Optical device

Abstract

To provide an optical device whose manufacturing cost is suppressed.SOLUTION: An optical device includes: an optical element that includes at least one liquid crystal cell for distributing light to be emitted from a light source; a power source unit that generates a first potential and a second potential different from the first potential; a control signal generation circuit unit that generates a control signal for controlling a pulse width of each of the first potential and the second potential; and a switch circuit unit that outputs a first potential signal including the first potential having a first pulse width and the second potential having a second pulse width on the basis of the control signal. The at least one liquid crystal cell includes: a first substrate where first transparent electrodes and second transparent electrodes are alternately disposed in a first direction; and a second substrate where third transparent electrodes and fourth transparent electrodes are alternately disposed in a second direction intersecting with the first direction. The first potential signal is input to the first transparent electrode.SELECTED DRAWING: Figure 1B

Description

[Technical field]

[0001] An embodiment of the present invention relates to an optical device that controls the distribution of light emitted from a light source, and in particular, to an optical device that uses liquid crystal. [Background technology]

[0002] Conventionally, optical elements that utilize the change in refractive index of liquid crystals by adjusting the voltage applied to the liquid crystal, so-called liquid crystal lenses, have been known (see, for example, Patent Document 1, Patent Document 2, or Patent Document 3). For example, the lighting devices described in Patent Document 1 and Patent Document 2 use liquid crystal lenses to distribute light from a light source in a circular shape. Also, in the beam shaping device described in Patent Document 3, the pattern of electrodes applied to the liquid crystal is changed to change the shape of the light distribution. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-317879 A [Patent Document 2] JP 2010-230887 A [Patent Document 3] JP 2014-160277 A Summary of the Invention [Problem to be solved by the invention]

[0004] In optical devices using liquid crystal, the light distribution may be controlled by changing the magnitude of the voltage applied to the liquid crystal. In this case, the optical device needs to be equipped with a digital-to-analog converter (DAC) or an amplifier (AMP), which complicates the light distribution control and increases the manufacturing cost.

[0005] In view of the above problems, an object of one embodiment of the present invention is to provide an optical device with reduced manufacturing costs. [Means for solving the problem]

[0006] An optical device according to one embodiment of the present invention includes an optical element including at least one liquid crystal cell that distributes light emitted from a light source, a power supply unit that generates a first potential and a second potential different from the first potential, a control signal generating circuit unit that generates a control signal that controls the pulse width of each of the first potential and the second potential, and a switch circuit unit that outputs a first potential signal including a first potential having a first pulse width and a second potential having a second pulse width based on the control signal, wherein the at least one liquid crystal cell includes a first substrate on which first transparent electrodes and second transparent electrodes are alternately arranged in a first direction, and a second substrate on which third transparent electrodes and fourth transparent electrodes are alternately arranged in a second direction intersecting the first direction, and the first potential signal is input to the first transparent electrode.

[0007] Also, an optical device according to an embodiment of the present invention includes an optical element including at least one liquid crystal cell that distributes light emitted from a light source; a power supply unit including a first power supply that generates a first potential and a second power supply that generates a second potential different from the first potential; a control signal generating unit that generates a first control signal, a second control signal, a third control signal, and a fourth control signal, each of which controls a pulse width of the first potential and the second potential; a first switch circuit that is electrically connected to the first power supply and the second power supply, each of which outputs the first potential signal based on the first control signal, a second switch circuit that outputs the second potential signal based on the second control signal, a third switch circuit that outputs the third potential signal based on the third control signal, and a fourth potential signal based on the fourth control signal. and a switch circuit section including a fourth switch circuit inputting a first potential signal to the first transparent electrode, and the optical element includes at least one liquid crystal cell, the at least one liquid crystal cell including a first substrate on which first transparent electrodes and second transparent electrodes are alternately arranged in a first direction, and a second substrate on which third transparent electrodes and fourth transparent electrodes are alternately arranged in a second direction intersecting the first direction, the first transparent electrode, the second transparent electrode, the third transparent electrode, and the fourth transparent electrode are electrically connected to the first switch circuit, the second switch circuit, the third switch circuit, and the fourth switch circuit, respectively, and a first potential signal, a second potential signal, a third potential signal, and a fourth potential signal are input to the first transparent electrode, the second transparent electrode, the third transparent electrode, and the fourth transparent electrode, respectively. [Brief description of the drawings]

[0008] [Figure 1A] 1 is a schematic perspective view of an optical device according to an embodiment of the present invention; [Figure 1B] 1 is a diagram illustrating an optical device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic perspective view of an optical element of an optical device according to one embodiment of the present invention. [Figure 3A] 1 is a schematic cross-sectional view of an optical element of an optical device according to one embodiment of the present invention. [Figure 3B]1 is a schematic cross-sectional view of an optical element of an optical device according to one embodiment of the present invention. [Figure 4A] 5A to 5C are schematic cross-sectional views illustrating control of light distribution by an optical element of an optical device according to one embodiment of the present invention. [Figure 4B] 5A to 5C are schematic cross-sectional views illustrating control of light distribution by an optical element of an optical device according to one embodiment of the present invention. [Diagram 5] 5A and 5B are schematic diagrams illustrating connections between transparent electrodes of optical elements and switch circuits in an optical device according to one embodiment of the present invention. [Figure 6] 4 is a circuit diagram showing a switch circuit included in a switch circuit unit in an optical device according to one embodiment of the present invention. FIG. [Figure 7A] 5 is a timing chart illustrating the relationship between a control signal input to a switch circuit section and a potential signal output from the switch circuit section in an optical device according to an embodiment of the present invention. [Figure 7B] 5 is a timing chart illustrating the relationship between a control signal input to a switch circuit section and a potential signal output from the switch circuit section in an optical device according to an embodiment of the present invention. [Figure 8] 5 is a timing chart showing the relationship between a potential signal and a potential difference between transparent electrodes in an optical device according to an embodiment of the present invention. [Figure 9] 5 is a timing chart showing the relationship between a potential signal and a potential difference between transparent electrodes in an optical device according to an embodiment of the present invention. [Figure 10] 5 is a timing chart showing the relationship between a potential signal and a potential difference between transparent electrodes in an optical device according to an embodiment of the present invention. [Figure 11] 4 is a graph showing a light distribution state using an optical device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, each embodiment of the present invention will be described with reference to the drawings, etc. However, the present invention can be embodied in various forms without departing from the gist of the technical idea thereof, and should not be interpreted as being limited to the description of the embodiments exemplified below.

[0010] In order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part in a schematic manner compared to the actual embodiment, but these are merely examples, and the illustrated shapes themselves do not limit the interpretation of the present invention. In addition, in the drawings, elements having the same functions as those explained in the drawings already shown in the specification may be given the same reference numerals even in different drawings, and duplicate explanations may be omitted.

[0011] When a film is processed to form multiple structures, each structure may have a different function or role, and each structure may be formed on a different base. However, these multiple structures are derived from a film formed as the same layer in the same process, and have the same material. Therefore, these multiple films are defined as existing in the same layer.

[0012] When expressing an aspect in which a structure is placed on top of another structure, the term "above" is used, unless otherwise specified, to include both a case in which another structure is placed directly above, in contact with, a structure, and a case in which another structure is placed above, via yet another structure.

[0013] An optical device 1 according to an embodiment of the present invention will be described with reference to Figures 1A to 11. First, the configuration of the optical device 1 will be described with reference to Figures 1A and 1B.

[0014] [1. Configuration of optical device 1] FIG. 1A is a schematic perspective view of an optical device 1 according to an embodiment of the present invention. FIG. 1B is a block diagram illustrating the optical device 1 according to an embodiment of the present invention. As shown in FIG. 1A, the optical device 1 includes an optical element 10 and a control unit 20 that controls the optical element 10. The optical device 1 may include not only the optical element 10 and the control unit 20, but also a light source 30 that irradiates the optical element 10 with light. The light irradiated from the light source 30 passes through the optical element 10 and is emitted. The control unit 20 controls the optical element 10 so as to diffuse or converge the light passing through the optical element 10. That is, the optical device 1 can control the light distribution.

[0015] 1B, the control unit 20 includes a power supply unit 210, a switch circuit unit 220, and a control signal generating circuit unit 230. The optical element 10 is connected to the switch circuit unit 220. In addition, the switch circuit unit 220 is connected to the power supply unit 210. That is, the optical element 10 is connected to the power supply unit 210 via the switch circuit unit 220.

[0016] The power supply unit 210 includes a power supply that generates a predetermined potential. For example, the power supply unit 210 may include two power supplies that generate two potentials, but is not limited to this. The power supply unit 210 may also include a potential that is GND (for example, 0 V). For convenience of explanation, in this specification, even in the case of GND, the power supply may be described as a power supply that generates a potential.

[0017] The control signal generating circuit section 230 generates a control signal for controlling the switch circuit section 220. A plurality of control signals for controlling the switch circuit section 220 may be generated. The switch circuit included in the switch circuit section 220 is a so-called analog switch. That is, the switch circuit section 220 can control the supply of the potential generated by the power supply section 210 to the optical element 10 based on a control signal from the control signal generating circuit section 230. In the optical device 1, the supply of the potential generated by the power supply section 210 is directly controlled using the switch circuit section 220, so that the optical device 1 does not require a DAC or AMP.

[0018] The control signal generating circuit unit 230 is a computer capable of performing arithmetic processing using data or information. The control signal generating circuit unit 230 includes, for example, a central processing unit (CPU), a microprocessor (MPU), a graphics processing unit (GPU), a field programmable gate array (FPGA), a random access memory (RAM), or a dynamic random access memory (DRAM). The control signal generating circuit unit 230 can generate a control signal according to predetermined information (such as a pulse width or a duty ratio).

[0019] Next, the configuration of the optical element 10 will be described with reference to FIGS. 2 to 3B.

[0020] [2. Configuration of optical element 10] FIG. 2 is a schematic perspective view of an optical element 10 of an optical device 1 according to an embodiment of the present invention. As shown in FIG. 2, the optical element 10 includes a first liquid crystal cell 110-1, a second liquid crystal cell 110-2, a third liquid crystal cell 110-3, and a fourth liquid crystal cell 110-4. The first liquid crystal cell 110-1, the second liquid crystal cell 110-2, the third liquid crystal cell 110-3, and the fourth liquid crystal cell 110-4 are stacked in the z-axis direction. The second liquid crystal cell 110-2 is provided on the first liquid crystal cell 110-1. The third liquid crystal cell 110-3 is provided on the second liquid crystal cell 110-2. The fourth liquid crystal cell 110-4 is provided on the third liquid crystal cell 110-3. Although not shown, the light source 30 is disposed below the first liquid crystal cell 110-1. Therefore, the light emitted from the light source 30 is transmitted through the first liquid crystal cell 110-1, the second liquid crystal cell 110-2, the third liquid crystal cell 110-3, and the fourth liquid crystal cell 110-4 in this order.

[0021] The first optical elastic resin layer 170-1 bonds and fixes the first liquid crystal cell 110-1 and the second liquid crystal cell 110-2. The second optical elastic resin layer 170-2 bonds and fixes the second liquid crystal cell 110-2 and the third liquid crystal cell 110-3. The third optical elastic resin layer 170-3 bonds and fixes the third liquid crystal cell 110-3 and the fourth liquid crystal cell 110-4. An adhesive containing an acrylic resin or an epoxy resin having light transmission can be used for each of the first optical elastic resin layer 170-1, the second optical elastic resin layer 170-2, and the third optical elastic resin layer 170-3.

[0022] Figures 3A and 3B are schematic cross-sectional views of the optical element 10 of the optical device 1 according to one embodiment of the present invention. Specifically, Figure 3A is a schematic cross-sectional view in the zx plane taken along the line A1-A2 shown in Figure 2, and Figure 3B is a schematic cross-sectional view in the yz plane taken along the line B1-B2 shown in Figure 2. In the following, the x-axis direction and the y-axis direction may be referred to as the first direction and the second direction, respectively.

[0023] The first liquid crystal cell 110-1 includes a first substrate 120-1 on which a first transparent electrode 130-1 and a second transparent electrode 130-2 are formed, and a second substrate 120-2 on which a third transparent electrode 130-3 and a fourth transparent electrode 130-4 are formed. A first alignment film 140-1 that covers the first transparent electrode 130-1 and the second transparent electrode 130-2 is formed on the first substrate 120-1. A second alignment film 140-2 that covers the third transparent electrode 130-3 and the fourth transparent electrode 130-4 is formed on the second substrate 120-2. The first substrate 120-1 and the second substrate 120-2 are arranged such that the first transparent electrode 130-1 and the second transparent electrode 130-2 on the first substrate 120-1 face the third transparent electrode 130-3 and the fourth transparent electrode 130-4 on the second substrate 120-2 in an intersecting manner (hereinafter, the same applies). In addition, a first seal material 150-1 is formed on the periphery of each of the first substrate 120-1 and the second substrate 120-2. That is, the first substrate 120-1 and the second substrate 120-2 are bonded via the first seal material 150-1. Furthermore, liquid crystal is sealed in the space surrounded by the first substrate 120-1 (more specifically, the first alignment film 140-1), the second substrate 120-2 (more specifically, the second alignment film 140-2), and the first sealing material 150-1, forming a first liquid crystal layer 160-1.

[0024] The second liquid crystal cell 110-2 includes a third substrate 120-3 on which a fifth transparent electrode 130-5 and a sixth transparent electrode 130-6 are formed, and a fourth substrate 120-4 on which a seventh transparent electrode 130-7 and an eighth transparent electrode 130-8 are formed. A third alignment film 140-3 is formed on the third substrate 120-3 to cover the fifth transparent electrode 130-5 and the sixth transparent electrode 130-6. A fourth alignment film 140-4 is formed on the fourth substrate 120-4 to cover the seventh transparent electrode 130-7 and the eighth transparent electrode 130-8. The third substrate 120-3 and the fourth substrate 120-4 are disposed such that the fifth transparent electrode 130-5 and the sixth transparent electrode 130-6 on the third substrate 120-3 face the seventh transparent electrode 130-7 and the eighth transparent electrode 130-8 on the fourth substrate 120-4. In addition, a second seal material 150-2 is formed on the periphery of each of the third substrate 120-3 and the fourth substrate 120-4. That is, the third substrate 120-3 and the fourth substrate 120-4 are bonded via the second seal material 150-2. Furthermore, liquid crystal is sealed in the space surrounded by the third substrate 120-3 (more specifically, the third alignment film 140-3), the fourth substrate 120-4 (more specifically, the fourth alignment film 140-4), and the second sealing material 150-2, forming a second liquid crystal layer 160-2.

[0025] The third liquid crystal cell 110-3 includes a fifth substrate 120-5 on which a ninth transparent electrode 130-9 and a tenth transparent electrode 130-10 are formed, and a sixth substrate 120-6 on which an eleventh transparent electrode 130-11 and a twelfth transparent electrode 130-12 are formed. A fifth alignment film 140-5 that covers the ninth transparent electrode 130-9 and the tenth transparent electrode 130-10 is formed on the fifth substrate 120-5. In addition, a sixth alignment film 140-6 that covers the eleventh transparent electrode 130-11 and the twelfth transparent electrode 130-12 is formed on the sixth substrate 120-6. The fifth substrate 120-5 and the sixth substrate 120-6 are arranged such that the ninth transparent electrode 130-9 and the tenth transparent electrode 130-10 on the fifth substrate 120-5 face the eleventh transparent electrode 130-11 and the twelfth transparent electrode 130-12 on the sixth substrate 120-6. In addition, a third sealant 150-3 is formed on the periphery of each of the fifth substrate 120-5 and the sixth substrate 120-6. That is, the fifth substrate 120-5 and the sixth substrate 120-6 are bonded via the third sealant 150-3. In addition, liquid crystal is sealed in the space surrounded by the fifth substrate 120-5 (more specifically, the fifth alignment film 140-5), the sixth substrate 120-6 (more specifically, the sixth alignment film 140-6), and the third sealing material 150-3, forming a third liquid crystal layer 160-3.

[0026] The fourth liquid crystal cell 110-4 includes a seventh substrate 120-7 on which a thirteenth transparent electrode 130-13 and a fourteenth transparent electrode 130-14 are formed, and an eighth substrate 120-8 on which a fifteenth transparent electrode 130-15 and a sixteenth transparent electrode 130-16 are formed. A seventh alignment film 140-7 that covers the thirteenth transparent electrode 130-13 and the fourteenth transparent electrode 130-14 is formed on the seventh substrate 120-7. In addition, an eighth alignment film 140-8 that covers the fifteenth transparent electrode 130-15 and the sixteenth transparent electrode 130-16 is formed on the eighth substrate 120-8. The seventh substrate 120-7 and the eighth substrate 120-8 are arranged such that the thirteenth transparent electrode 130-13 and the fourteenth transparent electrode 130-14 on the seventh substrate 120-7 face the fifteenth transparent electrode 130-15 and the sixteenth transparent electrode 130-16 on the eighth substrate 120-8. In addition, a fourth sealant 150-4 is formed on the periphery of each of the seventh substrate 120-7 and the eighth substrate 120-8. That is, the seventh substrate 120-7 and the eighth substrate 120-8 are bonded via the fourth sealant 150-4. In addition, liquid crystal is sealed in the space surrounded by the seventh substrate 120-7 (more specifically, the seventh alignment film 140-7), the eighth substrate 120-8 (more specifically, the eighth alignment film 140-8), and the fourth sealing material 150-4, forming a fourth liquid crystal layer 160-4.

[0027] The first liquid crystal cell 110-1, the second liquid crystal cell 110-2, the third liquid crystal cell 110-3, and the fourth liquid crystal cell 110-4 have the same basic configuration. Therefore, in the following, the arrangement of the transparent electrodes 130 of the first liquid crystal cell 110-1 will be described, and the arrangement of the transparent electrodes 130 of the second liquid crystal cell 110-2, the third liquid crystal cell 110-3, and the fourth liquid crystal cell 110-4 will not be described.

[0028] In the first liquid crystal cell 110-1, the first transparent electrode 130-1 and the second transparent electrode 130-2 extend in the y-axis direction, and the third transparent electrode 130-3 and the fourth transparent electrode 130-4 extend in the x-axis direction. The first transparent electrode 130-1 and the second transparent electrode 130-2 are arranged alternately in a comb-like manner in the x-axis direction, and the third transparent electrode 130-3 and the fourth transparent electrode 130-4 are arranged alternately in a comb-like manner in the second direction. In a plan view, the extension direction (y-axis direction) of the first transparent electrode 130-1 and the second transparent electrode 130-2 is perpendicular to the extension direction (x-axis direction) of the third transparent electrode 130-3 and the fourth transparent electrode 130-4, but may be slightly shifted from perpendicular to the extension direction.

[0029] In a plan view, the first transparent electrode 130-1 of the first liquid crystal cell 110-1, the fifth transparent electrode 130-5 of the second liquid crystal cell 110-2, the ninth transparent electrode 130-9 of the third liquid crystal cell 110-3, and the thirteenth transparent electrode 130-13 of the fourth liquid crystal cell 110-4 are overlapped such that their extending directions (y-axis direction) are substantially aligned with each other. However, the first liquid crystal cell 110-1 to the fourth liquid crystal cell 110-4 may be arranged such that the first transparent electrode 130-1, the fifth transparent electrode 130-5, the ninth transparent electrode 130-9, and the thirteenth transparent electrode 130-13 are slightly misaligned when overlapping.

[0030] Each of the first substrate 120-1 to the eighth substrate 120-8 may be a rigid substrate having light-transmitting properties, such as a glass substrate, a quartz substrate, a sapphire substrate, etc. Each of the first substrate 120-1 to the eighth substrate 120-8 may be a flexible substrate having light-transmitting properties, such as a polyimide resin substrate, an acrylic resin substrate, a siloxane resin substrate, a fluororesin substrate, etc.

[0031] Each of the first transparent electrode 130-1 to the sixteenth transparent electrode 130-16 functions as an electrode for forming an electric field in the liquid crystal layer 160. Each of the first transparent electrode 130-1 to the sixteenth transparent electrode 130-16 is made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO).

[0032] Each of the first liquid crystal layer 160-1 to the fourth liquid crystal layer 160-4 can refract the light passing therethrough or change the polarization state of the light passing therethrough depending on the alignment state of the liquid crystal molecules. Nematic liquid crystal or the like is used as the liquid crystal for each of the first liquid crystal layer 160-1 to the fourth liquid crystal layer 160-4. The liquid crystal described in this embodiment is of the positive type, but it is also possible to apply a negative type by changing the initial alignment direction of the liquid crystal molecules. In addition, the liquid crystal preferably contains a chiral agent that imparts a twist to the liquid crystal molecules.

[0033] Each of the first alignment film 140-1 to the eighth alignment film 140-8 aligns liquid crystal molecules in the liquid crystal layer 160 in a predetermined direction. Each of the first alignment film 140-1 to the eighth alignment film 140-8 is made of a material such as polyimide resin. Each of the first alignment film 140-1 to the eighth alignment film 140-8 may be given an alignment characteristic by an alignment treatment such as a rubbing method or a photo-alignment method. The rubbing method is a method in which the surface of the alignment film is rubbed in one direction. The photo-alignment method is a method in which the alignment film is irradiated with linearly polarized ultraviolet light.

[0034] Each of the first seal material 150-1 to the fourth seal material 150-4 is made of an adhesive material containing an epoxy resin or an acrylic resin, etc. The adhesive material may be an ultraviolet curing type or a thermosetting type.

[0035] The optical element 10 can control the distribution of unpolarized light by including at least two liquid crystal cells (for example, the first liquid crystal cell 110-1 and the second liquid crystal cell 110-2). Therefore, it is not necessary to provide a pair of polarizing plates, such as those provided on the front and back surfaces of a liquid crystal display element, on the surfaces of the first substrate 120-1 of the first liquid crystal cell 110-1 and the eighth substrate 120-8 of the fourth liquid crystal cell 110-4.

[0036] [3. Control of light distribution by optical element 10] 4A and 4B are schematic cross-sectional views for explaining the control of light distribution by the optical element 10 of the optical device 1 according to one embodiment of the present invention. In Fig. 4A and Fig. 4B, a part of the cross-sectional view of the first liquid crystal cell 110-1 and the second liquid crystal cell 110-2 shown in Fig. 3A is shown. Fig. 4A shows the optical element 10 in a state where no potential is supplied to the transparent electrode 130, and Fig. 4B shows the optical element 10 in a state where a potential is supplied to the transparent electrode 130. The control of the supply of the potential to the transparent electrode 130 will be described later.

[0037] The first alignment film 140-1 is aligned in the x-axis direction. Therefore, as shown in FIG. 4A, the liquid crystal molecules on the first substrate 120-1 side of the first liquid crystal layer 160-1 are aligned with their major axes along the x-axis direction. That is, the alignment direction of the liquid crystal molecules on the first substrate 120-1 side is perpendicular to the extension direction (y-axis direction) of the first transparent electrode 130-1 and the second transparent electrode 130-2. Also, the second alignment film 140-2 is aligned in the y-axis direction. Therefore, as shown in FIG. 3A, the liquid crystal molecules on the second substrate 120-2 side of the first liquid crystal layer 160-1 are aligned with their major axes along the y-axis direction. That is, the alignment direction of the liquid crystal molecules on the second substrate 120-2 side is perpendicular to the extension direction (x-axis direction) of the third transparent electrode 130-3 and the fourth transparent electrode 130-4. Therefore, the liquid crystal molecules in first liquid crystal layer 160-1 gradually change the direction of their major axes from the x-axis direction to the y-axis direction as they move from first substrate 120-1 to second substrate 120-2, and are aligned in a 90-degree twisted state.

[0038] The liquid crystal molecules of the second liquid crystal layer 160-2 are similar to those of the first liquid crystal layer 160-1, and therefore a description thereof will be omitted here.

[0039] When a potential is applied to the transparent electrode 130, the orientation of the liquid crystal molecules changes as shown in FIG. 4B. Here, it is assumed that a low potential is applied to the first transparent electrode 130-1, the third transparent electrode 130-3, the fifth transparent electrode 130-5, and the seventh transparent electrode 130-7, and a high potential is applied to the second transparent electrode 130-2, the fourth transparent electrode 130-4, the sixth transparent electrode 130-6, and the eighth transparent electrode 130-8. For convenience, in FIG. 4B, the low potential and the high potential are illustrated using the symbols "-" and "+", respectively. In the following, the electric field generated between adjacent transparent electrodes may be referred to as a transverse electric field.

[0040] As shown in FIG. 4B, due to the influence of the transverse electric field between the first transparent electrode 130-1 and the second transparent electrode 130-2, the liquid crystal molecules on the first substrate 120-1 are generally aligned in a convex arc shape along the x-axis direction with respect to the first substrate 120-1. Similarly, due to the influence of the transverse electric field between the third transparent electrode 130-3 and the fourth transparent electrode 130-4, the liquid crystal molecules on the second substrate 120-2 are generally aligned in a convex arc shape along the y-axis direction with respect to the second substrate 120-2. The alignment of the liquid crystal molecules located approximately in the center between the first transparent electrode 130-1 and the second transparent electrode 130-2 is hardly changed by any of the transverse electric fields. Therefore, light incident on the first liquid crystal layer 160-1 is diffused in the x-axis direction in accordance with the refractive index distribution of the liquid crystal molecules oriented in a convex arc shape along the x-axis direction on the first substrate 120-1 side, and is diffused in the y-axis direction in accordance with the refractive index distribution of the liquid crystal molecules oriented in a convex arc shape along the y-axis direction on the second substrate 120-2 side.

[0041] Since the first substrate 120-1 and the second substrate 120-2 are sufficiently separated from each other, the horizontal electric field between the first transparent electrode 130-1 and the second transparent electrode 130-2 of the first substrate 120-1 does not affect the alignment of the liquid crystal molecules on the second substrate 120-2 side, or is negligibly small. Similarly, the horizontal electric field between the third transparent electrode 130-3 and the fourth transparent electrode 130-4 of the second substrate 120-2 does not affect the alignment of the liquid crystal molecules on the first substrate 120-1 side, or is negligibly small.

[0042] The liquid crystal molecules in the second liquid crystal layer 160-2 when a potential is applied to the fifth transparent electrode 130-5 to the eighth transparent electrode 130-8 are similar to the liquid crystal molecules in the first liquid crystal layer 160-1, and therefore a description thereof will be omitted here.

[0043] Next, the light distribution of light passing through the optical element 10 will be described. The light emitted from the light source has a polarized component in the x-axis direction (hereinafter referred to as the "P polarized component") and a polarized component in the y-axis direction (hereinafter referred to as the "S polarized component"); however, for convenience, the light will be divided into the P polarized component and the S polarized component in the following description. That is, the light emitted from the light source (see (1) in Figures 4A and 4B) contains a first polarized light 310 having a P polarized component and a second polarized light 320 having an S polarized component. Note that the arrow symbol and the circle with a cross in Figures 4A and 4B represent the P polarized component and the S polarized component, respectively.

[0044] After entering first substrate 120-1, first polarized light 310 changes from a P-polarized component to an S-polarized component as it travels toward second substrate 120-2 due to the twisting of the orientation of the liquid crystal molecules (see (2) to (4) in FIGS. 4A and 4B). More specifically, first polarized light 310 has a polarization axis in the x-axis direction on the first substrate 120-1 side, but gradually changes its polarization axis while passing through first liquid crystal layer 160-1 in the thickness direction, and has a polarization axis in the y-axis direction on the second substrate 120-2 side, and is then emitted from the second substrate 120-2 side (see (5) in FIGS. 4A and 4B).

[0045] Here, when a transverse electric field is generated between the first transparent electrode 130-1 and the second transparent electrode 130-2, the liquid crystal molecules on the first substrate 120-1 side are oriented in a convex arc shape along the x-axis direction under the influence of the transverse electric field, and the refractive index distribution changes. Therefore, the first polarized light 310 is diffused in the x-axis direction according to the refractive index distribution of the liquid crystal molecules. Also, when a transverse electric field is generated between the third transparent electrode 130-3 and the fourth transparent electrode 130-4, the liquid crystal molecules on the second substrate 120-2 side are oriented in a convex arc shape along the y-axis direction under the influence of the transverse electric field, and the refractive index distribution changes. Therefore, the first polarized light 310 is diffused in the y-axis direction according to the change in the refractive index distribution of the liquid crystal molecules.

[0046] Therefore, when no transverse electric field is generated (see FIG. 4A), the polarization component of the first polarized light 310 passing through the first liquid crystal cell 110-1 changes from P polarization to S polarization. On the other hand, when a transverse electric field is generated (see FIG. 4B), the polarization component of the first polarized light 310 passing through the first liquid crystal cell changes from P polarization to S polarization and is diffused in the x-axis and y-axis directions.

[0047] After entering first substrate 120-1, second polarized light 320 changes from an S-polarized component to a P-polarized component as it travels toward second substrate 120-2 due to the twist in the orientation of the liquid crystal molecules (see (2) to (4) in FIGS. 4A and 4B). More specifically, second polarized light 320 has a polarization axis in the y-axis direction on the first substrate 120-1 side, but gradually changes its polarization axis while passing through first liquid crystal layer 160-1 in the thickness direction, and has a polarization axis in the x-axis direction on the second substrate 120-2 side, and is then emitted from the second substrate 120-2 side (see (5) in FIGS. 4A and 4B).

[0048] Here, when a transverse electric field is generated between the first transparent electrode 130-1 and the second transparent electrode 130-2, the liquid crystal molecules on the first substrate 120-1 side are oriented in a convex arc shape along the x-axis direction due to the influence of the transverse electric field, and the refractive index distribution changes. However, since the polarization axis of the second polarized light 320 is perpendicular to the orientation of the liquid crystal molecules on the first substrate 120-1 side, it is not affected by the refractive index distribution of the liquid crystal molecules, and passes through as it is without diffusing. Also, when a transverse electric field is generated between the third transparent electrode 130-3 and the fourth transparent electrode 130-4, the liquid crystal molecules on the second substrate 120-2 side are oriented in a convex arc shape along the y-axis direction due to the influence of the transverse electric field, and the refractive index distribution changes. However, since the polarization axis of the second polarized light 320 is perpendicular to the orientation of the liquid crystal molecules on the second substrate 120-2 side, it is not affected by the refractive index distribution of the liquid crystal molecules, and passes through as it is without diffusing.

[0049] Therefore, not only when a transverse electric field is not generated (see FIG. 4A) but also when a transverse electric field is generated (see FIG. 4B), the second polarized light 320 passing through the first liquid crystal cell 110-1 changes in polarization component from an S polarization component to a P polarization component, but does not diffuse.

[0050] The liquid crystal molecules of the second liquid crystal layer 160-2 of the second liquid crystal cell 110-2 have a refractive index distribution similar to that of the liquid crystal molecules of the first liquid crystal layer 160-1 of the first liquid crystal cell 110-1. However, since the polarization axes of the first polarized light 310 and the second polarized light 320 are changed by passing through the first liquid crystal cell 110-1, the polarization affected by the refractive index distribution of the liquid crystal molecules of the second liquid crystal layer 160-2 is reversed. That is, not only when a transverse electric field is not generated (see FIG. 4A) but also when a transverse electric field is generated (see FIG. 4B), the polarization component of the first polarized light 310 passing through the second liquid crystal cell 110-2 changes from an S-polarized component to a P-polarized component, but it is not diffused (see (6) to (8) in FIG. 4A and FIG. 4B). On the other hand, when no transverse electric field is generated (see FIG. 4A), the polarization component of the second polarized light 320 passing through the second liquid crystal cell 110-2 simply changes from a P polarization component to an S polarization component. However, when a transverse electric field is generated (see FIG. 4B), the polarization component of the second polarized light 320 passing through the second liquid crystal cell 110-2 changes from a P polarization component to an S polarization component and is diffused in the x-axis and y-axis directions.

[0051] As can be seen from the above, in the optical element 10, by stacking two liquid crystal cells 110 having the same structure, the polarization component of the light incident on the optical element 10 is changed twice, and as a result, the polarization component before and after the incident can be made to remain the same (see (1) and (9) in FIG. 4A and FIG. 4B). On the other hand, when a potential is applied to the transparent electrode 130, the optical element 10 can change the refractive index distribution of the liquid crystal molecules in the liquid crystal layer 160 of the liquid crystal cell 110, and refract the light passing through the liquid crystal cell 110. More specifically, the first liquid crystal cell 110-1 can diffuse the light of the first polarization 310 (P polarization component) in the x-axis direction, the y-axis direction, or both the x-axis and y-axis directions, and the second liquid crystal cell 110-2 can diffuse the light of the second polarization 320 (S polarization component) in the x-axis direction, the y-axis direction, or both the x-axis and y-axis directions.

[0052] 4A and 4B only show the first liquid crystal cell 110-1 and the second liquid crystal cell 110-2, and the light distribution of light passing through the first liquid crystal cell 110-1 and the second liquid crystal cell 110-2 has been described, but the light distribution of light passing through the third liquid crystal cell 110-3 and the fourth liquid crystal cell 110-4 is similar. In the optical element 10, by increasing the number of stacked liquid crystal cells 110, the diffused light can be further diffused, and the shape of the light distribution can be significantly changed.

[0053] [4. Control of supply of electric potential to transparent electrode 130 of optical element 10] Fig. 5 is a schematic diagram illustrating the connection between the transparent electrode 130 of the optical element 10 and the switch circuit section 220 in the optical device 1 according to one embodiment of the present invention. Note that Fig. 5 only shows the first transparent electrode 130-1 to the fourth transparent electrode 130-4 of the first liquid crystal cell 110-1. For ease of explanation, Fig. 5 shows the second substrate 120-2 by a dashed line.

[0054] The first transparent electrode 130-1, the second transparent electrode 130-2, the third transparent electrode 130-3, and the fourth transparent electrode 130-4 are electrically connected to a first potential signal line 224-1, a second potential signal line 224-2, a third potential signal line 224-3, and a fourth potential signal line 224-4, respectively. The switch circuit section 220 includes a first switch circuit 222-1, a second switch circuit 222-2, a third switch circuit 222-3, and a fourth switch circuit 222-4. The first switch circuit 222-1, the second switch circuit 222-2, the third switch circuit 222-3, and the fourth switch circuit 222-4 are electrically connected to the first potential signal line 224-1, the second potential signal line 224-2, the third potential signal line 224-3, and the fourth potential signal line 224-4, respectively. Therefore, the first potential signal controlled by the first switch circuit is input to the first transparent electrode 130-1 via the first potential signal line 224-1. Similarly, the second transparent electrode 130-2 receives a second potential signal controlled by the second switch circuit via the second potential signal line 224-2, the third transparent electrode 130-3 receives a third potential signal controlled by the third switch circuit via the third potential signal line 224-3, and the fourth transparent electrode 130-4 receives a fourth potential signal controlled by the fourth switch circuit via the fourth potential signal line 224-4. In this way, in the first liquid crystal cell 110-1, the switch circuit 222 included in the switch circuit unit 220 can supply potentials to each of the transparent electrodes 130 independently. The second liquid crystal cell 110-2 to the fourth liquid crystal cell 110-4 are similar, so a description thereof will be omitted here.

[0055] Fig. 6 is a circuit diagram showing the switch circuit 222 included in the switch circuit section 220 in the optical device 1 according to one embodiment of the present invention. Note that, although Fig. 6 shows only the first switch circuit 222-1 electrically connected to the first transparent electrode 130-1, the second switch circuit 222-2 to the fourth switch circuit 222-4 have the same configuration as the first switch circuit 222-1.

[0056] The first switch circuit 222-1 includes a first transistor Tr1, a second transistor Tr2, and a third transistor Tr3. In the first transistor Tr1, one of the source and the drain is electrically connected to a first power supply line 226-1 that supplies a first potential V1 from a first power supply of the power supply unit 210, and the other of the source and the drain is electrically connected to a first potential signal line 224-1. In addition, a first control signal line 228-1 is electrically connected to the gate of the first transistor Tr1, and a first control signal CL1 generated by the control signal generating circuit unit 230 is input. In the second transistor Tr2, one of the source and the drain is electrically connected to a second power supply line 226-2 that supplies a second potential V2 from a second power supply of the power supply unit 210, and the other of the source and the drain is electrically connected to the first potential signal line 224-1. The gate of the second transistor Tr2 is electrically connected to the second control signal line 228-2, and receives the second control signal CL2 generated by the control signal generating circuit unit 230. In the third transistor Tr3, one of the source and the drain is electrically connected to the third power supply line 226-3 that supplies the third potential V3 from the third power supply of the power supply unit 210, and the other of the source and the drain is electrically connected to the first potential signal line 224-1. The gate of the third transistor Tr3 is electrically connected to the third control signal line 228-3, and receives the third control signal CL3 generated by the control signal generating circuit unit 230.

[0057] In the first switch circuit 222-1, one of the first potential V1, the second potential V2, and the third potential V3 is selected by the first control signal CL1, the second control signal CL2, and the third control signal CL3, and a first potential signal VL1 including the selected potential is output to the first potential signal line 224-1. For convenience, the following description may be given assuming that the first potential V1, the second potential V2, and the third potential V3 are 30V, 15V, and 0V, respectively. However, the potentials of the first potential V1, the second potential V2, and the third potential V3 are not limited to this.

[0058] 7A and 7B are timing charts illustrating the relationship between the control signal input to the switch circuit section 220 and the potential signal output from the switch circuit section 220 in the optical device 1 according to one embodiment of the present invention. Note that, although only the first potential signal VL1 output to the first potential signal line 224-1 is shown in Fig. 7A and 7B, the second potential signal VL2 output to the second potential signal line 224-2 is similar, and therefore description thereof will be omitted here.

[0059] 7A, the first control signal CL1 is input to the switch circuit section 220, whereby the first potential V1 (30V) is supplied to the first potential signal line 224-1. Furthermore, the input of the first control signal CL1 to the switch circuit section 220 is stopped, and the second control signal CL2 is input to the switch circuit section 220, whereby the second potential V2 (15V) is supplied to the first potential signal line 224-1. Furthermore, the input of the second control signal CL2 to the switch circuit section 220 is stopped, and the third control signal CL3 is input to the switch circuit section 220, whereby the third potential V3 (0V) is supplied to the first potential signal line 224-1. Therefore, the first potential signal VL1 is a signal including a first potential, a second potential, and a third potential, and any one of the first potential, the second potential, and the third potential is supplied to the first transparent electrode 130-1 connected to the first potential signal line 224-1.

[0060] In Fig. 7A, the first control signal CL1 to the third control signal CL3 have the same pulse width, but as shown in Fig. 7B, the first control signal CL1 to the third control signal CL3 may have different pulse widths. Even in such a case, the first potential signal VL1 is a signal including a first potential, a second potential, and a third potential based on the pulse widths of the first control signal CL1, the second control signal CL2, and the third control signal CL3, respectively.

[0061] 8 to 10 are timing charts showing the relationship between the potential signal and the potential difference between the transparent electrodes 130 in the optical device 1 according to one embodiment of the present invention. Note that Fig. 8 to 10 show the first potential signal VL1 input to the first transparent electrode 130-1 and the second potential signal VL2 input to the second transparent electrode 130-2, as well as the potential difference VL1-VL2 between the first transparent electrode 130-1 and the second transparent electrode 130-2.

[0062] In FIG. 8, the first potential signal VL1 is a signal that sequentially supplies potentials of +30V, +15V, 0V, and +15V to the first transparent electrode 130-1. The second potential signal VL2 is a signal that sequentially supplies potentials of 0V, +15V, +30V, and +15V to the second transparent electrode 130-2. The first potential signal VL1 and the second potential signal VL2 have the same pulse width and are inverted in phase with each other. Therefore, potential differences (VL1-VL2) of +30V, 0V, -30V, and 0V are generated between the first transparent electrode 130-1 and the second transparent electrode 130-2. In this case, when the potential differences are +30V and -30V, the alignment state of the liquid crystal molecules of the first liquid crystal layer 160-1 changes, and light passing through the first liquid crystal cell 110-1 can be diffused. Therefore, in the optical device 1, the light distribution can be controlled by the potential difference between the transparent electrodes 130 having a pulse width H for a period T (since the orientation state of the liquid crystal molecules is the same at potential differences of +30 and -30 V, here the repeating unit of |VL1-VL2| is defined as one period).

[0063] The third transparent electrode 130-3 and the fourth transparent electrode 130-4 are similar to the first transparent electrode 130-1 and the second transparent electrode 130-2. The second liquid crystal cell 110-2, the third liquid crystal cell 110-3, and the fourth liquid crystal cell 110-4 are also similar to the first liquid crystal cell 110-1.

[0064] The first potential signal VL1 and the second potential signal VL2 may be out of phase with each other, as will be described with reference to FIG.

[0065] In FIG. 9, the first potential signal VL1 is a signal that sequentially supplies potentials of 30V, +15V, 0V, and +15V to the first transparent electrode 130-1. The second potential signal VL2 is a signal that sequentially supplies potentials of 0V, +15V, +30V, and +15V to the second transparent electrode 130-2. However, the phase of the second potential signal VL2 is different from the phase of the first potential signal VL1. Specifically, the second potential signal VL2 is out of phase with the first potential signal VL1 by +45° (π / 4). More specifically, the second potential signal VL2 is in reverse phase with respect to the first potential signal VL1, and is further delayed by π / 4. Thus, in this embodiment, the second potential signal VL2 has a phase other than the inversion of the phase of the first potential signal VL1. Therefore, potential differences of +15V, +30V, +15V, 0V, -15V, -30V, -15V, and 0V are generated between the first transparent electrode 130-1 and the second transparent electrode 130-2. In this case, when the potential differences are +15V, +30V, -15V, and -30V, the alignment state of the liquid crystal molecules in the first liquid crystal layer 160-1 changes, and light passing through the first liquid crystal cell 110-1 can be diffused. In the timing chart shown in FIG. 9, by combining the first potential signal VL1 or the second potential signal VL2, the light distribution can be controlled by the potential difference between the transparent electrodes 130 having a pulse width different from the pulse width of these signals.

[0066] The first and second power supply potential signals do not have to have the same pulse width, which will be described with reference to FIG.

[0067] In FIG. 10, the first potential signal VL1 is a signal that sequentially supplies potentials of 30V, +15V, 0V, and +15V to the first transparent electrode 130-1. The second potential signal VL2 is a signal that sequentially supplies potentials of 0V, +15V, +30V, and +15V to the second transparent electrode 130-2. However, the pulse width of the second potential signal VL2 is different from the pulse width of the first potential signal. More specifically, the first potential signal VL1 and the second potential signal VL2 are in phase with each other, but the pulse width of the second potential signal VL2 is half the pulse width of the first potential signal VL1, so there is a part of the time when the second potential signal VL2 has an intermediate potential even though the first potential signal VL1 is oscillated by the pulse width. Therefore, potential differences (VL1-VL2) of +30V, +15V, 0V, -30V, -15V, and 0V are generated between the first transparent electrode 130-1 and the second transparent electrode 130-2. In this case, when the potential differences are +15V, +30V, -15V, and -30V, the alignment state of the liquid crystal molecules in the first liquid crystal layer 160-1 changes, and light passing through the first liquid crystal cell 110-1 can be diffused. In the timing chart shown in FIG. 10, the light distribution can also be controlled by the potential difference between the transparent electrodes 130 having a pulse width different from the pulse width of the first potential signal VL1 or the second potential signal VL2.

[0068] As described above, in the optical device 1, the light distribution can be controlled by so-called pulse width modulation (PWM) driving using various pulse widths and duty ratios (for example, pulse width H for period T shown in FIG. 8) by changing the pulse width or phase of the potential signal input to the transparent electrodes 130. Note that the pulse width or duty ratio of the potential difference between the transparent electrodes 130 may be changed by changing the pulse widths of the first control signal CL1, the second control signal CL2, and the third control signal CL3.

[0069] As described above, in the optical device 1, the potential to be supplied to the optical element 10 can be selected using only a so-called analog switch, and the optical element 10 can be controlled by PWM driving. That is, the optical device 1 does not require expensive elements such as a DAC or AMP. Therefore, the optical device 1 can be manufactured inexpensively, and the manufacturing cost can be suppressed. EXAMPLES

[0070] Fig. 11 is a graph showing the light distribution state when the optical device 1 according to one embodiment of the present invention is used. The horizontal axis of the graph shown in Fig. 11 is the duty ratio (%), and the vertical axis is the half-value angle (degrees). The half-value angle is an angle at which the brightness is 50% of the brightness at the front (0 degrees) of the optical device 1 in an angle-dependent measurement of brightness. In other words, a larger half-value angle means that the light is more diffused.

[0071] The fabricated optical device 1 had four liquid crystal cells 110 in the optical element 10, the width of the transparent electrode 130 of each liquid crystal cell 110 was 8 (μm), and the distance between the transparent electrodes 130 was 8 (μm). In addition, the period T of the power supply potential signal input to each transparent electrode 130 was 60 Hz.

[0072] 11, as the duty ratio increases, the half-value angle also increases. In other words, it was found that the light was largely diffused by the optical device 1. In particular, it was found that the light was largely diffused when the duty ratio exceeded 10%.

[0073] Within the scope of the concept of the present invention, those skilled in the art may make various modifications and alterations, and it is understood that these modifications and alterations also fall within the scope of the present invention. For example, those in which a person skilled in the art appropriately adds, deletes, or modifies components of the above-mentioned embodiments, or adds, omits, or modifies conditions of steps, are also included in the scope of the present invention as long as they include the gist of the present invention.

[0074] Furthermore, other effects and advantages brought about by the aspects of this embodiment that are obvious from the description in this specification or that can be appropriately thought of by a person skilled in the art are naturally understood to be brought about by the present invention. [Explanation of symbols]

[0075] 1: optical device, 10: optical element, 20: control unit, 30: light source, 110: liquid crystal cell, 120: substrate, 130: transparent electrode, 140: alignment film, 150: seal material, 160: liquid crystal layer, 170: optical elastic resin layer, 210: power supply unit, 220: switch circuit unit, 222: switch circuit, 224: potential signal line, 226: power supply line, 228: control signal line, 230: control signal generating circuit unit, 310: first polarized light, 320: second polarized light

Claims

1. an optical element including at least one liquid crystal cell that distributes light emitted from a light source; a switch circuit section which receives a first potential and a second potential different from the first potential and outputs a first potential signal which combines the first potential and the second potential to form one cycle; The at least one liquid crystal cell comprises: a first substrate on which first transparent electrodes and second transparent electrodes are alternately arranged in a first direction; a second substrate on which third transparent electrodes and fourth transparent electrodes are alternately arranged in a second direction intersecting the first direction; a liquid crystal layer between the first substrate and the second substrate; when no potential is applied to the first transparent electrode, the second transparent electrode, the third transparent electrode, and the fourth transparent electrode, the liquid crystal molecules of the liquid crystal layer are aligned in a twisted state such that the major axis changes from the first direction to the second direction as the liquid crystal molecules move from the first substrate to the second substrate; The first potential signal is input to the first transparent electrode.

2. The optical device of claim 1 , wherein the second potential is lower than the first potential.

3. the switch circuit further outputs a second potential signal that forms one cycle by combining the first potential and the second potential; The optical device according to claim 1 , wherein the second potential signal is input to the second transparent electrode.

4. The optical device according to claim 3 , wherein the second potential signal is a signal obtained by inverting a phase of the first potential signal.

5. 4. The optical device according to claim 3, wherein the second potential signal is a signal obtained by inverting the phase of the first potential signal and shifting it by π / 4.

6. 2. The optical device according to claim 1, wherein the first potential signal has a period of the first potential different from a period of the second potential within one cycle.

7. 2. The optical device according to claim 1, wherein a third potential different from the first potential and the second potential is further input to the switch circuit portion, and the first potential signal is combined with the third potential to form one period.

8. the second potential is lower than the first potential; The optical device according to claim 7 , wherein the third potential is lower than the second potential.

9. The optical device according to claim 7 , wherein the first potential signal has a period in which the first potential is different from a period in which the second potential is different from the period in which the first potential is different from the period in which the second potential is different from the period in which the first potential is different.

10. 8. The optical device according to claim 7, wherein the first potential signal has a period in which the first potential is equal to a period in which the third potential is equal to the first potential within one period.

11. 8. The optical device according to claim 7, wherein the first potential signal has a length in one period during which the sum of the periods of the first potential and the third potential is shorter than a length of the period of the second potential.

12. the switch circuit further outputs a second potential signal that is a combination of the first potential, the second potential, and the third potential; The optical device according to claim 7 , wherein the second potential signal is input to the second transparent electrode.

13. The optical device according to claim 12 , wherein the second potential signal is a signal obtained by inverting a phase of the first potential signal.

14. 13. The optical device according to claim 12, wherein the second potential signal is a signal obtained by inverting the phase of the first potential signal and shifting it by π / 4.

15. the switch circuit further outputs a third potential signal and a fourth potential signal which are a combination of the first potential and the second potential; the third potential signal is input to the third transparent electrode; The optical device according to claim 12 , wherein the fourth potential signal is input to the fourth transparent electrode.

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