LCD light control device

Abstract

To provide a liquid crystal light control device suppressing color breakup.SOLUTION: A liquid crystal light control device includes first to fourth liquid crystal cells. Each of the first to fourth liquid crystal cells includes: a first board in which a first electrode including a strip pattern is provided; a second board in which a second electrode including a strip pattern is provided; a first alignment layer provided in the first board; a second alignment layer provided in the second board; and a liquid crystal layer between the first board and the second board. The first electrode includes at least one first strip electrode having a strip pattern and at least one second strip electrode having a strip pattern, at least one first strip electrode and at least one second strip electrode are disposed separately and alternately, and the second electrode includes at least one third strip electrode having a strip pattern and at least one fourth strip electrode having a strip pattern. At least one third strip electrode and at least one fourth strip electrode are disposed separately and alternately.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] One embodiment of the present invention relates to an apparatus for controlling the light distribution of light emitted from a light source by utilizing the electro-optical effect of liquid crystal.

Background Art

[0002] Techniques for controlling the light distribution of light emitted from a light source using a liquid crystal lens are known. For example, an illumination device that controls the spread of light emitted from a light source by a liquid crystal cell provided with annular electrodes in a concentric circle pattern is disclosed (see Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since the refraction angle of light changes depending on the wavelength, when the light emitted from a light source is diffused through a liquid crystal lens, an iridescent pattern may be visually recognized in the contour portion of the irradiation region. Such a phenomenon is also called color breakage, and the deterioration of the quality of the illumination light due to passing through the liquid crystal lens has become a problem.

[0005] One object of one embodiment of the present invention is to provide a liquid crystal light control device in which color breakage is suppressed.

Means for Solving the Problems

[0006] A liquid crystal light control device according to an embodiment of the present invention includes a first liquid crystal cell, a second liquid crystal cell overlapping the first liquid crystal cell, a third liquid crystal cell overlapping the second liquid crystal cell, and a fourth liquid crystal cell overlapping the third liquid crystal cell. Each of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell includes a first substrate provided with a first electrode including a strip-shaped pattern, a second substrate provided with a second electrode including a strip-shaped pattern, and a liquid crystal layer between the first substrate and the second substrate. The first substrate and the second substrate are arranged such that the longitudinal directions of the strip-shaped patterns of the first electrode and the second electrode intersect, and among the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell, two liquid crystal cells are arranged such that the longitudinal direction of the strip-shaped pattern of the first electrode is parallel to a first direction, and the longitudinal directions of the strip-shaped patterns of the first electrodes of the other two liquid crystal cells are arranged parallel to a second direction intersecting the first direction.

Brief Description of the Drawings

[0007] [Figure 1] It is a perspective view schematically showing the configuration of a liquid crystal light control device according to an embodiment of the present invention. [Figure 2] It shows a developed view of a liquid crystal light control element constituting a liquid crystal light control device according to an embodiment of the present invention. [Figure 3] It is a perspective view showing the arrangement of electrodes of a first liquid crystal cell, a second liquid crystal cell, a third liquid crystal cell, and a fourth liquid crystal cell constituting a liquid crystal light control element according to an embodiment of the present invention. [Figure 4A] It is a plan view showing an electrode provided on a first substrate of a liquid crystal cell constituting a liquid crystal light control element according to an embodiment of the present invention. [Figure 4B] It is a plan view showing an electrode provided on a second substrate of a liquid crystal cell constituting a liquid crystal light control element according to an embodiment of the present invention. [Figure 5] It is a diagram showing an example of a cross-sectional structure of a liquid crystal cell constituting a liquid crystal light control element according to an embodiment of the present invention. [Figure 6A] It is a diagram for explaining the operation of a liquid crystal cell constituting a liquid crystal light control element according to an embodiment of the present invention, and shows the alignment state of liquid crystal molecules in a state where no voltage is applied. [Figure 6B]1A and 1B are diagrams for explaining the operation of a liquid crystal cell constituting a liquid crystal light control element according to one embodiment of the present invention, showing the alignment state of liquid crystal molecules when a voltage is applied. [Figure 6C] 1A and 1B are diagrams for explaining the operation of a liquid crystal cell that constitutes a liquid crystal light control element according to one embodiment of the present invention, and show waveforms of control signals applied to electrodes that drive the liquid crystal. [Figure 7A] FIG. 2 is a diagram for explaining the operation of a liquid crystal cell that constitutes a liquid crystal light control element according to one embodiment of the present invention, and shows a perspective view illustrating the arrangement of a first electrode and a second electrode. [Figure 7B] 1A and 1B are diagrams for explaining the operation of a liquid crystal cell constituting a liquid crystal light control element according to one embodiment of the present invention, showing the alignment state of liquid crystal molecules when a voltage is applied to the first electrode. [Figure 7C] 4 is a diagram for explaining the operation of a liquid crystal cell constituting a liquid crystal light control element according to one embodiment of the present invention, showing the alignment state of liquid crystal molecules when a voltage is applied to the second electrode. FIG. [Figure 8] FIG. 2 is a diagram schematically illustrating the phenomenon in which a first polarized component and a second polarized component are diffused by two liquid crystal cells. [Figure 9] 1A and 1B are diagrams illustrating the operation of a liquid crystal light control device according to an embodiment of the present invention. [Figure 10A] 3 shows a voltage waveform applied to a liquid crystal cell in a liquid crystal light control device according to one embodiment of the present invention. [Figure 10B] 3 shows a voltage waveform applied to a liquid crystal cell in a liquid crystal light control device according to one embodiment of the present invention. [Figure 11A] 1 is a graph showing the angle dependence of chromaticity (x-coordinate axis) of a liquid crystal light control element according to one embodiment of the present invention and a liquid crystal light control element of a reference example. [Figure 11B] 1 is a graph showing the angle dependence of chromaticity (y coordinate axis) of a liquid crystal light control element according to one embodiment of the present invention and a liquid crystal light control element of a reference example. [Figure 12] 1A and 1B are diagrams illustrating the operation of a liquid crystal light control device according to an embodiment of the present invention. [Figure 13] 1A and 1B are diagrams illustrating the operation of a liquid crystal light control device according to an embodiment of the present invention. [Figure 14] It is a diagram for explaining the operation of a liquid crystal light control device according to an embodiment of the present invention. [Figure 15A] It shows the arrangement of a plurality of liquid crystal cells constituting a liquid crystal light control element according to an embodiment of the present invention, and shows a state in which the first liquid crystal cell and the second liquid crystal cell are rotated by 90 degrees. [Figure 15B] It shows the arrangement of a plurality of liquid crystal cells constituting a liquid crystal light control element according to an embodiment of the present invention, and shows a state in which the first liquid crystal cell and the third liquid crystal cell are rotated by 90 degrees. [Figure 16A] It shows the arrangement of a plurality of liquid crystal cells constituting a liquid crystal light control element according to an embodiment of the present invention, and shows a state in which the first to fourth liquid crystal cells are each rotated by 90 degrees. [Figure 16B] It shows the arrangement of a plurality of liquid crystal cells constituting a liquid crystal light control element according to an embodiment of the present invention, and shows a state in which the first liquid crystal cell and the third liquid crystal cell are inverted.

Mode for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like. However, the present invention can be implemented in many different modes and is not to be construed as being limited to the description of the embodiments illustrated below. For the sake of clarity in the explanation, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual mode, but this is merely an example and does not limit the interpretation of the present invention. Also, in this specification and each figure, the same reference numerals (or reference numerals with a, b, etc. appended after the number) are given to the same elements as those described above with respect to the previously shown figures, and detailed explanations may be omitted as appropriate. Furthermore, the letters "first" and "second" appended to each element are for convenience in distinguishing each element and have no further meaning unless otherwise specified.

[0009] In this specification, when a component or region is described as being "on (or under)" another component or region, unless otherwise specified, this includes not only the case where it is directly above (or directly under) the other component or region, but also the case where it is above (or under) the other component or region, i.e., the case where another component is included between the component or region and above (or under) the other component or region.

[0010] 1 shows a perspective view of a liquid crystal light control device 100 according to one embodiment of the present invention. The liquid crystal light control device 100 includes a liquid crystal light control element 102 and a circuit board 104. The liquid crystal light control element 102 includes a plurality of liquid crystal cells. In this embodiment, the liquid crystal light control element 102 includes at least four liquid crystal cells.

[0011] 1 shows an embodiment in which a liquid crystal light control element 102 is composed of a first liquid crystal cell 10, a second liquid crystal cell 20, a third liquid crystal cell 30, and a fourth liquid crystal cell 40. The first liquid crystal cell 10, the second liquid crystal cell 20, the third liquid crystal cell 30, and the fourth liquid crystal cell 40 are flat panels, and are arranged so that the flat surfaces of the respective liquid crystal cells overlap. Transparent adhesive layers (not shown) are provided between the first liquid crystal cell 10 and the second liquid crystal cell 20, between the second liquid crystal cell 20 and the third liquid crystal cell 30, and between the third liquid crystal cell 30 and the fourth liquid crystal cell 40. The liquid crystal light control element 102 has a structure in which adjacent liquid crystal cells arranged in the front and rear are bonded together with transparent adhesive layers.

[0012] The circuit board 104 includes a circuit for driving the liquid crystal light control element 102. The first liquid crystal cell 10 is connected to the circuit board 104 by a first flexible wiring board F1, the second liquid crystal cell 20 is connected to the circuit board 104 by a second flexible wiring board F2, the third liquid crystal cell 30 is connected to the circuit board 104 by a third flexible wiring board F3, and the fourth liquid crystal cell 40 is connected to the circuit board 104 by a fourth flexible wiring board F4. The circuit board 104 outputs control signals to each liquid crystal cell via the flexible wiring boards to control the alignment state of the liquid crystal.

[0013] 1, a light source unit 106 is disposed on the rear side of a liquid crystal light control element 102. The liquid crystal light control element 100 is configured so that light emitted from the light source unit 106 is emitted to the front side of the drawing through the liquid crystal light control element 102. In the liquid crystal light control element 102, a first liquid crystal cell 10, a second liquid crystal cell 20, a third liquid crystal cell 30, and a fourth liquid crystal cell 40 are disposed in this order from the light source unit 106 side.

[0014] The light source unit 106 includes a white light source, and an optical element such as a lens may be disposed between the white light source and the liquid crystal light control element 102 as needed. The white light source is a light source that emits light similar to natural light, and may emit dimmed light such as daylight white or warm white. The liquid crystal light control device 100 has a function of controlling the diffusion direction of light emitted from the light source unit 106 using the liquid crystal light control element 102. The liquid crystal light control element 102 has a function of shaping the light emitted from the light source unit 106 into a light distribution pattern such as a square, cross, or line.

[0015] Fig. 2 shows an exploded view of the liquid crystal light control element 102 shown in Fig. 1. The liquid crystal light control element 102 includes a first liquid crystal cell 10, a second liquid crystal cell 20, a third liquid crystal cell 30, and a fourth liquid crystal cell 40.

[0016] The first liquid crystal cell 10 includes a first substrate S11 and a second substrate S12. The first substrate S11 and the second substrate S12 are disposed opposite each other with a gap therebetween. A liquid crystal layer (not shown) is provided in the gap between the first substrate S11 and the second substrate S12. The first flexible wiring substrate F1 is connected to the first substrate S11.

[0017] The second liquid crystal cell 20 includes a first substrate S21, a second substrate S22, and a second flexible wiring substrate F2, and has a configuration similar to that of the first liquid crystal cell 10. The third liquid crystal cell 30 includes a first substrate S31, a second substrate S32, and a third flexible wiring substrate F3, and has a configuration similar to that of the first liquid crystal cell 10. The fourth liquid crystal cell 40 includes a first substrate S41, a second substrate S42, and a fourth flexible wiring substrate F4, and has a configuration similar to that of the first liquid crystal cell 10.

[0018] A first transparent adhesive layer TA1 is disposed between the first liquid crystal cell 10 and the second liquid crystal cell 20. The first transparent adhesive layer TA1 transmits visible light and bonds the second substrate S12 of the first liquid crystal cell 10 to the first substrate S21 of the second liquid crystal cell 20. A second transparent adhesive layer TA2 is disposed between the second liquid crystal cell 20 and the third liquid crystal cell 30. The second transparent adhesive layer TA2 transmits visible light and bonds the second substrate S22 of the second liquid crystal cell 20 to the first substrate S31 of the third liquid crystal cell 30. A third transparent adhesive layer TA3 is disposed between the third liquid crystal cell 30 and the fourth liquid crystal cell 40. The third transparent adhesive layer TA3 transmits visible light and bonds the second substrate S32 of the third liquid crystal cell 30 to the first substrate S41 of the fourth liquid crystal cell 40.

[0019] The first transparent adhesive layer TA1, the second transparent adhesive layer TA2, and the third transparent adhesive layer TA3 preferably have high transmittance and refractive indices close to those of the first substrates S11, S21, S31, and S41 and the second substrates S12, S22, S23, and S24. Optically elastic resins, such as adhesives containing translucent acrylic resins, can be used for the first transparent adhesive layer TA1, the second transparent adhesive layer TA2, and the third transparent adhesive layer TA3. Furthermore, because the temperature of the liquid crystal light control element 102 increases due to heat radiated from the light source unit 106, the thermal expansion coefficients of the first transparent adhesive layer TA1, the second transparent adhesive layer TA2, and the third transparent adhesive layer TA3 preferably have values close to those of the first and second substrates.

[0020] However, since the thermal expansion coefficients of the first transparent adhesive layer TA1, the second transparent adhesive layer TA2, and the third transparent adhesive layer TA3 are often higher than that of, for example, a glass substrate, it is necessary to consider stress relaxation when the temperature rises. The thicknesses of the first transparent adhesive layer TA1, the second transparent adhesive layer TA2, and the third transparent adhesive layer TA3 are preferably thicker than the cell gap (thickness of the liquid crystal layer) of each liquid crystal cell (first liquid crystal cell 10, second liquid crystal cell 20, third liquid crystal cell 30, fourth liquid crystal cell 40) in order to relax thermal stress when the temperature rises.

[0021] As will be described later, the first liquid crystal cell 10, the second liquid crystal cell 20, the third liquid crystal cell 30, and the fourth liquid crystal cell 40 have substantially the same structure. The liquid crystal light control element 102 according to the present embodiment has a structure in which the third liquid crystal cell 30 and the fourth liquid crystal cell 40 are stacked on the first liquid crystal cell 10 and the second liquid crystal cell 20 in a state rotated by 90 degrees. In other words, the liquid crystal light control element 102 according to the present embodiment includes a plurality of liquid crystal cells, and includes a structure in which at least one liquid crystal cell and another liquid crystal cell adjacent to (overlapping) the at least one liquid crystal cell are arranged in a state rotated within a range of 90 ± 10 degrees. Note that the rotation angle of the third liquid crystal cell 30 and the fourth liquid crystal cell 40 can be set within a range of 90 degrees ± 10 degrees.

[0022] FIG. 2 shows that when the arrangement of the first liquid crystal cell 10 and the second liquid crystal cell 20 is used as a reference, the third liquid crystal cell 30 and the fourth liquid crystal cell 40 are arranged in a state rotated by 90 degrees. On the other hand, when the third liquid crystal cell 30 and the fourth liquid crystal cell 40 are used as a reference, it can be said that the first liquid crystal cell 10 and the second liquid crystal cell 20 are arranged in a state rotated by 90 degrees. By stacking a plurality of liquid crystal cells having the same electrode pattern and rotating some of the liquid crystal cells, the electrode arrangement can be changed, and the diffusion of light passing through the stacked liquid crystal cells can be changed. The details will be described below.

[0023] FIG. 3 is a perspective view showing the arrangement of electrodes provided in each of the first liquid crystal cell 10, the second liquid crystal cell 20, the third liquid crystal cell 30, and the fourth liquid crystal cell 40.

[0024] The first liquid crystal cell 10 includes a first substrate S11, a second substrate S12, and a first liquid crystal layer LC1 between the first substrate S11 and the second substrate S12. The first substrate S11 is provided with a first electrode E11 on the surface facing the first liquid crystal layer LC1, and the second substrate S12 is provided with a second electrode E12 on the surface facing the first liquid crystal layer LC1. The first electrode E11 and the second electrode E12 are arranged to face each other with the first liquid crystal layer LC1 therebetween. As described above, the first substrate S11 and the second substrate S12 face each other, and it is also possible to define the facing surfaces as the inner surfaces and the surfaces on the opposite side of the inner surfaces as the outer surfaces. In this case, the first electrode E11 is provided on the inner surface of the first substrate, and the second electrode E12 is provided on the inner surface of the second substrate.

[0025] The first electrode E11 includes a plurality of first strip electrodes E11A formed in a strip shape and a plurality of second strip electrodes E11B formed in a strip shape. The second electrode E12 includes a plurality of third strip electrodes E12A formed in a strip shape and a plurality of fourth strip electrodes E12B formed in a strip shape. The plurality of first strip electrodes 11A and the plurality of second strip electrodes E11B are alternately arranged, and the plurality of third strip electrodes 12A and the plurality of fourth strip electrodes E12B are alternately arranged.

[0026] FIG. 3 shows the X, Y, and Z axis directions for explanation. The first liquid crystal cell 10, the second liquid crystal cell 20, the third liquid crystal cell 30, and the fourth liquid crystal cell 40 are arranged to overlap in the Z axis direction. In the first liquid crystal cell 10, the longitudinal directions of the plurality of first strip electrodes E11A and the plurality of second strip electrodes E11B are arranged in a direction parallel to the Y axis direction, and the longitudinal directions of the plurality of third strip electrodes 12A and the plurality of fourth strip electrodes E12B are arranged in a direction parallel to the X axis direction. That is, the plurality of first strip electrodes E11A and the plurality of second strip electrodes E11B, and the plurality of third strip electrodes E12A and the plurality of fourth strip electrodes E12B are arranged to intersect. The longitudinal directions of the plurality of first strip electrodes E11A and the plurality of second strip electrodes E11B, and the longitudinal directions of the plurality of third strip electrodes E12A and the plurality of fourth strip electrodes E12B can be arranged to intersect in a range of, for example, 90 degrees ± 10 degrees, and are preferably arranged to be orthogonal (90 degrees). In the present embodiment, these longitudinal directions are orthogonal to each other.

[0027] The second liquid crystal cell 20 includes a first substrate S21, a second substrate S22, and a second liquid crystal layer LC2 between the first substrate S21 and the second substrate S22. The first electrode E21 is provided on the surface of the first substrate S21 facing the second liquid crystal layer LC2, and the second electrode E22 is provided on the surface of the second substrate S22 facing the second liquid crystal layer LC2. The first electrode E21 includes a plurality of first strip electrodes E21A formed in a strip shape and a plurality of second strip electrodes E21B formed in a strip shape, and the second electrode E22 includes a plurality of third strip electrodes E22A formed in a strip shape and a plurality of fourth strip electrodes E22B formed in a strip shape.

[0028] In the second liquid crystal cell 20, the plurality of first strip electrodes 21A and the plurality of second strip electrodes E21B are alternately arranged, and the plurality of third strip electrodes 22A and the plurality of fourth strip electrodes E22B are alternately arranged. In the second liquid crystal cell 20, the longitudinal directions of the plurality of first strip electrodes 21A and the plurality of second strip electrodes E21B are arranged in a direction parallel to the Y-axis direction, and the longitudinal directions of the plurality of third strip electrodes 22A and the plurality of strip fourth electrodes E22B are arranged in a direction parallel to the X-axis direction. That is, the plurality of first strip electrodes E21A and the plurality of second strip electrodes E21B, and the plurality of third strip electrodes E22A and the plurality of fourth strip electrodes E22B are arranged to intersect. The longitudinal direction of the plurality of first strip electrodes E21A and the plurality of second strip electrodes E21B, and the longitudinal direction of the plurality of third strip electrodes E22A and the plurality of fourth strip electrodes E22B can be arranged to intersect in a range of, for example, 90 degrees ± 10 degrees, and are preferably arranged to be orthogonal (90 degrees). In this embodiment, these longitudinal directions are orthogonal to each other.

[0029] The third liquid crystal cell 30 includes a first substrate S31, a second substrate S32, and a third liquid crystal layer LC3 between the first substrate S31 and the second substrate S32. A first electrode E31 is provided on the surface of the first substrate S31 facing the third liquid crystal layer LC3, and a second electrode E32 is provided on the surface of the second substrate S32 facing the third liquid crystal layer LC3. The first electrode E31 includes a plurality of first strip-shaped electrodes E31A and a plurality of second strip-shaped electrodes E31B, and the second electrode E32 includes a plurality of third strip-shaped electrodes E32A and a plurality of fourth strip-shaped electrodes E32B.

[0030] In the third liquid crystal cell 30, a plurality of first strip electrodes 31A and a plurality of second strip electrodes E31B are alternately arranged, and a plurality of third strip electrodes 32A and a plurality of fourth strip electrodes E32B are alternately arranged. In the third liquid crystal cell 30, the longitudinal directions of the plurality of first strip electrodes 31A and the plurality of second strip electrodes E31B are arranged parallel to the X-axis direction, and the longitudinal directions of the plurality of third strip electrodes 32A and the plurality of fourth strip electrodes E32B are arranged parallel to the Y-axis direction. In other words, the plurality of first strip electrodes E31A and the plurality of second strip electrodes E31B are arranged so as to intersect with the plurality of third strip electrodes E32A and the plurality of fourth strip electrodes E32B. The longitudinal direction of the plurality of first strip electrodes E31A and the plurality of second strip electrodes E31B and the longitudinal direction of the plurality of third strip electrodes E32A and the plurality of fourth strip electrodes E32B can be arranged to intersect within a range of 90 degrees ±10 degrees, for example, and are preferably arranged to be orthogonal (90 degrees). In this embodiment, these longitudinal directions are orthogonal to each other.

[0031] The fourth liquid crystal cell 40 includes a first substrate S41, a second substrate S42, and a fourth liquid crystal layer LC4 between the first substrate S41 and the second substrate S42. A first electrode E41 is provided on the surface of the first substrate S41 facing the fourth liquid crystal layer LC4, and a second electrode E42 is provided on the surface of the second substrate S42 facing the fourth liquid crystal layer LC4. The first electrode E41 includes a plurality of first strip-shaped electrodes E41A and a plurality of second strip-shaped electrodes E41B, and the second electrode E42 includes a plurality of third strip-shaped electrodes E42A and a plurality of fourth strip-shaped electrodes E42B. In this embodiment, the longitudinal directions of these electrodes are perpendicular to each other.

[0032] In the fourth liquid crystal cell 40, a plurality of first strip electrodes 41A and a plurality of second strip electrodes E41B are alternately arranged, and a plurality of third strip electrodes 42A and a plurality of fourth strip electrodes E42B are alternately arranged. In the fourth liquid crystal cell 40, the longitudinal directions of the plurality of first strip electrodes 41A and the plurality of second strip electrodes E41B are arranged parallel to the X-axis direction, and the longitudinal directions of the plurality of third strip electrodes 42A and the plurality of fourth strip electrodes E42B are arranged parallel to the Y-axis direction. In other words, the plurality of first strip electrodes E41A and the plurality of second strip electrodes E41B are arranged so as to intersect with the plurality of third strip electrodes E42A and the plurality of fourth strip electrodes E42B. The longitudinal direction of the plurality of first strip electrodes E41A and the plurality of second strip electrodes E41B and the longitudinal direction of the plurality of third strip electrodes E42A and the plurality of fourth strip electrodes E42B can be arranged to intersect within a range of 90 degrees ±10 degrees, for example, and are preferably arranged to be orthogonal (90 degrees). In this embodiment, these longitudinal directions are orthogonal to each other.

[0033] As is clear from the above description, in the liquid crystal light control element 102, the first strip electrodes E11A and the second strip electrodes E11B of the first liquid crystal cell 10 and the first strip electrodes E21A and the second strip electrodes E21B of the second liquid crystal cell 20 are arranged in the same longitudinal direction, and the first strip electrodes E31A and the second strip electrodes E31B of the third liquid crystal cell 30 and the first strip electrodes E41A and the second strip electrodes E41B of the fourth liquid crystal cell 40 are arranged in the same longitudinal direction. The first strip electrodes E11A and the second strip electrodes E11B of the first liquid crystal cell 10 and the first strip electrodes E21A and the second strip electrodes E21B of the second liquid crystal cell 20 are arranged so that their longitudinal directions intersect. In this embodiment, the intersection angle is 90 degrees.

[0034] Similarly, in the liquid crystal light control element 102, the third strip electrodes E12A and the fourth strip electrodes E12B of the first liquid crystal cell 10 and the third strip electrodes E22A and the fourth strip electrodes E22B of the second liquid crystal cell 20 are arranged in the same longitudinal direction, and the third strip electrodes E32A and the fourth strip electrodes E32B of the third liquid crystal cell 30 and the third strip electrodes E42A and the fourth strip electrodes E42B of the fourth liquid crystal cell 40 are arranged in the same longitudinal direction. The third strip electrodes E12A and the fourth strip electrodes E12B of the first liquid crystal cell 10 and the third strip electrodes E22A and the fourth strip electrodes E22B of the second liquid crystal cell 20 are arranged so that the longitudinal directions of the third strip electrodes E32A and the fourth strip electrodes E32B of the third liquid crystal cell 30 and the third strip electrodes E42A and the fourth strip electrodes E42B of the fourth liquid crystal cell 40 intersect. In this case, the crossing angle is preferably in the range of 90 degrees ±10 degrees, and more preferably perpendicular (90 degrees). In this embodiment, the crossing angle is 90 degrees.

[0035] That is, in the liquid crystal light control element 102 according to this embodiment, the longitudinal direction of the strip-shaped pattern of the first electrodes E11 and E21 of the first liquid crystal cell 10 and the second liquid crystal cell 20 is parallel to the Y-axis direction, and the longitudinal direction of the strip-shaped pattern of the first electrodes E31 and E41 of the third liquid crystal cell 30 and the fourth liquid crystal cell 40 is parallel to the X-axis direction. In other words, the longitudinal direction of the strip-shaped pattern of the first electrodes E11 and E21 of the first liquid crystal cell 10 and the second liquid crystal cell 20 intersects with the longitudinal direction of the strip-shaped pattern of the first electrodes E31 and E41 of the third liquid crystal cell 30 and the fourth liquid crystal cell 40. As described above, the crossing angle is preferably within the range of 90 degrees ±10 degrees, and more preferably perpendicular (90 degrees). In this embodiment, the crossing angle is 90 degrees.

[0036] The first electrode E11 and the second electrode E12 provided in the first liquid crystal cell 10, the first electrode E21 and the second electrode E22 provided in the second liquid crystal cell 20, the first electrode E31 and the second electrode E32 provided in the third liquid crystal cell 30, and the first electrode E41 and the second electrode E42 provided in the fourth liquid crystal cell 40 have approximately the same size in a planar view. Although not shown in FIG. 3, the light source unit (106) is disposed below the first liquid crystal cell 10. Light emitted from the light source unit (106) and incident on the liquid crystal light control element 102 passes through all of the first liquid crystal cell 10, the second liquid crystal cell 20, the third liquid crystal cell 30, and the fourth liquid crystal cell 40 before being emitted.

[0037] The first liquid crystal cell 10, the second liquid crystal cell 20, the third liquid crystal cell 30, and the fourth liquid crystal cell 40 have substantially the same configuration, but the first liquid crystal cell 10 will be described in more detail below as a representative.

[0038] Fig. 4A shows a plan view of the first substrate S11, and Fig. 4B shows a plan view of the second substrate S12, which is a plan view seen from the inner surface side of the second substrate S12.

[0039] 4A, a first electrode E11 is provided on a first substrate S11. The first electrode E11 includes a plurality of first strip electrodes E11A and a plurality of second strip electrodes E11B. The plurality of first strip electrodes E11A and the plurality of second strip electrodes E11B have strip-shaped patterns. The strip-shaped patterns of the plurality of first strip electrodes E11A and the strip-shaped patterns of the plurality of second strip electrodes E11B are alternately arranged at predetermined intervals in a direction intersecting the longitudinal direction.

[0040] The first strip-shaped electrodes E11A are each connected to a first power supply line PL11, and the second strip-shaped electrodes E11B are each connected to a second power supply line PL12. The first power supply line PL11 is connected to a first connection terminal T11, and the second power supply line PL12 is connected to a second connection terminal T12. The first connection terminal T11 and the second connection terminal T12 are provided along one edge of the first substrate S11. The first substrate S11 is provided with a third connection terminal T13 adjacent to the first connection terminal T11 and a fourth connection terminal T14 adjacent to the second connection terminal T12. The third connection terminal T13 is connected to a fifth power supply line PL15. The fifth power supply line PL15 is connected to a first power supply terminal PT11 provided at a predetermined position within the surface of the first substrate S11. The fourth connection terminal T14 is connected to a sixth power supply line PL16. The sixth power supply line PL16 is connected to a second power supply terminal PT12 provided at a predetermined position on the surface of the first substrate S11.

[0041] The first strip electrodes E11A are connected to a first power supply line PL11, and the same voltage is applied to them. The second strip electrodes E11B are connected to a second power supply line PL12, and the same voltage is applied to them. As shown in FIG. 4A, the first strip electrodes E11A and the second strip electrodes E11B are alternately arranged. The first strip electrodes E11A and the second strip electrodes E11B are electrically isolated from each other. When voltages of different levels are applied to the first strip electrodes E11A and the second strip electrodes E11B, an electric field is generated between the electrodes due to the potential difference. In other words, a horizontal electric field can be generated by the first strip electrodes E11A and the second strip electrodes E11B.

[0042] As shown in FIG. 4B, a second electrode E12 is provided on the second substrate S12. The second electrode E12 includes a plurality of third strip electrodes E12A and a plurality of fourth strip electrodes E12B. The plurality of third strip electrodes E12A and the plurality of fourth strip electrodes E12B have a strip pattern. The strip patterns of the plurality of third strip electrodes E12A and the strip patterns of the plurality of fourth strip electrodes E12B are alternately arranged at a predetermined interval in a direction intersecting the longitudinal direction.

[0043] Each of the plurality of third strip electrodes E12A is connected to a third power supply line PL13, and each of the plurality of fourth strip electrodes E12B is connected to a fourth power supply line PL14. The third power supply line PL13 is connected to a third power supply terminal PT13, and the fourth power supply line PL14 is connected to a fourth power supply terminal PT14. The third power supply terminal PT13 is provided at a position corresponding to the first power supply terminal PT11 of the first substrate S11, and the fourth power supply terminal PT14 is provided at a position corresponding to the second power supply terminal PT12 of the first substrate S11.

[0044] The same voltage is applied to the plurality of third strip electrodes E12A by being connected to the third power supply line PL13. The same voltage is applied to the plurality of fourth strip electrodes E12B by being connected to the fourth power supply line PL14. As shown in FIG. 4B, the plurality of third strip electrodes E12A and the plurality of fourth strip electrodes E12B are alternately arranged. The plurality of third strip electrodes E12A and the plurality of fourth strip electrodes E12B are electrically separated. When different levels of voltage are applied to the plurality of third strip electrodes E12A and the plurality of fourth strip electrodes E12B, an electric field is generated between the two electrodes due to the potential difference. That is, a lateral electric field can be generated by the plurality of third strip electrodes E12A and the plurality of fourth strip electrodes E12B.

[0045] The first connection terminal T11, the second connection terminal T12, the third connection terminal 13, and the fourth connection terminal T14 provided on the first substrate S11 are terminals connected to a flexible wiring board. In the first liquid crystal cell 10, the first power supply terminal PT11 and the third power supply terminal PT13 are electrically connected by a conductive material, and the second power supply terminal PT12 and the fourth power supply terminal PT14 are electrically connected by a conductive material.

[0046] FIG. 5 shows a cross-sectional view of the first liquid crystal cell 10. The cross-sectional structure of the first liquid crystal cell 10 shown in FIG. 5 shows a cross-sectional structure corresponding to the A1-A2 line of the first substrate S11 shown in FIG. 4A and the second substrate S12 shown in FIG. 4B.

[0047] The first liquid crystal cell 10 has an effective region AA capable of polarizing and scattering incident light. The first electrode E11 and the second electrode E12 are disposed in the effective region AA. The first substrate S11 and the second substrate S12 are adhered by a sealing material SE provided outside the effective region AA. A gap for enclosing the first liquid crystal layer LC1 is provided between the first substrate S11 and the second substrate S12. The first liquid crystal layer LC1 is enclosed between the first substrate S11 and the second substrate S12 by the sealing material SE.

[0048] The first substrate S11 has a first electrode E11 and a first power supply terminal PT11, and has a structure in which a first alignment film AL11 is provided on the first electrode E11. The first electrode E11 includes a first strip-shaped electrode E11A and a second strip-shaped electrode E11B. The first power supply terminal PT11 has a structure continuous from the fifth power supply line PL15 and is disposed outside the sealing material SE.

[0049] The second substrate S12 has a second electrode E12 and a third power supply terminal PT13, and has a structure in which a second alignment film AL12 is provided on the second electrode E12. The second electrode E12 includes a third strip-shaped electrode E12A and a fourth strip-shaped electrode E12B. The third power supply terminal PT13 has a structure continuous from the third power supply line PL13 and is disposed outside the sealing material SE.

[0050] The first electrode E11 and the second electrode E12 are provided such that the longitudinal directions of the strip-shaped electrode patterns intersect. That is, they are arranged such that the longitudinal directions of the first strip-shaped electrodes E11A and E11B and the longitudinal directions of the third strip-shaped electrodes E12A and E12B intersect. In this embodiment, the first strip-shaped electrodes E11A and E11B and the third strip-shaped electrodes E12A and E12B intersect at an angle of 90 degrees. Note that the intersection angle between the first electrode E11 and the second electrode E12 can be set, for example, at 90 degrees ± 10 degrees as described above.

[0051] The first power supply terminal PT11 and the third power supply terminal PT13 face each other and are arranged to face each other in a region outside the sealing material SE. The first conductive member CP11 is disposed between the first power supply terminal PT11 and the third power supply terminal PT13 and electrically connects the two. The first conductive member CP11 can be formed of a conductive paste material. For example, a silver paste or a carbon paste is used. Although not shown in FIG. 5, the second power supply terminal PT12 and the fourth power supply terminal PT14 are also electrically connected by a conductive member in the same manner.

[0052] The first substrate S11 and the second substrate S12 are light-transmitting substrates, such as a glass substrate or a resin substrate. The first electrode E11 and the second electrode E12 are transparent electrodes made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). The power supply lines (first power supply line PL11, second power supply line PL12, third power supply line PL13, fourth power supply line PL14, fifth power supply line PL15, sixth power supply line PL16), connection terminals (first connection terminal T11, second connection terminal T12, third connection terminal T13, fourth connection terminal T14), and power supply terminals (first power supply terminal PT11, second power supply terminal PT12, third power supply terminal PT13, fourth power supply terminal PT14) are made of a metal material such as aluminum, titanium, molybdenum, or tungsten. The power supply lines (first power supply line PL11, second power supply line PL12, third power supply line PL13, fourth power supply line PL14, fifth power supply line PL15, and sixth power supply line PL16) may be formed of the same transparent conductive film as the first electrode E11 and the second electrode E12. The alignment films AL1 and AL2 are formed of a horizontal alignment film having an alignment restriction force substantially parallel to the main planes of the substrates. The first liquid crystal layer LC1 is made of, for example, twisted nematic liquid crystal (TN (Twisted Nematic) liquid crystal). Although not shown in FIG. 5, a spacer may be provided between the first substrate S11 and the second substrate S12 to keep the gap between the two substrates constant.

[0053] Next, the electro-optical action of the first liquid crystal cell 10 will be described with reference to Figures 6A, 6B, 6C, 7A, 7B, 7C, and 8. Note that Figures 6 to 8 show only the configuration necessary for the description.

[0054] Fig. 6A shows a partial cross-sectional schematic structure of the first liquid crystal cell 10. Fig. 6B shows the first strip electrodes E11A and second strip electrodes E11B, which are provided on the first substrate S11, the first alignment film AL11, the second alignment film AL12, which is provided on the second substrate S12, and the first liquid crystal layer LC1. In Fig. 6A, the third strip electrodes E12A and the fourth strip electrodes E12B are omitted for simplicity of explanation.

[0055] FIG. 6A shows that the alignment direction of the first alignment film AL11 is different from that of the second alignment film AL12. Specifically, as shown in FIG. 4A, the first alignment film AL11 is aligned in a direction ALD1 that intersects the longitudinal direction of the first strip electrodes E11A and the second strip electrodes E11B at a 90-degree angle. As shown in FIG. 4B, the second alignment film AL12 is aligned in a direction ALD2 that intersects the longitudinal direction of the third strip electrodes E12A and the fourth strip electrodes E12B at a 90-degree angle. Therefore, in the first liquid crystal cell 10 shown in FIG. 6A, the first alignment film AL11 is aligned in the left-right direction of the paper, and the second alignment film AL12 is aligned in the normal direction of the paper. The alignment may be performed by rubbing or light distribution. The alignment direction of the alignment film can be set within a range of 90 degrees ±10 degrees with respect to the extension direction of the strip electrodes.

[0056] The first liquid crystal layer LC1 uses TN liquid crystal. Because the alignment direction ALD1 of the first alignment film AL11 and the alignment direction ALD2 of the second alignment film AL12 are perpendicular to each other, the liquid crystal molecules in the first liquid crystal layer LC1 are aligned such that the long axis directions of the liquid crystal molecules are twisted by 90 degrees from the first alignment film AL11 to the second alignment film AL12 when not subjected to the action of an external electric field. Figure 6A shows a state in which no voltage is applied to the first strip-shaped electrodes E11A and the second strip-shaped electrodes E11B, and shows a state in which the long axis directions of the liquid crystal molecules are twisted by 90 degrees.

[0057] 6A shows an example in which the liquid crystal layer LC1 is formed of positive twisted nematic liquid crystal (TN liquid crystal), with the long axes of the liquid crystal molecules oriented in the same direction as the alignment direction of the alignment film, but negative liquid crystal can be used by rotating the alignment direction of the alignment film by 90 degrees, i.e., by aligning the alignment direction of each alignment film AL11, AL12 with the extension direction of the strip electrodes E11A, E12A of each substrate S11, S12. The liquid crystal preferably contains a chiral agent that imparts a twist to the liquid crystal molecules.

[0058] FIG. 6B shows a state in which a low-level voltage VL is applied to the first strip electrode E11A and a high-level voltage VH is applied to the second strip electrode E11B. In this state, a horizontal electric field is generated between the first strip electrode E11A and the second strip electrode E11B. As shown in FIG. 6B, the liquid crystal molecules on the side of the first substrate S11 are affected by the horizontal electric field and the alignment direction changes. For example, the liquid crystal molecules on the side of the first substrate S11 change their alignment so that the major axis direction faces a direction parallel to the direction of the electric field.

[0059] The values of the low-level voltage VL and the high-level voltage VH applied to the first strip electrode E11A and the second strip electrode E11B are set as appropriate. For example, 0 V is applied as the low-level voltage VL1, and a voltage of 5 to 30 V is applied as the high-level voltage VH1. A voltage in which the low-level voltage VL and the high-level voltage VH are alternately switched is applied to the first strip electrode E11A and the second strip electrode E11B. For example, as shown in FIG. 6C, during a certain period, a low-level voltage VL is applied to the first strip electrode E11A and a high-level voltage VH is applied to the second strip electrode E11B, and in the next certain period, a high-level voltage VH is applied to the first strip electrode E11A and a low-level voltage VL is applied to the second strip electrode E11B. The voltage may be applied so that the voltage levels between the two electrodes change periodically in synchronization.

[0060] By alternately applying the low-level voltage VL and the high-level voltage VH to the first strip electrode E11A and the second strip electrode E11B, an alternating electric field is generated to suppress the deterioration of the first liquid crystal layer LC1. The frequency of the voltage applied to the first strip electrode E11A and the second strip electrode E11B may be any frequency at which the liquid crystal molecules can follow the change of the electric field. For example, it may be 15 to 100 Hz.

[0061] FIG. 7A is a partial perspective view of the first liquid crystal cell 10, showing the arrangement of the first and second strip electrodes E11A and E11B, the third and fourth strip electrodes E12A and E12B, and the first liquid crystal layer LC1. FIGS. 7B and 7C are cross-sectional views of the first liquid crystal cell 10. FIG. 7B is a cross-sectional view of the first liquid crystal cell 10 shown in FIG. 7A, viewed from side A, and FIG. 7C is a cross-sectional view of the first liquid crystal cell 10 viewed from side B. Note that FIGS. 7B and 7C show that the alignment treatment direction of the first alignment film AL11 is different from the alignment treatment direction of the second alignment film AL12.

[0062] As shown in FIGS. 7A and 7C, the first strip electrode E11A and the second strip electrode E11B are disposed with a center-to-center distance W, and the third strip electrode E12A and the fourth strip electrode E12B are similarly disposed with a center-to-center distance W. This center-to-center distance W satisfies the relationship W=a+b, where a is the width of the first strip electrode E11A and b is the distance from the end of the first strip electrode E11A to the end of the second strip electrode E11B, as shown in FIG. 7A. The first strip electrode E11A and the second strip electrode E11B, and the third strip electrode E12A and the fourth strip electrode E12B, are disposed apart from each other and perpendicular to each other. The first substrate S11 and the second substrate S12 are disposed opposite each other with a distance D, which is substantially equivalent to the thickness of the liquid crystal layer LC1. In reality, the first substrate S11 is provided with a first strip electrode E11A and a first alignment film AL11, and the second substrate S12 is provided with a third strip electrode E12A and a second alignment film AL12, etc., but the thicknesses of these electrodes and alignment films are sufficiently small compared to the size of the gap D, so the thickness of the liquid crystal layer LC1 can be considered to be the same as the gap D.

[0063] In the first liquid crystal cell 10, the distance D between the strip electrodes sandwiching the first liquid crystal layer LC1 is preferably equal to or greater than the center-to-center distance W of the strip electrodes. That is, the distance D is preferably at least one time the center-to-center distance W. For example, the distance D is preferably at least twice the center-to-center distance W of the strip electrodes. When the width of the first strip electrode E11A is 5 μm, the widths a of the first strip electrode E11A and the second strip electrode E11B are 5 μm, and the distance b from the end of the first strip electrode E11A to the end of the second strip electrode E11B is 5 μm, the center-to-center distance W of the strip electrodes is 10 μm. In contrast, the distance D is preferably 10 μm or greater.

[0064] The relationship between the center-to-center distance W of the strip electrodes and the interval D prevents the electric field generated by the first strip electrodes E11A and the second strip electrodes E11B from interfering with the electric field generated by the third strip electrodes E12A and the fourth strip electrodes E12B. That is, as shown in Fig. 7B, the first strip electrodes E11A and the second strip electrodes E11B can control the orientation of liquid crystal molecules in their vicinity without being affected by the third strip electrodes E12A and the fourth strip electrodes E12B, and as shown in Fig. 7C, the third strip electrodes E12A and the fourth strip electrodes E12B can control the orientation of liquid crystal molecules in their vicinity without being affected by the first strip electrodes E11A and the second strip electrodes E11B.

[0065] It is known that the refractive index of liquid crystal changes depending on its orientation. As shown in FIG. 6A, in the OFF state where no electric field is applied to the first liquid crystal layer LC1, the long axis direction of the liquid crystal molecules is aligned horizontally to the substrate surfaces, and is twisted 90 degrees from the first substrate S11 side to the second substrate S12 side. The liquid crystal layer LC1 has a substantially uniform refractive index distribution in this orientation state. Therefore, the first polarization component PL1 and the second polarization component PL2 (see FIG. 8) perpendicular to the first polarization component PL1 of light incident on the first liquid crystal cell 10 are rotated by the initial orientation of the liquid crystal molecules, but are transmitted through the first liquid crystal layer LC1 with almost no refraction (or scattering). Here, the first polarization component PL1 corresponds to, for example, P-polarized light, and the second polarization component corresponds to, for example, S-polarized light, of natural light.

[0066] On the other hand, as shown in Fig. 6B, in the ON state where a voltage is applied to the first strip electrodes E11A and the second strip electrodes E11B to form an electric field, if the first liquid crystal layer LC1 has positive dielectric anisotropy, the liquid crystal molecules are oriented with their major axes aligned with the electric field. As a result, as shown in Fig. 6B, the first liquid crystal layer LC1 has regions where the liquid crystal molecules stand almost vertically above the first strip electrodes E11A and the second strip electrodes E11B, regions where they are oriented obliquely along the distribution of the electric field between the first strip electrodes E11A and the second strip electrodes E11B, and regions where the initial alignment state is relatively maintained in regions away from the first strip electrodes E11A and the second strip electrodes E11B.

[0067] As shown in Fig. 6B, between the first strip electrode E11A and the second strip electrode E11B, the long axes of the liquid crystal molecules are aligned in a convex arc shape along the direction of the electric field. That is, as shown in Figs. 6A and 6B, the initial alignment direction of the liquid crystal molecules is the same as the direction of the transverse electric field generated between the first strip electrode E11A and the second strip electrode E11B. As shown in Fig. 6B, the alignment direction of the liquid crystal molecules located approximately in the center between the two electrodes remains almost unchanged. However, the liquid crystal molecules located from the center toward each electrode are aligned with a tilt in the direction normal to the surface of the first substrate S11 in accordance with the electric field intensity distribution. Therefore, when the liquid crystal on the first substrate S11 side is viewed as a whole, the liquid crystal molecules are aligned in an arc shape between the first strip electrode E11A and the second strip electrode E11B.

[0068] As a result, an arc-shaped dielectric constant distribution is formed in the liquid crystal layer LC1, and incident light (polarized components parallel to the direction of the initial alignment of the liquid crystal molecules) is diffused radially. On the second substrate S12 side, a similar phenomenon occurs due to the third strip-shaped electrodes E12Aa and fourth strip-shaped electrodes E12B (see FIG. 7C), which are arranged perpendicular to the electrodes of the first substrate S11, and incident light (polarized components parallel to the direction of the initial alignment of the liquid crystal molecules on the second substrate S12) is diffused radially.

[0069] As explained with reference to Figures 7B and 7C, the thickness of the liquid crystal layer LC1 is sufficiently large so that the diffusion of different polarized components can be controlled independently on the first substrate S11 side and the second substrate S12 side.

[0070] Liquid crystal molecules have a refractive index anisotropy Δn. Therefore, in the on state, the first liquid crystal layer LC1 has a refractive index distribution, or retardation distribution, that corresponds to the alignment state of the liquid crystal molecules. Here, retardation is expressed as Δn·d, where d is the thickness of the first liquid crystal layer LC1. In the on state, the first polarization component PL1 is scattered by the refractive index distribution of the first liquid crystal layer LC1 as it passes through the first liquid crystal layer LC1.

[0071] FIG. 8 schematically shows the phenomenon in which the first polarization component PL1 and the second polarization component PL2 are diffused by the liquid crystal layer. FIG. 8 shows a state in which the first liquid crystal cell 10 and the second liquid crystal cell 20 are stacked, and for simplicity, only the first substrates S11, S21, the second substrates S12, S22, the first strip electrodes E11A, E21A and the second strip electrodes E11B, E21B, and the first liquid crystal layer LC1 and the second liquid crystal layer LC2 of each liquid crystal cell are shown. For example, the first transparent adhesive layer TA1 provided between the first liquid crystal cell 10 and the second liquid crystal cell 20 is omitted. It is assumed that the first strip electrodes E11A and the second strip electrodes E11B of the first liquid crystal cell 10 and the first strip electrodes E21A and the second strip electrodes E21B of the second liquid crystal cell 20 are arranged in the same direction. Also, the alignment direction ALD1 of the alignment film (not shown) on the side of the first substrate S11 of the first liquid crystal cell 10 and the first substrate S21 of the second liquid crystal cell 20 is in the horizontal direction of the paper surface, and the alignment direction ALD2 of the alignment film (not shown) on the side of the second substrate S12 of the first liquid crystal cell 10 and the second substrate S22 of the second liquid crystal cell 20 is in the normal direction of the paper surface.

[0072] In FIG. 8, it is assumed that the first liquid crystal cell 10 and the second liquid crystal cell 20 are such that the polarization direction of the first polarization component PL1 is parallel to the initial alignment direction of the liquid crystal molecules on the side of the first substrate S11 of the first liquid crystal layer LC1 and the initial alignment direction of the liquid crystal molecules on the side of the first substrate S12 of the second liquid crystal layer LC2 (the direction in which the long axis of the liquid crystal molecules is aligned in the non-electric field state). And it is assumed that the polarization direction of the second polarization component PL2 is orthogonal to the alignment direction of the liquid crystal molecules on the side of the first substrate S11 of the first liquid crystal layer LC1 and the side of the first substrate S21 of the second liquid crystal layer LC2.

[0073] When a voltage is applied to the first strip electrodes E11A and the second strip electrodes E11B of the first liquid crystal cell 10, in the first liquid crystal layer LC1, regions where the liquid crystal molecules stand vertically, regions where they are obliquely aligned along the distribution of the electric field, regions where the initial alignment state is maintained, etc. are formed. Similarly, in a state where a voltage is applied to the first strip electrodes E21A and the second strip electrodes E21B of the second liquid crystal cell 20, in the second liquid crystal layer LC2, regions where the liquid crystal molecules stand vertically, regions where they are obliquely aligned along the distribution of the electric field, regions where the initial alignment state is maintained, etc. are formed.

[0074] The first polarization component PL1 is diffused in the first liquid crystal layer LC1 and rotated by 90 degrees. In the second liquid crystal layer LC2, it is not diffused but rotated by 90 degrees. The second polarization component PL2 is not diffused in the first liquid crystal layer LC1 but rotated by 90 degrees. In the second liquid crystal layer LC2, it is diffused and rotated by 90 degrees. That is, the first polarization component PL1 incident on the first substrate S11 is diffused in the first liquid crystal layer LC1 and rotated by the first liquid crystal layer LC1 and the second liquid crystal layer LC2 respectively. The second polarization component PL2 incident on the first substrate S11 is diffused in the second liquid crystal layer LC2 and rotated by the first liquid crystal layer LC1 and the second liquid crystal layer LC2 respectively. Here, optical rotation refers to the phenomenon in which the polarization axis of a linearly polarized light component (for example, the first polarization component PL1 or the second polarization component PL2) is rotated along the twisted alignment of liquid crystal molecules during the process of passing through the liquid crystal layer.

[0075] FIG. 8 will be described in more detail. The first electrode E11 and the second electrode E12 of the first liquid crystal cell 10 are orthogonal to each other, and the first electrode E21 and the second electrode E22 of the second liquid crystal cell 20 are orthogonal to each other. Also, the extending direction of the first electrode E11 of the first liquid crystal cell 10 coincides with the extending direction of the first electrode E21 of the second liquid crystal cell 20. Further, light including the first polarization component PL1 (polarization component in the X-axis direction) and the second polarization component PL2 (polarization component in the Y-axis direction) is incident from a direction perpendicular to the first substrate S11 of the first liquid crystal cell 10 and exits from the second substrate S22 of the second liquid crystal cell 20.

[0076] Since the liquid crystal molecules of the liquid crystal layer LC1 on the first substrate S11 side of the first liquid crystal cell 10 have their major axes oriented along the X-axis direction, when a transverse electric field is generated between the first strip electrode E11A and the second strip electrode E11B, as described with reference to FIG. 7B, the liquid crystal molecules are oriented in a convex arc shape in the X-axis direction under the action of the electric field. Also, since the liquid crystal molecules of the first liquid crystal layer LC1 on the second substrate S12 side of the first liquid crystal cell 10 have their major axes oriented along the Y-axis direction, when a transverse electric field is generated between the third strip electrode E12A and the fourth strip electrode E12B (not shown), as described with reference to FIG. 7C, the liquid crystal molecules are oriented in a convex arc shape in the Y-axis direction. Due to such an alignment of liquid crystal molecules, a refractive index distribution depending on the alignment of liquid crystal molecules is formed on the first substrate S11 side and the second substrate S12 side.

[0077] The first polarization component PL1 parallel to the X-axis incident on the first liquid crystal cell 10 is rotated when passing through the first liquid crystal layer LC1 and becomes a polarization component parallel to the Y-axis on the second substrate S12 side. That is, the first polarization component PL1 has a polarization axis in the X-axis direction on the first substrate S11 side, but the polarization axis gradually changes in the thickness direction of the first liquid crystal layer LC1 and has a polarization axis in the Y-axis direction on the second substrate S12 side, and is emitted from the second substrate S12 side.

[0078] Here, the first polarization component PL1 incident on the first liquid crystal cell 10 from the first substrate S11 side has a polarization axis parallel to the alignment direction of the liquid crystal molecules of the first liquid crystal layer LC1 on the first substrate S11 side, so it diffuses in the X-axis direction according to the change in the refractive index distribution of the liquid crystal molecules. In addition, the first polarization component PL1 changes its polarization axis from the X-axis direction to the Y-axis direction by passing through the first liquid crystal layer LC1, so that it becomes parallel to the alignment direction of the liquid crystal molecules on the second substrate S12 side, and diffuses in the Y-axis direction according to the change in the refractive index distribution of the liquid crystal molecules. That is, the first polarization component PL1 parallel to the X-axis before entering the first liquid crystal cell 10 changes its polarization axis from the X-axis direction to the Y-axis direction in the process of passing through the first liquid crystal cell 10 and diffuses in the X-axis direction and the Y-axis direction.

[0079] In contrast, the second polarization component PL2 incident on the first liquid crystal cell 10 from the side of the first substrate S11 enters the first substrate S11 and, during the period until it exits from the second substrate S12, is affected by the action of the first liquid crystal layer LC1 and the polarization axis changes from the Y-axis direction to the X-axis direction. Here, on the side of the first substrate S11, since the polarization axis of the second polarization component PL2 is orthogonal to the alignment direction of the liquid crystal molecules on the side of the first substrate S11 of the first liquid crystal layer LC1, it is not affected by the refractive index distribution caused by the liquid crystal molecules and passes through without diffusion. Also, since the polarization axis of the second polarization component PL2 changes from the Y-axis direction to the X-axis direction in the first liquid crystal layer LC1, on the side of the second substrate S12, its polarization axis is also orthogonal to the alignment direction of the liquid crystal molecules on the side of the second substrate S12 of the first liquid crystal layer LC1, so it is not affected by the refractive index distribution caused by the liquid crystal molecules and passes through without diffusion. That is, the second polarization component PL2 having a polarization axis in the Y-axis direction incident on the first liquid crystal cell 10 changes its polarization axis from the Y-axis direction to the X-axis direction in the process of passing through the first liquid crystal cell 10, but is not diffused by the first liquid crystal layer LC1 and exits from the second substrate S12.

[0080] The second liquid crystal layer LC2 of the second liquid crystal cell 20 also has the same refractive index distribution as the first liquid crystal layer LC1 of the first liquid crystal cell 10. For this reason, basically the same phenomenon as that of the first liquid crystal cell 10 also occurs in the second liquid crystal cell 20. On the other hand, since the polarization axes of the initial first polarization component PL1 and the second polarization component PL2 are interchanged by passing through the first liquid crystal cell 10, the polarization components affected by the refractive index distribution in the second liquid crystal layer LC2 are also interchanged. That is, in the process of passing through the second liquid crystal cell 20, although the initial first polarization component PL1 changes its polarization axis from the Y-axis to the X-axis direction again, no diffusion occurs. On the other hand, the initial second polarization component PL2 changes its polarization axis from the X-axis to the Y-axis direction again and is diffused under the influence of the refractive index distribution of the second liquid crystal layer LC2.

[0081] As is clear from the above, by laminating two liquid crystal cells having the same structure, the polarization direction of light passing through these two liquid crystal cells can be changed over 2 degrees, and as a result, the polarization direction before incidence and after emission can be made unchanged. On the other hand, the two liquid crystal cells can diffuse the transmitted light by forming a convex arc-shaped refractive index distribution on the upper and lower sides of the liquid crystal layer by a horizontal electric field. Specifically, the first liquid crystal cell 10 can diffuse the light of the first polarization component PL1 in the X-axis direction, the Y-axis direction, or both the X-axis and Y-axis directions, and the second liquid crystal cell 20 can diffuse the light of the second polarization component PL2 in the X-axis direction, the Y-axis direction, or both the X-axis and Y-axis directions. That is, by laminating the first liquid crystal cell 10 and the second liquid crystal cell 20 and forming a refractive index distribution in the liquid crystal layer of each liquid crystal cell, the light can be diffused without changing the polarization state of the light.

[0082] As described above, by laminating two liquid crystal cells having the same structure, the polarization direction of the incident light can be changed twice so that the polarization direction does not change before and after passing through the two liquid crystal cells. On the other hand, by applying a horizontal electric field to the liquid crystal layer to form a refractive index distribution, the transmitted light can be refracted in a specific direction. More specifically, the first liquid crystal cell 10 can diffuse the light of the first polarization component PL1 in the X-axis direction, the Y-axis direction, or both the X-axis and Y-axis directions, and the second liquid crystal cell 20 can diffuse the light of the second polarization component PL2 in the X-axis direction, the Y-axis direction, or both the X-axis and Y-axis directions.

[0083] In this way, for the incident light passing through the first liquid crystal layer LC1 and the second liquid crystal layer LC2, the first polarization component PL1 is diffused by the first liquid crystal layer LC1, and the second polarization component PL2 is diffused by the second liquid crystal layer LC2. Also, the incident light passing through the first liquid crystal layer LC1 and the second liquid crystal layer LC2 is rotated by 90 degrees in the first liquid crystal layer LC1 and the second liquid crystal layer LC2, respectively. In other words, for the incident light including the first polarization component PL1 and the second polarization component PL2, the first polarization component PL1 is diffused in the first liquid crystal cell 10, and the second polarization component PL2 is diffused in the second liquid crystal cell 20. That is, by overlapping the first liquid crystal cell 10 and the second liquid crystal cell 20, the scattering of a specific polarization component can be individually controlled, and the light distribution of the light emitted from the light source can be controlled.

[0084] By the way, it is known that light refracts at the interface between different media, and the refraction angle varies depending on the wavelength of the light. When light is incident on a liquid crystal layer with a refractive index distribution formed, since the refraction angle is different for each wavelength, depending on the type of light source and the distance to the object being irradiated, color fringing may be visually recognized in the peripheral portion of the light distribution pattern formed by transmitting the light through the liquid crystal light control element 102.

[0085] On the other hand, as shown in FIG. 3, the liquid crystal light control element 102 according to the present embodiment suppresses color fringing by overlapping four liquid crystal cells on the optical path of the light source and arranging at least two of the four liquid crystal cells to be rotated by 90 degrees with respect to the other liquid crystal cells. Specifically, the liquid crystal light control element 102 suppresses color fringing by arranging at least one set of adjacent overlapping liquid crystal cells such that the longitudinal directions of the electrodes having a strip-shaped pattern face different directions. Hereinafter, the configuration will be described in detail based on the electrode configuration and operation of each liquid crystal cell.

[0086] FIG. 9 shows the arrangement of the strip electrodes in each liquid crystal cell of the liquid crystal light control element 102, and the mode in which the polarization state and scattering of the incident light are controlled by each liquid crystal cell. The arrangement of the electrodes in the first liquid crystal cell 10, the second liquid crystal cell 20, the third liquid crystal cell 30, and the fourth liquid crystal cell 40 is the same as the structure shown in FIG. 3. Specifically, in the liquid crystal light control element 102 shown in FIG. 9, the alignment directions of the liquid crystal molecules in each substrate (S11, S12, S21, S22) of the first liquid crystal cell 10 and the second liquid crystal cell 20 are the same, and the longitudinal directions of the strip electrodes (E11A, E11B, E21A, E21B) in the first electrodes E11, E21 are the same. The longitudinal directions of the strip electrodes (E12A, E12B, E22A, E22B) in the second electrodes E12, E22 that intersect these electrodes are the same. Also, the alignment directions of the liquid crystal molecules in each substrate (S31, S32, S41, S42) of the third liquid crystal cell 30 and the fourth liquid crystal cell 40 are the same, and the longitudinal directions of the strip electrodes (E31A, E31B, E41A, E41B) in the first electrodes E31, E41 are the same. The longitudinal directions of the strip electrodes (E32A, E32B, E42A, E42B) in the second electrodes E32, E42 that intersect these electrodes are the same. And the longitudinal direction of the strip electrodes (E11A, E11B, E21A, E21B) in the first liquid crystal cell 10 and the second liquid crystal cell 20 intersects at a 90-degree angle with the longitudinal direction of the strip electrodes (E31A, E31B, E41A, E41B) in the first electrodes E31, E41 in the third liquid crystal cell 30 and the fourth liquid crystal cell 40.

[0087] In the embodiment shown in Fig. 9, the first liquid crystal cell 10 and the second liquid crystal cell 20 are stacked with their first electrodes E11 and E21 facing in the same direction, and the third liquid crystal cell 30 and the fourth liquid crystal cell 40 are stacked with their first electrodes E31 and E41 facing in the same direction, but the orientations of the first electrodes E31 and E41 of the third liquid crystal cell 30 and the fourth liquid crystal cell 40 are rotated 90 degrees relative to the orientations of the first electrodes E11 and E21 of the first liquid crystal cell 10 and the second liquid crystal cell 20. Furthermore, the extension directions of the first electrodes (E11, E21, E31, E41) and second electrodes (E12, E22, E32, E42) of each liquid crystal cell are perpendicular to each other. This also applies to the embodiments shown in Figs. 12 to 14, which will be described later. It is also possible to employ a configuration in which the third liquid crystal cell 30 and the fourth liquid crystal cell 40 are stacked while rotated within a range of 90 degrees ±10 degrees relative to the first liquid crystal cell 10 and the second liquid crystal cell 20. It is also possible to employ a configuration in which the extension directions of the first electrodes (E11, E21, E31, E41) and second electrodes (E12, E22, E32, E42) of each liquid crystal cell are set within a range of 90 degrees ±10 degrees.

[0088] 9, the second electrode E12 of the first liquid crystal cell 10 and the first electrode E41 of the fourth liquid crystal cell 40 are oriented in the same direction, which allows the second polarized component PL2 to be diffused in the Y-axis direction. Furthermore, the first electrode E11 of the first liquid crystal cell 10 and the second electrode E42 of the fourth liquid crystal cell 40 are oriented in the same direction, which allows the second polarized component PL2 to be diffused in the X-axis direction. Similarly, the first polarized component PL1 is diffused in the same way. The second electrode E22 of the second liquid crystal cell 20 and the first electrode E31 of the third liquid crystal cell 30 are oriented in the same direction, which allows the first polarized component PL1 to be diffused in the Y-axis direction, and the first electrode E21 of the second liquid crystal cell 20 and the second electrode E32 of the third liquid crystal cell 30 are oriented in the same direction, which allows the first polarized component PL1 to be diffused in the X-axis direction.

[0089] The liquid crystal light control element 102 has a first liquid crystal cell 10, a second liquid crystal cell 20, a third liquid crystal cell 30, and a fourth liquid crystal cell 40 arranged in this order from the light incident side. The light incident on the liquid crystal light control element 102 includes a first polarization component PL1 and a second polarization component PL2 that is orthogonal to the first polarization component PL1.

[0090] In order for the liquid crystal light control element 102 to control the polarization and scattering state of incident light, a control signal is input to each liquid crystal cell. FIG. 10A shows an example of the waveform of a control signal applied to the electrode of each liquid crystal cell. One of the control signals A, B, and E shown in FIG. 10A is input to each liquid crystal cell. In the control signals A and B, VL1 denotes a low-level voltage and VH1 denotes a high-level voltage. For example, VL1 is a voltage of 0 V or −15 V, and VH1 is 30 V (relative to 0 V) or 15 V (relative to −15 V). The control signals A and B are synchronized. When the control signal A is at the VL1 level, the control signal B is at the VH1 level. When the control signal A changes to the VH1 level, the control signal B changes to the VL1 level. The cycle of the control signals A and B is approximately 15 to 100 Hz. On the other hand, the control signal E is a constant voltage signal. For example, the control signal E is an intermediate voltage between VL1 and VH1, and when VL1=-15V and VH1=+15V, VE=0V.

[0091] Below, examples will be shown in which a square light distribution pattern, a cross light distribution pattern, and a line light distribution pattern are formed by the liquid crystal light control element 102 using such control signals.

[0092] (1) Square light distribution pattern The liquid crystal light control device 100 can control the light distribution pattern of the light emitted from the light source unit (106) in various ways by selecting the control signal to be applied to each liquid crystal cell of the liquid crystal light control element 102. Figure 9 shows, as an example, a case where the light emitted from the light source unit (106) is controlled to have a rectangular light distribution pattern.

[0093] Table 1 shows the control signals applied to each liquid crystal cell in the liquid crystal light control element 102 shown in Fig. 9. Note that control signals A and B shown in Table 1 correspond to the control signals shown in Fig. 10A. [Table 1]

[0094] 9, a control signal A is input to the first strip electrode E11A of the first liquid crystal cell 10, a control signal B is input to the second strip electrode E11B, a control signal A is input to the third strip electrode E12A, and a control signal B is input to the fourth strip electrode E12B. As shown in Table 1, the control signals A and B are also input to the second liquid crystal cell 20, the third liquid crystal cell 30, and the fourth liquid crystal cell 40, as with the first liquid crystal cell 10. That is, in the example shown in FIG. 9, the control signals A and B are alternately applied to all electrodes arranged alternately on each substrate, and an electric field is generated between all of the electrodes.

[0095] 9, the alignment direction defined by the alignment film formed on each substrate is perpendicular to the longitudinal direction of the strip electrodes, as indicated by the arrows in the figure. The liquid crystal layer is made of positive liquid crystal, and in the initial state where no control signal is input to each liquid crystal cell, the long axis direction of the liquid crystal is aligned in a direction intersecting (perpendicular to) the strip electrodes. In this embodiment, the alignment direction of the alignment film is set at 90 degrees to the extension direction of the strip electrodes, but it can also be set to a direction 90 degrees ±10 degrees.

[0096] When the liquid crystal light control element 102 is in operation, the control signals shown in Table 1 are input to the strip electrodes of each liquid crystal cell. When the control signals shown in Table 1 are input to the first liquid crystal cell 10, the second liquid crystal cell 20, the third liquid crystal cell 30, and the fourth liquid crystal cell 40, the liquid crystal molecules in each liquid crystal cell are affected by the transverse electric field and the alignment state changes as shown in FIGS. 7A and 7B. The table inserted in FIG. 9 shows how each polarization component changes when light containing a first polarization component PL1 and a second polarization component PL2 passes through each liquid crystal cell. In the following description, the same direction as the first polarization direction is defined as the Y-axis direction, and the same direction as the second polarization direction is defined as the X-axis direction.

[0097] Focusing on the first polarization component PL1 in FIG. 9, the polarization direction of the first polarization component PL1 incident on the first liquid crystal cell 10 is in a direction (orthogonal direction) intersecting the major axis direction of the liquid crystal molecules on the first substrate S11 side of the first liquid crystal layer LC1. Therefore, although the refractive index distribution of the liquid crystal molecules on the first substrate S11 side is changed by the electric field generated by the first electrode E11, the first polarization component PL1 is not diffused and goes straight toward the second substrate S12 side. Further, the first polarization component PL1 is rotated by 90 degrees according to the twisted alignment of the liquid crystal molecules in the process of passing through the first liquid crystal layer LC1 from the first substrate S11 side to the second substrate S12 side. As a result, the first polarization component PL1 transitions to the second polarization component PL2. Also, the polarization direction of the second polarization component PL2 is in a direction intersecting the major axis direction of the liquid crystal molecules on the second substrate S12 side. Therefore, although the refractive index distribution of the liquid crystal molecules on the second substrate S12 side is changed by the electric field generated by the second electrode E12, the second polarization component PL2 is not affected by it and is transmitted as it is. That is, the first polarization component PL1 transitions to the second polarization component PL2 in the process of passing through the first liquid crystal cell 10, while not being diffused or the like and is emitted from the second substrate S12 side.

[0098] The second polarized component PL2 then enters the second liquid crystal cell 20. The polarization direction of the second polarized component PL2 is parallel to the long axis direction of the liquid crystal molecules on the first substrate S21 side of the second liquid crystal layer LC2. Here, the refractive index distribution of the liquid crystal molecules on the first substrate S21 side is changed by the electric field generated by the first electrode E21, so the second polarized component PL2 is diffused in the X-axis direction. Furthermore, this diffused second polarized component PL2 is rotated by 90 degrees in accordance with the twisted orientation of the liquid crystal molecules as it travels through the second liquid crystal layer LC2 from the first substrate S21 side to the second substrate S22 side. As a result, the second polarized component PL2 transitions back to the first polarized component PL1. Furthermore, the polarization direction of the first polarized component PL1 is parallel to the long axis direction of the liquid crystal molecules on the second substrate S22 side. Here, the liquid crystal molecules on the second substrate S22 side have their refractive index distribution changed by the electric field generated by the second electrode E22, so the first polarized component is further affected by the refractive index distribution of the liquid crystal molecules and diffused in the Y-axis direction before being emitted. That is, the second polarized component PL2 incident on the second liquid crystal cell 20 is transformed into the first polarized component PL1 while passing through the second liquid crystal cell 20, and is diffused in the X-axis and Y-axis directions.

[0099] In this way, of the incident light, the first polarization component PL1 enters the first liquid crystal cell 10, transitions once to the second polarization component PL2, and then transitions again to the first polarization component PL1 before being emitted from the second liquid crystal cell 20, and is diffused once each in the X-axis direction and the Y-axis direction by the second liquid crystal cell 20.

[0100] The longitudinal direction of the first electrode E31 of the third liquid crystal cell 30 intersects at a 90-degree angle with the longitudinal direction of the first electrode E11 of the first liquid crystal cell 10 and the longitudinal direction of the first electrode E21 of the second liquid crystal cell 20, and the longitudinal direction of the second electrode E32 intersects at a 90-degree angle with the longitudinal direction of the second electrode E12 of the first liquid crystal cell 10 and the longitudinal direction of the second electrode E22 of the second liquid crystal cell 20. Similarly, for the fourth liquid crystal cell 40, the longitudinal direction of the first electrode E41 intersects at a 90-degree angle with the longitudinal direction of the first electrode E11 of the first liquid crystal cell 10 and the longitudinal direction of the first electrode E21 of the second liquid crystal cell 20, and the longitudinal direction of the second electrode E42 intersects at a 90-degree angle with the longitudinal direction of the second electrode E12 of the first liquid crystal cell 10 and the longitudinal direction of the second electrode E22 of the second liquid crystal cell 20. Therefore, in these third and fourth liquid crystal cells, for each polarization component, the phenomena occurring in the first liquid crystal cell 10 and the second liquid crystal cell 20 are reversed. Note that the intersection angle can be set in the range of 90 ± 10 degrees as described above.

[0101] That is, when the first polarization component PL1 that has been diffused once in the X-axis direction and the Y-axis direction after passing through the second liquid crystal cell 20 enters the third liquid crystal cell 30, the polarization direction of the first polarization component PL1 becomes parallel to the long axis direction of the liquid crystal molecules on the first substrate S31 side of the third liquid crystal layer LC3. Here, since the refractive index distribution of the liquid crystal molecules on the first substrate S31 side is changed by the electric field generated by the first electrode E31, the first polarization component PL1 is diffused in the X-axis direction. Further, this diffused first polarization component PL1 is rotated by 90 degrees according to the twisted alignment of the liquid crystal molecules in the process of passing through the third liquid crystal layer LC3 from the first substrate S31 side to the second substrate S32 side. As a result, the first polarization component PL1 transitions back to the second polarization component PL2 again. Also, the polarization direction of the second polarization component PL2 is parallel to the long axis direction of the liquid crystal molecules on the second substrate S32 side. Here, since the refractive index distribution of the liquid crystal molecules on the second substrate S32 side is changed by the electric field generated by the second electrode E32, the second polarization component PL2 is further diffused in the Y-axis direction under the influence of the refractive index distribution of the liquid crystal molecules and then exits. That is, the first polarization component PL1 incident on the third liquid crystal cell 30 diffuses again in the X-axis direction and the Y-axis direction while transitioning to the second polarization component PL2 in the process of passing through the third liquid crystal cell 30.

[0102] The polarization direction of the second polarization component PL2 emitted from the third liquid crystal cell 30 and incident on the fourth liquid crystal cell 40 is in a direction intersecting the major axis direction of the liquid crystal molecules on the side of the first substrate S41 of the fourth liquid crystal layer LC4. Therefore, although the liquid crystal molecules on the side of the first substrate S41 change their refractive index distribution due to the electric field generated by the first electrode E41, the second polarization component PL2 is not diffused and goes straight toward the second substrate S42 side. Further, the second polarization component PL2 is optically rotated by 90 degrees according to the twisted alignment of the liquid crystal molecules in the process of passing through the fourth liquid crystal layer LC4 from the side of the first substrate S41 toward the second substrate S42 side. As a result, the second polarization component PL2 transitions to the first polarization component PL1. Also, the polarization direction of the first polarization component PL1 is in a direction intersecting the major axis direction of the liquid crystal molecules on the side of the second substrate S42. Therefore, although the liquid crystal molecules on the side of the second substrate S42 change their refractive index distribution due to the electric field generated by the second electrode E12, the first polarization component PL1 is not affected by it and is transmitted as it is. That is, the second polarization component PL2 transitions to the first polarization component PL1 in the process of passing through the fourth liquid crystal cell 40, while passing through the fourth liquid crystal cell 40 without being diffused or the like.

[0103] In this way, the first polarization component PL1 incident on the third liquid crystal cell 30 transitions to the second polarization component PL2 once and then transitions back to the first polarization component PL1 again before being emitted from the fourth liquid crystal cell 40, and is diffused once each in the X-axis direction and the Y-axis direction in the third liquid crystal cell 30.

[0104] Therefore, the first polarization component PL1 emitted from the light source is diffused twice in the X-axis direction and twice in the Y-axis direction between the time it is incident on the first liquid crystal cell 10 and the time it is emitted from the fourth liquid crystal cell 40.

[0105] In FIG. 9, "transmission" indicates that the polarized component passes through as is without being diffused or rotated. "Optical rotation" indicates that the polarization direction of the polarized component is shifted by 90 degrees. "Diffusion" indicates that the polarized component is diffused due to the influence of the refractive index distribution of the liquid crystal molecules. Therefore, in the diagram, for example, "transmission" at the first electrode indicates that the "transmission" phenomenon occurs in the vicinity of the first electrode in the liquid crystal layer. "Optical rotation" at the liquid crystal layer indicates that the polarization direction of the polarized component is shifted by 90 degrees as it travels through the liquid crystal layer from the first substrate side to the second substrate side. The same applies to FIGS. 12 to 14.

[0106] On the other hand, the polarization direction of the second polarized component PL2 is parallel to the long axis direction of the liquid crystal molecules on the first substrate S11 side of the first liquid crystal layer LC1. Therefore, the liquid crystal molecules on the first substrate S11 side have a refractive index distribution due to the electric field generated by the first electrode E11, and this effect diffuses the second polarized component PL2. The second polarized component PL2 is then rotated by 90 degrees in accordance with the twisted orientation of the liquid crystal molecules as it travels through the first liquid crystal layer LC1 from the first substrate S11 side to the second substrate S12 side. As a result, the second polarized component PL2 transitions to the first polarized component PL1. The polarization direction of the first polarized component PL1 is also parallel to the long axis direction of the liquid crystal molecules on the second substrate S12 side. Because the refractive index distribution of the liquid crystal molecules on the second substrate S12 side is changed by the electric field generated by the second electrode E12, the first polarized component PL1 transitioned by the first liquid crystal layer LC1 is diffused in the Y-axis direction due to the refractive index distribution formed by the liquid crystal molecules on the second substrate S12 side. That is, the second polarized component PL2 incident on the first liquid crystal cell 10 is transformed into the first polarized component PL1 while passing through the first liquid crystal cell 10, and is diffused in the X-axis and Y-axis directions.

[0107] Then, the first polarization component PL1 emitted from the second substrate S12 side of the first liquid crystal cell 10 enters the second liquid crystal cell 20. The polarization direction of the first polarization component PL1 entering the second liquid crystal cell 20 is in a direction (orthogonal direction) intersecting the major axis direction of the liquid crystal molecules on the first substrate S21 side of the second liquid crystal layer LC2. Therefore, although the refractive index distribution of the liquid crystal molecules on the first substrate S21 side is changed by the electric field generated by the first electrode E21, the first polarization component PL1 is not diffused and directly travels toward the second substrate S22 side. Further, the first polarization component PL1 is rotated by 90 degrees according to the twisted alignment of the liquid crystal molecules in the process of passing through the second liquid crystal layer LC2 from the first substrate S21 side to the second substrate S22 side. As a result, the first polarization component PL1 transitions to the second polarization component PL2. Also, the polarization direction of the second polarization component PL2 is in a direction intersecting the major axis direction of the liquid crystal molecules on the second substrate S22 side. Therefore, although the refractive index distribution of the liquid crystal molecules on the second substrate S22 side is changed by the electric field generated by the second electrode E22, the second polarization component PL2 is not affected by it and is transmitted as it is. That is, the first polarization component PL1 incident on the second liquid crystal cell 20 transitions to the second polarization component PL2 in the process of passing through the second liquid crystal cell 20, but is transmitted without being diffused.

[0108] The second polarization component PL2, which is rotated by 90 degrees by the first liquid crystal cell 10 and the second liquid crystal cell 20 respectively, and diffused once in the X-axis direction and the Y-axis direction by the first liquid crystal cell 10, is incident on the third liquid crystal cell 30. The polarization direction of the second polarization component PL2 incident on the third liquid crystal cell 30 is in a direction (perpendicular direction) intersecting the major axis direction of the liquid crystal molecules on the first substrate S31 side of the third liquid crystal layer LC3. Therefore, although the liquid crystal molecules on the first substrate S31 side change the refractive index distribution due to the electric field generated by the first electrode E31, the second polarization component PL2 is not diffused and travels straight toward the second substrate S32 side. Further, the second polarization component PL2 is rotated by 90 degrees according to the twisted alignment of the liquid crystal molecules in the process of passing through the third liquid crystal layer LC3 from the first substrate S31 side to the second substrate S32 side. As a result, the second polarization component PL2 transitions to the first polarization component PL1. Also, the polarization direction of the first polarization component PL1 is in a direction intersecting the major axis direction of the liquid crystal molecules on the second substrate S32 side. Therefore, although the liquid crystal molecules on the second substrate S32 side change the refractive index distribution due to the electric field generated by the second electrode E32, the first polarization component PL1 is not affected by it and passes through as it is. That is, the second polarization component PL2 incident on the third liquid crystal cell 30 transitions to the first polarization component PL1 in the process of passing through the third liquid crystal cell 30, but passes through without being diffused.

[0109] The first polarized component PL1 passes through the third liquid crystal cell 30, is diffused once in the X-axis direction and once in the Y-axis direction, and is then rotated 90 degrees by each of the first liquid crystal cell 10, the second liquid crystal cell 20, and the third liquid crystal cell 30. When the first polarized component PL1 enters the fourth liquid crystal cell 40, its polarization direction is parallel to the long axis direction of the liquid crystal molecules on the first substrate S41 side of the fourth liquid crystal cell LC4. Because the refractive index distribution of the liquid crystal molecules on the first substrate S41 side of the fourth liquid crystal cell 40 is changed by the electric field generated by the first electrode E41, the first polarized component PL1 is diffused in the X-axis direction. Furthermore, as the diffused first polarized component PL1 travels through the fourth liquid crystal layer LC4 from the first substrate S41 side to the second substrate S42 side, it is rotated 90 degrees in accordance with the twisted orientation of the liquid crystal molecules. As a result, the first polarized component PL1 transitions back to the second polarized component PL2. The polarization direction of the second polarized component PL2 is parallel to the long axis direction of the liquid crystal molecules on the second substrate S42 side. Here, since the liquid crystal molecules on the second substrate S42 side have their refractive index distribution changed by the electric field generated by the second electrode E42, this second polarization component PL2 is further affected by the refractive index distribution of the liquid crystal molecules and is diffused in the Y-axis direction before being emitted from the second substrate S42 side.

[0110] In this way, the second polarization component PL2 incident on the third liquid crystal cell 30 transitions once to the first polarization component PL1 and then transitions again to the second polarization component PL2 before exiting from the fourth liquid crystal cell 40, and is diffused once each in the X-axis direction and the Y-axis direction by the fourth liquid crystal cell 40.

[0111] Therefore, the second polarized component PL2 emitted from the light source is diffused twice in the X-axis direction and twice in the Y-axis direction from the time it enters the first liquid crystal cell 10 until it exits the fourth liquid crystal cell 40.

[0112] 9 indicates that the polarized light component has diffused once in the X-axis direction before reaching the position, and (diffused light 1X1Y) indicates that the polarized light component has diffused once in the X-axis direction and once in the Y-axis direction before reaching the position.

[0113] 11A and 11B are graphs showing the angular dependence of chromaticity of a liquid crystal light control element. FIG. 11A shows the angular dependence of the x-coordinate value of the chromaticity coordinates, and FIG. 11B shows the angular dependence of the y-coordinate value. FIGS. 11A and 11B show the angular dependence of chromaticity of an element (A) that uses four liquid crystal cells, with the third and fourth liquid crystal cells rotated 90 degrees, like the liquid crystal light control element 102 according to this embodiment. Each graph also shows the characteristics of an element (B) composed of two liquid crystal cells as a reference example.

[0114] 11A and 11B, in the reference example, the characteristics of the element (B) having two liquid crystal cells, the x-coordinate and y-coordinate values, change significantly with change in angle, indicating that the angle dependence of chromaticity is significant. In contrast, the element (A) having four liquid crystal cells, in which the third and fourth liquid crystal cells are rotated 90 degrees as in the liquid crystal light control element 102 of this embodiment, shows further improvement in the angle dependence of chromaticity. In other words, the configuration of the liquid crystal light control element 102 of this embodiment can suppress color breakup.

[0115] In this way, color breakup can be prevented by diffusing one polarized light component in the same direction at least twice using an electrode that is provided in different liquid crystal cells and is arranged on the light incident side with the liquid crystal layer in between and an electrode that is arranged on the opposite side from the light incident side.

[0116] From this perspective, when forming a rectangular light distribution pattern, it is not necessary to input control signals of the same voltage level to the electrodes of all liquid crystal cells, and it is also possible to use different control signals for each of the following pairs: the pair of the second electrode E12 of the first liquid crystal cell 10 and the first electrode E41 of the fourth liquid crystal cell 40, which diffuses the second polarization component PL2 in the Y-axis direction; the pair of the first electrode E11 of the first liquid crystal cell 10 and the second electrode E42 of the fourth liquid crystal cell 40, which diffuses the second polarization component PL2 in the X-axis direction; the pair of the second electrode E22 of the second liquid crystal cell 20 and the first electrode E31 of the third liquid crystal cell 30, which diffuses the first polarization component PL1 in the Y-axis direction; and the pair of the first electrode E21 of the second liquid crystal cell 20 and the second electrode E32 of the third liquid crystal cell 30, which diffuses the first polarization component PL1 in the X-axis direction.

[0117] Table 2 shows an example of inputting control signals of different voltage levels to the first and second electrodes of a single liquid crystal cell while setting the voltage levels of the control signals for each group as the same. Note that control signals A, B, C, D, and E in Table 2 correspond to the control signals shown in FIG. 10B. Note that in FIG. 10B, the voltage levels of control signals A, B, C, D, and E have the relationship VH1>VH2>VE>VL2>VL1. For example, if VL1=-15V and VH1=15V, then VL2=-12V and VH2=12V can be set. [Table 2]

[0118] The combinations of control signals shown in Table 2 allow the amount of diffusion of each polarization component in the Y-axis direction and the X-axis direction to be varied, thereby providing variation to the rectangular light distribution pattern. For example, by adjusting the voltage levels of control signals A, B, C, and D, a square light distribution pattern or a rectangular light distribution pattern can be formed.

[0119] When control signals of the same pattern as shown in Table 1 are applied to each liquid crystal cell of the liquid crystal light control element 102 having such an arrangement of liquid crystal cells, the first polarized component PL1 and the second polarized component PL2 are diffused evenly in the X-axis direction and the Y-axis direction as described above, thereby forming a rectangular light distribution pattern. Furthermore, as will be described later, color breakup in the light distribution pattern can be prevented.

[0120] (2) Cross light distribution pattern 12 shows an example in which light emitted from a light source unit 106 is controlled to have a cross-shaped light distribution pattern. The arrangement of the liquid crystal cells of the liquid crystal light control element 102 shown in FIG.

[0121] Table 3 shows the control signals applied to each liquid crystal cell in the liquid crystal light control element 102 shown in FIG. 12. Note that the control signals A, B, and C shown in Table 3 correspond to the control signals shown in FIG. 10A.

Table 3

[0122] As shown in Table 3, when forming a cross-shaped light distribution pattern, a control signal for generating a horizontal electric field is input to the first electrode E11 of the first liquid crystal cell 10, the second electrode E22 of the second liquid crystal cell 20, the first electrode E31 of the third liquid crystal cell 30, and the second electrode E42 of the fourth liquid crystal cell 40, and a control signal E of a constant voltage is input to the second electrode E12 of the first liquid crystal cell 10, the first electrode E21 of the second liquid crystal cell 20, the second electrode E32 of the third liquid crystal cell 30, and the first electrode E41 of the fourth liquid crystal cell 40 to control the state so that no horizontal electric field is generated. Note that "transmission", "diffusion", and "optical rotation" in the figure and table basically correspond to "transmission", "diffusion", and "optical rotation" mentioned in the description of FIG. 9. Also, in the driving of FIG. 12, there is a configuration in which the same potential is applied to the electrodes located on the same substrate. However, in the state where the same potential is applied, no potential is generated between the electrodes and no electric field is generated in the liquid crystal layer. Therefore, the liquid crystal molecules located on the substrate side do not change their alignment state from the initial alignment. For this reason, the polarized light component passing through the liquid crystal layer in such a non-electrolytic state passes through without diffusion. This case is also included in "transmission".

[0123] In FIG. 12, first, focus on the first polarization component PL1. The polarization direction of the first polarization component PL1 incident on the first liquid crystal cell 10 is in a direction intersecting the major axis direction of the liquid crystal molecules on the first substrate S11 side of the first liquid crystal layer LC1, and the first electrode E11 on the first substrate S11 side forms an electric field (in FIG. 12, the electrode forming the electric field is indicated by hatching. The same applies hereinafter in FIGS. 13 and 14). Under such conditions, the first polarization component PL1 passes through the first liquid crystal layer LC1 on the first substrate S11 side without diffusion. Further, the first polarization component PL1 is optically rotated by 90 degrees in the process of passing through the first liquid crystal layer LC1 and transitions to the second polarization component PL2. Also, the polarization direction of the second polarization component PL2 is in a direction intersecting the major axis direction of the liquid crystal molecules on the second substrate S12 side, and the second electrode E12 on the second substrate S12 side does not form an electric field (in FIG. 12, the electrode not forming the electric field is indicated by white-out. The same applies hereinafter in FIGS. 13 and 14). Under such conditions, the second polarization component PL2 passes through the first liquid crystal layer LC1 on the second substrate S12 side without diffusion and is emitted to the second liquid crystal cell 20.

[0124] The polarization direction of the second polarization component PL2 incident on the second liquid crystal cell 20 is in a direction parallel to the major axis direction of the liquid crystal molecules on the first substrate S21 side of the second liquid crystal layer LC2, and the first electrode E21 on the first substrate S21 side does not form an electric field. Under such conditions, the second polarization component PL2 passes through the second liquid crystal layer LC2 on the first substrate S21 side without diffusion. Further, the second polarization component PL2 is optically rotated by 90 degrees in the process of passing through the second liquid crystal layer LC2 and transitions back to the first polarization component PL1. Also, the polarization direction of the first polarization component PL1 is in a direction parallel to the major axis direction of the liquid crystal molecules on the second substrate S22 side, and the second electrode E22 on the second substrate S22 side forms an electric field. Under such conditions, the first polarization component PL1 diffuses in the Y-axis direction and is then emitted to the third liquid crystal cell 30.

[0125] The polarization direction of the first polarized component PL1 entering the third liquid crystal cell 30 is parallel to the long axis direction of the liquid crystal molecules on the first substrate S31 side of the third liquid crystal layer LC3, and the first electrode E31 on the first substrate S31 side forms an electric field. Under these conditions, the first polarized component PL1 is diffused in the Y-axis direction and proceeds toward the second substrate S32 side. Furthermore, the first polarized component PL1 is rotated by 90 degrees while passing through the third liquid crystal layer LC3 and transitions back to the second polarized component PL2. Furthermore, the polarization direction of the second polarized component PL2 is parallel to the long axis direction of the liquid crystal molecules on the second substrate S32 side, and the second electrode E32 on the second substrate S32 side does not form an electric field. Under these conditions, the second polarized component PL2 passes through the third liquid crystal layer LC3 on the second substrate S32 side without being diffused and is emitted to the fourth liquid crystal cell 40.

[0126] The polarization direction of the second polarized component PL2 entering the fourth liquid crystal cell 40 is a direction intersecting the long axis direction of the liquid crystal molecules on the first substrate S41 side of the fourth liquid crystal layer LC4, and the first electrode E41 on the first substrate S41 side does not form an electric field. Under these conditions, the second polarized component PL2 passes through the fourth liquid crystal layer LC4 on the first substrate S41 side without being diffused. Furthermore, the second polarized component PL2 is rotated by 90 degrees while passing through the fourth liquid crystal layer LC4 and transitions back to the first polarized component PL1. Furthermore, the polarization direction of the first polarized component PL1 is a direction intersecting the long axis direction of the liquid crystal molecules on the second substrate S42 side, and the second electrode E42 on the second substrate S42 side forms an electric field. Under these conditions, the first polarized component PL1 exits the fourth liquid crystal cell 40 without being diffused.

[0127] In this way, when the liquid crystal light control element 102 shown in Figure 12 is driven with the potential shown in Table 3, the first polarization component PL1 of the light emitted from the light source is rotated four times as it passes through the first liquid crystal cell 10 and the fourth liquid crystal cell 40, and is diffused twice in the Y-axis direction.

[0128] Next, in FIG. 12, attention is paid to the second polarization component PL2. The polarization direction of the second polarization component PL2 incident on the first liquid crystal cell 10 is parallel to the major axis direction of the liquid crystal molecules on the first substrate S11 side of the first liquid crystal layer LC1, and the first electrode E11 on the first substrate S11 side forms an electric field. Under such conditions, the second polarization component PL2 diffuses in the X-axis direction and passes through the first liquid crystal layer LC1 on the first substrate side. Further, the second polarization component PL2 is optically rotated by 90 degrees in the process of passing through the first liquid crystal layer LC1 and transitions to the first polarization component PL1. Also, the polarization direction of the first polarization component PL1 is parallel to the major axis direction of the liquid crystal molecules on the second substrate S12 side, and the second electrode E12 on the second substrate S12 side does not form an electric field. Under such conditions, the first polarization component PL1 passes through the first liquid crystal layer PC1 on the second substrate S12 side without diffusion and is emitted to the second liquid crystal cell 20.

[0129] The polarization direction of the first polarization component PL1 incident on the second liquid crystal cell 20 intersects the major axis direction of the liquid crystal molecules on the first substrate S21 side of the second liquid crystal layer LC2, and the first electrode E21 on the first substrate S21 side does not form an electric field. Under such conditions, the first polarization component PL1 passes through the second liquid crystal layer LC2 on the first substrate S21 side without diffusion. Also, the first polarization component PL1 is optically rotated by 90 degrees in the process of passing through the second liquid crystal layer LC2 and becomes the second polarization component PL2 again. Further, the polarization direction of the second polarization component PL2 is parallel to the major axis direction of the liquid crystal molecules on the second substrate S22 side of the second liquid crystal layer LC2, and the second electrode E22 on the second substrate S22 side forms an electric field. Under such conditions, the second polarization component diffuses in the X-axis direction and is then emitted to the third liquid crystal cell 30.

[0130] The polarization direction of the second polarized component PL2 entering the third liquid crystal cell 30 is a direction intersecting the long axis direction of the liquid crystal molecules on the first substrate S31 side of the third liquid crystal layer LC3, and the first electrode E31 on the first substrate S31 side forms an electric field. Under these conditions, the second polarized component PL2 passes through the third liquid crystal layer LC3 on the first substrate side without being diffused. Furthermore, the second polarized component PL2 is optically rotated by 90 degrees while passing through the third liquid crystal layer LC3 and becomes the first polarized component PL1 again. Furthermore, the polarization direction of the first polarized component PL1 is a direction intersecting the long axis direction of the liquid crystal molecules on the second substrate S32 side, and the second electrode E32 on the second substrate S32 side does not form an electric field. Under these conditions, the first polarized component PL1 passes through the third liquid crystal layer LC3 on the second substrate S32 side without being diffused and is emitted to the fourth liquid crystal cell 40.

[0131] The polarization direction of the first polarized component PL1 entering the fourth liquid crystal cell 40 is parallel to the long axis direction of the liquid crystal molecules on the first substrate S41 side of the fourth liquid crystal layer LC4, and the first electrode E41 on the first substrate S41 side does not form an electric field. Under these conditions, the first polarized component PL1 passes through the fourth liquid crystal layer LC4 on the first substrate S41 side without being diffused. Furthermore, the first polarized component PL1 is rotated by 90 degrees while passing through the fourth liquid crystal layer LC4, and becomes the second polarized component PL2 again. Furthermore, the polarization direction of the second polarized component PL2 is parallel to the long axis direction of the liquid crystal molecules on the second substrate S42 side, and the second electrode E42 on the second substrate S42 side forms an electric field. Under these conditions, the second polarized component PL2 diffuses in the X-axis direction and then exits the fourth liquid crystal cell 40.

[0132] In this way, when the liquid crystal light control element 102 shown in Figure 12 is driven with the potential shown in Table 3, the second polarization component PL2 of the light emitted from the light source is rotated four times as it passes through the first liquid crystal cell 10 and the fourth liquid crystal cell 40, and is diffused twice in the X-axis direction.

[0133] Thus, according to the operation modes shown in FIG. 12 and Table 3, when the light emitted from the light source unit 106 passes through the liquid crystal light control element 102, the first polarization component PL1 is diffused twice in the Y-axis direction, and the second polarization component PL2 is diffused twice in the X-axis direction. Thereby, the light emitted from the light source unit 106 can be shaped into a cross-shaped light distribution pattern. Also, as will be described later, color breakage can be prevented even in this light distribution pattern.

[0134] Also, similar to the example of square light distribution, corresponding to the pair of the second electrode E12 of the first liquid crystal cell 10 and the first electrode E41 of the fourth liquid crystal cell 40 that diffuses the second polarization component PL2 in the Y-axis direction, the pair of the first electrode E11 of the first liquid crystal cell 10 and the second electrode E42 of the fourth liquid crystal cell 40 that diffuses the second polarization component PL2 in the X-axis direction, the pair of the second electrode E22 of the second liquid crystal cell 20 and the first electrode E31 of the third liquid crystal cell 30 that diffuses the first polarization component PL1 in the Y-axis direction, and the pair of the first electrode E21 of the second liquid crystal cell 20 and the second electrode E32 of the third liquid crystal cell 30 that diffuses the first polarization component PL1 in the X-axis direction, a cross-shaped light distribution pattern can be formed by applying the control signals shown in Table 4. Note that the control signals shown in Table 4 correspond to FIG. 10B. [Table 4]

[0135] (3) Line light distribution pattern (X-axis direction) FIG. 13 shows an example of controlling the light emitted from the light source unit 106 into a linear (X-axis direction) light distribution pattern. The arrangement of each liquid crystal cell of the liquid crystal light control element 102 shown in FIG. 13 is the same as that in FIG. 9.

[0136] Table 5 shows the control signals applied to each liquid crystal cell in the liquid crystal light control element 102 shown in FIG. 13. Note that the control signals A, B, and C shown in Table 5 correspond to the control signals shown in FIG. 10A. [Table 5]

[0137] As shown in Table 5, when forming a linear light distribution pattern extending in the X-axis direction, a control signal for generating a transverse electric field is input to the first electrode E11 of the first liquid crystal cell 10, the first electrode E21 of the second liquid crystal cell 20, the second electrode E32 of the third liquid crystal cell 30, and the second electrode E42 of the fourth liquid crystal cell 40. A control signal E with a constant voltage is input to the second electrode E12 of the first liquid crystal cell 10, the first electrode E21 of the second liquid crystal cell 20, the first electrode E31 of the third liquid crystal cell 30, and the first electrode E41 of the fourth liquid crystal cell 40 to control the state where no transverse electric field is generated.

[0138] Focusing on the first polarization component PL1 in FIG. 13, the polarization direction of the first polarization component PL1 incident on the first liquid crystal cell 10 is in a direction (orthogonal direction) intersecting the long axis direction of the liquid crystal molecules in the first liquid crystal layer LC1. Therefore, it enters without being scattered, is optically rotated by 90 degrees in the first liquid crystal layer LC1, and becomes the second polarization component PL2.

[0139] The second polarization component PL2 incident on the second liquid crystal cell 20 is diffused in the X-axis direction by the liquid crystal molecules affected by the electric field of the first electrode E21, is optically rotated in the second liquid crystal layer LC2, and becomes the first polarization component PL1(1X) and passes through the second liquid crystal cell 20. The first polarization component PL1(1X) incident on the third liquid crystal cell 30 is optically rotated in the third liquid crystal layer LC3 to become the second polarization component PL2(1X), and is further diffused in the X-axis direction by the liquid crystal molecules affected by the electric field of the second electrode E32. After passing through the third liquid crystal cell 30, it becomes the second polarization component PL2(2X). The second polarization component PL2(2X) incident on the fourth liquid crystal cell 40 is optically rotated in the fourth liquid crystal layer LC4 to become the first polarization component PL1(2X), and is emitted from the fourth liquid crystal cell 40.

[0140] On the other hand, the second polarization component PL2 is diffused in the X-axis direction by the liquid crystal molecules affected by the electric field of the first electrode E11 of the first liquid crystal cell 10, and is optically rotated in the first liquid crystal layer LC1 to become the first polarization component PL1(1X), and then enters the second liquid crystal cell 20. The first polarization component PL1(1X) diffused once in the X-axis direction is optically rotated in the second liquid crystal layer LC2 of the second liquid crystal cell 20 to become the second polarization component PL2(1X), and then enters the third liquid crystal cell 30. This second polarization component PL2(1X) is optically rotated in the third liquid crystal layer LC3 of the third liquid crystal cell 30 and enters the fourth liquid crystal cell 40 as the first polarization component PL1(1X). The first polarization component PL1(1X) is optically rotated in the fourth liquid crystal layer LC4, and is diffused again in the X-axis direction by the liquid crystal molecules affected by the electric field of the second electrode E42, and is emitted from the fourth liquid crystal cell 40 as the second polarization component PL2(2X).

[0141] Also, similar to the example of square light distribution, corresponding to the pair of the first electrode E11 of the first liquid crystal cell 10 that diffuses the second polarization component PL2 in the X-axis direction and the second electrode E42 of the fourth liquid crystal cell 40, and the pair of the first electrode E21 of the second liquid crystal cell 20 that diffuses the first polarization component PL1 in the X-axis direction and the second electrode E32 of the third liquid crystal cell 30, by applying the control signals shown in Table 6, a linear light distribution pattern extending in the X-axis direction can be formed. Note that the control signals shown in Table 6 correspond to FIG. 10B.

Table 6

[0142] Thus, according to the operation modes shown in FIGS. 13 and Tables 5 and 6, when the light emitted from the light source unit 106 passes through the liquid crystal light control element 102, the first polarization component PL1 is diffused twice in the X-axis direction, and the second polarization component PL2 is diffused twice in the X-axis direction. Thereby, the light emitted from the light source unit 106 can be shaped into a linear light distribution pattern extending in the X-axis direction. Also, as will be described later, color breakage can be prevented in this light distribution pattern.

[0143] (4) Linear light distribution pattern (Y-axis direction) FIG. 14 shows an example of controlling the light emitted from the light source unit 106 into a linear (Y-axis direction) light distribution pattern. The arrangement of each liquid crystal cell of the liquid crystal light control element 102 shown in FIG. 14 is the same as that in FIG. 9.

[0144] Table 7 shows the control signals applied to each liquid crystal cell in the liquid crystal light control element 102 shown in FIG. 14. Note that the control signals A, B, and E shown in Table 7 correspond to the control signals shown in FIG. 10A.

Table 7

[0145] As shown in Table 7, when forming a linear light distribution pattern extending in the Y-axis direction, a control signal E with a constant voltage is input to the first electrode E11 of the first liquid crystal cell 10, the first electrode E21 of the second liquid crystal cell 20, the second electrode E32 of the third liquid crystal cell 30, and the second electrode E42 of the fourth liquid crystal cell 40 to control so that no transverse electric field is generated, and control signals A and B that generate a transverse electric field are input to the second electrode E12 of the first liquid crystal cell 10, the first electrode E22 of the second liquid crystal cell 20, the first electrode E31 of the third liquid crystal cell 30, and the first electrode E41 of the fourth liquid crystal cell 40.

[0146] Focusing on the first polarization component PL1 in FIG. 14, the polarization direction of the first polarization component PL1 incident on the first liquid crystal cell 10 is in a direction (perpendicular direction) intersecting the long axis direction of the liquid crystal molecules in the first liquid crystal layer LC1, so it does not scatter and enters as it is, and is optically rotated by 90 degrees in the first liquid crystal layer LC1 to become the second polarization component PL2.

[0147] The second polarized component PL2 incident on the second liquid crystal cell 20 is rotated by the second liquid crystal layer LC2 and diffused in the Y-axis direction by liquid crystal molecules affected by the electric field of the second electrode E22, becoming the first polarized component PL1(1Y). The first polarized component PL1(1Y) incident on the third liquid crystal cell 30 is diffused in the Y-axis direction by liquid crystal molecules affected by the electric field of the first electrode E31 and is rotated by the third liquid crystal layer LC3 to become the second polarized component PL2(2Y). The second polarized component PL2(2Y) incident on the fourth liquid crystal cell 40 is rotated by the fourth liquid crystal layer LC4 to become the first polarized component PL1(2Y), and is emitted from the fourth liquid crystal cell 40.

[0148] On the other hand, the second polarized component PL2 is optically rotated by the first liquid crystal layer LC1 and diffused in the Y-axis direction by liquid crystal molecules affected by the electric field of the second electrode E12, becoming the first polarized component PL1(1Y). The first polarized component PL1(1Y) incident on the second liquid crystal cell 20 is optically rotated by the second liquid crystal layer LC2 and becomes the second polarized component PL2(1Y). The second polarized component PL2(1Y) incident on the third liquid crystal cell 30 is optically rotated by the third liquid crystal layer LC3, becomes the first polarized component PL1(1Y), and enters the fourth liquid crystal cell 40. The first polarized component PL1(1Y) is diffused in the Y-axis direction by liquid crystal molecules affected by the electric field of the first electrode E41, is optically rotated by the fourth liquid crystal layer LC4, and emerges as the second polarized component LC2(2Y).

[0149] Furthermore, similar to the example of rectangular light distribution, a linear light distribution pattern extending in the Y-axis direction can be formed by applying the control signals shown in Table 8 to a pair of the second electrode E12 of the first liquid crystal cell 10 and the first electrode E41 of the fourth liquid crystal cell 40 that diffuses the second polarization component PL2 in the Y-axis direction, and a pair of the second electrode E22 of the second liquid crystal cell 20 and the first electrode E31 of the third liquid crystal cell 30 that diffuses the first polarization component PL1 in the Y-axis direction. The control signals shown in Table 8 correspond to FIG. 10B. [Table 8]

[0150] 14 and Tables 7 and 8, the light emitted from the light source unit 106 passes through the liquid crystal light control element 102, causing the first polarization component PL1 to be diffused twice in the Y-axis direction and the second polarization component PL2 to be diffused twice in the Y-axis direction. This allows the light emitted from the light source unit 106 to be shaped into a linear light distribution pattern extending in the Y-axis direction. Furthermore, as will be described later, color breakup can also be prevented in this light distribution pattern.

[0151] The liquid crystal light control element 102 according to this embodiment includes multiple liquid crystal cells, with at least one liquid crystal cell and another liquid crystal cell adjacent to (overlapping) the at least one liquid crystal cell rotated 90 degrees. This prevents color breakup in the light distribution pattern. The effect of rotating the liquid crystal cells 90 degrees is believed to be due to the asymmetry of the liquid crystal, such as the pretilt direction. Therefore, the liquid crystal cells can be arranged to break up the asymmetry of the liquid crystal. More specifically, as shown in FIG. 14 , the alignment direction of the first liquid crystal cell 10 on the first substrate S11 side is in the +x direction, while the alignment direction of the fourth liquid crystal cell 40 on the second substrate S42 side is in the -x direction. Other combinations, such as a structure in which the alignment direction of the first liquid crystal cell 10 on the second substrate S12 side and the alignment direction of the fourth liquid crystal cell 40 on the first substrate S41 side are aligned in the y direction and face each other, are also possible. Similarly, a configuration can also be adopted in which the alignment direction of the first substrate S21 side of the second liquid crystal cell 20 and the alignment direction of the second substrate S32 side of the third liquid crystal cell 30 are aligned in the x direction and the alignment direction of the second substrate S22 side of the second liquid crystal cell 20 and the alignment direction of the first substrate S31 side of the third liquid crystal cell 30 are aligned in the y direction and the alignment directions ... first substrate S31 side of the third liquid crystal cell 30 are aligned in the y direction and the alignment directions of the second substrate S22 side of the second liquid crystal cell 20 and the first substrate S31 side of the third liquid crystal cell 30 are aligned in the y direction and the alignment directions of the second substrate S2

[0152] 15A and 15B, and 16A and 16B show examples of the arrangement of liquid crystal cells in the liquid crystal light control element 102. Fig. 15A shows an example in which the first liquid crystal cell 10 and the second liquid crystal cell 20 are grouped together, and the third liquid crystal cell 30 and the fourth liquid crystal cell 40 are grouped together, with one group being used as the reference and the other group being rotated 90 degrees. This arrangement corresponds to the arrangement in Figs. 2 and 3.

[0153] FIG. 15B shows a structure in which the odd-numbered liquid crystal cells are rotated 90 degrees with respect to the even-numbered liquid crystal cells among the four liquid crystal cells. In other words, FIG. 15B shows a structure in which the even-numbered liquid crystal cells are rotated 90 degrees with respect to the odd-numbered liquid crystal cells.

[0154] Further, FIG. 16A shows a combination in which the first liquid crystal cell 10, the second liquid crystal cell 20, the third liquid crystal cell 30, and the fourth liquid crystal cell 40 are each rotated 90 degrees. FIG. 16B shows a combination in which the first liquid crystal cell 10 and the third liquid crystal cell 30 are turned inside out.

[0155] In FIGS. 15A and 15B and FIGS. 16A and 16B, it is assumed that the first electrodes E11, E21, E31, E41 are electrodes formed on the first substrate S11 (lower side), and the second electrodes E12, E22, E32, E42 are electrodes formed on the second substrate S12 (upper side). As described with reference to FIG. 3, the first electrode E11 includes a first strip electrode (E11A) and a second strip electrode (E11B), and the second electrode E12 includes a third strip electrode (E12A) and a fourth strip electrode (E12B). The same applies to the first electrodes E21, E31, E41 and the second electrodes E22, E32, E42. In FIGS. 15A and 15B and FIGS. 16A and 16B, the direction of the arrow indicates the longitudinal direction of the strip electrode.

[0156] The liquid crystal light control element 102 shown in FIG. 15A is arranged such that the longitudinal direction of the strip patterns of the first electrode E11 of the first liquid crystal cell 10 and the first electrode E21 of the second liquid crystal cell 20 is parallel to the Y-axis direction shown in the figure, and the longitudinal direction of the strip patterns of the second electrode E12 of the first liquid crystal cell 10 and the second electrode E22 of the second liquid crystal cell 20 is parallel to the X-axis direction. The longitudinal direction of the strip patterns of the first electrode E31 of the third liquid crystal cell 30 and the first electrode E41 of the fourth liquid crystal cell 40 is parallel to the X-axis direction, and the longitudinal direction of the strip patterns of the second electrode E32 of the third liquid crystal cell 30 and the second electrode E42 of the fourth liquid crystal cell 40 is parallel to the Y-axis direction. According to such a combination of the electrode arrangements of the respective liquid crystal cells, the diffusion direction of the polarization component can be controlled at least twice in different liquid crystal cells, and color breakage of the distributed illumination light can be prevented.

[0157] In the liquid crystal light control element 102 shown in FIGS. 15B, 16A, and 16B, the longitudinal direction of the strip patterns of the first electrode E11 of the first liquid crystal cell 10 and the first electrode E31 of the third liquid crystal cell 30 is parallel to the Y-axis direction, and the longitudinal direction of the strip patterns of the second electrode E12 of the first liquid crystal cell 10 and the second electrode E32 of the third liquid crystal cell 30 is parallel to the X-axis direction. The longitudinal direction of the strip patterns of the first electrode E21 of the second liquid crystal cell 20 and the first electrode E41 of the fourth liquid crystal cell 40 is parallel to the X-axis direction, and the longitudinal direction of the strip patterns of the second electrode E22 of the second liquid crystal cell 20 and the second electrode E42 of the fourth liquid crystal cell 40 is parallel to the Y-axis direction. According to such a combination of the electrode arrangements of the respective liquid crystal cells, the diffusion direction of the polarization component can be controlled at least twice in different liquid crystal cells, and color breakage of the distributed illumination light can be prevented.

[0158] As described in this embodiment, in the liquid crystal light control element 102 in which a plurality of liquid crystal cells are stacked, by the electrodes at different positions of different liquid crystal cells (for example, the second electrode E12 of the first liquid crystal cell 10 and the first electrode E11 of the fourth liquid crystal cell 40), it is possible to prevent color breakage from occurring in the light distribution pattern by controlling the diffusion of the same polarization component among the polarization components of the incident light.

[0159] As described above, according to the present embodiment, in a liquid crystal light control device that controls the light distribution of illumination light by utilizing the electro-optical effect of liquid crystal, it is possible to suppress the occurrence of color breakage in a light distribution pattern formed in a predetermined shape.

[0160] Note that the present invention is not limited to the embodiments disclosed in this specification, and components can be modified and embodied without departing from the gist of the present invention. Also, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiments of this specification. For example, some components may be deleted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined.

Explanation of Reference Numerals

[0161] 10: First liquid crystal cell, 20: Second liquid crystal cell, 30: Third liquid crystal cell, 40: Fourth liquid crystal cell, 100: Liquid crystal light control device, 102: Liquid crystal light control element, 104: Circuit board, 106: Light source unit, S11, S21, S31, S41: First substrate, S12, S22, S32, S42: Second substrate, F1: First flexible wiring board, F2: Second flexible wiring board, F3: Third flexible wiring board, F4: Fourth flexible wiring board, TA1: First transparent adhesive layer, TA2: Second transparent adhesive layer, TA3: Third transparent adhesive layer, LC1: First liquid crystal layer, LC2: Second liquid crystal layer, LC3: Third liquid crystal layer, LC4: Fourth liquid crystal layer, E11, E21, E31, E41: First electrode, E11A, E21A, E31A, E41A: First strip electrode, E11B, E21B, E31B, E41B: Second strip electrode, E12, E22, E32, E42: Second electrode, E12A, E22A, E32A, E42A: Third strip electrode, E12B, E22B, E32B, E42B: Fourth strip electrode, PL11: First power supply line, PL12: Second power supply line, PL13: Third power supply line, PL14: Fourth power supply line, PL15: Fifth power supply line, PL16: Sixth power supply line, T11: First connection terminal, T12: Second connection terminal, T13: Third connection terminal, T14: Fourth connection terminal, PT11: First power supply terminal, PT12: Second power supply terminal, PT13: Third power supply terminal, PT14: Fourth power supply terminal, AL11: First alignment film, AL12: Second alignment film, SE: Sealant, CP11: First conductive member

Claims

1. A first liquid crystal cell, a second liquid crystal cell, a third liquid crystal cell, and a fourth liquid crystal cell, wherein each of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell includes a first substrate provided with a first electrode including a strip pattern, a second substrate provided with a second electrode including a strip pattern, a first alignment film provided on the first substrate, a second alignment film provided on the second substrate, and a liquid crystal layer between the first substrate and the second substrate, the first electrode includes at least one first strip electrode having the strip pattern and at least one second strip electrode having the strip pattern, and the at least one first strip electrode and the at least one second strip electrode are alternately arranged at intervals, the second electrode includes at least one third strip electrode having the strip pattern and at least one fourth strip electrode having the strip pattern, and the at least one third strip electrode and the at least one fourth strip electrode are alternately arranged at intervals, the first substrate and the second substrate are arranged such that the longitudinal directions of the strip patterns of the first electrode and the second electrode intersect, the alignment direction of the first alignment film is a direction intersecting the longitudinal direction of the strip pattern of the first electrode, the alignment direction of the second alignment film is a direction intersecting the longitudinal direction of the strip pattern of the second electrode, the first to fourth liquid crystal cells are arranged such that the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell overlap in this order from the side where light is incident, and the remaining liquid crystal cells are stacked in a state rotated by 90 degrees with respect to two liquid crystal cells. A liquid crystal light control device, characterized in that.

2. The liquid crystal display device according to claim 1, wherein the third liquid crystal cell and the fourth liquid crystal cell are stacked in a state rotated by 90 degrees with respect to the first liquid crystal cell and the second liquid crystal cell.

3. The liquid crystal display device according to claim 1, wherein the second liquid crystal cell and the fourth liquid crystal cell are stacked in a state rotated by 90 degrees with respect to the first liquid crystal cell and the third liquid crystal cell.

4. The liquid crystal light control device according to claim 1, wherein the first electrode generates a horizontal electric field between the first strip electrode and the second strip electrode, and the second electrode generates a horizontal electric field between the third strip electrode and the fourth strip electrode.

5. The liquid crystal light control device according to claim 1, wherein the thickness of the liquid crystal layer of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell has a length that is 1 time or more the center-to-center distance between the first strip electrode and the second strip electrode.

6. The liquid crystal light control device according to claim 1, wherein each of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell has a thickness such that the transverse electric field generated by the first electrode and the transverse electric field generated by the second electrode do not interfere with each other in the liquid crystal layer.

7. The liquid crystal light control device according to claim 1, wherein the liquid crystal layer is a twisted nematic liquid crystal.

Images