Liquid crystal light control device

Abstract

To provide a liquid crystal light control device in which color breakup is suppressed.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 substrate where a first electrode including a band-shaped pattern is provided, a second substrate where a second electrode including a band-shaped pattern is provided, 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 to fourth liquid crystal cells are stacked in this order from the light incidence side. The second liquid crystal cell is stacked while being rotated by 90 degrees with respect to the first liquid crystal cell, the third liquid crystal cell is stacked while being rotated by 90 degrees with respect to the second liquid crystal cell, and the fourth liquid crystal cell is stacked while being rotated by 90 degrees with respect to the third liquid crystal cell.SELECTED DRAWING: Figure 16A

Description

Technical Field

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[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

[0007] [Figure 1] This is a schematic perspective view showing the configuration of a liquid crystal light control device according to one embodiment of the present invention. [Figure 2] This diagram shows an exploded view of a liquid crystal light control element constituting a liquid crystal light control device according to one embodiment of the present invention. [Figure 3] This 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 that constitute a liquid crystal light control element according to one embodiment of the present invention. [Figure 4A] This is a plan view showing electrodes provided on a first substrate of a liquid crystal cell constituting a liquid crystal light control element according to one embodiment of the present invention. [Figure 4B] This is a plan view showing electrodes provided on a second substrate of a liquid crystal cell constituting a liquid crystal light control element according to one embodiment of the present invention. [Figure 5] This figure shows an example of a cross-sectional structure of a liquid crystal cell constituting a liquid crystal light control element according to one embodiment of the present invention. [Figure 6A] This figure illustrates the operation of a liquid crystal cell constituting a liquid crystal light control element according to one embodiment of the present invention, showing the orientation state of liquid crystal molecules when no voltage is applied. [Figure 6B]This figure illustrates the operation of a liquid crystal cell constituting a liquid crystal light control element according to one embodiment of the present invention, showing the orientation state of liquid crystal molecules when a voltage is applied. [Figure 6C] This figure illustrates the operation of a liquid crystal cell constituting a liquid crystal light control element according to one embodiment of the present invention, and shows the waveform of a control signal applied to the electrode that drives the liquid crystal. [Figure 7A] This figure illustrates the operation of a liquid crystal cell constituting a liquid crystal light control element according to one embodiment of the present invention, and shows a perspective view illustrating the arrangement of the first electrode and the second electrode. [Figure 7B] This figure illustrates the operation of a liquid crystal cell constituting a liquid crystal light control element according to one embodiment of the present invention, showing the orientation state of liquid crystal molecules when a voltage is applied to the first electrode. [Figure 7C] This figure illustrates the operation of a liquid crystal cell constituting a liquid crystal light control element according to one embodiment of the present invention, showing the orientation state of liquid crystal molecules when a voltage is applied to the second electrode. [Figure 8] This diagram schematically illustrates the phenomenon in which the first and second polarization components are diffused by two liquid crystal cells. [Figure 9] This diagram illustrates the operation of a liquid crystal light control device according to one embodiment of the present invention. [Figure 10A] This shows the 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] This shows the 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] This graph shows the angular dependence of the chromaticity (x-axis) of a liquid crystal light control element according to one embodiment of the present invention and a reference example of a liquid crystal light control element. [Figure 11B] This graph shows the angular dependence of the chromaticity (y-coordinate axis) of a liquid crystal light control element according to one embodiment of the present invention and a reference example of a liquid crystal light control element. [Figure 12] This diagram illustrates the operation of a liquid crystal light control device according to one embodiment of the present invention. [Figure 13] This diagram illustrates the operation of a liquid crystal light control device according to one 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 exemplified below. For the sake of clearer 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 already shown figures, and detailed description may be omitted as appropriate. Furthermore, the letters "first" and "second" appended to each element are for convenience of distinguishing each element and have no further meaning unless otherwise specified.

[0009] In this specification, when a member or region is said to be "above (or below)" another member or region, unless otherwise specified, this includes not only cases where it is directly above (or directly below) the other member or region, but also cases where it is above (or below) the other member or region, that is, cases where another component is included between them above (or below) the other member or region.

[0010] Figure 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] Figure 1 shows an embodiment in which the 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 the flat surfaces of each liquid crystal cell are arranged to 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 liquid crystal cells arranged adjacent to each other front to back are bonded together by 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 via a first flexible wiring board F1, the second liquid crystal cell 20 is connected to the circuit board 104 via a second flexible wiring board F2, the third liquid crystal cell 30 is connected to the circuit board 104 via a third flexible wiring board F3, and the fourth liquid crystal cell 40 is connected to the circuit board 104 via a fourth flexible wiring board F4. The circuit board 104 outputs a control signal to each liquid crystal cell via the flexible wiring board to control the orientation state of the liquid crystal.

[0013] The liquid crystal light control device 100 shown in Figure 1 has a light source unit 106 positioned on the back side of the liquid crystal light control element 102. The liquid crystal light control device 100 is configured so that light emitted from the light source unit 106 is emitted from the liquid crystal light control element 102 to the front side of the drawing. The liquid crystal light control element 102 has 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 arranged in this order from the side of the light source unit 106.

[0014] The light source unit 106 includes a white light source, and optical elements such as lenses may be placed 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 incandescent light. The liquid crystal light control device 100 has the function of controlling the diffusion direction of the light emitted from the light source unit 106 using the liquid crystal light control element 102. The liquid crystal light control element 102 has the 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] Figure 2 shows an exploded view of the liquid crystal light control element 102 shown in Figure 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 arranged opposite each other with a gap between them. 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 board 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 board F2, and has the same configuration as 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 board F3, and has the same configuration as 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 board F4, and has the same configuration as the first liquid crystal cell 10.

[0018] A first transparent adhesive layer TA1 is placed between the first liquid crystal cell 10 and the second liquid crystal cell 20. The first transparent adhesive layer TA1 transmits visible light and adheres 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 placed between the second liquid crystal cell 20 and the third liquid crystal cell 30. The second transparent adhesive layer TA2 transmits visible light and adheres 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 placed between the third liquid crystal cell 30 and the fourth liquid crystal cell 40. The third transparent adhesive layer TA3 transmits visible light and adheres 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 substrate S11, S21, S31, S41 and the second substrate S12, S22, S23, S24. Optical elastic resins can be used as the first transparent adhesive layer TA1, the second transparent adhesive layer TA2, and the third transparent adhesive layer TA3; for example, an adhesive containing a light-transmitting acrylic resin can be used. Furthermore, since the temperature of the liquid crystal light control element 102 rises due to the heat radiated from the light source 106, it is preferable that 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 close to those of the thermal expansion coefficients 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 those of the glass substrate, for example, it is necessary to consider stress relaxation when the temperature rises. The thickness of the first transparent adhesive layer TA1, the second transparent adhesive layer TA2, and the third transparent adhesive layer TA3 is preferably greater 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 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 this embodiment has a structure in which the third liquid crystal cell 30 and the fourth liquid crystal cell 40 are superimposed 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 this embodiment includes a plurality of liquid crystal cells, and includes a structure in which at least one liquid crystal cell and other liquid crystal cells adjacent to (overlapping with) that at least one liquid crystal cell are arranged in a state rotated within a range of 90 ± 10 degrees. The rotation angles of the third liquid crystal cell 30 and the fourth liquid crystal cell 40 can be set within a range of 90 ± 10 degrees.

[0022] Figure 2 shows that, relative to the arrangement of the first liquid crystal cell 10 and the second liquid crystal cell 20, the third liquid crystal cell 30 and the fourth liquid crystal cell 40 are arranged in a 90-degree rotation. Conversely, relative to the third liquid crystal cell 30 and the fourth liquid crystal cell 40, the first liquid crystal cell 10 and the second liquid crystal cell 20 are arranged in a 90-degree rotation. By stacking multiple liquid crystal cells having the same electrode pattern and rotating some of the liquid crystal cells, it is possible to change the electrode arrangement and thus change the diffusion of light passing through the stacked liquid crystal cells. The details are explained below.

[0023] Figure 3 is a perspective view showing the arrangement of electrodes provided 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, respectively.

[0024] The first liquid crystal cell 10 includes a first substrate S11 and 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 has a first electrode E11 on the side facing the first liquid crystal layer LC1, and the second substrate S12 has a second electrode E12 on the side 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 in between. As described above, the first substrate S11 and the second substrate S12 face each other, and it is also possible to define the facing surface as the inner surface and the surface opposite the inner surface as the outer surface. 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 strip-shaped first strip electrodes E11A and a plurality of strip-shaped second strip electrodes E11B. The second electrode E12 includes a plurality of strip-shaped third strip electrodes E12A and a plurality of strip-shaped fourth strip electrodes E12B. The plurality of first strip electrodes 11A and the plurality of second strip electrodes E11B are arranged alternately, and the plurality of third strip electrodes 12A and the plurality of fourth strip electrodes E12B are arranged alternately.

[0026] Figure 3 shows the X, Y, and Z axis directions for illustrative purposes. 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 in a superimposed direction along the Z axis. In the first liquid crystal cell 10, the longitudinal directions of the multiple first strip electrodes E11A and multiple second strip electrodes E11B are arranged parallel to the Y axis, and the longitudinal directions of the multiple third strip electrodes 12A and multiple fourth strip electrodes E12B are arranged parallel to the X axis. That is, the multiple first strip electrodes E11A and multiple second strip electrodes E11B and the multiple third strip electrodes E12A and multiple fourth strip electrodes E12B are arranged to intersect. The longitudinal directions of the multiple first strip electrodes E11A and the multiple second strip electrodes E11B and the longitudinal directions of the multiple third strip electrodes E12A and the multiple fourth strip electrodes E12B can be arranged to intersect, for example, within a range of 90 degrees ± 10 degrees, and preferably to be orthogonal (90 degrees). In this embodiment, these longitudinal directions are orthogonal to each other.

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

[0028] The second liquid crystal cell 20 has multiple first strip electrodes 21A and multiple second strip electrodes E21B arranged alternately, and multiple third strip electrodes 22A and multiple fourth strip electrodes E22B arranged alternately. In the second liquid crystal cell 20, the longitudinal directions of the multiple first strip electrodes 21A and multiple second strip electrodes E21B are arranged parallel to the Y-axis direction, and the longitudinal directions of the multiple third strip electrodes 22A and multiple strip fourth electrodes E22B are arranged parallel to the X-axis direction. That is, the multiple first strip electrodes E21A and multiple second strip electrodes E21B and the multiple third strip electrodes E22A and multiple fourth strip electrodes E22B are arranged to intersect. The longitudinal directions of the multiple first strip electrodes E21A and the multiple second strip electrodes E21B and the longitudinal directions of the multiple third strip electrodes E22A and the multiple fourth strip electrodes E22B can be arranged to intersect, for example, within a range of 90 degrees ± 10 degrees, and preferably 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 and a second substrate S32, and a third liquid crystal layer LC3 between the first substrate S31 and the second substrate S32. The first substrate S31 is provided with a first electrode E31 on the side facing the third liquid crystal layer LC3, and the second substrate S32 is provided with a second electrode E32 on the side facing the third liquid crystal layer LC3. The first electrode E31 includes a plurality of strip-shaped first strip electrodes E31A and a plurality of strip-shaped second strip electrodes E31B, and the second electrode E32 includes a plurality of strip-shaped third strip electrodes E32A and a plurality of strip-shaped fourth strip electrodes E32B.

[0030] In the third liquid crystal cell 30, multiple first strip electrodes 31A and multiple second strip electrodes E31B are arranged alternately, and multiple third strip electrodes 32A and multiple fourth strip electrodes E32B are arranged alternately. In the third liquid crystal cell 30, the longitudinal directions of the multiple first strip electrodes 31A and multiple second strip electrodes E31B are arranged parallel to the X-axis direction, and the longitudinal directions of the multiple third strip electrodes 32A and multiple fourth strip electrodes E32B are arranged parallel to the Y-axis direction. That is, the multiple first strip electrodes E31A and multiple second strip electrodes E31B and the multiple third strip electrodes E32A and multiple fourth strip electrodes E32B are arranged to intersect. The longitudinal directions of the multiple first strip electrodes E31A and the multiple second strip electrodes E31B, and the longitudinal directions of the multiple third strip electrodes E32A and the multiple fourth strip electrodes E32B can be arranged to intersect, for example, within a range of 90 degrees ± 10 degrees, and preferably 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 and a second substrate S42, and a fourth liquid crystal layer LC4 between the first substrate S41 and the second substrate S42. The first substrate S41 has a first electrode E41 on the side facing the fourth liquid crystal layer LC4, and the second substrate S42 has a second electrode E42 on the side facing the fourth liquid crystal layer LC4. The first electrode E41 includes a plurality of strip-shaped first strip electrodes E41A and a plurality of strip-shaped second strip electrodes E41B, and the second electrode E42 includes a plurality of strip-shaped third strip electrodes E42A and a plurality of strip-shaped fourth strip electrodes E42B. In this embodiment, their longitudinal directions are orthogonal to each other.

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

[0033] As is clear from the above description, the liquid crystal light control element 102 is arranged such that the first strip electrode E11A and the second strip electrode E11B of the first liquid crystal cell 10 and the first strip electrode E21A and the second strip electrode E21B of the second liquid crystal cell 20 are arranged in the same longitudinal direction, and the first strip electrode E31A and the second strip electrode E31B of the third liquid crystal cell 30 and the first strip electrode E41A and the second strip electrode E41B of the fourth liquid crystal cell 40 are arranged in the same longitudinal direction. Furthermore, the first strip electrode E11A and the second strip electrode E11B of the first liquid crystal cell 10 and the first strip electrode E21A and the second strip electrode E21B of the second liquid crystal cell 20 are arranged such 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 electrode E12A and fourth strip electrode E12B of the first liquid crystal cell 10 and the third strip electrode E22A and fourth strip electrode E22B of the second liquid crystal cell 20 are arranged in the same longitudinal direction, and the third strip electrode E32A and fourth strip electrode E32B of the third liquid crystal cell 30 and the third strip electrode E42A and fourth strip electrode E42B of the fourth liquid crystal cell 40 are arranged in the same longitudinal direction. Furthermore, the third strip electrode E12A and fourth strip electrode E12B of the first liquid crystal cell 10 and the third strip electrode E22A and fourth strip electrode E22B of the second liquid crystal cell 20 are arranged so that their longitudinal directions intersect. The intersection angle at this time is preferably in the range of 90 degrees ± 10 degrees, and more preferably orthogonal (90 degrees). In this embodiment, the intersection angle is 90 degrees.

[0035] In other words, in the liquid crystal light control element 102 according to this embodiment, the first electrodes E11 and E21 of the first liquid crystal cell 10 and the second liquid crystal cell 20 have a strip-shaped pattern whose longitudinal direction is parallel to the Y-axis direction, and the first electrodes E31 and E41 of the third liquid crystal cell 30 and the fourth liquid crystal cell 40 have a strip-shaped pattern whose longitudinal direction is parallel to the X-axis direction. In other words, the strip-shaped patterns of the first electrodes E11 and E21 of the first liquid crystal cell 10 and the second liquid crystal cell 20 are arranged to intersect with the strip-shaped patterns of the first electrodes E31 and E41 of the third liquid crystal cell 30 and the fourth liquid crystal cell 40. The intersection angle is preferably in the range of 90 degrees ± 10 degrees, and more preferably orthogonal (90 degrees), as described above. In this embodiment, the intersection angle is 90 degrees.

[0036] The first electrode E11 and second electrode E12 provided in the first liquid crystal cell 10, the first electrode E21 and second electrode E22 provided in the second liquid crystal cell 20, the first electrode E31 and second electrode E32 provided in the third liquid crystal cell 30, and the first electrode E41 and second electrode E42 provided in the fourth liquid crystal cell 40 have substantially the same size in a plan view. Although not shown in Figure 3, the light source unit (106) is located below the first liquid crystal cell 10. The 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 similar configurations, but the first liquid crystal cell 10 will be described in more detail below as a representative example.

[0038] Figure 4A shows a plan view of the first substrate S11, and Figure 4B shows a plan view of the second substrate S12. Note that Figure 4B is a plan view of the second substrate S12 as seen from the inner surface.

[0039] As shown in Figure 4A, a first electrode E11 is provided on the 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 arranged alternately at predetermined intervals in a direction intersecting the longitudinal direction.

[0040] Multiple first strip electrodes E11A are each connected to a first power supply line PL11, and multiple second strip 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. A third connection terminal T13 is provided adjacent to the first connection terminal T11 on the first substrate S11, and a fourth connection terminal T14 is provided 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 in the plane of the first substrate S11. The fourth connection terminal T14 is connected to the sixth power supply line PL16. The sixth power supply line PL16 is connected to the second power supply terminal PT12, which is located at a predetermined position within the plane of the first substrate S11.

[0041] Multiple first strip electrodes E11A are connected to the first power supply line PL11, thereby applying the same voltage. Multiple second strip electrodes E11B are connected to the second power supply line PL12, thereby applying the same voltage. As shown in Figure 4A, the multiple first strip electrodes E11A and the multiple second strip electrodes E11B are arranged alternately. The multiple first strip electrodes E11A and the multiple second strip electrodes E11B are electrically isolated. When different voltage levels are applied to the multiple first strip electrodes E11A and the multiple second strip electrodes E11B, 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 multiple first strip electrodes E11A and the multiple second strip electrodes E11B.

[0042] As shown in Figure 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-shaped pattern. The strip-shaped patterns of the plurality of third strip electrodes E12A and the strip-shaped patterns of the plurality of fourth strip electrodes E12B are arranged alternately at predetermined intervals in a direction intersecting the longitudinal direction.

[0043] Multiple third strip electrodes E12A are each connected to a third power supply line PL13, and multiple fourth strip electrodes E12B are each 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 located at a position corresponding to the first power supply terminal PT11 on the first substrate S11, and the fourth power supply terminal PT14 is located at a position corresponding to the second power supply terminal PT12 on the first substrate S11.

[0044] Multiple third strip electrodes E12A are connected to the third power supply line PL13, thereby applying the same voltage. Multiple fourth strip electrodes E12B are connected to the fourth power supply line PL14, thereby applying the same voltage. As shown in Figure 4B, the multiple third strip electrodes E12A and the multiple fourth strip electrodes E12B are arranged alternately. The multiple third strip electrodes E12A and the multiple fourth strip electrodes E12B are electrically isolated. When different voltage levels are applied to the multiple third strip electrodes E12A and the multiple 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 multiple third strip electrodes E12A and the multiple fourth strip electrodes E12B.

[0045] The first connection terminal T11, second connection terminal T12, third connection terminal 13, and fourth connection terminal T14 provided on the first substrate S11 are terminals that connect 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 to a conductive material.

[0046] Figure 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 Figure 5 corresponds to the cross-sectional structure of the first substrate S11 shown in Figure 4A and the second substrate S12 shown in Figure 4B, along the A1-A2 line.

[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 arranged within the effective region AA. The first substrate S11 and the second substrate S12 are bonded together by a sealing material SE provided on the outside of the effective region AA. A gap is provided between the first substrate S11 and the second substrate S12 for encapsulating the first liquid crystal layer LC1. The first liquid crystal layer LC1 is encapsulated between the first substrate S11 and the second substrate S12 by the sealing material SE.

[0048] The first substrate S11 has a structure in which a first electrode E11 and a first power supply terminal PT11 are provided on the first electrode E11, and a first orientation film AL11 is provided on the first electrode E11. The first electrode E11 includes a first strip electrode E11A and a second strip electrode E11B. The first power supply terminal PT11 has a structure that is continuous with the fifth power supply line PL15 and is located 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 orientation film AL12 is provided on the second electrode E12. The second electrode E12 includes a third strip electrode E12A and a fourth strip electrode E12B. The third power supply terminal PT13 has a structure that is continuous with the third power supply line PL13 and is located outside the sealing material SE.

[0050] The first electrode E11 and the second electrode E12 are positioned so that the longitudinal directions of their strip-shaped electrode patterns intersect. That is, the longitudinal directions of the first strip-shaped electrode E11A and the second strip-shaped electrode E11B intersect with the longitudinal directions of the third strip-shaped electrode E12A and the fourth strip-shaped electrode E12B. In this embodiment, the first strip-shaped electrode E11A and the second strip-shaped electrode E11B intersect with the third strip-shaped electrode E12A and the fourth strip-shaped electrode E12B at a 90-degree angle. The intersection angle of the first electrode E11 and the second electrode E12 can be set to, for example, 90 degrees ± 10 degrees, as described above.

[0051] The first power supply terminal PT11 and the third power supply terminal PT13 are positioned opposite each other, facing each other in the area outside the sealing material SE. The first conductive member CP11 is positioned between the first power supply terminal PT11 and the third power supply terminal PT13, electrically connecting them. The first conductive member CP11 can be formed from a conductive paste material, such as silver paste or carbon paste. Although not shown in Figure 5, the second power supply terminal PT12 and the fourth power supply terminal PT14 are similarly electrically connected by conductive members.

[0052] The first substrate S11 and the second substrate S12 are translucent substrates, such as glass substrates and resin substrates. The first electrode E11 and the second electrode E12 are transparent electrodes formed from transparent conductive materials such as indium tin oxide (ITO) and 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 formed from metallic materials such as aluminum, titanium, molybdenum, and 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, sixth power supply line PL16) may be formed from the same transparent conductive film as the first electrode E11 and second electrode E12. The alignment films AL1 and AL2 are formed from horizontal alignment films having an alignment restricting force substantially parallel to the main plane of the substrate. For the first liquid crystal layer LC1, for example, twisted nematic liquid crystal (TN) is used. Although not shown in Figure 5, a spacer may be provided between the first substrate S11 and the second substrate S12 to maintain a constant distance between the two substrates.

[0053] Next, the electro-optic operation in the first liquid crystal cell 10 will be explained with reference to Figures 6A, 6B, 6C, 7A, 7B, 7C, and 8. Note that only the configurations necessary for the explanation are shown in Figures 6 through 8.

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

[0055] Figure 6A shows that the orientation processing direction of the first orientation film AL11 and the orientation processing direction of the second orientation film AL12 are different. Specifically, as shown in Figure 4A, the first orientation film AL11 is oriented in the direction ALD1, which intersects the longitudinal directions of the first strip electrode E11A and the second strip electrode E11B at a 90-degree angle, and as shown in Figure 4B, the second orientation film AL12 is oriented in the direction ALD2, which intersects the longitudinal directions of the third strip electrode E12A and the fourth strip electrode E12B at a 90-degree angle. Therefore, in the first liquid crystal cell 10 shown in Figure 6A, the first orientation film AL11 is oriented in the left-right direction of the paper, and the second orientation film AL12 is oriented in the direction normal to the paper. The orientation processing may be rubbing or optical distribution. Furthermore, the orientation direction of the orientation film can be set within a range of 90 degrees ± 10 degrees with respect to the extending direction of the strip electrodes.

[0056] TN liquid crystal is used as the first liquid crystal layer LC1. Since the orientation direction ALD1 of the first alignment film AL11 and the orientation direction ALD2 of the second alignment film AL12 are orthogonal, the liquid crystal molecules in the first liquid crystal layer LC1 are oriented such that their long axis is twisted by 90 degrees from the first alignment film AL11 to the second alignment film AL12 when not subjected to an external electric field. Figure 6A shows the state in which no voltage is applied to the first strip electrode E11A and the second strip electrode E11B, and shows the state in which the liquid crystal molecules are oriented with their long axis twisted by 90 degrees.

[0057] Figure 6A shows an example where the liquid crystal layer LC1 is formed as a positive-type twisted nematic liquid crystal (TN liquid crystal), and the long axis of the liquid crystal molecules is oriented in the same direction as the orientation direction of the alignment film. However, by rotating the orientation direction of the alignment film by 90 degrees, that is, by aligning the orientation direction of each alignment film AL11 and AL12 with the extending direction of the strip electrodes E11A and E12A of each substrate S11 and S12, a negative-type liquid crystal can be used. Preferably, the liquid crystal contains a chiral agent that imparts twist to the liquid crystal molecules.

[0058] Figure 6B shows the 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 transverse electric field is generated between the first strip electrode E11A and the second strip electrode E11B. As shown in Figure 6B, the liquid crystal molecules on the first substrate S11 side change their orientation direction due to the influence of the transverse electric field. For example, the liquid crystal molecules on the first substrate S11 side change their orientation so that their long axis is parallel to the direction of the electric field.

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

[0060] By alternately applying a low-level voltage VL and a high-level voltage VH to the first strip-shaped electrode E11A and the second strip-shaped electrode E11B, an alternating electric field is generated, suppressing the degradation of the first liquid crystal layer LC1. The frequency of the voltage applied to the first strip-shaped electrode E11A and the second strip-shaped electrode E11B should be a frequency at which the liquid crystal molecules can follow the change in the electric field, for example, 15 to 100 Hz.

[0061] Figure 7A is a partial perspective view of the first liquid crystal cell 10, showing the arrangement of the first strip electrode E11A and the second strip electrode E11B, the third strip electrode E12A and the fourth strip electrode E12B, and the first liquid crystal layer LC1. Figures 7B and 7C show schematic cross-sectional views of the first liquid crystal cell 10. Figure 7B shows a schematic cross-sectional view of the first liquid crystal cell 10 shown in Figure 7A, viewed from side A shown in the figure, and Figure 7C shows a schematic cross-sectional view viewed from side B shown in the figure. Figures 7B and 7C show that the orientation processing direction of the first orientation film AL11 and the orientation processing direction of the second orientation film AL12 are different.

[0062] As shown in Figures 7A and 7C, the first strip electrode E11A and the second strip electrode E11B are positioned at a center-to-center distance W, and the third strip electrode E12A and the fourth strip electrode E12B are similarly positioned at a center-to-center distance W. This center-to-center distance W has the relationship W = a + b, where a is the width of the first strip electrode E11A shown in Figure 7A, and b is the distance from the end of the first strip electrode E11A to the end of the second strip electrode E11B. Furthermore, the first strip electrode E11A and the second strip electrode E11B are spaced apart from the third strip electrode E12A and the fourth strip electrode E12B, and are positioned opposite each other in an orthogonal manner. The first substrate S11 and the second substrate S12 are positioned opposite each other at a distance D, where the distance D substantially corresponds to the thickness of the liquid crystal layer LC1. In practice, 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. However, since the thickness of these electrodes and alignment films is sufficiently small compared to the size of the gap D, the thickness of the liquid crystal layer LC1 can be considered equivalent to the gap D.

[0063] In the first liquid crystal cell 10, it is preferable that the spacing D between the strip electrodes across the first liquid crystal layer LC1 is equal to or greater than the distance W between the centers of the strip electrodes. That is, it is preferable that the spacing D has a length of at least 1 times the distance W between the centers. For example, it is preferable that the spacing D has a size of at least 2 times the distance W between the centers of the strip electrodes. If the width of the first strip electrode E11A is 5 μm, the width a of the first strip electrode E11A and the second strip electrode E11B is 5 μm, and the spacing b from the end of the first strip electrode E11A to the end of the second strip electrode E11B is 5 μm, then the distance W between the centers of the strip electrodes is 10 μm. In contrast, it is preferable that the spacing D has a size of 10 μm or more.

[0064] The relationship between the centers W of the strip electrodes and the above-mentioned interval D makes it possible to prevent the electric fields generated by the first strip electrode E11A and the second strip electrode E11B from interfering with each other. That is, as shown in Figure 7B, the orientation of liquid crystal molecules in the vicinity of the first strip electrode E11A and the second strip electrode E11B can be controlled without being affected by the third strip electrode E12A and the fourth strip electrode E12B, and as shown in Figure 7C, the orientation of liquid crystal molecules in the vicinity of the third strip electrode E12A and the fourth strip electrode E12B can be controlled without being affected by the first strip electrode E11A and the second strip electrode E11B.

[0065] Incidentally, it is known that the refractive index of liquid crystals changes depending on their orientation. As shown in Figure 6A, in the OFF state where no electric field is acting on the first liquid crystal layer LC1, the long axis of the liquid crystal molecules is oriented horizontally to the surface of the substrate, and is oriented with a 90-degree twist from the first substrate S11 side to the second substrate S12 side. In this orientation state, the liquid crystal layer LC1 has a nearly uniform refractive index distribution. Therefore, the first polarization component PL1 and the second polarization component PL2 (see Figure 8) orthogonal to the first polarization component PL1 of the light incident on the first liquid crystal cell 10 rotate under the influence of 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 in natural light, and the second polarization component corresponds to, for example, S-polarized light.

[0066] On the other hand, as shown in Figure 6B, in the ON state, when a voltage is applied to the first strip electrode E11A and the second strip electrode E11B and an electric field is formed, if the first liquid crystal layer LC1 has positive dielectric anisotropy, the liquid crystal molecules will orient themselves so that their long axes are aligned with the electric field. As a result, as shown in Figure 6B, the first liquid crystal layer LC1 forms regions where the liquid crystal molecules stand almost vertically above the first strip electrode E11A and the second strip electrode E11B, regions where they are orienting diagonally along the distribution of the electric field between the first strip electrode E11A and the second strip electrode E11B, and regions where the initial orientation state is relatively maintained away from the first strip electrode E11A and the second strip electrode E11B.

[0067] As shown in Figure 6B, between the first strip electrode E11A and the second strip electrode E11B, the long axes of the liquid crystal molecules are oriented in a convex arc shape along the direction in which the electric field is generated. That is, as shown in Figures 6A and 6B, the initial orientation 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 schematically shown in Figure 6B, the orientation direction of the liquid crystal molecules located approximately in the center between the two electrodes hardly changes. However, the liquid crystal molecules located on each electrode side from the center are oriented tilted in the direction normal to the surface of the first substrate S11 according to the electric field intensity distribution. Therefore, when considering the liquid crystal on the first substrate S11 as a whole, the liquid crystal molecules are oriented 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, causing the incident light (polarization component parallel to the initial orientation direction of the liquid crystal molecules) to diffuse radially. Similarly, on the second substrate S12 side, a similar phenomenon occurs due to the third strip electrode E12Aa and the fourth strip electrode E12B, which are positioned orthogonal to the electrodes of the first substrate S11 (see Figure 7C), causing the incident light (polarization component parallel to the initial orientation direction of the liquid crystal molecules on the second substrate S12 side) to diffuse radially.

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

[0070] Liquid crystal molecules have refractive index anisotropy Δn. Therefore, the first liquid crystal layer LC1 in the ON state has a refractive index distribution, or retardation distribution, corresponding to the orientation 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 as it passes through the first liquid crystal layer LC1, influenced by the refractive index distribution of the first liquid crystal layer LC1.

[0071] Figure 8 schematically illustrates the phenomenon in which the first polarization component PL1 and the second polarization component PL2 are diffused by the liquid crystal layer. Figure 8 shows the 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 of each liquid crystal cell, and the first liquid crystal layer LC1 and the second liquid crystal layer LC2 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 E11B of the first liquid crystal cell 10 and the first strip electrodes E21A and E21B of the second liquid crystal cell 20 are arranged in the same direction. Furthermore, the orientation direction ALD1 of the alignment film (not shown) on 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 left-right direction of the paper, and the orientation direction ALD2 of the alignment film (not shown) on 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 direction normal to the paper.

[0072] In Figure 8, the first liquid crystal cell 10 and the second liquid crystal cell 20 are assumed to have a polarization direction of the first polarization component PL1 that is parallel to the initial orientation direction of the liquid crystal molecules on the first substrate S11 side of the first liquid crystal layer LC1 and the initial orientation direction of the liquid crystal molecules on the first substrate S12 side of the second liquid crystal layer LC2 (the direction in which the long axis of the liquid crystal molecules is oriented in a non-electric field state). Furthermore, the polarization direction of the second polarization component PL2 is assumed to be orthogonal to the orientation direction of the liquid crystal molecules on the first substrate S11 side of the first liquid crystal layer LC1 and on the first substrate S21 side of the second liquid crystal layer LC2.

[0073] When a voltage is applied to the first strip electrode E11A and the second strip electrode E11B of the first liquid crystal cell 10, liquid crystal molecules in the first liquid crystal layer LC1 form regions where they stand vertically, regions where they are obliquely oriented along the distribution of the electric field, regions where their initial orientation is maintained, and so on. Similarly, when a voltage is applied to the first strip electrode E21A and the second strip electrode E21B of the second liquid crystal cell 20, liquid crystal molecules in the second liquid crystal layer LC2 form regions where they stand vertically, regions where they are obliquely oriented along the distribution of the electric field, regions where their initial orientation is maintained, and so on.

[0074] The first polarization component PL1 is diffused and rotated by 90 degrees in the first liquid crystal layer LC1, and is not diffused and rotated by 90 degrees in the second liquid crystal layer LC2. The second polarization component PL2 is not diffused and rotated by 90 degrees in the first liquid crystal layer LC1, and is diffused and rotated by 90 degrees in the second liquid crystal layer LC2. In other words, the first polarization component PL1 incident on the first substrate S11 is diffused in the first liquid crystal layer LC1 and rotated by 90 degrees in 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 90 degrees in the first liquid crystal layer LC1 and the second liquid crystal layer LC2, respectively. Here, optical rotation refers to the phenomenon in which linearly polarized components (for example, the first polarization component PL1 and the second polarization component PL2 described above) rotate their polarization axis along the torsional orientation of the liquid crystal molecules as they pass through the liquid crystal layers.

[0075] Figure 8 will be explained 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. In addition, the extending direction of the first electrode E11 of the first liquid crystal cell 10 and the extending direction of the first electrode E21 of the second liquid crystal cell 20 are the same. Furthermore, light containing 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 on the first substrate S11 of the first liquid crystal cell 10 from a direction perpendicular to it and exits from the second substrate S22 of the second liquid crystal cell 20.

[0076] In the first substrate S11 side of the first liquid crystal cell 10, the liquid crystal molecules of the liquid crystal layer LC1 are oriented with their long axes along the X-axis direction. Therefore, when a transverse electric field is generated between the first strip electrode E11A and the second strip electrode E11B, the liquid crystal molecules are affected by the electric field and oriented in a convex arc shape along the X-axis direction, as explained with reference to Figure 7B. Similarly, in the second substrate S12 side of the first liquid crystal cell 10, the liquid crystal molecules of the first liquid crystal layer LC1 are oriented with their long axes along the Y-axis direction. Therefore, when a transverse electric field is generated between the third strip electrode E12A and the fourth strip electrode E12B (not shown), the liquid crystal molecules are oriented in a convex arc shape along the Y-axis direction, as explained with reference to Figure 7C. Due to this orientation of the liquid crystal molecules, a refractive index distribution dependent on the orientation of the liquid crystal molecules is formed on both the first substrate S11 side and the second substrate S12 side.

[0077] The first polarization component PL1, which is parallel to the X-axis and incident on the first liquid crystal cell 10, rotates as it passes through the first liquid crystal layer LC1, becoming 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 as it passes through the first liquid crystal layer LC1 in the thickness direction, its polarization axis gradually changes, and on the second substrate S12 side it has a polarization axis in the Y-axis direction 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 diffuses in the X-axis direction in accordance with the change in the refractive index distribution of the liquid crystal molecules, because its polarization axis on the first substrate S11 side is parallel to the orientation direction of the liquid crystal molecules in the first liquid crystal layer LC1 on the first substrate S11 side. Furthermore, as the first polarization component PL1 passes through the first liquid crystal layer LC1, its polarization axis changes from the X-axis direction to the Y-axis direction, becoming parallel to the orientation direction of the liquid crystal molecules on the second substrate S12 side, and it diffuses in the Y-axis direction in accordance with the change in the refractive index distribution of the liquid crystal molecules. In other words, the first polarization component PL1, which is parallel to the X-axis before being incident on the first liquid crystal cell 10, changes its polarization axis from the X-axis direction to the Y-axis direction and diffuses in both the X-axis and Y-axis directions as it passes through the first liquid crystal cell 10.

[0079] In contrast, the second polarization component PL2 incident on the first liquid crystal cell 10 from the first substrate S11 side undergoes a change in polarization axis from the Y-axis direction to the X-axis direction due to the action of the first liquid crystal layer LC1 between the time it is incident on the first substrate S11 and the time it is emitted from the second substrate S12. Here, on the first substrate S11 side, the polarization axis of the second polarization component PL2 is perpendicular to the orientation direction of the liquid crystal molecules in the first liquid crystal layer LC1 on the first substrate S11 side, so it is not affected by the refractive index distribution due to the liquid crystal molecules and passes through without diffusion. Furthermore, as 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 second substrate S12 side, its polarization axis is also perpendicular to the orientation direction of the liquid crystal molecules in the first liquid crystal layer LC1 on the second substrate S12 side, so it is not affected by the refractive index distribution due to the liquid crystal molecules and passes through without diffusion. In other words, the second polarization component PL2, which has its polarization axis in the Y-axis direction and is incident on the first liquid crystal cell 10, changes its polarization axis from the Y-axis direction to the X-axis direction as it passes through the first liquid crystal cell 10, but is not diffused by the first liquid crystal layer LC1 and is emitted from the second substrate S12.

[0080] The second liquid crystal layer LC2 of the second liquid crystal cell 20 has the same refractive index distribution as the first liquid crystal layer LC1 of the first liquid crystal cell 10. Therefore, basically the same phenomena as in the first liquid crystal cell 10 occur in the second liquid crystal cell 20. On the other hand, as the initial first polarization component PL1 and the second polarization component PL2 are swapped after 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 swapped. That is, during the process of passing through the second liquid crystal cell 20, the initial first polarization component PL1 changes its polarization axis from the Y axis back to the X axis, but no diffusion occurs. On the other hand, the initial second polarization component PL2 changes its polarization axis from the X axis back to the Y axis and diffuses under the influence of the refractive index distribution of the second liquid crystal layer LC2.

[0081] As is clear from the above, by stacking two liquid crystal cells having the same structure, the polarization direction of light passing through these two liquid crystal cells can be changed twice, resulting in a state where the polarization direction remains unchanged before incidence and after emission. On the other hand, the two liquid crystal cells can diffuse transmitted light by forming a convex arc-shaped refractive index distribution on the upper and lower sides of the liquid crystal layer using a transverse electric field. Specifically, the first liquid crystal cell 10 diffuses 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 direction, and the second liquid crystal cell 20 diffuses 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 direction. In other words, by stacking 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, light can be diffused without changing the polarization state of the light.

[0082] As described above, by stacking 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 transverse electric field to the liquid crystal layer and forming a refractive index distribution, the passing 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 direction, 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 direction.

[0083] Thus, incident light passing through the first liquid crystal layer LC1 and the second liquid crystal layer LC2 has its first polarization component PL1 diffused in the first liquid crystal layer LC1 and its second polarization component PL2 diffused in the second liquid crystal layer LC2. In addition, 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, incident light containing the first polarization component PL1 and the second polarization component PL2 has its first polarization component PL1 diffused in the first liquid crystal cell 10 and its second polarization component PL2 diffused in the second liquid crystal cell 20. That is, by stacking the first liquid crystal cell 10 and the second liquid crystal cell 20, the scattering of specific polarization components can be controlled individually, and the light distribution of light emitted from the light source can be controlled.

[0084] Incidentally, light is refracted at the interface of different media, and it is known that the angle of refraction changes depending on the wavelength of light. When light is incident on a liquid crystal layer in which a refractive index distribution has been formed, the angle of refraction differs for each wavelength. Therefore, depending on the type of light source and the distance to the object being illuminated, color cracking may be visible in the peripheral part of the light distribution pattern formed by transmitting light through the liquid crystal light control element 102.

[0085] In contrast, the liquid crystal light control element 102 according to this embodiment suppresses color breakage by superimposing four liquid crystal cells on the optical path of the light source, and arranging at least two of the four liquid crystal cells rotated 90 degrees relative to the other liquid crystal cells, as shown in Figure 3. Specifically, the liquid crystal light control element 102 suppresses color breakage by arranging at least one pair of adjacent overlapping liquid crystal cells such that the longitudinal directions of the electrodes having a strip-shaped pattern face different directions. The configuration will be described in detail below based on the electrode configuration and operation of each liquid crystal cell.

[0086] Figure 9 shows the arrangement of strip electrodes in each liquid crystal cell of the liquid crystal light control element 102, and how the polarization state and scattering of incident light are controlled by each liquid crystal cell. The arrangement of 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 Figure 3. Specifically, in the liquid crystal light control element 102 shown in Figure 9, the orientation direction with respect to liquid crystal molecules is the same for each substrate (S11, S12, S21, S22) of the first liquid crystal cell 10 and the second liquid crystal cell 20, the longitudinal direction of the strip electrodes (E11A, E11B, E21A, E21B) in the first electrodes E11, E21 is the same, and the longitudinal direction of the strip electrodes (E12A, E12B, E22A, E22B) in the second electrodes E12, E22 that intersect these electrodes is the same. Furthermore, the orientation direction with respect to liquid crystal molecules is the same for each substrate (S31, S32, S41, S42) of the third liquid crystal cell 30 and the fourth liquid crystal cell 40, the longitudinal direction of the strip electrodes (E31A, E31B, E41A, E41B) of the first electrodes E31, E41 is the same, and the longitudinal direction of the strip electrodes (E32A, E32B, E42A, E42B) of the second electrodes E32, E42 that intersect these electrodes is the same. In addition, the longitudinal direction of the strip electrodes (E11A, E11B, E21A, E21B) of the first liquid crystal cell 10 and the second liquid crystal cell 20 intersects with the longitudinal direction of the strip electrodes (E31A, E31B, E41A, E41B) of the first electrodes E31, E41 of the third liquid crystal cell 30 and the fourth liquid crystal cell 40 at an angle of 90 degrees.

[0087] In the embodiment shown in Figure 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 orientation of the first electrodes E31 and E41 of the third liquid crystal cell 30 and the fourth liquid crystal cell 40 is rotated by 90 degrees with respect to the orientation of the first electrodes E11 and E21 of the first liquid crystal cell 10 and the second liquid crystal cell 20. Also, the first electrodes (E11, E21, E31, E41) and second electrodes (E12, E22, E32, E42) of each liquid crystal cell are perpendicular to each other in their extending directions. The same applies to the embodiments shown in Figures 12 to 14, which will be described later. Furthermore, a configuration in which the third liquid crystal cell 30 and the fourth liquid crystal cell 40 are stacked with the first liquid crystal cell 10 and the second liquid crystal cell 20 rotated within a range of 90 degrees ± 10 degrees is also possible. Additionally, a configuration in which the extension direction of the first electrode (E11, E21, E31, E41) and the second electrode (E12, E22, E32, E42) of each liquid crystal cell is set within a range of 90 degrees ± 10 degrees is also possible.

[0088] As shown in Figure 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 positioned in the same direction, allowing the second polarization component PL2 to be diffused in the Y-axis direction. Similarly, the first electrode E11 of the first liquid crystal cell 10 and the second electrode E42 of the fourth liquid crystal cell 40 are positioned in the same direction, allowing the second polarization component PL2 to be diffused in the X-axis direction. The same applies to the diffusion of the first polarization component PL1; the second electrode E22 of the second liquid crystal cell 20 and the first electrode E31 of the third liquid crystal cell 30 are positioned in the same direction, allowing the first polarization 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 positioned in the same direction, allowing the first polarization component PL1 to be diffused in the X-axis direction.

[0089] The liquid crystal light control element 102 is arranged in the following order from the light incident side: first liquid crystal cell 10, second liquid crystal cell 20, third liquid crystal cell 30, and fourth liquid crystal cell 40. 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] Control signals are input to each liquid crystal cell in order for the liquid crystal light control element 102 to control the polarization and scattering state of the incident light. Figure 10A shows an example of the waveform of the control signal applied to the electrodes of each liquid crystal cell. Each liquid crystal cell is input to one of the signals shown in Figure 10A: control signal A, control signal B, or control signal E. In control signals A and B, VL1 represents a low-level voltage and VH1 represents a high-level voltage. For example, VL1 is a voltage of 0V or -15V, and VH1 is 30V (relative to 0V) or 15V (relative to -15V). Control signals A and B are synchronized; when control signal A is at the VL1 level, control signal B is at the VH1 level, and when control signal A changes to the VH1 level, control signal B changes to the VL1 level. The period of 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 the intermediate voltage between VL1 and VH1, and if VL1 = -15V and VH1 = +15V, then VE = 0V.

[0091] The following shows an example in which a liquid crystal light control element 102 forms a square light distribution pattern, a cross light distribution pattern, and a line light distribution pattern using such a control signal.

[0092] (1) Square beam 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 signals applied to each liquid crystal cell of the liquid crystal light control element 102. Figure 9 shows, as an example, a case in which the light emitted from the light source unit (106) is controlled to a square-shaped 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 Figure 9. Note that control signals A and B shown in Table 1 correspond to the control signals shown in Figure 10A. [Table 1]

[0094] In the example shown in Figure 9, control signal A is input to the first strip electrode E11A of the first liquid crystal cell 10, control signal B is input to the second strip electrode E11B, control signal A is input to the third strip electrode E12A, and control signal B is input to the fourth strip electrode E12B. As shown in Table 1, 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 in the same way as to the first liquid crystal cell 10. In other words, in the example shown in Figure 9, control signals A and B are alternately applied to all electrodes that are alternately arranged on each substrate, and an electric field is generated between all electrodes.

[0095] In Figure 9, the orientation direction defined by the alignment film formed on each substrate is perpendicular to the longitudinal direction of the strip-shaped electrode, as indicated by the arrows in the figure. The liquid crystal layer is formed of positive-type liquid crystal, and in the initial state where no control signal is input to each liquid crystal cell, the long axis of the liquid crystal is oriented in a direction that intersects (orthogonal to) the strip-shaped electrode. In this embodiment, the orientation direction of the alignment film is set at 90 degrees to the extending direction of the strip-shaped electrode, but it can also be set to a direction of 90 degrees ± 10 degrees.

[0096] When the liquid crystal light control element 102 is operating, the control signals shown in Table 1 are input to each strip-shaped electrode 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 orientation state of each liquid crystal cell changes as the liquid crystal molecules are affected by the transverse electric field, as shown in Figures 7A and 7B. The table inserted in Figure 9 shows how the polarization components change when light containing the first polarization component PL1 and the second polarization component PL2 passes through each liquid crystal cell. In the following explanation, the direction of the first polarization direction is defined as the Y-axis direction, and the direction of the second polarization direction is defined as the X-axis direction.

[0097] Focusing on the first polarization component PL1 in Figure 9, the polarization direction of the first polarization component PL1 incident on the first liquid crystal cell 10 is perpendicular to the direction of the long axis of the liquid crystal molecules on the first substrate S11 side of the first liquid crystal layer LC1. Therefore, although the liquid crystal molecules on the first substrate S11 side change their refractive index distribution due to the electric field generated by the first electrode E11, the first polarization component PL1 is not diffused and continues toward the second substrate S12 side. Furthermore, as the first polarization component PL1 moves from the first substrate S11 side to the second substrate S12 side of the first liquid crystal layer LC1, it rotates 90 degrees according to the torsional orientation of the liquid crystal molecules. As a result, the first polarization component PL1 transitions to the second polarization component PL2. The polarization direction of the second polarization component PL2 is perpendicular to the direction of the long axis of the liquid crystal molecules on the second substrate S12 side. Therefore, although the liquid crystal molecules on the second substrate S12 side change their refractive index distribution due to the electric field generated by the second electrode E12, the second polarization component PL2 is not affected and is transmitted as is. In other words, the first polarization component PL1 transitions to the second polarization component PL2 during the process of passing through the first liquid crystal cell 10, while being emitted from the second substrate S12 side without diffusion or other processes.

[0098] Then, the second polarization component PL2 is incident on the second liquid crystal cell 20. The polarization direction of the second polarization 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, since the liquid crystal molecules on the first substrate S21 side have their refractive index distribution changed by the electric field generated by the first electrode E21, the second polarization component PL2 is diffused in the X-axis direction. Furthermore, as this diffused second polarization component PL2 moves from the first substrate S21 side to the second substrate S22 side of the second liquid crystal layer LC2, it rotates 90 degrees according to the torsional orientation of the liquid crystal molecules. As a result, the second polarization component PL2 transitions back into the first polarization component PL1. Furthermore, the polarization direction of the first polarization 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 change their refractive index distribution due to the electric field generated by the second electrode E22. Therefore, the first polarization component is further affected by the refractive index distribution of the liquid crystal molecules and diffuses in the Y-axis direction before being emitted. That is, the second polarization component PL2 incident on the second liquid crystal cell 20 transitions to the first polarization component PL1 as it passes through the second liquid crystal cell 20, while diffusing in the X-axis and Y-axis directions.

[0099] Thus, of the incident light, the first polarization component PL1, before being incident on the first liquid crystal cell 10 and exiting the second liquid crystal cell 20, transitions once to the second polarization component PL2 and then back to the first polarization component PL1, and is diffused once each in the X-axis direction and the Y-axis direction in the second liquid crystal cell 20.

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

[0101] In other words, when the first polarization component PL1, which has passed through the second liquid crystal cell 20 and been diffused once in the X-axis and Y-axis directions, is incident on 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 liquid crystal molecules on the first substrate S31 side have their refractive index distribution changed by the electric field generated by the first electrode E31, the first polarization component PL1 is diffused in the X-axis direction. Furthermore, as this diffused first polarization component PL1 moves from the first substrate S31 side to the second substrate S32 side of the third liquid crystal layer LC3, it rotates 90 degrees according to the torsional orientation of the liquid crystal molecules. As a result, the first polarization component PL1 transitions back into the second polarization component PL2. Furthermore, 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, the liquid crystal molecules on the second substrate S32 have their refractive index distribution changed by the electric field generated by the second electrode E32. Therefore, the second polarization component PL2 is further affected by the refractive index distribution of the liquid crystal molecules and diffuses in the Y-axis direction before being emitted. That is, the first polarization component PL1 incident on the third liquid crystal cell 30 transitions to the second polarization component PL2 as it passes through the third liquid crystal cell 30, and then diffuses again in the X-axis and Y-axis directions.

[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 intersecting with the long axis direction of the liquid crystal molecules on the first substrate S41 side of the fourth liquid crystal layer LC4. Therefore, although the liquid crystal molecules on the first substrate S41 side 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 continues toward the second substrate S42 side. Furthermore, as the second polarization component PL2 moves from the first substrate S41 side to the second substrate S42 side of the fourth liquid crystal layer LC4, it rotates 90 degrees according to the torsional orientation of the liquid crystal molecules. As a result, the second polarization component PL2 transitions to the first polarization component PL1. The polarization direction of the first polarization component PL1 is intersecting with the long axis direction of the liquid crystal molecules on the second substrate S42 side. Therefore, although the liquid crystal molecules on the second substrate S42 side change their refractive index distribution due to the electric field generated by the second electrode E12, the first polarization component PL1 is not affected and is transmitted as is. In other words, the second polarization component PL2 transitions to the first polarization component PL1 as it passes through the fourth liquid crystal cell 40, while passing through the fourth liquid crystal cell 40 without diffusion or other processes.

[0103] Thus, the first polarization component PL1 incident on the third liquid crystal cell 30 transitions once to the second polarization component PL2 before being emitted from the fourth liquid crystal cell 40, and then transitions back to the first polarization component PL1, 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 enters the first liquid crystal cell 10 and the time it exits the fourth liquid crystal cell 40.

[0105] In Figure 9, "transmission" indicates that the polarized component passes through without diffusion or optical rotation. "Optical rotation" indicates that the polarized component undergoes a 90-degree shift in its polarization direction. "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 figures, for example, "transmission" at the first electrode indicates that the above-mentioned "transmission" phenomenon is occurring near the first electrode in the liquid crystal layer. Also, "optical rotation" in the liquid crystal layer indicates that the polarized component undergoes a 90-degree shift in its polarization direction as it moves from the first substrate side to the second substrate side in the liquid crystal layer. The same applies to Figures 12 to 14.

[0106] On the other hand, the polarization direction of the second polarization 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 the second polarization component PL2 is diffused by this effect. Then, as the second polarization component PL2 moves from the first substrate S11 side to the second substrate S12 side of the first liquid crystal layer LC1, it rotates 90 degrees according to the torsional orientation of the liquid crystal molecules. As a result, the second polarization component PL2 transitions to the first polarization component PL1. Furthermore, the polarization direction of the first polarization component PL1 is parallel to the long axis direction of the liquid crystal molecules on the second substrate S12 side. Since the liquid crystal molecules on the second substrate S12 side change their refractive index distribution due to the electric field generated by the second electrode E12, the first polarization component PL1 transitioned by the first liquid crystal layer LC1 is diffused in the Y-axis direction by the refractive index distribution formed by the liquid crystal molecules on the second substrate S12 side. In other words, the second polarization component PL2 incident on the first liquid crystal cell 10 transforms into the first polarization component PL1 as it passes through the first liquid crystal cell 10, while diffusing 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 is incident on the second liquid crystal cell 20. The polarization direction of the first polarization component PL1 incident on the second liquid crystal cell 20 is in a direction that intersects (orthogonal to) the long axis direction of the liquid crystal molecules on the first substrate S21 side of the second liquid crystal layer LC2. Therefore, although the liquid crystal molecules on the first substrate S21 side change their refractive index distribution due to the electric field generated by the first electrode E21, the first polarization component PL1 is not diffused and continues toward the second substrate S22 side. Furthermore, as the first polarization component PL1 moves toward the second substrate S22 side of the second liquid crystal layer LC2 from the first substrate S21 side, it rotates 90 degrees according to the torsional orientation of the liquid crystal molecules. As a result, the first polarization component PL1 transitions to the second polarization component PL2. Furthermore, the polarization direction of the second polarization component PL2 is in a direction that intersects the long axis direction of the liquid crystal molecules on the second substrate S22 side. Therefore, although the liquid crystal molecules on the second substrate S22 side change their refractive index distribution due to the electric field generated by the second electrode E22, the second polarization component PL2 is not affected and is transmitted as is. In other words, 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 diffusion.

[0108] The second polarization component PL2, which is rotated by 90 degrees in the first liquid crystal cell 10 and the second liquid crystal cell 20, and diffused once in the X-axis and Y-axis directions in 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 that intersects (orthogonal to) the long 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 their refractive index distribution due to the electric field generated by the first electrode E31, the second polarization component PL2 is not diffused and continues toward the second substrate S32 side. Furthermore, as the second polarization component PL2 moves from the first substrate S31 side to the second substrate S32 side of the third liquid crystal layer LC3, it is rotated by 90 degrees according to the torsional orientation of the liquid crystal molecules. As a result, the second polarization component PL2 transitions to the first polarization component PL1. Furthermore, the polarization direction of the first polarization component PL1 is intersecting the direction of the long axis of the liquid crystal molecules on the second substrate S32 side. Therefore, although the liquid crystal molecules on the second substrate S32 side change their refractive index distribution due to the electric field generated by the second electrode E32, the first polarization component PL1 is not affected and is transmitted as is. In other words, 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 is transmitted without diffusion.

[0109] When the first polarization component PL1, which has passed through the third liquid crystal cell 30, diffused once in the X-axis and Y-axis directions, and rotated by 90 degrees in the first liquid crystal cell 10, the second liquid crystal cell 20, and the third liquid crystal cell 30, is incident on the fourth liquid crystal cell 40, the polarization direction of the first polarization component PL1 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. Because the liquid crystal molecules on the first substrate S41 side of the fourth liquid crystal cell 40 have their refractive index distribution changed by the electric field generated by the first electrode E41, the first polarization component PL1 is diffused in the X-axis direction. Furthermore, as this diffused first polarization component PL1 moves from the first substrate S41 side to the second substrate S42 side of the fourth liquid crystal layer LC4, it rotates by 90 degrees according to the torsional orientation of the liquid crystal molecules. As a result, the first polarization component PL1 transitions back into the second polarization component PL2. The polarization direction of this second polarization 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 diffuses in the Y axis direction before being emitted from the second substrate S42 side.

[0110] Thus, the second polarization component PL2 incident on the third liquid crystal cell 30 transitions once to the first polarization component PL1 before transitioning back to the second polarization component PL2 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 fourth liquid crystal cell 40.

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

[0112] In the table in Figure 9, (diffuse light 1X) indicates that the polarization component diffused 1 degree in the X-axis direction before reaching that position, and (diffuse light 1X1Y) indicates that the polarization component diffused 1 degree in the X-axis direction and 1 degree in the Y-axis direction before reaching that position. The same applies to the others.

[0113] Figures 11A and 11B are graphs showing the angular dependence of the chromaticity of a liquid crystal light control element. Figure 11A shows the angular dependence of the x-coordinate value within the chromaticity coordinate, and Figure 11B shows the angular dependence of the y-coordinate. Figures 11A and 11B show the angular dependence of the chromaticity of an element (A) that uses four liquid crystal cells, as in the liquid crystal light control element 102 according to this embodiment, with the third and fourth liquid crystal cells rotated by 90 degrees. In addition, each graph shows the characteristics of an element (B) composed of two liquid crystal cells as a reference example.

[0114] As shown in Figures 11A and 11B, in the reference example, the characteristics of element (B) with a two-cell liquid crystal structure, specifically the x and y coordinate values, change significantly with the angle, indicating a large angular dependence of chromaticity. In contrast, element (A) with a four-cell liquid crystal structure, where 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 angular dependence of chromaticity. In other words, the configuration of the liquid crystal light control element 102 according to this embodiment can suppress color cracking.

[0115] In this way, by providing electrodes on different liquid crystal cells, one electrode positioned on the light incidence side with the liquid crystal layer in between, and the other electrode positioned on the opposite side from the light incidence side, a single polarization component can be diffused in the same direction at least twice, thereby preventing color breakage.

[0116] From this perspective, when forming a square-shaped light distribution pattern, it is not necessary to input the same voltage level control signal to the electrodes of all liquid crystal cells. It is also possible to apply different control signals to each set of electrodes, such as the set 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 set 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 set 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 set 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 where the voltage levels of the control signals are the same for each of the above sets, but different voltage levels of control signals are input to the first and second electrodes of a single liquid crystal cell. Note that control signals A, B, C, D, and E in Table 2 correspond to the control signals shown in Figure 10B. In Figure 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 voltages VL2 = -12V and VH2 = 12V can be set. [Table 2]

[0118] The combinations of control signals shown in Table 2 allow for variations in the diffusion of each polarization component in the Y-axis and X-axis directions, thus enabling variations in the rectangular light distribution pattern. For example, by adjusting the voltage levels of control signals A, B, C, and D, a square or rectangular light distribution pattern can be formed.

[0119] When the same control signal pattern as shown in Table 1 is applied to each liquid crystal cell of the liquid crystal light control element 102 having such a liquid crystal cell arrangement, the first polarization component PL1 and the second polarization component PL2 are diffused evenly in the X-axis and Y-axis directions, as described above, so that a square-shaped light distribution pattern can be formed. Furthermore, as will be described later, color breakage can be prevented in the light distribution pattern.

[0120] (2) Cross beam pattern Figure 12 shows an example of controlling the light emitted from the light source unit 106 to a cross-shaped light distribution pattern. The arrangement of each liquid crystal cell in the liquid crystal light control element 102 shown in Figure 12 is the same as in Figure 9.

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

[0122] As shown in Table 3, when forming a cross-shaped light distribution pattern, a control signal that generates a transverse 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. 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 them so that no transverse electric field is generated. Note that "transmission," "diffusion," and "optical rotation" in the figures and tables basically correspond to "transmission," "diffusion," and "optical rotation" mentioned in the explanation of Figure 9. In addition, in the drive shown in Figure 12, there is a configuration in which the same potential is applied to electrodes located on the same substrate, but in this 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 orientation state from the initial orientation. Therefore, in this electroless state, the polarization components passing through the liquid crystal layer do not diffuse. This case is also included in "transmission."

[0123] In Figure 12, we 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 perpendicular to the long 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 Figure 12, the electrode forming the electric field is shown with hatching. The same applies to Figures 13 and 14). Under these conditions, the first polarization component PL1 passes through the first liquid crystal layer LC1 on the first substrate S11 side without diffusion. Furthermore, the first polarization component PL1 rotates 90 degrees during the process of passing through the first liquid crystal layer LC1 and transitions to the second polarization component PL2. Furthermore, the polarization direction of the second polarization component PL2 is perpendicular to the long 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 Figure 12, electrodes that do not form an electric field are shown in white. The same applies to Figures 13 and 14 below). Under these 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 parallel to the long 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 these conditions, the second polarization component PL2 passes through the second liquid crystal layer LC2 on the first substrate S21 side without diffusing. Also, the second polarization component PL2 rotates 90 degrees in the process of passing through the second liquid crystal layer LC2 and transitions back to the first polarization component PL1. Furthermore, the polarization direction of the first polarization component PL1 is parallel to the long 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 these 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 polarization component PL1 incident on 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 polarization component PL1 diffuses in the Y-axis direction and moves toward the second substrate S32 side. Furthermore, the first polarization component PL1 rotates 90 degrees as it passes through the third liquid crystal layer LC3 and transitions again to the second polarization component PL2. Furthermore, 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, and the second electrode E32 on the second substrate S32 side does not form an electric field. Under these conditions, the second polarization component PL2 passes through the third liquid crystal layer LC3 on the second substrate S32 side without diffusion and is emitted to the fourth liquid crystal cell 40.

[0126] The polarization direction of the second polarization component PL2 incident on the fourth liquid crystal cell 40 is in a direction that intersects with 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 polarization component PL2 passes through the fourth liquid crystal layer LC4 on the first substrate S41 side without diffusion. Also, the second polarization component PL2 rotates 90 degrees in the process of passing through the fourth liquid crystal layer LC4 and transitions back to the first polarization component PL1. Furthermore, the polarization direction of the first polarization component PL1 is in a direction that intersects with 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 polarization component PL1 is emitted from the fourth liquid crystal cell 40 without diffusion.

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

[0128] Next, in Figure 12, we focus on 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 long 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 these 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. Also, the second polarization component PL2 rotates 90 degrees in the process of passing through the first liquid crystal layer LC1 and transitions to the first polarization component PL1. Furthermore, the polarization direction of the first polarization component PL1 is parallel to the long 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 these conditions, the first polarization component PL1 passes through the first liquid crystal layer PC1 on the second substrate S12 side without diffusing 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 is perpendicular to the long 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 these conditions, the first polarization component PL1 passes through the second liquid crystal layer LC2 on the first substrate S21 side without diffusion. Furthermore, the first polarization component PL1 rotates 90 degrees as it passes through the second liquid crystal layer LC2, becoming the second polarization component PL2 again. Furthermore, 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 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 these 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 polarization component PL2 incident on the third liquid crystal cell 30 is in a direction that intersects with 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 polarization component PL2 passes through the third liquid crystal layer LC3 on the first substrate side without diffusion. Also, the second polarization component PL2 rotates 90 degrees in the process of passing through the third liquid crystal layer LC3 and becomes the first polarization component PL1 again. The polarization direction of the first polarization component PL1 is in a direction that intersects with 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 polarization component PL1 passes through the third liquid crystal layer LC3 on the second substrate S32 side without diffusion and is emitted to the fourth liquid crystal cell 40.

[0131] The polarization direction of the first polarization component PL1 incident on 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 polarization component PL1 passes through the fourth liquid crystal layer LC4 on the first substrate S41 side without diffusion. Furthermore, the first polarization component PL1 rotates 90 degrees as it passes through the fourth liquid crystal layer LC4, and becomes the second polarization component PL2 again. Furthermore, 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 S42 side, and the second electrode E42 on the second substrate S42 side forms an electric field. Under these conditions, the second polarization component PL2 diffuses in the X-axis direction and is then emitted from the fourth liquid crystal cell 40.

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

[0133] As described above, according to the operating modes shown in Figure 12 and Table 3, the light emitted from the light source 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 X-axis direction. This allows the light emitted from the light source 106 to be formed into a cross-shaped light distribution pattern. Furthermore, as will be described later, color breakage can be prevented even with this light distribution pattern.

[0134] Furthermore, similar to the example of the square light distribution, a cross-shaped light distribution pattern can also be formed by applying the control signals shown in Table 4 to the following pairs: the second electrode E12 of the first liquid crystal cell 10 and the first electrode E41 of the fourth liquid crystal cell 40, which diffuse the second polarization component PL2 in the Y-axis direction; the first electrode E11 of the first liquid crystal cell 10 and the second electrode E42 of the fourth liquid crystal cell 40, which diffuse the second polarization component PL2 in the X-axis direction; the second electrode E22 of the second liquid crystal cell 20 and the first electrode E31 of the third liquid crystal cell 30, which diffuse the first polarization component PL1 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, which diffuse the first polarization component PL1 in the X-axis direction. The control signals shown in Table 4 correspond to Figure 10B. [Table 4]

[0135] (3) Line light distribution pattern (X-axis direction) Figure 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 in the liquid crystal light control element 102 shown in Figure 13 is the same as in Figure 9.

[0136] Table 5 shows the control signals applied to each liquid crystal cell in the liquid crystal light control element 102 shown in Figure 13. Note that control signals A, B, and C shown in Table 5 correspond to the control signals shown in Figure 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 to generate 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. At the same time, 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 first electrode E31 of the third liquid crystal cell 30, and the first electrode E41 of the fourth liquid crystal cell 40 to control them to a state where no transverse electric field is generated.

[0138] Focusing on the first polarization component PL1 in Figure 13, the polarization direction of the first polarization component PL1 incident on the first liquid crystal cell 10 is perpendicular to the direction of the long axis of the liquid crystal molecules in the first liquid crystal layer LC1. Therefore, it enters without scattering, is 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 liquid crystal molecules acting on the electric field of the first electrode E21, rotated in the second liquid crystal layer LC2 to become 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 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 liquid crystal molecules acting on the electric field of the second electrode E32, and after passing through the third liquid crystal cell 30 becomes the second polarization component PL2(2X). The second polarization component PL2(2X) incident on the fourth liquid crystal cell 40 is 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] Meanwhile, the second polarization component PL2 is diffused in the X-axis direction by liquid crystal molecules acting on the electric field of the first electrode E11 of the first liquid crystal cell 10, rotated in the first liquid crystal layer LC1 to become the first polarization component PL1(1X), and incident on the second liquid crystal cell 20. The first polarization component PL1(1X), which has been diffused once in the X-axis direction, is rotated in the second liquid crystal layer LC2 of the second liquid crystal cell 20 to become the second polarization component PL2(1X), and incident on the third liquid crystal cell 30. This second polarization component PL2(1X) is rotated in the third liquid crystal layer LC3 of the third liquid crystal cell 30 to become the first polarization component PL1(1X), and incident on the fourth liquid crystal cell 40. The first polarization component PL1(1X) is rotated in the fourth liquid crystal layer LC4, and is further diffused in the X-axis direction by liquid crystal molecules acting on 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] Furthermore, similar to the example of the square light distribution, a linear light distribution pattern extending in the X-axis direction can be formed by applying the control signals shown in Table 6 to 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, 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. Note that the control signals shown in Table 6 correspond to Figure 10B. [Table 6]

[0142] As described above, according to the operating modes shown in Figure 13 and Tables 5 and 6, the light emitted from the light source 106 passes through the liquid crystal light control element 102, causing the first polarization component PL1 to be diffused twice in the X-axis direction and the second polarization component PL2 to be diffused twice in the X-axis direction. This makes it possible to shape the light emitted from the light source 106 into a linear light distribution pattern extending in the X-axis direction. Furthermore, as will be described later, color breakage can be prevented even in this light distribution pattern.

[0143] (4) Line light distribution pattern (Y axis) Figure 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 in the liquid crystal light control element 102 shown in Figure 14 is the same as in Figure 9.

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

[0145] As shown in Table 7, when forming a linear light distribution pattern extending in the Y-axis direction, a constant voltage control signal E 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 the generation of a transverse electric field, while control signals A and B 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 to generate a transverse electric field.

[0146] Focusing on the first polarization component PL1 in Figure 14, the polarization direction of the first polarization component PL1 incident on the first liquid crystal cell 10 is perpendicular to the direction of the long axis of the liquid crystal molecules in the first liquid crystal layer LC1. Therefore, it enters without scattering, is rotated by 90 degrees in the first liquid crystal layer LC1, and becomes the second polarization component PL2.

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

[0148] Meanwhile, the second polarization component PL2 is rotated in the first liquid crystal layer LC1 and diffused in the Y-axis direction by liquid crystal molecules acting on the electric field of the second electrode E12, becoming the first polarization component PL1(1Y). The first polarization component PL1(1Y) incident on the second liquid crystal cell 20 is rotated in the second liquid crystal layer LC2, becoming the second polarization component PL2(1Y). The second polarization component PL2(1Y) is incident on the third liquid crystal cell 30, rotated in the third liquid crystal layer LC3, and becomes the first polarization component PL1(1Y) before being incident on the fourth liquid crystal cell 40. The first polarization component PL1(1Y) is diffused in the Y-axis direction by liquid crystal molecules acting on the electric field of the first electrode E41, rotated in the fourth liquid crystal layer LC4, and emitted as the second polarization component LC2(2Y).

[0149] Furthermore, similar to the example of the square 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 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, and 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. Note that the control signals shown in Table 8 correspond to Figure 10B. [Table 8]

[0150] As described above, according to the operating modes shown in Figure 14 and Tables 7 and 8, the light emitted from the light source 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 makes it possible to shape the light emitted from the light source 106 into a linear light distribution pattern extending in the Y-axis direction. Furthermore, as will be described later, color breakage can be prevented even in this light distribution pattern.

[0151] The liquid crystal light control element 102 according to this embodiment includes a plurality of liquid crystal cells, and has a structure in which at least one liquid crystal cell and another liquid crystal cell adjacent to (overlapping with) that at least one liquid crystal cell are superimposed in a state rotated by 90 degrees, thereby preventing color cracking in the light distribution pattern. The effect of rotating the liquid crystal cells by 90 degrees in this way is thought to be caused by the asymmetry of the liquid crystal, such as the direction of pre-tilt. Therefore, each liquid crystal cell should be arranged in such a way as to break the asymmetry of the liquid crystal. More specifically, as shown in Figure 14, the orientation direction of the first liquid crystal cell 10 on the first substrate S11 side is oriented in the +x direction, while the orientation direction of the fourth liquid crystal cell 40 on the second substrate S42 side is oriented in the -x direction. In addition, other combinations can also be adopted, for example, a structure in which the orientation direction of the first liquid crystal cell 10 on the second substrate S12 side and the orientation direction of the fourth liquid crystal cell 40 on the first substrate S41 side are oriented in the y direction and face each other. Similarly, a configuration can be adopted in which the orientation direction of the second liquid crystal cell 20 on the first substrate S21 side and the orientation direction of the third liquid crystal cell 30 on the second substrate S32 side are set to the x direction and face each other, and the orientation direction of the second substrate S22 side of the second liquid crystal cell 20 and the orientation direction of the first substrate S31 side of the third liquid crystal cell 30 are set to the y direction and face each other.

[0152] Figures 15A and 15B, and 16A and 16B show examples of the arrangement of liquid crystal cells in the liquid crystal light control element 102. Figure 15A shows an example where the first liquid crystal cell 10 and the second liquid crystal cell 20 are considered as one pair, and the third liquid crystal cell 30 and the fourth liquid crystal cell 40 are considered as another pair, with one pair rotated 90 degrees relative to the other pair. This arrangement corresponds to the arrangements in Figures 2 and 3.

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

[0154] Figure 16A also shows combinations 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 by 90 degrees. Figure 16B shows combinations in which the first liquid crystal cell 10 and the third liquid crystal cell 30 are flipped over.

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

[0156] The liquid crystal light control element 102 shown in Figure 15A has the following arrangement: the longitudinal direction of the strip-shaped 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; the longitudinal direction of the strip-shaped 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-shaped 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-shaped 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. With this combination of electrode arrangements for each liquid crystal cell, the diffusion direction of the polarization component can be controlled at least twice in different liquid crystal cells, preventing color breakage of the distributed illumination light.

[0157] The liquid crystal light control element 102 shown in Figures 15B, 16A, and 16B has the following arrangement: the longitudinal direction of the strip-shaped 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; the longitudinal direction of the strip-shaped 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-shaped 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-shaped 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. With this combination of electrode arrangements for each liquid crystal cell, the diffusion direction of the polarization component can be controlled at least twice in different liquid crystal cells, preventing color breakage of the distributed illumination light.

[0158] As described in this embodiment, in a liquid crystal light control element 102 in which multiple liquid crystal cells are stacked, the diffusion of the same polarization component among the polarization components of the incident light can be controlled by electrodes at different positions on 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), thereby preventing color breakage in the light distribution pattern.

[0159] As described above, according to this embodiment, in a liquid crystal light control device that controls the light distribution of illumination light using the electro-optic effect of liquid crystal, it is possible to suppress the occurrence of color cracking in a light distribution pattern formed into a predetermined shape.

[0160] It should be noted that the present invention is not limited to the embodiments disclosed herein, and the components can be modified and embodied without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining multiple components disclosed in the embodiments herein. For example, some components may be deleted from all the components shown in the embodiments. Moreover, components from different embodiments may be appropriately combined. [Explanation of Symbols]

[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 shaped electrode, E12B, E22B, E32B, E42B: 4th strip electrode, PL11: 1st feed line, PL12: 2nd feed line, PL13: 3rd feed line, PL14: 4th feed line, PL 15: 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 orientation film, AL12: Second orientation film, SE: Sealing material, CP11: First conductive member

Claims

1. The first liquid crystal cell and The second liquid crystal cell, The third liquid crystal cell, Including a fourth liquid crystal cell, The first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell Each of them is, A first substrate provided with a first electrode including a strip-shaped pattern, A second substrate on which a second electrode including a strip-shaped pattern is provided, The first alignment film provided on the first substrate, The second orientation film provided on the second substrate, The liquid crystal layer between the first substrate and the second substrate is included, 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, wherein the at least one first strip electrode and the at least one second strip electrode are arranged alternately at a distance from each other. The second electrode includes at least one third strip-shaped electrode having the strip-shaped pattern and at least one fourth strip-shaped electrode having the strip-shaped pattern, wherein the at least one third strip-shaped electrode and the at least one fourth strip-shaped electrode are arranged alternately at a distance from each other. 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. The orientation direction of the first orientation film is in a direction that intersects with the longitudinal direction of the strip-shaped pattern of the first electrode, The orientation direction of the second orientation film is such that it intersects with the longitudinal direction of the strip-shaped pattern of the second electrode. The first to fourth liquid crystal cells are stacked such that, from the side where light is incident, the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell are stacked in this order, and The second liquid crystal cell is stacked in a state rotated 90 degrees relative to the first liquid crystal cell. The third liquid crystal cell is stacked in a state rotated 90 degrees relative to the second liquid crystal cell. The fourth liquid crystal cell is stacked in a state rotated 90 degrees relative to the third liquid crystal cell. A liquid crystal light control device characterized by the following features.

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

3. 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 is at least one times the distance between the centers of the first strip electrode and the second strip electrode.

4. 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 liquid crystal layer with a thickness such that the transverse electric field generated at the first electrode and the transverse electric field generated at the second electrode do not interfere with each other.

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

6. The first liquid crystal cell and The second liquid crystal cell, The third liquid crystal cell, Including a fourth 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 is, A first substrate provided with a first electrode including a strip-shaped pattern, A second substrate on which a second electrode including a strip-shaped pattern is provided, The first alignment film provided on the first substrate, The second orientation film provided on the second substrate, The liquid crystal layer between the first substrate and the second substrate is included, 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, wherein the at least one first strip electrode and the at least one second strip electrode are arranged alternately at a distance from each other. The second electrode includes at least one third strip-shaped electrode having the strip-shaped pattern and at least one fourth strip-shaped electrode having the strip-shaped pattern, wherein the at least one third strip-shaped electrode and the at least one fourth strip-shaped electrode are arranged alternately at a distance from each other. 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. The orientation direction of the first orientation film is in a direction that intersects with the longitudinal direction of the strip-shaped pattern of the first electrode, The orientation direction of the second orientation film is such that it intersects with the longitudinal direction of the strip-shaped pattern of the second electrode. The first to fourth liquid crystal cells are arranged such that, from the side where light is incident, the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell are stacked in this order, and the remaining liquid crystal cells are stacked with two liquid crystal cells inverted. A liquid crystal light control device characterized by the following features.

7. The liquid crystal display device according to claim 6, wherein the second liquid crystal cell and the fourth liquid crystal cell are stacked with respect to the first liquid crystal cell and the third liquid crystal cell in an inverted state.

8. The liquid crystal light control device according to claim 6, wherein the first electrode generates a transverse electric field between the first strip electrode and the second strip electrode, and the second electrode generates a transverse electric field between the third strip electrode and the fourth strip electrode.

9. The liquid crystal light control device according to claim 6, 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 is at least one times the distance between the centers of the first strip electrode and the second strip electrode.

10. The liquid crystal light control device according to claim 6, 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 liquid crystal layer with a thickness such that the transverse electric field generated at the first electrode and the transverse electric field generated at the second electrode do not interfere with each other.

11. The liquid crystal light control device according to claim 6, wherein the liquid crystal layer is a twisted nematic liquid crystal.

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