JP6017212B2 - Optical system, liquid crystal element, and method of manufacturing liquid crystal element - Google Patents

Description

  The present invention relates to an optical system, a liquid crystal element, and a method for manufacturing the liquid crystal element.

  For example, in coherent optical communication, since the polarization state of the original signal changes during propagation, it is desirable to first convert the polarization state of the reception signal to a predetermined state when demodulating the reception signal. For example, when a semiconductor optical amplifier is used, it is desirable that the incident polarized light is set to a predetermined polarization state in advance because its characteristic (gain) depends on the polarization state of the incident polarized light.

  For example, by rotating the half-wave plate manually or mechanically, the polarization direction (polarization plane) of the linearly polarized light incident on the half-wave plate can be rotated and emitted in an arbitrary direction. it can. By manually or mechanically rotating the quarter-wave plate, elliptically polarized light incident on the quarter-wave plate can be converted into linearly polarized light polarized in an arbitrary direction and emitted. Further, by manually or mechanically rotating the linear polarizer, natural light incident on the linear polarizer can be converted into linearly polarized light polarized in an arbitrary direction and emitted.

  In Patent Document 1, incident linearly polarized light can be converted into elliptically polarized light without rotating it, and an optical element that can electrically control the retardation in the thickness direction reversibly and elliptically polarized light can be converted into linearly polarized light. An optical system is proposed in which the polarization direction can be set electrically in any direction by combining with other optical elements. In such an optical system, since the polarization direction is electrically controlled, accuracy and work efficiency are relatively high. Further, since a mechanical movable part for rotating the optical element is not required, the size can be reduced.

  Patent Document 2 discloses a pattern polarizing device having different polarization directions in different regions. In the technique of Patent Document 2, the alignment film formed on the glass substrate is subjected to a rubbing process through a mask to pattern different alignment directions for each region, and the twist angle of the liquid crystal polymer is determined for each region. Different.

JP 2003-167267 A JP-A-9-138308

  As described above, when the polarization direction is controlled using the wave plate, in order to obtain polarized light that vibrates in different directions for each place, manual placement of the wave plate, linear polarizer, etc. can improve accuracy and work efficiency. In addition to this, problems such as light scattering and retardation shift occur at the boundary of the wave plate and the like. Furthermore, it is virtually impossible to change the polarization direction continuously.

  In addition, although the technique disclosed in Patent Document 1 can electrically control the polarization direction, it requires a driving device for that purpose, and it is also necessary to electrically connect the driving device and the optical element.

  Further, the technique disclosed in Patent Document 2 requires precise alignment control such as rubbing through a mask, and has low productivity. Further, when the polarization direction is changed into a plurality of directions by this technique, it is necessary to perform the alignment process while precisely shifting the mask by the number of necessary polarization directions.

  An object of the present invention is to provide an optical system that is small in size and low in manufacturing cost.

  Another object of the present invention is to provide an optical system having low retardation and different retardation for each place.

  According to one aspect of the present invention, an optical system includes a pair of transparent substrates and a liquid crystal layer sandwiched between the pair of transparent substrates, and the thickness direction is parallel to the incident optical axis of linearly polarized light. The liquid crystal element is arranged, wherein the liquid crystal layer is uniaxially oriented in the azimuth direction, the retardation in a non-electric field state varies depending on the region, and the linearly polarized light has an elliptical principal axis in a different direction for each region. A liquid crystal element that converts to elliptically polarized light, and a later stage of the liquid crystal element, a slow axis direction is parallel to a polarization direction of linearly polarized light incident on the liquid crystal element, and the slow axis direction and the uniaxial direction are An optical element which is arranged so that an in-plane angle is 45 degrees or 135 degrees, and which converts elliptically polarized light having an elliptical principal axis in a different direction emitted from the liquid crystal element into linearly polarized light having the same polarization direction as the elliptical principal axis; Have

According to another aspect of the present invention, a method of manufacturing a liquid crystal device includes a step of bonding a pair of transparent substrates on which a solid pattern of transparent electrodes is formed with a gap, and a light beam in the gap between the pair of transparent substrates. A step of injecting a liquid crystal to which a curable monomer is added and a voltage applied to the liquid crystal layer are changed according to a region, and ultraviolet light is irradiated through an opening of a slit mask to photocure the photocurable monomer. Process.

  According to another aspect of the present invention, a liquid crystal element includes a pair of transparent substrates and a liquid crystal layer sandwiched between the pair of transparent substrates, and the liquid crystal layer is uniaxial with respect to the azimuth direction. When the linearly polarized light having an optical axis parallel to the thickness direction is incident, the linearly polarized light has an elliptical main axis in a different direction for each region. Convert to elliptically polarized light.

  According to the present invention, it is possible to provide an optical system that is small in size and low in manufacturing cost.

  In addition, according to the present invention, it is possible to provide an optical system having different retardation for each place at low cost.

1 is a schematic diagram showing a configuration of an optical system 100 according to a first embodiment of the present invention. It is a schematic sectional drawing which shows the cross-section of the 1st optical element 101 by the 1st Example of this invention. It is a schematic sectional drawing for demonstrating the manufacturing method of the 1st optical element 101 by the 1st Example of this invention. It is a graph which shows the measurement result of the polarization rotation angle with respect to a voltage. It is a graph showing the polarization state of the linearly polarized light radiate | emitted from the voltage applied to the cell 101a, and the optical element ((lambda) / 4 board) of the cell 101a back | latter stage. It is a graph showing the calculation result which analyzed the relationship between the voltage applied to the cell 101a, and the Stokes parameters S0 to S3 of the linearly polarized light emitted from the optical element (λ / 4 plate) downstream of the cell 101a. It is a schematic plan view for demonstrating the ultraviolet-ray exposure method by the 1st Example of this invention. It is a schematic plan view for demonstrating the manufacturing method of the 1st optical element 101 by the 1st Example of this invention. It is a top view for demonstrating the manufacturing method of the optical element 102 by the 2nd Example of this invention. It is a schematic plan view for demonstrating the ultraviolet-ray exposure method by the 2nd Example of this invention. It is a schematic plan view for demonstrating the manufacturing method of the 1st optical element 102 by the 2nd Example of this invention. It is a schematic plan view for demonstrating the manufacturing method of the 1st optical element 103 by the 3rd Example of this invention.

  FIG. 1 is a schematic diagram showing the configuration of an optical system 100 according to the first embodiment of the present invention. The optical system 100 includes a light source device 110 that emits linearly polarized light PL1 polarized in a predetermined direction, a first optical element (liquid crystal element) 101 having a refractive index anisotropy, and a delay in a plane perpendicular to the thickness direction. And a second optical element (phase plate) 120 having a phase axis.

  The light source device 110 is, for example, a light source device including an artificial light source that emits desired light and a polarizer that converts light into linearly polarized light PL1 that is polarized in a predetermined direction. As the artificial light source, for example, a monochromatic light source combining a halogen lamp and an optical filter, a laser oscillator, or the like is used. As the polarizer, for example, a linear polarizing film or a polarizing prism is used.

  The first optical element 101 is composed of, for example, a liquid crystal element, and is arranged so that its thickness direction is parallel to the optical axis of the optical system. The first optical element 101 has a plurality of regions, and different states of the liquid crystal layer retardation (retardation) are formed for each region. As a method of changing the phase difference, a method of changing Δn and a method of changing the thickness of the liquid crystal layer are conceivable. In this embodiment, the method of changing Δn will be mainly described.

  Although details will be described later, for example, the first optical element 101 adds a small amount of an ultraviolet curable liquid crystal monomer to the liquid crystal to be injected, and irradiates ultraviolet rays in a state where a predetermined voltage is applied to each region, thereby causing liquid crystal properties. A monomer is polymerized, and the liquid crystal alignment state in the region is fixed in a state where the predetermined voltage is applied. When the alignment state of the liquid crystal is different for each region, Δn when the element is viewed from the normal direction is different for each region, so that different states of liquid crystal layer retardation (retardation) can be formed for each region.

  When the linearly polarized light PL1 is incident on the first optical element 101 in parallel with the thickness direction, the linearly polarized light PL1 has a refractive index distribution (a retardation in the thickness direction) in each region of the first optical element 101. Accordingly, it is converted into elliptically polarized light PL2 having an elliptical principal axis in a predetermined direction. In the first optical element 101, the linearly polarized light PL1 does not rotate.

  Similar to the first optical element 101, the second optical element 120 is disposed so that its thickness direction is parallel to the optical axis of the optical system. The second optical element 120 converts the elliptically polarized light PL2 emitted from the first optical element 101 and incident in parallel with the thickness direction of the second optical element 120 into linearly polarized light PL3. The polarization direction of the linearly polarized light PL3 is the same as the direction of the elliptical principal axis of the elliptically polarized light PL2. For example, the second optical element 120 is configured by a ¼ wavelength plate.

  Next, a preferable example of the arrangement of the first optical element 101 and the second optical element 120 will be described. In FIG. 1, the polarization direction A0 of the linearly polarized light PL1 to be incident on the first optical element 101 and the x-axis of the orthogonal coordinate system are drawn in parallel to each other. The z axis of the orthogonal coordinate system corresponds to the optical axis.

  The first optical element 101 has an in-plane angle θ1 between the liquid crystal alignment direction A1 and the polarization direction A0 of the linearly polarized light PL1 at the interface between the liquid crystal layer 15 and the alignment film 13 (or 23), which will be described later, that is, the liquid crystal alignment direction. When A1 and the polarization direction A0 are orthogonally projected on one plane perpendicular to the optical axis, the angle θ1 formed by these is arranged to be 45 °. This in-plane angle may be 135 °.

  The second optical element 120 is arranged so that the in-plane angle between the slow axis A2 and the liquid crystal alignment direction A1 of the first optical element 101 is 45 °. This in-plane angle may be 135 °. In the illustrated example, the slow axis A2 of the second optical element 120 is parallel to the polarization direction A0 of the linearly polarized light PL1.

  By arranging the first optical element 101 and the second optical element 120 as described above, it is possible to easily obtain linearly polarized light PL3 polarized in an arbitrarily selected direction.

  FIG. 2 is a schematic sectional view showing the sectional structure of the first optical element 101 according to the first embodiment of the present invention.

  The first optical element 101 includes a pair of transparent substrates 11 and 21, a transparent electrode 12 and a vertical alignment film 13 formed on one surface of the transparent substrate 11, and a transparent electrode 22 formed on one surface of the transparent substrate 21. And a vertical alignment film 23.

  A liquid crystal layer 15 is sandwiched between the pair of transparent substrates 11 and 21. As will be described later, the liquid crystal layer 15 is obtained by adding a small amount of an ultraviolet curable liquid crystal monomer to the liquid crystal and irradiating ultraviolet rays in a state where a predetermined voltage is applied to each region to polymerize the liquid crystalline monomer. The liquid crystal alignment state when a predetermined voltage is applied is fixed. Therefore, different states of the liquid crystal layer retardation (retardation) are formed for each region.

  Next, a method for manufacturing the first optical element 101 according to the first embodiment of the present invention will be described.

  FIG. 3 is a schematic cross-sectional view for explaining a method for manufacturing the first optical element 101 according to the first embodiment of the present invention.

  First, a vertically aligned antiparallel cell having a cell thickness of 4 μm and a pretilt angle of about 89.5 ° is manufactured. The cell process is the same as a general process. Transparent electrodes 12 and 22 are formed by forming indium tin oxide (ITO), which is a transparent electrode, on the glass substrates 11 and 21 by vapor deposition, sputtering, etc., and forming a desired ITO pattern by a photolithography process. In this embodiment, a solid pattern electrode is formed. Moreover, although a transparent electrode is formed using indium tin oxide (ITO), another metal oxide film such as indium zinc oxide (IZO), a thin film metal such as gold, or the like can also be used.

  Next, the glass substrates 11 and 21 with the ITO pattern are washed with a washing machine. The cleaning can be performed by, for example, brush cleaning using an alkaline detergent, pure water cleaning, air blow, UV irradiation, and IR drying in this order, but is not limited thereto. For example, high pressure spray cleaning or plasma cleaning may be performed.

  Thereafter, the vertical alignment films 13 and 23 are formed on the ITO patterned glass substrates 11 and 21 by flexographic printing, respectively. As a technique for obtaining a uniform monodomain orientation, for example, the method described in the section “Best Mode for Carrying Out the Invention” of JP-A-2005-234254 is preferably used. In this embodiment, for example, SE-1211 (manufactured by Nissan Chemical Industries) is used as the vertical alignment films 13 and 23.

  Next, rubbing is performed on the vertical alignment films 13 and 23 as an alignment process. Rubbing is a process in which a cylindrical roll wrapped with a cloth is rotated at high speed and rubbed on the alignment film, whereby liquid crystal molecules can be aligned uniaxially. In this embodiment, the processing is performed so that the alignment state between the upper and lower substrates is in an antiparallel (antiparallel) state. The alignment method is not limited to rubbing, and a photo alignment method, an ion beam alignment method, a plasma beam alignment method, an oblique deposition method, or the like can be used.

  Next, a main sealant 16 containing a gap control agent of several wt% is formed on a glass substrate on one side (for example, the glass substrate 11). As a forming method, screen printing or a dispenser is used. For example, a plastic fiber having a diameter of 3.9 μm is selected as a gap control agent, and 2 wt% of this is added to a sealing agent ES-7500 manufactured by Mitsui Chemicals to obtain the main sealing agent 16. As a liquid crystal injection method, a pattern having an injection port is formed when a vacuum injection method is used, and a closed pattern without an injection port is prepared when an ODF method is used. Further, the sealant is not limited to a thermosetting material, and a photocurable sealant or a combined light / heat type sealant can be used.

  On the other glass substrate (for example, glass substrate 21), a plastic ball having a diameter of 4 μm is dispersed as a gap control agent 14 using a dry gap spreader. As the gap agent, a straight sphere may be used instead of the plastic ball. Further, a gap agent that has been subjected to a surface treatment so as not to disturb the alignment of the liquid crystal may be used.

  Next, both the glass substrates 11 and 21 are overlapped at predetermined positions, and the main sealant is cured by heat treatment in a state where pressure is constantly applied by a press or the like. Thereafter, the glass is scratched with a scriber device, and divided into a predetermined size and shape by breaking.

  The liquid crystal layer 15 is formed by vacuum-injecting the liquid crystal added with the liquid crystalline monomer into the empty cell thus prepared. In this embodiment, the liquid crystal has a negative dielectric anisotropy, and a liquid crystal monomer that can be polymerized with ultraviolet rays is added to about 4 wt%, and a photoreaction initiator is added about 0.1 wt%. Although used, the amount added is not limited to this. Moreover, although a liquid crystalline thing is used as a monomer, liquid crystalline property is not essential. However, it is preferable to use a liquid crystalline monomer in that there is little disorder of alignment. The liquid crystalline monomer can be used regardless of whether the dielectric anisotropy is positive or negative. If the dielectric constant anisotropy is a liquid crystal monomer, the amount added may be increased. The photoinitiator is not particularly limited, and a material having sensitivity to ultraviolet rays (around 365 nm) is desirable. After liquid crystal injection, an end sealant is applied to the injection port and sealed.

  The present inventors actually manufactured the optical element (cell) 101a through the steps up to here, and connected the wiring to the terminal portions 12t and 22t of the transparent electrodes 12 and 22, as shown in the figure, and the AC voltage ( About 150 Hz) was applied. As a result, it was confirmed that the liquid crystal molecules in the cell 101a responded by the voltage, and the retardation value of the cell 101a changed. Therefore, it can be seen that even when about 4 wt% of the liquid crystalline monomer is added, the liquid crystal molecules respond in a direction perpendicular to the electric field direction. In addition, the threshold value here is about 3.5V, the retardation value (phase difference) is 0 nm in the range of applied voltage 0-3V, and the tendency to increase by voltage application was confirmed. Moreover, the emitted light was observed through the polarizing plate, and it confirmed that it became linearly polarized light.

  Next, an optical system similar to the optical system 100 shown in FIG. 1 is produced using a cell 101a in which wiring is connected to the terminal portions 12t and 22t of the transparent electrodes 12 and 22 instead of the optical element 101, and the voltage Experiments were carried out to control the polarization direction of light. That is, using a linearly polarized light source as a light source (for example, a linearly polarized light produced by passing a polarizing plate through a polarizing laser or light from the light source), the polarization direction of the linearly polarized light on the light source side and the liquid crystal alignment of the cell 101a Arranged so that the angle formed between them when projected orthogonally onto one plane perpendicular to the optical axis was 45 °, and an optical element such as a λ / 4 plate was arranged at the subsequent stage of the cell 101a. With such a configuration, it was confirmed that the polarization direction of light transmitted through the optical element can be controlled by voltage.

  FIG. 4 is a graph showing the measurement result of the polarization rotation angle with respect to the voltage. It can be seen that the direction of linearly polarized light changes depending on the applied voltage, and the polarization direction can be controlled in an arbitrary direction of 360 ° within a range up to about 20V, and the polarization direction can be controlled in an arbitrary direction up to 180 ° within a range of 7V or less. The range of the polarization rotation angle and the applied voltage can be freely set by selecting cell conditions and liquid crystal material.

  Note that the polarization rotation angle in FIG. 4 was determined from the angle at which the amount of transmitted light was minimized when the angle of the analyzer was changed. Further, the amount of transmitted light at the minimum was almost 0, and the longest value was almost 0 even when the polarization rotation angle was changed. From this, it can be seen that the light transmitted through the λ / 4 plate is linearly polarized light.

  FIG. 5 is a graph showing a simulation result of the voltage applied to the cell 101a and the polarization state of linearly polarized light emitted from the optical element (λ / 4 plate) downstream of the cell 101a. In this graph, the y-axis is the reference direction.

  As is apparent from the graph shown in FIG. 5, it can be seen that the polarization direction rotates about 58 ° when the voltage applied to the cell 101a is 2.4V, about 90 ° when 2.6V, and about 223 ° when 4V. Since the simulation here was performed with parameters different from the actual measurement of FIG. 4, the threshold voltage and the like are different. In any case, it can be seen that the polarization direction rotates according to the voltage applied to the cell 101a.

  FIG. 6 is a graph showing a calculation result obtained by analyzing the relationship between the voltage applied to the cell 101a and the Stokes parameters S0 to S3 of linearly polarized light emitted from the optical element (λ / 4 plate) at the subsequent stage of the cell 101a.

  As is clear from the graph shown in FIG. 6, the value of the Stokes parameter S1 that is the value of the x component in the Poincare sphere and the value of the Stokes parameter S2 that is the value of the y component in the Poincare sphere are applied to the cell 101a. It changes according to the magnitude of the voltage. On the other hand, the value of the Stokes parameter S3, which is the value of the z component in the Poincare sphere, is constant at 0 (zero) regardless of the magnitude of the voltage applied to the cell 101a. That is, since the value of the Stokes parameter S3 is 0 (zero) regardless of the magnitude of the voltage applied to the cell 101a, the polarization shown on the equator of the Poincare sphere, that is, the linear polarization, is always driven when the cell 101a is driven. Is emitted from the optical element (λ / 4 plate) at the rear stage of the cell 101a.

  FIG. 7 is a schematic plan view for explaining the ultraviolet exposure method according to the first embodiment of the present invention.

  First, as shown in FIG. 3, wiring is connected to the transparent electrodes 12 and 22 so that a voltage can be applied to the cell 101a. The slit mask 130 is used so that the ultraviolet ray only hits a region having a certain width. In other words, the ultraviolet ray only hits the region exposed from the opening portion of the slit mask 130.

While the cell 101a is transported under the slit mask 130 and stopped (or transported at a predetermined speed), a predetermined voltage is applied and only to a predetermined portion (a region exposed from the mask). The liquid crystalline monomer in the liquid crystal layer 15 is cured by irradiating a predetermined amount of ultraviolet rays. In addition, it is preferable that the amount of ultraviolet irradiation exists in the range of about 0.5-5 J / cm < ² >.

The inventors of the present invention set the irradiation amount of ultraviolet rays to ² J / cm ² and actually irradiate the cell 101a with ultraviolet rays by the above process to cure the liquid crystalline monomer. It was possible to fix it. In the region irradiated with ultraviolet rays while applying voltage, the generated retardation was maintained without applying voltage. For example, a retardation value of about 60 nm in a region cured while applying 2.1 V, about 120 nm in a region cured while applying 2.5 V, and a retardation value of about 200 nm in a region cured while applying 3 V, It was found that the voltage was not applied.

  That is, the liquid crystal molecules in the liquid crystal layer 15 are aligned in the uniaxial direction in the azimuth direction by the above-described alignment treatment, and in the polar angle direction in the direction corresponding to the voltage applied to the region during ultraviolet curing. . Therefore, since the voltage applied at the time of ultraviolet curing is changed for each region, the polar angle direction is fixed in a state where the orientation direction is different for each region.

  Next, the terminal portions 12t and 22t of the cell 101a are cut at the positions of the dotted lines shown in FIG. 8A to complete the optical element 101 from which the terminal portions 12t and 22t are removed as shown in FIG. 8B. It was. Since it is not necessary to apply a voltage when in use, in this embodiment, the upper and lower substrates are made to have the same outer shape when viewed from above. As described with reference to FIG. 1, the completed optical element 101 was combined with the light source device 110 and the second optical element 120 to produce the optical system 100 according to the first example.

  The polarization direction of the light transmitted through the optical system 100 according to the first embodiment of the present invention differs depending on which region of the optical element 101 is transmitted, and in the region cured while applying 0-3V. Although light having the same polarization direction as the linearly polarized light of the light source was emitted, it was emitted in a state where it was rotated in the same direction as the polarization rotation angle shown in the graph of FIG. 4 with respect to each voltage (about 3 to 20 V). Further, the degree of polarization was as extremely high as 99% or more.

  FIGS. 9A and 9B are plan views for explaining a method of manufacturing the optical element 102 according to the second embodiment of the present invention.

  The first optical element 102 according to the second embodiment is an optical element using a horizontal alignment cell having a cell thickness of 4 μm and a pretilt angle of about 1.5 °. The first optical element in the optical system 100 shown in FIG. Instead of 101, the first optical element 102 can be used in combination with the light source device 110 and the second optical element 120.

  The first difference between the optical element 101 according to the first embodiment and the optical element 102 according to the second embodiment is that, in the first embodiment, the transparent electrodes 12 and 22 are solid electrode patterns. In the second embodiment, as shown in FIG. 9A, the transparent electrodes 12 and 22 have a plurality of stripe patterns orthogonal to each other. The areas facing the transparent electrodes 12 and 22 will be areas where the liquid crystal layer retardation (retardation) will be different later.

  Further, as a second difference, in the first embodiment, vertical alignment films are used as the alignment films 13 and 23. However, in the second embodiment, for example, horizontal alignment such as SE-130B manufactured by Nissan Chemical Industries, Ltd. is used. Use a membrane. The alignment treatment for the alignment films 13 and 23 can be performed by rubbing or the like as in the first embodiment. Other cell processes such as the formation of the sealing agent 16 and the application of the gap control agent 14 and the superposition of the glass substrates 11 and 12 are the same as in the first embodiment. Thereafter, as shown by a broken line in FIG. 9A, the glass is scratched by a scriber device and divided into a predetermined size and shape by breaking to produce an empty cell 102a shown in FIG. 9B.

  Liquid crystal is injected into the empty cell 102a thus manufactured by the same method as in the first embodiment. The liquid crystal injected in the second embodiment has a positive dielectric anisotropy, about 12 wt% of a liquid crystalline monomer (positive dielectric anisotropy) that can be polymerized with ultraviolet rays, and a photoreaction initiator of 0.02%. What added about 3 wt% is used. Note that the amount of liquid crystal monomer added to the liquid crystal to be injected is not limited to this. Moreover, although a liquid crystalline thing is used as a monomer, liquid crystalline property is not essential. However, it is preferable to use a liquid crystalline monomer in that there is little disorder of alignment. The photoinitiator is not particularly limited, and a material having sensitivity to ultraviolet rays (around 365 nm) is desirable. After liquid crystal injection, an end sealant is applied to the injection port and sealed.

  The present inventors actually manufactured the optical element (cell) 102a through the steps so far, and connected the wiring to the transparent electrodes 12 and 22 as in the first example shown in FIG. (About 150 Hz) was applied. As a result, it was confirmed that the liquid crystal molecules in the cell 102a responded by the voltage, and the retardation value of the cell 102a changed. Therefore, it can be seen that even when about 4 wt% of the liquid crystalline monomer is added, the liquid crystal molecules respond in a direction perpendicular to the electric field direction. Here, the threshold value is about 1.5 V, and there is a retardation value (phase difference) even when the applied voltage is 0 V, and the retardation value gradually decreases with the voltage. The state of change due to the voltage was not different from the case of the vertical alignment according to the first embodiment, although the direction of increase / decrease was different depending on the voltage. However, in the second embodiment, retardation exists even in the initial state.

  FIG. 10 is a schematic plan view for explaining the ultraviolet exposure method according to the second embodiment of the present invention.

  First, as shown in the figure, wirings are connected to the respective terminal portions 12t and 22t of the plurality of regions where the transparent electrodes 12 and 22 overlap, and different voltages (V1 to V6) can be applied to the plurality of regions of the cell 102a. Like that.

Next, a predetermined amount of ultraviolet light is irradiated on the entire surface of the cell 102a to cure the liquid crystalline monomer. In addition, it is preferable that the amount of ultraviolet irradiation exists in the range of about 0.5-5 J / cm < ² >. The inventors of the present invention actually cured the liquid crystalline monomer by irradiating the cell 102a with ultraviolet rays by the above-mentioned process with the ultraviolet irradiation amount being ² J / cm ² (irradiating light of about 16 mW / cm ² for 60 seconds). The alignment state of the liquid crystal molecules could be fixed as it was when the ultraviolet rays were irradiated. Moreover, even if it did not apply a voltage, it has confirmed that the value of the retardation as confirmed beforehand was shown in each area | region.

  That is, as in the first embodiment, the liquid crystal molecules in the liquid crystal layer 15 are aligned in the uniaxial direction by the above-described alignment treatment in the azimuth angle direction, and applied to the region in the polar angle direction during ultraviolet curing. Oriented in the direction according to the voltage. Therefore, since the voltage applied at the time of ultraviolet curing is changed for each region, the polar angle direction is fixed in a state where the orientation direction is different for each region.

  Next, the terminal portions 12t and 22t of the cell 102a are cut at the positions of the dotted lines shown in FIG. 11A, and the terminal portions 12t and 22t are removed as shown in FIG. I let you. Since it is not necessary to apply a voltage when in use, in this embodiment, the upper and lower substrates are made to have the same outer shape when viewed from above. The completed optical element 102 is used in place of the first optical element 101 according to the first embodiment described with reference to FIG. 1 and combined with the light source device 110 and the second optical element 120 to obtain the second optical element 102. An optical system 100 according to the example was prepared. That is, as in the first embodiment shown in FIG. 1, when the polarization direction of the linearly polarized light on the light source 110 side and the liquid crystal alignment direction of the cell 102a are orthogonally projected onto one plane perpendicular to the optical axis, they are orthogonal to each other. The second optical element 120 such as a λ / 4 plate was disposed at the subsequent stage of the cell 102a.

  The polarization direction of the light transmitted through the optical system 100 according to the second embodiment of the present invention varies depending on the region of the optical element 102, and the polarization direction varies depending on the region irradiated with ultraviolet rays while changing the applied voltage. Light was emitted. Further, the degree of polarization was as extremely high as 99% or more.

  Note that light in the same direction as when no voltage was applied was emitted from between the electrodes. Since the light cannot be controlled between the electrodes, the distance between the electrodes of the ITO pattern is preferably as small as possible. In addition, if the distance between the electrodes is too narrow, there is a possibility of short-circuit between the electrodes, so it is desirable to optimize according to the application. In general, a distance between electrodes of 20 μm or less is desirable. Further, the number, shape, width, and the like of the electrode patterns to be formed are not limited to the illustrated example. For example, although the case where the widths of the electrodes are substantially equal is illustrated in the above-described embodiments, the width of the electrodes may be changed for each column (or row). Further, instead of batch exposure, exposure using a slit mask may be performed as in the first embodiment.

  FIG. 12 is a schematic plan view for explaining the manufacturing method of the first optical element 103 according to the third embodiment of the present invention. The first optical element 103 according to the third embodiment uses the first optical element 103 instead of the first optical element 101 in the optical system 100 shown in FIG. 1, and uses the light source device 110 and the second optical element. 120 can be used in combination.

  When the width W in the figure is approximately 10 mm or less, more preferably 5 mm or less, the surroundings can be obtained without spraying the gap control agent 14 in the plane of the liquid crystal cell 103 in the elongated liquid crystal cell 103 as shown in FIG. The in-plane gap can be made almost equal by the size of the diameter of the gap control agent contained in the main sealant 16 (when the glass thickness is 0.7 mm or 1.1 mm, the thinner glass is used). There is a tendency for the value of W to obtain a uniform cell thickness to decrease).

  In the third embodiment, the size of the diameter of the gap control agent contained in the sealing agent is changed at the left and right positions as shown in FIG. Along with this, it is possible to change the value of the cell thickness in each region. The cell thickness obtained in this way is approximately equal to the size of the diameter of the gap control agent contained in the main sealant 16 closest to the region.

  Therefore, as shown in FIG. 12, the thickness of the liquid crystal layer 15 can be changed depending on the location by changing the particle size of the gap control agent added to the sealing agent 16 depending on the region. Specifically, the sealing agent 16 having different diameters of the gap control agent to be contained may be applied in a pattern at a predetermined position by a multiple dispenser system (printing) or the like. The thickness of the liquid crystal layer 15 can be gradually changed as the number of times of application is increased. In this third embodiment, since the retardation is changed depending on the thickness of the liquid crystal layer 15, it is not necessary to apply a voltage to cure the ultraviolet rays as in the first and second embodiments. There is an advantage that it is not necessary to use an electrode or to perform ultraviolet curing.

  In order to change the thickness of the liquid crystal layer 15 for each region, a method of changing the particle size of the gap control agent added to the above-described sealing agent 16 depending on the region (the first optical element has an elongated shape and is thin). In addition to a method of changing the particle size of the gap control agent 14 dispersed in the surface according to the region (sequentially masking the gap agent), or forming in the surface. A method of changing the height of the spacer rib depending on the region (controllable by exposure conditions, spin coating conditions, etc.) and the like can be considered.

  As mentioned above, according to the 1st-3rd Example of this invention, the polarization direction of the light which permeate | transmits the said liquid crystal cell by forming the state which has a different retardation for every area | region in the liquid crystal cell which comprises an optical system. Can be changed for each region.

  Moreover, since it is not necessary to use a polarizing plate as an optical element other than the light source, a transparent optical system can be produced. The optical system according to the first to third embodiments of the present invention is basically composed of a material that does not absorb light (visible light, infrared light, etc.).

  Moreover, the optical system according to the first to third embodiments of the present invention does not require a driving power source or wiring. In addition, a terminal portion for wiring connection is not necessary. Therefore, the optical system can be reduced in size and weight. In the third embodiment, no driving power source or wiring is required even in the manufacturing process, and no terminal portion for wiring connection is required.

  In the first and second embodiments, the slit mask is synchronized with the voltage application, and a method of performing ultraviolet exposure while transporting the cell or a method of performing batch exposure by applying different voltages to the pattern electrodes respectively. In addition, it is possible to easily obtain different states of retardation. Therefore, it becomes possible to manufacture an optical system at low cost.

  Moreover, you may make it provide an antireflection film in the member which comprises an optical system, such as a 1st optical element and a 2nd optical element. The wavelength of the light source device 110 can be freely selected from visible light to infrared light. However, ultraviolet light having a wavelength shorter than 365 nm is not preferable because the liquid crystal may be deteriorated.

  In addition, although all of the examples have an outer shape having a longitudinal direction and the retardation changes in one direction, the present invention is not limited to this. For example, you may provide the area | region where retardation changes in two directions of the vertical direction and horizontal direction in a surface. Further, the change in retardation may not have a law, and a region with a small retardation may be sandwiched between regions with a large retardation.

  In the first to third embodiments described above, the optical system 100 includes the light source device 110 that is a polarized light source. However, the light source device 110 is omitted, and the first optical element and the second optical device are omitted. It is also possible to configure so that light from an external polarized light source is incident on the optical element.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

  In the optical system described above, the characteristic (gain) varies depending on the polarization state of incident polarized light, such as a device for converting the polarization state of a received signal into a predetermined state in coherent optical communication and a semiconductor optical amplifier. It can be used as a device for supplying predetermined incident polarized light to an element, a device for obtaining measurement light used in an ellipsometer, a light source device for analyzing polarization characteristics of an optical element, and the like. In addition, products that use lasers such as projectors, general products that use polarizing optical systems such as liquid crystal products, laser processing machines (welding, cutting, markers), laser printers, laser projectors, various sensors, measuring instruments, and analytical instruments It can be used in general.

DESCRIPTION OF SYMBOLS 11, 21 ... Glass substrate, 12, 22 ... Transparent electrode, 13, 23 ... Alignment film, 14 ... Gap control agent, 15 ... Liquid crystal layer, 16 ... Main seal, 100 ... Optical system, 101, 102 ... First optical Element, 110 ... light source device, 120 ... second optical element

Claims (5)

A liquid crystal element having a pair of transparent substrates and a liquid crystal layer sandwiched between the pair of transparent substrates, the thickness direction of which is arranged parallel to the optical axis of linearly polarized light, wherein the liquid crystal layer includes: With respect to the azimuth direction, a liquid crystal element that is aligned in a uniaxial direction, retardation in an electric field state varies depending on a region, and converts the linearly polarized light into elliptically polarized light having an elliptical principal axis in a different direction for each region;
At the subsequent stage of the liquid crystal element, the direction of the slow axis is parallel to the polarization direction of the linearly polarized light incident on the liquid crystal element, and the in-plane angle between the direction of the slow axis and the uniaxial direction is 45 degrees or 135 degrees. And an optical element that converts elliptically polarized light having an elliptical principal axis in a different direction, which is emitted from the liquid crystal element, into linearly polarized light having the same polarization direction as the elliptical principal axis.   2. The optical system according to claim 1, wherein the liquid crystal molecules of the liquid crystal layer are fixed in a state in which the polar angle orientation is changed in at least two directions depending on the region.   3. The optical system according to claim 2, wherein the liquid crystal molecules of the liquid crystal layer have a polar angle orientation fixed by photocuring the photocurable monomer added. Bonding a pair of transparent substrates on which a solid pattern of transparent electrodes is formed with a gap;
Injecting a liquid crystal added with a photocurable monomer into the gap between the pair of transparent substrates;
A method of manufacturing a liquid crystal element , comprising: irradiating ultraviolet rays through an opening of a slit mask while photovoltage is applied to the liquid crystal layer, and photocuring the photocurable monomer. A pair of transparent substrates;
A liquid crystal layer sandwiched between the pair of transparent substrates,
The liquid crystal layer is aligned in a uniaxial direction with respect to the azimuth direction, and the retardation in the non-electric field state varies depending on the region,
A liquid crystal element that converts linearly polarized light into elliptically polarized light having an elliptical principal axis in a different direction for each region when linearly polarized light having an optical axis parallel to the thickness direction is incident.

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