 2.6 μm for holding the gap is printed on the sealing contact portion of one transparent substrate, and the transparent substrate 1 and the transparent substrate 2 are thermocompression bonded to form a liquid crystal cell. Form. By doing so, a narrow liquid crystal cell in which the substrate transparent member gap between the transparent electrodes 35a and 35b and the transparent substrates 1 and 2 is 1/10 or less compared to the height of the transparent member of about 0.2 μm. Can be formed.

  A liquid crystal having positive dielectric anisotropy having an ordinary light refractive index of 1.508 and an extraordinary light refractive index of 1.653 is injected into the liquid crystal cell formed as described above and sealed. Next, an electrode pad is formed on each ITO film left on the substrate surfaces of the transparent substrates 1 and 2 so that an electric field can be applied between the transparent electrode 35a and the transparent electrode 35b. This is a terminal to which an electric signal for controlling is applied. By applying an electric signal to this terminal, a lateral electric field parallel to the transparent substrate can be applied to the liquid crystal 3.

  The diffraction efficiency variable element 300 manufactured as described above has wavelengths of about 470 nm (blue), about 550 nm (green), and about 630 nm (red), and is 95 when no electric field is applied to grating orthogonal polarization light. % Transmittance is shown. When an electric field is applied between the transparent electrodes 35a and 35b and the electric field strength is gradually increased, the refractive index of the liquid crystal with respect to the lattice-polarized light gradually changes from the ordinary light refractive index to the extraordinary light refractive index.

For this reason, the transmittance with respect to the lattice-polarized light gradually decreases, and the transmittance with respect to the electric field when a voltage of about 7 V is applied is 10% or less for all the wavelengths of blue, green, and red. On the other hand, with respect to longitudinally polarized light, when no electric field is applied, the transmittance is 10% or less for all three incident wavelengths. Gradually changes from refractive index to ordinary refractive index. For this reason, the transmittance with respect to the longitudinally polarized light gradually increases, and the transmittance with respect to the electric field when a voltage of about 7 V is applied is 95% or more with respect to all three incident wavelengths.
(Third embodiment)
A third embodiment in which the transverse electric field drive liquid crystal cell of the present invention is applied to a wavelength tunable filter element will be described below. FIG. 6 is a side sectional view showing a conceptual configuration of a horizontal electric field drive liquid crystal cell according to a third embodiment of the present invention. A lateral electric field drive liquid crystal cell 600 according to the third embodiment of the present invention has a configuration in which a first liquid crystal cell 60 and a second liquid crystal cell 70 are bonded together by an adhesive 7.

  FIG. 1 is a cross-sectional view showing a conceptual configuration of each of the liquid crystal cells 60 and 70 constituting the horizontal electric field drive liquid crystal cell 600. The shape and arrangement of the transparent members 64 and 74 included in the liquid crystal cells 60 and 70 constituting the horizontal electric field drive liquid crystal cell 600 and the shapes and arrangement of the transparent electrodes 65a, 65b, 75a and 75b are the first embodiment of the present invention. This is the same as the shape and arrangement of the transparent member 4 and the shapes and arrangement of the transparent electrodes 5a and 5b constituting the horizontal electric field drive liquid crystal cell.

  A quartz glass substrate having a refractive index of 1.46 is used as the transparent substrates 1 and 2 of the liquid crystal cells 60 and 70, respectively. First, a SiON film having a refractive index of 1.53 and a thickness of about 7 μm is formed on the surface of the transparent substrate 1 of each liquid crystal cell 60, 70 by sputtering. Next, the transparent members 64 and 74 are formed using a photolithography technique and a dry etching technique. The grating period of the grating formed by the transparent members 64 and 74 is 20 μm, the width of the transparent member 4 is approximately 1.6 μm, and the height of the transparent member is approximately 7 μm.

  Next, an ITO film having a thickness of 30 nm is deposited by sputtering on the substrate surface side where the transparent members 64 and 74 of the transparent substrate 1 of the liquid crystal cells 60 and 70 are formed, and the ITO film on the transparent members 64 and 74 is deposited. As transparent electrodes 65a, 65b, 75a, 75b, and conduction is obtained independently between the transparent electrodes 65a, between the transparent electrodes 65b, between the transparent electrodes 75a and between the transparent electrodes 75b, and between the transparent electrodes 65a and 65b. The ITO film on the substrate surface is left so that an electric field can be applied between the transparent electrode 75a and the transparent electrode 75b, and the other part of the ITO film is removed. The removal of the ITO film is performed using a photolithography technique and a dry etching technique.

  Next, a portion where the sealing material 6 on the opposing substrate surface of the transparent substrate 2 of each of the liquid crystal cells 60 and 70 is provided is removed by etching to a depth of 5.2 μm from the opposing substrate surface to form a sealing contact portion. Next, a vertical alignment film is applied and fired on the transparent member contact surface side of the transparent substrate 1 of each liquid crystal cell 60, 70 and on the opposite substrate surface side of the transparent substrate 2 of each liquid crystal cell 60, 70, and alignment treatment is performed. Apply.

  Next, the sealing material 6 mixed with a spacer having a diameter of 5.5 μm for holding the gap is printed on the sealing contact portion of the opposite substrate surface of the transparent substrate 2 of each liquid crystal cell 60, 70, and the liquid crystal cell 60, The transparent substrate 1 and the transparent substrate 2 are thermocompression bonded every 70 to form a liquid crystal cell. By doing so, a narrow liquid crystal cell in which the substrate transparent member gap between the transparent electrodes 65a, 65b, 75a, 75b and the opposing substrate surface of the transparent substrate 2 is about 0.3 μm can be formed.

  Of the liquid crystal cells formed as described above, chiral smectic C liquid crystal having a spiral rotation direction clockwise and a spiral pitch of about 370 nm is injected and sealed into the first liquid crystal cell 60. Similarly, chiral smectic C liquid crystal in which the spiral rotation direction is counterclockwise and the spiral pitch is approximately the same as the spiral pitch is injected into the second liquid crystal cell and sealed. When the first liquid crystal cell and the second liquid crystal cell thus formed are viewed from a direction perpendicular to the substrate surface as shown in FIG. 6, the positions of the transparent electrodes 5a and 5b in the two liquid crystal cells are It was made to adhere so that it might not overlap.

  Next, in order to control the alignment of the liquid crystal, an electrode pad is formed on each ITO film left on the substrate surface so that an electric field can be applied between the transparent electrodes 65a and 65b and between the transparent electrodes 75a and 75b. The terminal to which the electrical signal is applied. By applying an electric signal to this terminal, a horizontal electric field parallel to the substrate surface of the transparent substrate can be applied to the liquid crystals 63 and 73.

  The lateral electric field drive liquid crystal cell 600 manufactured as described above exhibits a transmittance of 15% or less for incident light having a wavelength of about 470 nm (blue), regardless of the polarization direction when no electric field is applied, It functions as a blue complementary color filter. When an electric field is started to be applied between the transparent electrodes 65a and 65b and between the transparent electrodes 75a and 75b and the electric field strength is gradually increased, the wavelength of the reflected light shifts to the long wavelength side, and the transmittance is 15% or less. The function changes from a complementary color filter having a wavelength of about 550 nm to a red color filter having a transmittance of 15% or less (wavelength is about 630 nm).

  The lateral electric field drive liquid crystal cell according to the present invention can also be applied to uses such as optical parts and optical elements that have an advantageous effect that the aperture ratio can be improved as compared with the conventional lateral electric field drive liquid crystal cell.

1 is a side sectional view showing a conceptual configuration of a horizontal electric field drive liquid crystal cell according to a first embodiment of the present invention. Explanatory drawing for demonstrating the effect | action of the horizontal electric field drive liquid crystal cell which concerns on the 1st Embodiment of this invention. Side sectional view which shows the notional structure of the horizontal electric field drive liquid crystal cell which concerns on the 2nd Embodiment of this invention. Explanatory drawing for demonstrating the effect | action of the horizontal electric field drive liquid crystal cell which concerns on the 2nd Embodiment of this invention. The figure which shows notionally the edge part effect which arises in the end surface vicinity of the transparent member 4 of the horizontal electric field drive liquid crystal cell 100 being suppressed in the end surface vicinity of the transparent members 4a and 4b of the horizontal electric field drive liquid crystal cell 300. Side sectional view which shows the notional structure of the horizontal electric field drive liquid crystal cell which concerns on the 3rd Embodiment of this invention. Explanatory drawing for demonstrating the effect | action of the horizontal electric field drive liquid crystal cell which concerns on the 3rd Embodiment of this invention.

Explanation of symbols

1, 2, Transparent substrate 3, 63, 73 Liquid crystal 4, 4a, 4b, 64, 74 Transparent member 5a, 5b, 35a, 35b, 65a, 65b, 75a, 75b Transparent electrode 6 Sealing material 7 Adhesive 31, 32 Liquid crystal molecule 60, 70 Liquid crystal cell 100, 300, 600 Horizontal electric field drive liquid crystal cell

Claims (13)

A pair of opposing transparent substrates, a plurality of transparent members provided between the opposing transparent substrates, a transparent electrode provided on a predetermined surface of the transparent member, a pair of the transparent substrates and the plurality of transparent A liquid crystal sandwiched between the member or the transparent electrode,
Each of the transparent members is provided on a transparent member contact surface parallel to the opposing substrate surface of at least one of the opposing substrate surfaces, which are opposing substrate surfaces of the transparent substrates, and the transparent member The cross-sectional shape is substantially constant in a direction perpendicular to the contact surface, and the transparent electrode is provided on at least the side surface of the transparent member so that a lateral electric field can be applied to the liquid crystal between the adjacent transparent electrodes. A lateral electric field drive liquid crystal cell, characterized in that the liquid crystal cell is electrically connected to the liquid crystal cell.   The horizontal electric field drive liquid crystal cell according to claim 1, wherein each of the transparent members has a columnar shape, and a central axis of the columnar shape faces a direction perpendicular to the transparent member contact surface.   The horizontal electric field drive liquid crystal cell according to claim 1, wherein each of the transparent members has a rectangular parallelepiped shape and is periodically arranged to form a partition-like lattice.   4. The method according to claim 1, wherein each of the transparent members is tapered so that an area of a cross-sectional shape decreases in a direction away from the transparent member contact surface of the transparent substrate on which the transparent member is provided. 2. A lateral electric field drive liquid crystal cell according to 1.   5. The lateral electric field driving liquid crystal cell according to claim 1, wherein at least a refractive index of the transparent member is substantially equal to an ordinary light refractive index or an extraordinary light refractive index of the liquid crystal. 6.   The horizontal direction according to any one of claims 1 to 4, wherein at least the refractive index of the transparent member is a refractive index of any value between an ordinary light refractive index and an extraordinary light refractive index of the liquid crystal. Electric field driven liquid crystal cell.   The horizontal electric field drive liquid crystal cell according to any one of claims 1 to 6, wherein a plurality of the transparent members are periodically arranged on the transparent member contact surface to form a lattice.   The horizontal electric field drive liquid crystal cell according to any one of claims 1 to 7, wherein a plurality of the transparent members are distributed and formed on the transparent member contact surfaces of two transparent substrates.   The horizontal electric field drive liquid crystal cell according to claim 8, wherein a relative arrangement of the plurality of transparent members distributed and formed on each transparent substrate is the same between the two transparent substrates.   The lateral electric field driving liquid crystal according to any one of claims 1 to 9, wherein the liquid crystal is a cholesteric liquid crystal, and a spiral axis of the cholesteric liquid crystal is aligned in a direction substantially perpendicular to the contact surface of the transparent member. cell.   The lateral electric field drive liquid crystal cell according to claim 10, wherein the cholesteric liquid crystal includes a liquid crystal exhibiting a chiral smectic C phase.   12. A horizontal electric field drive liquid crystal cell, wherein a plurality of the horizontal electric field drive liquid crystal cells according to claim 1 are stacked.   The horizontal electric field drive liquid crystal cells are stacked such that the transparent members of the stacked horizontal electric field drive liquid crystal cells do not overlap each other between the stacked horizontal electric field drive liquid crystal cells. 13. A transverse electric field drive liquid crystal cell according to item 12.

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