Lighting device

Abstract

A lighting device 100 comprises a panel unit 110 and a light source 630. In the panel unit 110, a plurality of liquid crystal panels are stacked. Each of the liquid crystal panels has a plurality of first drive electrodes and a plurality of second drive electrodes. In the panel unit 110, when viewed from a Z direction, a second liquid crystal panel 20 is disposed at an angle of 180±10 degrees clockwise with respect to a first liquid crystal panel 10. A third liquid crystal panel 30 is disposed at an angle of 315±10 degrees clockwise with respect to the first liquid crystal panel 10. A fourth liquid crystal panel 40 is disposed at an angle of 135±10 degrees clockwise with respect to the first liquid crystal panel 10.

Description

Lighting device

[0001] The present disclosure relates to a lighting device.

[0002] A lighting device including a panel unit in which a plurality of liquid crystal panels are stacked in a first direction is known (see, for example, Patent Document 1). The liquid crystal panel has a first substrate, a second substrate, a first driving electrode provided on the first substrate, and a second driving electrode provided on the second substrate. The first driving electrode and the second driving electrode extend substantially orthogonally when viewed from the first direction. Further, when the panel unit is viewed from the first direction, each of the plurality of liquid crystal panels is stacked in a state rotated by an integer multiple of approximately 90 degrees, for example, in the clockwise direction, with respect to a predetermined liquid crystal panel.

[0003] Japanese Patent Application Laid-Open No. 2020-149021

[0004] Light from a light source enters from one end side in the first direction of the panel unit, passes through the inside of the panel unit while diffusing, and then exits from the other end side in the first direction of the panel unit. Here, as described above, when the panel unit is viewed from the first direction, each of the plurality of liquid crystal panels is stacked in a state rotated by an integer multiple of approximately 90 degrees, for example, in the clockwise direction, with respect to a predetermined liquid crystal panel. Here, when the applied voltage is low, the light emitted from the panel unit may appear to have a light distribution pattern in which a circular light distribution pattern is close to a cross-shaped light distribution pattern. The phenomenon that the circular light distribution pattern appears to be close to the cross-shaped light distribution pattern becomes more prominent when a light source with a narrow light distribution is used.

[0005] The present disclosure has been made in view of the above, and an object thereof is to provide a lighting device in which the light of the circular light distribution pattern emitted is likely to be seen as circular.

[0006] An illumination device according to one aspect of the present disclosure comprises a panel unit in which a plurality of liquid crystal panels are stacked in a first direction, and a light source that irradiates the panel unit with light from the first direction, wherein each of the plurality of liquid crystal panels comprises a first substrate, a second substrate stacked on one side of the first substrate in the first direction, a liquid crystal layer provided between the first substrate and the second substrate, a plurality of first drive electrodes provided on the first substrate and arranged at intervals, and a plurality of first drive electrodes provided on the second substrate and extending in a direction that intersects the first drive electrodes at an angle of 90 degrees ± 10 degrees when viewed from the first direction and arranged at intervals The liquid crystal panel comprises a plurality of second drive electrodes, the plurality of liquid crystal panels including a first liquid crystal panel, a second liquid crystal panel, a third liquid crystal panel, and a fourth liquid crystal panel having the same configuration, and when viewed from one side in the first direction, the second liquid crystal panel is positioned rotated clockwise at an angle of 180 degrees ± 10 degrees relative to the first liquid crystal panel, the third liquid crystal panel is positioned rotated clockwise at an angle of 315 degrees ± 10 degrees relative to the first liquid crystal panel, and the fourth liquid crystal panel is positioned rotated clockwise at an angle of 135 degrees ± 10 degrees relative to the first liquid crystal panel.

[0007] Figure 1 is a schematic diagram of four liquid crystal panels constituting a lighting device according to an embodiment. Figure 2 is a schematic diagram showing the arrangement of the first substrate and the second substrate in each of the four liquid crystal panels. Figure 3 is a schematic diagram of the first liquid crystal panel viewed from above. Figure 4 is a schematic diagram showing the surface of the first substrate included in the first liquid crystal panel. Figure 5 is a schematic diagram showing the surface of the second substrate included in the first liquid crystal panel. Figure 6 is a cross-sectional view taken along the line VI-VI in Figure 4. Figure 7 is a schematic perspective view of the first liquid crystal panel, showing the arrangement of the first drive electrode and the second drive electrode. Figure 8 is a cross-sectional view of the first liquid crystal panel viewed from the direction of arrow 610 in Figure 7, showing the orientation state of liquid crystal molecules when no voltage is applied to the electrodes that drive the liquid crystal. Figure 9 is a cross-sectional view of the first liquid crystal panel viewed from the direction of arrow 610 in Figure 7, showing the orientation state of liquid crystal molecules when a voltage is applied to the electrodes that drive the liquid crystal. Figure 10 is a cross-sectional view of the first liquid crystal panel as seen from the direction of arrow 620 in Figure 7, and shows the orientation state of liquid crystal molecules when a voltage is applied to the electrodes that drive the liquid crystal. Figure 11 is a schematic diagram of the second liquid crystal panel as seen from above. Figure 12 is a schematic diagram of the third liquid crystal panel as seen from above. Figure 13 is a schematic diagram of the fourth liquid crystal panel as seen from above. Figure 14 is a schematic diagram showing the light distribution pattern due to light passing through the lighting device according to the embodiment. Figure 15A is a graph showing the relationship between the potential difference applied to the first and second drive electrodes included in each of the first to fourth liquid crystal panels and the grayscale. Figure 15B is a table showing the potential difference profile (specifications) of the voltage applied to the first and second drive electrodes included in each of the first to fourth liquid crystal panels. Figure 16 is a block diagram of the lighting device according to the embodiment. Figure 17A is a schematic diagram comparing the light distribution pattern of vertical line light distribution according to Example 1 of the present invention with the light distribution pattern of vertical line light distribution according to Example 2 of the present invention. Figure 17B is an image and schematic diagram comparing the light distribution pattern of horizontal line light distribution according to Example 3 of the present invention with the light distribution pattern of horizontal line light distribution according to Example 4 of the present invention. Figure 17C is a schematic diagram comparing the light distribution pattern of diagonal line light distribution according to Example 5 of the present invention with the light distribution pattern of diagonal line light distribution according to Example 6 of the present invention.Figure 17D is a schematic diagram comparing the diagonal line light distribution pattern according to Example 7 of the present invention with the diagonal line light distribution pattern according to Example 8 of the present invention. Figure 18A is a plan view of a modified first substrate. Figure 18B is a plan view of a modified second substrate. Figure 18C is a plan view of a modified liquid crystal panel, in which the second substrate of Figure 18B is superimposed on the first substrate of Figure 18A.

[0008] Embodiments for implementing this disclosure will be described in detail with reference to the drawings. This disclosure is not limited to the embodiments described below. Furthermore, the components described below include those that are easily conceivable to those skilled in the art, and those that are substantially the same. In addition, the components described below can be combined as appropriate.

[0009] Furthermore, the disclosure is merely an example, and any modifications that a person skilled in the art could easily conceive of while maintaining the intent of the disclosure are naturally included within the scope of this disclosure. In addition, drawings may schematically represent the width, thickness, shape, etc. of each part in order to clarify the explanation, but these are merely examples and do not limit the interpretation of this disclosure. Moreover, in this specification and each drawing, elements similar to those described above in previously shown drawings are denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.

[0010] In the XYZ coordinate system shown in the diagram, the Y direction is the left-right direction, with Y1 being the opposite of Y2. Y1 is also referred to as the left side, and Y2 as the right side. The X direction is the front-back direction, with X1 being the opposite of X2. X1 is also referred to as the front side, and X2 as the rear side. The Z direction is the up-down direction (stack direction). Z1 is the opposite of Z2. Z1 is also referred to as the top side, and Z2 as the bottom side. The Z direction is also referred to as the first direction.

[0011] (Configuration of the lighting device) Figure 1 is a schematic diagram of the four liquid crystal panels constituting the lighting device according to the embodiment. As shown in Figure 1, the lighting device 100 comprises a light source 630 and a panel unit 110. The light source 630 is located above (on the Z1 side) the panel unit 110. The panel unit 110 is constructed by stacking the first liquid crystal panel 10, the second liquid crystal panel 20, the third liquid crystal panel 30, and the fourth liquid crystal panel 40 in order from top to bottom. The number of liquid crystal panels included in the lighting device 100 is not limited to four, but can be three or more. In this embodiment, the first liquid crystal panel 10, the second liquid crystal panel 20, the third liquid crystal panel 30, and the fourth liquid crystal panel 40 all have a regular octagonal shape in plan view, and therefore the panel unit 110 also has a regular octagonal shape in plan view. However, in the present invention, the external shape of the liquid crystal panel is not particularly limited, and polygons other than octagons, as well as circles and ellipses, can also be applied.

[0012] As shown in Figure 1, in the first liquid crystal panel 10, the first terminal group 10A (see Figure 3) provided at the end 2c of the first substrate 2 is located on the X1 side, and the flexible printed circuit board 200 is electrically connected to the first terminal group 10A. The second liquid crystal panel 20 is the first liquid crystal panel 10 rotated clockwise by a range of 180 degrees ± 10 degrees in a plan view. Therefore, the first terminal group 10A is located on the X2 side, and the flexible printed circuit board 200 is electrically connected to the first terminal group 10A.

[0013] The third liquid crystal panel 30 is positioned rotated clockwise in a plan view by a range of 315 degrees ± 10 degrees relative to the first liquid crystal panel 10, and the flexible printed circuit board 200 is electrically connected to the first terminal group 10A. The fourth liquid crystal panel 40 is positioned rotated clockwise in a plan view by an angle of a range of 135 degrees ± 10 degrees relative to the first liquid crystal panel 10, and the flexible printed circuit board 200 is electrically connected to the first terminal group 10A. In each liquid crystal panel, the active area (effective area) AA is approximately circular in a plan view.

[0014] (Configuration of Liquid Crystal Panels) Figure 2 is a schematic diagram showing the arrangement of the first and second substrates in each of the four liquid crystal panels. Figure 3 is a schematic diagram of the first liquid crystal panel viewed from above. Figure 4 is a schematic diagram showing the surface of the first substrate included in the first liquid crystal panel. Figure 5 is a schematic diagram showing the surface of the second substrate included in the first liquid crystal panel. Since the configuration is the same from the first liquid crystal panel 10 to the fourth liquid crystal panel 40, the configuration of the liquid crystal panels will be explained using the first liquid crystal panel 10 as an example. In this embodiment, since the first liquid crystal panel 10 to the fourth liquid crystal panel 40 are regular octagons, the center in a plan view is designated as center AX.

[0015] As shown in Figure 3, the first liquid crystal panel 10 comprises a first substrate S11 and a second substrate S12 positioned on the Z1 side of the first substrate S11. The first liquid crystal panel 10 is a regular octagon in plan view and has a first side 11, a second side 12, a third side 13, a fourth side 14, a fifth side 15, a sixth side 16, a seventh side 17, and an eighth side 18.

[0016] The first side 11 is located on the X1 side of the first liquid crystal panel 10. The first side 11 is parallel to the Y direction in the figure. The first side 11 of the first liquid crystal panel 10 coincides with the first side 211 of the first substrate S11 shown in Figure 4. In contrast, the first side 311 of the second substrate S12 shown in Figure 5 is located on the X2 side of the first substrate S11 than the first side 211 of the first substrate S11. Therefore, as shown in Figure 3, when the second substrate S12 is laminated on the front side of the first substrate S11, the X1 side end 2c of the first substrate S11 is exposed. The first terminal group 10A is provided on the end 2c.

[0017] The second side 12 is located on the Y1 side of the first liquid crystal panel 10. The second side 12 is parallel to the X direction in the figure. The second side 12 of the first liquid crystal panel 10 coincides with the second side 212 of the first substrate S11 shown in Figure 4. In contrast, the second side 312 of the second substrate S12 shown in Figure 5 is located on the Y2 side of the second side 212 of the first substrate S11. Therefore, as shown in Figure 3, when the second substrate S12 is laminated on the front side of the first substrate S11, the Y1 side end 2d of the first substrate S11 is exposed. The second terminal group 20A is provided on the end 2d.

[0018] The third side 13 intersects both the X1 and Y1 directions. The intersection angle is 45 degrees. The third side 13 coincides with the third side 213 of the first substrate S11 shown in Figure 4. In contrast, the third side 313 of the second substrate S12 shown in Figure 5 is located X2 and Y2 side further than the third side 213 of the first substrate S11. In other words, in a plan view, the third side 313 of the second substrate S12 is located closer to the center than the third side 213 of the first substrate S11. Therefore, as shown in Figure 3, when the second substrate S12 is laminated on the front side of the first substrate S11, the edge 2e of the first substrate S11 is exposed.

[0019] The fourth side 14 intersects both the Y1 direction and the X2 direction. The intersection angle is 45 degrees. The fourth side 14 overlaps with the fourth side 214 of the first substrate S11 shown in Figure 4 and the fourth side 314 of the second substrate S12 shown in Figure 5.

[0020] The fifth side 15 is located on the X2 side of the first liquid crystal panel 10. The fifth side 15 overlaps with the fifth side 215 of the first substrate S11 shown in Figure 4 and the fifth side 315 of the second substrate S12 shown in Figure 5.

[0021] The sixth side 16 intersects in both the X2 and Y2 directions. The intersection angle is 45 degrees. The sixth side 16 overlaps with the sixth side 216 of the first substrate S11 shown in Figure 4 and the sixth side 316 of the second substrate S12 shown in Figure 5.

[0022] The seventh side 17 is located on the Y2 side of the first liquid crystal panel 10. The seventh side 17 overlaps with the seventh side 217 of the first substrate S11 shown in Figure 4 and the seventh side 317 of the second substrate S12 shown in Figure 5.

[0023] The eighth side 18 intersects in both the Y2 direction and the X1 direction. The intersection angle is 45 degrees. The eighth side 18 overlaps with the eighth side 218 of the first substrate S11 shown in Figure 4 and the eighth side 318 of the second substrate S12 shown in Figure 5.

[0024] Thus, since the area of ​​the second substrate S12 is smaller than the area of ​​the first substrate S11, the first terminal group 10A provided at the end 2c of the first substrate S11 and the second terminal group 20A provided at the end 2d are exposed. The first terminal group 10A or the second terminal group 20A are electrically connected to the flexible printed circuit board 200.

[0025] Next, the first substrate S11 and the second substrate S12 will be described with reference to Figures 4 and 5. Figure 4 shows a center line CL1 extending in the X direction through the center AX of the first substrate S11, and a center line CL2 extending in the Y direction through the center AX of the first substrate S11. Figure 5 also shows the center lines CL1 and CL2.

[0026] As shown in Figure 4, end 2c is the X1 side end of the first substrate S11. A first terminal group 10A is provided on the Y1 side of end 2c. As shown in Figure 4, the first terminal group 10A includes a first terminal 101, a second terminal 102, a third terminal 103, and a fourth terminal 104.

[0027] Furthermore, as shown in Figure 4, at the end portion 2d of the first substrate S11 along the second side 212, a second terminal group 20A is provided on the side of the first side 211 (or the side of the third side 213) rather than the center of the second side 212. As shown in Figure 4, the second terminal group 20A includes a fifth terminal 201, a sixth terminal 202, a seventh terminal 203, and an eighth terminal 204.

[0028] Next, the wiring of the first substrate S11 and the second substrate S12 will be described. Note that the wiring is provided on the front surface of the substrate, which is one of the front and back surfaces. That is, the surface on which the wiring is provided is called the front surface, and the surface opposite the front surface is called the back surface.

[0029] As shown in Figure 4, wiring, drive electrodes, and connection parts are provided on the surface 2Aa of the first substrate S11. The connection part C1 of the first substrate S11 and the connection part C3 of the second substrate S12 (see Figure 5) are electrically connected via conductive pillars that can conduct electricity. Similarly, the connection part C2 of the first substrate S11 and the connection part C4 of the second substrate S12 (see Figure 5) are electrically connected via conductive pillars that can conduct electricity.

[0030] The first terminal 101 and the fifth terminal 201 are electrically connected via wiring 241. A branching point 242 is provided in the middle of wiring 241, and the wiring extends from branching point 242 to connection point C1.

[0031] The second terminal 102 and the sixth terminal 202 are electrically connected via wires 243 and 245. Wire 243 has a branch point 244, and wire 246 extends from the branch point 244 to the end 247.

[0032] The third terminal 103 and the seventh terminal 203 are electrically connected via wiring 248. The fourth terminal 104 and the eighth terminal 204 are electrically connected via wirings 249 and 251. Wiring 249 extends from the fourth terminal 104 toward the X2 side to branch point 250. Wiring 251 extends from branch point 250 toward the eighth terminal 204. Wiring extends from branch point 250 toward connection point C2.

[0033] Here, we will describe the electrodes that drive the liquid crystal. The drive electrodes in the first liquid crystal panel 10 include a drive electrode (first drive electrode) E11 and a drive electrode (second drive electrode) E12.

[0034] The drive electrode E11 includes drive electrode E11A and drive electrode E11B. The drive electrode E12 includes drive electrode E12A and drive electrode E12B.

[0035] Multiple drive electrodes E11A are connected to wiring 243 and 246. The drive electrodes E11A extend linearly along the Y direction. The drive electrodes E11A are arranged at equal intervals in the X direction.

[0036] Multiple drive electrodes E11B are connected to wiring 248. The drive electrodes E11B extend linearly along the Y direction. The drive electrodes E11B are arranged at equal intervals in the X direction. Note that the drive electrodes E11A and E11B are arranged alternately in the X direction.

[0037] As shown in Figure 5, wiring, drive electrodes, and connection parts are provided on the surface 3Aa of the second substrate S12. The center lines CL1 and CL2 shown in Figure 5 correspond to the center lines CL1 and CL2 shown in Figure 4.

[0038] Connection C3 is connected to wiring 342 and 343 via branch point 341. Wiring 342 extends to end 348. Wiring 343 extends to end 349. Connection C4 is connected to wiring 345 and 346 via branch point 344. Wiring 346 extends to end 347.

[0039] Multiple drive electrodes E12A are connected to wiring 342 and 343. The drive electrodes E12A extend linearly along the X direction. The drive electrodes E12A are arranged at equal intervals in the Y direction.

[0040] Multiple drive electrodes E12B are connected to wiring 346. The drive electrodes E12B extend linearly along the X direction. The drive electrodes E12B are arranged at equal intervals in the Y direction. Note that the drive electrodes E12A and E12B are arranged alternately in the Y direction. The orientation of the drive electrodes described above is summarized in Figure 2. That is, in Figure 2, for example, since the drive electrode E11 of the first substrate S11 extends in the Y direction as described above, the white arrow is positioned pointing in the Y direction. The arrangement (orientation) of the panels of the third liquid crystal panel 30 and the fourth liquid crystal panel 40 will be described in detail later.

[0041] Next, the cross-sectional structure of the first liquid crystal panel 10 will be briefly described. Figure 6 is a cross-sectional view taken along the line VI-VI in Figure 4. As shown in Figure 6, the first liquid crystal panel 10 comprises a first substrate S11, a second substrate S12, and a liquid crystal layer LC1 (60). As shown in Figure 6, the second substrate S12 is placed on the front side (Z1 side) of the first substrate S11. The liquid crystal layer LC1 is provided between the second substrate S12 and the first substrate S11. That is, the surface 2Aa of the first substrate S11 and the surface 3Aa of the second substrate S12 are arranged to face each other with the liquid crystal layer LC1 in between. The opposite side of the surface 2Aa of the first substrate S11 is the back surface 2Ab, and the opposite side of the surface 3Aa of the second substrate S12 is the back surface 3Ab. Furthermore, as mentioned above, since the area of ​​the second substrate S12 is smaller than that of the first substrate S11, the third terminal 103 provided on the surface 2Aa of the first substrate S11 is exposed. Although an insulating layer is provided to prevent contact between the two wirings, in the first liquid crystal panel 10 according to this embodiment, there is no overlapping portion of the wiring on the first substrate S11, so no insulating layer is provided.

[0042] Further, as shown in FIG. 6, alignment films AL11 and AL12 are laminated on both substrates and electrodes. Specifically, the alignment film AL11 is laminated on the surface 2Aa of the first substrate S11, the driving electrodes E11A and E11B, and a part of the upper surface of the wiring 248. Also, the alignment film AL12 is laminated on the surface 3Aa of the second substrate S12 and the upper surface of the driving electrode E12A. Then, the first substrate S11 and the second substrate S12 are adhered by a seal member 59 that surrounds the effective region, and the liquid crystal layer LC1 is filled in the space formed by the seal member 59.

[0043] Next, the operation mode for general light diffusion will be described.

[0044] (Light diffusion in a single liquid crystal panel) FIG. 7 is a schematic perspective view of a first liquid crystal panel, showing the arrangement of the first driving electrode and the second driving electrode. FIG. 8 is a cross-sectional view of the first liquid crystal panel as viewed from the direction of arrow 610 in FIG. 7, showing the alignment state of liquid crystal molecules when no voltage is applied to the electrodes for driving the liquid crystal. FIG. 9 is a cross-sectional view of the first liquid crystal panel as viewed from the direction of arrow 610 in FIG. 7, showing the alignment state of liquid crystal molecules when a voltage is applied to the electrodes for driving the liquid crystal. FIG. 10 is a cross-sectional view of the first liquid crystal panel as viewed from the direction of arrow 620 in FIG. 7, showing the alignment state of liquid crystal molecules when a voltage is applied to the electrodes for driving the liquid crystal.

[0045] FIG. 8 shows that in the first liquid crystal panel 10, the alignment treatment directions of the first alignment film AL11 and the second alignment film AL12 are different. Specifically, the first alignment film AL11 is alignment-treated in the X direction, and the second alignment film AL12 is alignment-treated in the Y direction. Thus, the alignment direction of the first alignment film AL11 and the alignment direction of the second alignment film AL12 are substantially orthogonal. Thereby, the direction of the initial light distribution on the side of the first substrate S11 in the first liquid crystal panel 10 is orthogonal (crosses) to the direction of the initial light distribution on the side of the second substrate S12 when viewed from the Z direction. Note that the alignment treatment may be a rubbing treatment or a photoalignment treatment. Also, the alignment direction of the alignment film can be set within a range of 90 degrees ± 10 degrees with respect to the extending direction of the driving electrode E11.

[0046] Since the alignment direction of the first alignment layer AL11 and the alignment direction of the second alignment layer AL12 are substantially orthogonal, the liquid crystal molecules 60A in the first liquid crystal layer LC1 are aligned such that the long axis direction of the liquid crystal molecules 60A is twisted by 90 degrees from the first alignment layer AL11 to the second alignment layer AL12 without being affected by an external electric field. FIG. 8 shows a state where no voltage is applied to the drive electrodes E11A and E11B. Therefore, as shown in FIG. 8, from the first alignment layer AL11 to the second alignment layer AL12, the long axis direction of the liquid crystal molecules 60A is twisted by 90 degrees and aligned.

[0047] As the first liquid crystal layer LC1, for example, a positive twist nematic liquid crystal (TN liquid crystal) is used, and an example is shown in which the long axis of the liquid crystal molecules 60A is aligned in the same direction as the alignment direction of the alignment layer. It is preferable that the liquid crystal layer 60 contains a chiral agent that imparts twist to the liquid crystal molecules 60A.

[0048] As shown in FIG. 9, a transverse electric field is generated between the drive electrode E11A and the drive electrode E11B, and the liquid crystal molecules 60A on the side of the first substrate S11 are affected by the transverse electric field and the alignment direction changes. Here, it is known that the refractive index of a liquid crystal changes depending on the alignment state. As shown in FIG. 8, in the off (OFF) state where no electric field acts on the first liquid crystal layer LC1, the long axis direction of the liquid crystal molecules 60A is horizontally aligned with the surface of the substrate, and is aligned in a state of being twisted by 90 degrees from the first substrate S11 side to the second substrate S12 side. The first liquid crystal layer LC1 has a substantially uniform refractive index distribution in this alignment state. Therefore, the S wave and the P wave orthogonal to the S wave of the light incident on the first liquid crystal panel 10 pass through the first liquid crystal layer LC1 in the Z direction almost without being refracted (or scattered), although they are optically rotated under the influence of the initial alignment of the liquid crystal molecules 60A. Note that optical rotation means that the polarization component changes the direction of polarization in the process of passing through the liquid crystal layer 60. Hereinafter, it means that the P polarization component (P wave) changes to the S polarization component (S wave) and the S polarization component (S wave) changes to the P polarization component (P wave) in the process of passing through the liquid crystal layer 60 of each first liquid crystal panel 10.

[0049] On the other hand, as shown in Figure 9, in the ON state where a voltage is applied to the driving electrodes E11A and 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 9, the first liquid crystal layer LC1 will have regions where the liquid crystal molecules 60A stand almost vertically above the driving electrodes E11A and E11B, regions where they are orienting diagonally along the distribution of the electric field between the driving electrodes E11A and E11B, and regions where the initial orientation state is maintained away from the driving electrodes E11A and E11B.

[0050] As shown in Figure 9, between the driving electrodes E11A and E11B, the long axis of the liquid crystal molecules 60A is oriented in a convex arc shape toward Z1 along the direction in which the electric field is generated. That is, as shown in Figures 8 and 9, the initial orientation direction of the liquid crystal molecules 60A is the same as the direction of the transverse electric field generated between the driving electrodes E11A and E11B. As schematically shown in Figure 9, the orientation direction of the liquid crystal molecules 60A 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 in a tilt direction relative to the surface of the first substrate S11 according to the intensity distribution of the electric field. Therefore, when considering the liquid crystal on the first substrate S11 as a whole, the liquid crystal molecules 60A between the driving electrodes E11A and E11B are oriented in a convex arc shape toward Z1.

[0051] As a result, an arc-shaped dielectric constant distribution is formed in the first liquid crystal layer LC1, and the incident light (polarization component parallel to the initial orientation direction of the liquid crystal molecules 60A) diffuses radially. Also, as shown in Figure 10, a similar phenomenon occurs on the second substrate S12 side due to the driving electrodes E12A and E12B, and the polarization component of the incident light parallel to the initial orientation direction of the liquid crystal molecules 60A on the second substrate S12 side diffuses radially. That is, if, for example, S waves are diffused on the first substrate S11 side of the liquid crystal layer 60, P waves are diffused on the second substrate S12 side of the liquid crystal layer 60. Also, if, for example, P waves are diffused on the first substrate S11 side of the liquid crystal layer 60, S waves are diffused on the second substrate S12 side of the liquid crystal layer 60.

[0052] (Arrangement of each liquid crystal panel) Next, the arrangement of the first to fourth liquid crystal panels will be explained. In detail, the angles around the axis AX of the center when the first to fourth liquid crystal panels are viewed from above will be explained. Figure 11 is a schematic diagram of the second liquid crystal panel viewed from above. Figure 12 is a schematic diagram of the third liquid crystal panel viewed from above. Figure 13 is a schematic diagram of the fourth liquid crystal panel viewed from above.

[0053] As shown in Figure 11 and the aforementioned Figure 2, the second liquid crystal panel 20 rotates the first liquid crystal panel 10 clockwise by 180 degrees ± 10 degrees in a plan view, with the center AX as the center. Therefore, the first terminal group 10A is located on the X2 side, and the second terminal group 20A is located on the Y2 side.

[0054] As shown in Figures 12 and 2, the third liquid crystal panel 30 rotates the first liquid crystal panel 10 clockwise by 315 degrees ± 10 degrees in a plan view, with the center AX as the center. Therefore, the first terminal group 10A is located on the X1 side and the Y2 side, and the second terminal group 20A is located on the X1 side and the Y1 side.

[0055] As shown in Figures 13 and 2, the fourth liquid crystal panel 40 rotates the first liquid crystal panel 10 clockwise by 135 degrees ± 10 degrees in a plan view, with the center AX as the center. Therefore, the first terminal group 10A is located on the X2 side and the Y1 side, and the second terminal group 20A is located on the X2 side and the Y2 side.

[0056] (Light Distribution Pattern) Figure 14 is a schematic diagram showing the light distribution pattern of light passing through the lighting device according to the embodiment. A detailed explanation follows below.

[0057] As shown in Figure 14, the light distribution pattern 600 is an elliptical light distribution pattern with its major axis aligned with the Y axis. The light distribution pattern 600 is formed, for example, by the diffusion of light that has passed through the first liquid crystal panel 10 in the Y direction. The light distribution pattern 601 is an elliptical light distribution pattern with its major axis aligned with the X axis. The light distribution pattern 601 is formed, for example, by the diffusion of light that has passed through the second liquid crystal panel 20 in the X direction.

[0058] The light distribution pattern 602 is an elliptical light distribution pattern in which the major axis is tilted 45 degrees counterclockwise (leftward) with respect to the X axis. The light distribution pattern 602 is formed, for example, by the diffusion of light that has passed through the third liquid crystal panel 30 in the X direction. This is because, for example, as shown in Figure 2, the extension direction of the drive electrode of the first substrate S31 is oriented diagonally towards the X2 and Y2 sides, and the extension direction of the drive electrode of the second substrate S32 is oriented diagonally towards the X2 and Y1 sides.

[0059] The light distribution pattern 603 is an elliptical light distribution pattern in which the major axis is tilted 45 degrees clockwise (rightward) with respect to the X axis. The light distribution pattern 603 is formed, for example, by the diffusion of light that has passed through the fourth liquid crystal panel 40 in the X direction. This is because, for example, as shown in Figure 2, the extension direction of the drive electrode of the first substrate S41 is oriented diagonally toward the X2 and Y2 sides, and the extension direction of the drive electrode of the second substrate S42 is oriented diagonally toward the X2 and Y1 sides.

[0060] The four light distribution patterns 600, 601, 602, and 603 described above distribute light substantially evenly around the axis of the center AX. More specifically, compared to a configuration in which the second liquid crystal panel 20, the third liquid crystal panel 30, and the fourth liquid crystal panel 40 are rotated by an angle of 90 degrees × n times relative to the first liquid crystal panel 10, the arrangement of the liquid crystal panels according to this embodiment distributes light substantially evenly around the axis of the center AX.

[0061] (Potential Difference Profile) Next, we will explain the potential difference profile of the voltage applied to the drive electrodes of each liquid crystal panel. Figure 15A is a graph showing the relationship between the voltage applied to the first drive electrode and the second drive electrode included in each of the first to fourth liquid crystal panels and the grayscale.

[0062] In the embodiments, "gradation" refers to "the degree to which light is diffused in a specific direction." That is, the following explanation assumes that "the degree to which light is diffused in a specific direction" in the present invention and "gradation" in the embodiments have the same meaning.

[0063] As shown in Figure 15A, in this embodiment, the potential differences of four potential difference profiles are set. Specifically, the four potential difference profiles are potential difference profile (1), potential difference profile (2), potential difference profile (3), and potential difference profile (4). In each potential difference profile, the potential difference between adjacent drive electrodes changes according to the grayscale. For example, the potential difference between the first drive electrode E11A and the first drive electrode E11B provided on the first substrate S11 in the first liquid crystal panel 10 is the potential difference of the potential difference profile. Specifically, as the grayscale increases, the potential difference changes to remain constant or increase.

[0064] The potential difference profile (1) shows that the potential difference between adjacent drive electrodes rises sharply from 0V to approximately 2.5V from 0 to approximately 2 levels, and then the potential difference continues to rise gradually up to 150 levels, where it intersects with the potential difference profile (4). After that, the potential difference rises sharply from around 200 levels, reaching approximately 15V at 255 levels.

[0065] The potential difference profile (2) shows that the potential difference rises sharply from 0V to approximately 3.5V from 0 to approximately 1 level, and then remains constant at approximately 3.5V up to 255 levels.

[0066] The potential difference profile (3) shows a rapid increase in potential difference from 0V to approximately 3.5V from 0 to approximately 1 level, and then the potential difference continues to rise gradually to approximately 5V at 110 levels. After that, the potential difference rises rapidly from around 110 levels, reaching approximately 15V at 255 levels. From 110 levels to 255 levels, the potential difference remains higher than that of potential difference profile (1), and at 255 levels, it becomes the same as that of potential difference profile (1).

[0067] The potential difference profile (4) maintains the same potential difference as the potential difference profile (3) from 0 to 110 levels, and remains constant at approximately 5V from 110 to 255 levels.

[0068] (Potential difference profiles for each liquid crystal panel) Figure 15B is a table showing the potential difference profiles (specifications) of the voltages applied to the first and second drive electrodes included in each of the first to fourth liquid crystal panels.

[0069] (Vertical and Horizontal Diffusion) In the vertical and horizontal diffusion shown in Figure 15B, the potential difference applied to the first and second drive electrodes included in each of the first to fourth liquid crystal panels is all the potential difference profile (1). That is, for all of the first to fourth liquid crystal panels, the potential difference between the first drive electrode and the second drive electrode increases as the grayscale level increases. In particular, the potential difference between the first drive electrode and the second drive electrode increases sharply from around 150 grayscale levels. Furthermore, the degree of light diffusion also increases in accordance with this potential difference, so in vertical and horizontal diffusion, as the grayscale level increases, the light diffuses in the vertical and horizontal directions, and the degree of diffusion in the 45-degree and 135-degree diagonal directions also increases.

[0070] (90-degree line) Figure 17A is a schematic diagram comparing the light distribution pattern of vertical line light distribution according to Example 1 of the present invention with the light distribution pattern of vertical line light distribution according to Example 2 of the present invention. The 90-degree line is a light distribution pattern that extends long in the vertical direction (in this embodiment, the X direction). In the 90-degree line light distribution pattern, the voltage of potential difference profile (2) is applied to the first drive electrode of the first substrate of the first liquid crystal panel 10, and the voltage of potential difference profile (3) is applied to the second drive electrode of the second substrate. Since the potential difference of potential difference profile (3) is greater than the potential difference of potential difference profile (2), the degree of diffusion on the upper second substrate is greater than the degree of diffusion on the lower first substrate. In the second liquid crystal panel 20 as well, the degree of diffusion on the upper second substrate is greater than the degree of diffusion on the lower first substrate. Therefore, the light passing through the first liquid crystal panel 10 and the second liquid crystal panel 20 is greatly diffused vertically due to the large diffusion in the upper second substrate, resulting in a light distribution pattern that extends over a long distance. The voltage of the potential difference profile (4) is applied to the third liquid crystal panel 30 and the fourth liquid crystal panel 40. As a result, the degree of diffusion along the 45-degree and 135-degree diagonal directions is smaller than the diffusion in the vertical direction, and its influence on the vertical diffusion is reduced. Consequently, as shown in Figure 17A, the 90-degree line in Example 1 of the Invention (255 gradations) results in a light distribution pattern that extends over a longer distance vertically compared to Example 2 of the Invention (100 gradations).

[0071] (0-degree line) Figure 17B is an image and schematic diagram comparing the light distribution pattern of a horizontal line according to Example 3 of the present invention and the light distribution pattern of a horizontal line according to Example 4 of the present invention. The 0-degree line is a light distribution pattern that extends long in the horizontal direction (Y direction in this embodiment). In the light distribution pattern of the 0-degree line, the potential difference profiles of the voltages applied to the drive electrodes of the first liquid crystal panel 10 and the second liquid crystal panel 20 are set inversely to the potential difference profile of the 90-degree line, as shown in Figure 15B. Also, the potential difference profiles of the voltages applied to the drive electrodes of the third liquid crystal panel 30 and the fourth liquid crystal panel 40 are the same as the potential difference profile of the 90-degree line. Therefore, the light passing through the first liquid crystal panel 10 and the second liquid crystal panel 20 is greatly diffused horizontally by the first substrate on the lower side, resulting in a light distribution pattern that extends long. Furthermore, the third liquid crystal panel 30 and the fourth liquid crystal panel 40 are subjected to a voltage of potential difference profile (4) that is lower than the potential difference of potential difference profile (3) and remains approximately constant even when the grayscale changes. As a result, the degree of diffusion along the 45-degree and 135-degree diagonal directions is smaller than the diffusion in the lateral direction, and the influence on the lateral diffusion is reduced. Consequently, as shown in Figure 17B, the 0-degree line in the present invention example 3 (255 grayscales) has a light distribution pattern that extends longer in the lateral direction compared to the present invention example 4 (100 grayscales).

[0072] (45-degree line) Figure 17C is a schematic diagram comparing the oblique line light distribution pattern according to Example 5 of the present invention with the oblique line light distribution pattern according to Example 6 of the present invention. The 45-degree line is a light distribution pattern that extends long in a direction that is tilted 45 degrees clockwise with respect to the 0-degree line, around the axis of the center AX. In the 45-degree line light distribution pattern, the potential difference profiles of the voltages applied to the drive electrodes of the first liquid crystal panel 10 and the second liquid crystal panel 20 are all potential difference profiles (4), as shown in Figure 15B. The potential difference profiles of the voltages applied to the drive electrodes of the third liquid crystal panel 30 are the same potential difference profiles (2) and (3) as the voltages applied to the drive electrodes of the first liquid crystal panel 10 in the 90-degree line. The potential difference profile of the voltages applied to the drive electrodes of the fourth liquid crystal panel 40 is also the same as the voltages applied to the drive electrodes of the third liquid crystal panel 30. Therefore, the light passing through the third liquid crystal panel 30 and the fourth liquid crystal panel 40 diffuses significantly in the 45-degree diagonal direction due to the large diffusion in the upper second substrate, resulting in a light distribution pattern that extends over a long distance. The first liquid crystal panel 10 and the second liquid crystal panel 20 are subjected to a voltage of potential difference profile (4) that is lower than the potential difference of potential difference profile (3) and remains approximately constant even when the grayscale changes. As a result, the degree of diffusion along the 45-degree diagonal direction is smaller than the diffusion in the horizontal and vertical directions, and the influence on the horizontal and vertical diffusion is reduced. Consequently, as shown in Figure 17C, the 45-degree line in the present invention example 5 (255 grayscales) results in a light distribution pattern that extends over a longer distance in the diagonal direction compared to the present invention example 6 (100 grayscales).

[0073] (135-degree line) Figure 17D is a schematic diagram comparing the diagonal line light distribution pattern according to Example 7 of the present invention with the diagonal line light distribution pattern according to Example 8 of the present invention. The 135-degree line is a light distribution pattern that extends long in a direction that is tilted 135 degrees clockwise with respect to the 0-degree line. In the 135-degree line light distribution pattern, the potential difference profiles of the voltages applied to the drive electrodes of the first liquid crystal panel 10 and the second liquid crystal panel 20 are all potential difference profiles (4), as shown in Figure 15B. The potential difference profiles of the voltages applied to the drive electrodes of the third liquid crystal panel 30 are the same as the potential difference profiles (3) and (2) of the voltages applied to the drive electrodes of the first liquid crystal panel 10 in the 0-degree line. The potential difference profiles of the voltages applied to the drive electrodes of the fourth liquid crystal panel 40 are also the same as the potential difference profiles of the voltages applied to the drive electrodes of the third liquid crystal panel 30. Therefore, the degree of diffusion along the 135-degree diagonal direction is greater than the diffusion in the horizontal and vertical directions, and its influence on the horizontal and vertical diffusion becomes smaller. Consequently, as shown in Figure 17D, the 135-degree line in Invention Example 7 (255 gradations) results in a light distribution pattern that extends longer in the diagonal direction compared to Invention Example 8 (100 gradations).

[0074] (Block diagram of the lighting device) Next, a block diagram of the lighting device will be described. Figure 16 is a block diagram of the lighting device according to the embodiment. As shown in Figure 16, the lighting device 100 according to the embodiment includes an electrode drive circuit 112, a memory circuit 113, and a processing circuit 114 as control blocks for controlling the panel unit 110 described above. The processing circuit 114 determines the voltages to be applied to the first liquid crystal panel 10, the second liquid crystal panel 20, the third liquid crystal panel 30, and the fourth liquid crystal panel 40 based on the potential difference profile.

[0075] The electrode drive circuit 112 supplies voltage to each drive electrode of each liquid crystal panel of the panel unit 110 based on the processing results in the processing circuit 114. The processing in the processing circuit 114 will be described later.

[0076] The memory circuit 113 includes, for example, an internal memory implemented in a microcontroller that constitutes the processing circuit 114. The memory area of ​​the memory circuit 113 stores a potential difference profile that indicates a voltage control pattern corresponding to the degree to which light is diffused in a specific direction.

[0077] Furthermore, the memory circuit 113 includes a setting circuit 1131. The setting circuit 1131 is used to set various setting items, such as the gradation shown in Figure 15A and the types of the five light distribution patterns shown in Figure 15B.

[0078] As described above, the lighting device 100 comprises a panel unit 110 and a light source 630. The panel unit 110 is made up of multiple stacked liquid crystal panels. Each liquid crystal panel has multiple first drive electrodes and multiple second drive electrodes. When viewed from the Z direction, the second liquid crystal panel 20 is positioned rotated clockwise by an angle of 180 degrees ± 10 degrees relative to the first liquid crystal panel 10. The third liquid crystal panel 30 is positioned rotated clockwise by an angle of 315 degrees ± 10 degrees relative to the first liquid crystal panel 10. The fourth liquid crystal panel 40 is positioned rotated clockwise by an angle of 135 degrees ± 10 degrees relative to the first liquid crystal panel 10.

[0079] As mentioned above, conventionally, when the applied voltage is low, the light emitted from the panel unit may appear as a cross-shaped pattern instead of a circular pattern. This phenomenon of a circular pattern appearing as a cross-shaped pattern becomes more pronounced when using a light source with a narrow beam angle.

[0080] In contrast, in the lighting device 100 according to this embodiment, the third liquid crystal panel 30 is arranged rotated clockwise at an angle of 315 degrees ± 10 degrees relative to the first liquid crystal panel 10, and the fourth liquid crystal panel 40 is arranged rotated clockwise at an angle of 135 degrees ± 10 degrees relative to the first liquid crystal panel 10. That is, two of the four liquid crystal panels are stacked rotated by approximately an integer multiple of 45 degrees clockwise with respect to a predetermined liquid crystal panel. Therefore, the lighting device 100 according to this embodiment has the advantage that the light from the emitted circular light distribution pattern appears more circular.

[0081] The first liquid crystal panel 10, the second liquid crystal panel 20, the third liquid crystal panel 30, and the fourth liquid crystal panel 40 are stacked in order from the Z1 side to the Z2 side.

[0082] Thus, with respect to the first liquid crystal panel 10, the second liquid crystal panel 20 is positioned at a rotation angle that is an integer multiple of 90 degrees, and the third liquid crystal panel 30 and the fourth liquid crystal panel 40 are positioned at a rotation angle that is an integer multiple of 45 degrees, which has the advantage of simplifying the stacking process.

[0083] The lighting device 100 includes a storage circuit 113 that stores a potential difference profile indicating a potential difference control pattern corresponding to the degree to which light is diffused in a specific direction, and a processing circuit 114 that determines the voltage applied to the first liquid crystal panel 10, the second liquid crystal panel 20, the third liquid crystal panel 30, and the fourth liquid crystal panel 40 based on the potential difference profile.

[0084] Conventionally, four liquid crystal panels are stacked with respect to a predetermined liquid crystal panel, rotated by approximately an integer multiple of 90 degrees in the clockwise direction. As a result, when a horizontal or vertical light distribution pattern is created, the coloring at the edges of the lines becomes smaller.

[0085] However, in this embodiment, to prevent the formation of a light distribution pattern that is close to a cross shape when a circular light distribution pattern is desired, two of the four liquid crystal panels are stacked rotated by approximately an integer multiple of 45 degrees clockwise relative to a predetermined liquid crystal panel. As a result, when a light distribution pattern of horizontal or vertical lines is created, the coloring at the edges of the lines becomes more pronounced.

[0086] Therefore, a potential difference profile is set that shows a potential difference control pattern corresponding to the degree to which light is diffused in a specific direction. Based on this potential difference profile, the voltage applied to the first liquid crystal panel 10, the second liquid crystal panel 20, the third liquid crystal panel 30, and the fourth liquid crystal panel 40 is appropriately changed to reduce the coloration at the edges of the line when a line light distribution pattern is formed. A brief explanation follows below.

[0087] For example, when creating a light distribution pattern of a 0-degree line (a line extending horizontally), increasing the degree of diffusion in the horizontal direction (Y direction) and creating a light distribution pattern with a longer horizontal line can reduce the coloration at the ends of that line.

[0088] In this case, in order to increase the degree of diffusion in the lateral direction (Y direction), the potential difference between adjacent electrodes among the plurality of first drive electrodes in the first liquid crystal panel 10 and the second liquid crystal panel 20, and the potential difference between adjacent electrodes among the plurality of second drive electrodes are increased. For this reason, voltages of potential difference profiles (2) and (3) with higher potential differences are applied to the first drive electrodes and second drive electrodes of the first liquid crystal panel 10 and the second liquid crystal panel 20.

[0089] Furthermore, it is desirable to minimize the effect of light diffusion in an oblique direction due to the third liquid crystal panel 30 and the fourth liquid crystal panel 40, which are rotated by an integer multiple of approximately 45 degrees clockwise. For this reason, the potential difference between adjacent electrodes among the plurality of first drive electrodes in the third liquid crystal panel 30 and the fourth liquid crystal panel 40, and the potential difference between adjacent electrodes among the plurality of second drive electrodes are made smaller. For this reason, a voltage with a lower potential difference profile (4) is applied to the first drive electrodes and second drive electrodes of the third liquid crystal panel 30 and the fourth liquid crystal panel 40.

[0090] (Modifications) Next, modifications will be described. In the embodiments described above, the shape of the drive electrode is a straight line extending in the X or Y direction. However, in the present invention, the shape of the drive electrode is not limited to a straight line, and may be V-shaped in plan view. A brief explanation follows below. Figure 18A is a plan view of a first substrate according to a modification. Figure 18B is a plan view of a second substrate according to a modification. Figure 18C is a plan view of a liquid crystal panel according to a modification, in which the second substrate of Figure 18B is superimposed on the first substrate of Figure 18A.

[0091] As shown in Figures 18A and 18C, the first substrate S11a is provided with drive electrodes E11Aa and E11Ba. Both drive electrodes E11Aa and E11Ba extend along the Y direction. Specifically, drive electrodes E11Aa and E11Ba are bent in a V-shape that is convex toward the X2 side. Drive electrodes E11Aa and E11Ba are arranged alternately in the X direction.

[0092] As shown in Figures 18B and 18C, the second substrate S12a is provided with drive electrodes E12Aa and E12Ba. Both drive electrodes E12Aa and E12Ba extend in the X direction. Specifically, drive electrodes E12Aa and E12Ba are bent in a V-shape that is convex toward the Y2 side. Drive electrodes E12Aa and E12Ba are arranged alternately in the Y direction.

[0093] 10 First liquid crystal panel 10A First terminal group 20 Second liquid crystal panel 20A Second terminal group 30 Third liquid crystal panel 40 Fourth liquid crystal panel 60 Liquid crystal layer 100 Lighting device 113 Memory circuit 114 Processing circuit 200 Flexible printed circuit board 630 Light source

Claims

1. A panel unit comprising a plurality of liquid crystal panels stacked in a first direction, and a light source that irradiates the panel unit with light from the first direction, wherein each of the plurality of liquid crystal panels comprises a first substrate, a second substrate stacked on one side of the first substrate in the first direction, a liquid crystal layer provided between the first substrate and the second substrate, a plurality of first drive electrodes provided on the first substrate and spaced apart, and a plurality of second drive electrodes provided on the second substrate and extending in a direction that intersects the first drive electrodes at an angle of 90 degrees ± 10 degrees when viewed from the first direction and spaced apart, wherein the plurality of liquid crystal panels include a first liquid crystal panel, a second liquid crystal panel, a third liquid crystal panel, and a fourth liquid crystal panel having the same configuration, wherein, when viewed from one side in the first direction, the second liquid crystal panel is positioned rotated clockwise at an angle of 180 degrees ± 10 degrees relative to the first liquid crystal panel, and the third liquid crystal panel is positioned rotated clockwise at an angle of 315 degrees ± 10 degrees relative to the first liquid crystal panel. The fourth liquid crystal panel is positioned rotated clockwise at an angle of 135 degrees ± 10 degrees relative to the first liquid crystal panel in a lighting device.

2. The lighting device according to claim 1, wherein the first liquid crystal panel, the second liquid crystal panel, the third liquid crystal panel, and the fourth liquid crystal panel are stacked in order from one side to the other in the first direction.

3. The lighting device according to claim 1 or 2, comprising: a storage circuit for storing a potential difference profile that shows a potential difference control pattern corresponding to the degree to which light is diffused in a specific direction; and a processing circuit that determines the voltage applied to the first liquid crystal panel, the second liquid crystal panel, the third liquid crystal panel, and the fourth liquid crystal panel based on the potential difference profile.

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