lighting system

Abstract

This illumination system comprises: a light source; a liquid crystal cell that changes the light distribution angle of light emitted from the light source; and a control device that controls the gradation of the light distribution angle. The liquid crystal cell comprises a first substrate on which first transparent electrodes and second transparent electrodes each extending in a first direction are alternately provided, a second substrate on which third transparent electrodes and fourth transparent electrodes each extending in a second direction crossing the first direction are alternately provided, and a liquid crystal layer between the first substrate and the second substrate. The control device comprises a communication unit that receives gradation information of the light distribution angle from an information communication terminal, a storage unit that stores weighting coefficients associating the amounts of change of the light distribution angle with changes in the gradation of the light distribution angle, and a control unit that, on the basis of the gradation information and the weighting coefficients, calculates first voltage to fourth voltage to be inputted to the first transparent electrode to the fourth transparent electrode.

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a lighting system that uses liquid crystal to control the luminous intensity distribution angle of light emitted from a light source. [Background technology]

[0002] In controlling the light distribution of a lighting device, a method of adjusting the lens position by combining lenses or a method of adjusting the focal position by a motor has been proposed (see, for example, Patent Document 1).On the other hand, in recent years, development has been progressing on lighting devices that use optical elements, so-called liquid crystal lenses, that utilize the change in the refractive index of liquid crystals by adjusting the voltage applied to the liquid crystal (see, for example, Technical Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-39026 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-69409 Summary of the Invention [Problem to be solved by the invention]

[0004] In lighting devices that use liquid crystal lenses, the light distribution is controlled by the voltage applied to the liquid crystal. However, because the refractive index of the liquid crystal changes in response to voltage inconsistently, controlling the light distribution is difficult, and this has led to problems such as inconsistency with the user's operating experience.

[0005] In view of the above-mentioned problems, one object of an embodiment of the present invention is to provide a lighting system that enables control of light distribution to suit the user's operational feel. [Means for solving the problem]

[0006] An illumination system according to one embodiment of the present invention includes a light source, a liquid crystal cell that changes the light distribution angle of light emitted from the light source, and a control device that controls the gradation of the light distribution angle. The liquid crystal cell includes a first substrate on which first transparent electrodes and second transparent electrodes are alternately arranged, each extending in a first direction, a second substrate on which third transparent electrodes and fourth transparent electrodes are alternately arranged, each extending in a second direction intersecting the first direction, and a liquid crystal layer between the first substrate and the second substrate. The control device includes a communication unit that receives gradation information of the light distribution angle from an information communication terminal, a memory unit that stores a weighting coefficient that associates a change in the light distribution angle with a change in the gradation of the light distribution angle, and a control unit that calculates a first voltage to be input to the first transparent electrode, a second voltage to be input to the second transparent electrode, a third voltage to be input to the third transparent electrode, and a fourth voltage to be input to the fourth transparent electrode based on the gradation information and the weighting coefficient. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram illustrating a configuration of a lighting system according to an embodiment of the present invention. [Figure 2] 1 is a block diagram showing a configuration of a lighting system according to an embodiment of the present invention. [Figure 3A] 1 is a schematic cross-sectional view showing a configuration of a lighting system according to an embodiment of the present invention. [Figure 3B] 1 is a schematic cross-sectional view showing a configuration of a lighting system according to an embodiment of the present invention. [Figure 4A] 1 is a schematic plan view showing an electrode pattern of a liquid crystal cell included in an optical element of an illumination system according to one embodiment of the present invention. [Figure 4B] 1 is a schematic plan view showing an electrode pattern of a liquid crystal cell included in an optical element of an illumination system according to one embodiment of the present invention. [Figure 5A] 3A and 3B are schematic diagrams illustrating optical characteristics of a liquid crystal cell included in an optical element of an illumination system according to one embodiment of the present invention. [Figure 5B] 3A and 3B are schematic diagrams illustrating optical characteristics of a liquid crystal cell included in an optical element of an illumination system according to one embodiment of the present invention. [Figure 6A] 10 is a timing chart of signals input to transparent electrodes of optical elements to control the light distribution shape in an illumination system according to an embodiment of the present invention. [Figure 6B] 10 is a timing chart of signals input to transparent electrodes of optical elements to control the light distribution shape in an illumination system according to an embodiment of the present invention. [Figure 6C] 10 is a timing chart of signals input to transparent electrodes of optical elements to control the light distribution shape in an illumination system according to an embodiment of the present invention. [Figure 7A] FIG. 2 is a schematic diagram illustrating the definitions of a light distribution angle and a half width at half maximum in a lighting system according to an embodiment of the present invention. [Figure 7B] FIG. 2 is a schematic diagram illustrating the definitions of a light distribution angle and a half width at half maximum in a lighting system according to an embodiment of the present invention. [Figure 8] 10 is a graph showing the correlation between the voltage applied to the transparent electrode of the optical element and the half width at half maximum in the illumination system according to one embodiment of the present invention. [Figure 9] 10 is a flowchart illustrating a gradation control process in the lighting system according to one embodiment of the present invention. [Figure 10A] 10 is a graph showing the correlation between gray level and half width at half maximum when weighting coefficient b=1 in an illumination system according to an embodiment of the present invention. [Figure 10B] 10 is a graph showing the correlation between gray scale and voltage applied to a transparent electrode when weighting coefficient b=1 in an illumination system according to an embodiment of the present invention. [Figure 11A] 10 is a graph showing the correlation between gray level and half width at half maximum when weighting coefficient b=2 in an illumination system according to an embodiment of the present invention. [Figure 11B] 10 is a graph showing the correlation between gray scale and voltage applied to a transparent electrode when weighting coefficient b=2 in an illumination system according to an embodiment of the present invention. [Figure 12A]10 is a graph showing the correlation between gray level and half width at half maximum when weighting coefficient b=3 in an illumination system according to an embodiment of the present invention. [Figure 12B] 10 is a graph showing the correlation between gray scale and voltage applied to a transparent electrode when weighting coefficient b=3 in an illumination system according to an embodiment of the present invention. [Figure 13] 1 is a block diagram illustrating a lighting system according to an embodiment of the present invention. [Figure 14] 1 is a block diagram illustrating a lighting system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] 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 construed as being limited to the description of the embodiments exemplified below.

[0009] In order to clarify the explanation, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual embodiment, but these are merely examples, and the illustrated shapes themselves do not limit the interpretation of the present invention. Furthermore, in the drawings, elements having the same functions as those explained in relation to previous drawings in the specification may be given the same reference numerals, even if they are different drawings, and duplicate explanations may be omitted.

[0010] When a single 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 substrate. However, these multiple structures originate from a film formed as the same layer in the same process and are made of the same material. Therefore, these multiple films are defined as existing in the same layer.

[0011] When expressing the manner 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.

[0012] First Embodiment A lighting system 1 according to one embodiment of the present invention will be described with reference to FIGS. 1 to 12B.

[0013] [1. Configuration of Lighting System 1] 1 is a schematic diagram showing the configuration of a lighting system 1 according to one embodiment of the present invention. As shown in FIG. 1, the lighting system 1 includes an optical element 10, a light source 20, a control device 30, and an information communication terminal 40.

[0014] The optical element 10 includes four liquid crystal cells 100 (a first liquid crystal cell 100-1, a second liquid crystal cell 100-2, a third liquid crystal cell 100-3, and a fourth liquid crystal cell 100-4). In the optical element 10, the first liquid crystal cell 100-1, the second liquid crystal cell 100-2, the third liquid crystal cell 100-3, and the fourth liquid crystal cell 100-4 are stacked in order in the z-axis direction, starting from the cell closest to the light source 20. Note that, although a configuration in which the optical element 10 includes four liquid crystal cells 100 will be described below, the number of liquid crystal cells 100 included in the optical element 10 is not limited to four. It is sufficient that the optical element 10 includes at least two liquid crystal cells 100. The configuration of the optical element 10 will be described in detail below.

[0015] The light source 20 emits light to the optical element 10. The light emitted from the light source 20 is incident on the first liquid crystal cell 100-1 and is emitted from the fourth liquid crystal cell 100-4. In the lighting system 1, the diffusion and polarization of light are controlled by the four liquid crystal cells included in the optical element 10, and the spread (light distribution) of the light emitted from the fourth liquid crystal cell 100-4 can be changed. For example, light emitting diodes (LEDs) can be used as the light source 20, but the light source 20 is not limited to this. The light source 20 may be any element or device that can emit light.

[0016] The control device 30 is connected to the optical element 10 and the light source 20 and controls the optical element 10 and the light source 20. The control device 30 includes, for example, a central processing unit (CPU), a microprocessor (MPU), an integrated circuit (IC), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a random access memory (RAM). The configuration of the control device 30 will be described in detail later.

[0017] The information communication terminal 40 is, for example, a mobile phone, a smartphone, a tablet, or a personal computer, but is not limited to these. The information communication terminal 40 is communicably connected to the control device 30 via a network NW. The network NW may be wired or wireless. However, if the information communication terminal 40 is a mobile terminal, it is preferable that the network NW is wireless. The network NW is, for example, a LAN (Local Area Network) or the Internet, but is not limited to these. The network NW may also be a network via a communication base station managed by a telecommunications carrier. The configuration of the information communication terminal 40 will be described in detail later.

[0018] A user can use the information communication terminal 40 to set the light distribution of the light emitted from the light source 20. That is, in the lighting system 1, the control device 30 controls the optical element 10 and the light source 20 based on user input information from the information communication terminal 40, and can change the light distribution of the light emitted from the light source 20.

[0019] Fig. 2 is a block diagram showing the configuration of a lighting system 1 according to one embodiment of the present invention. As shown in Fig. 2, the control device 30 includes a communication unit 310, a light source control unit 320, an optical element control unit 330, and a storage unit 340. The information communication terminal 40 includes a communication unit 410, a display unit 420, and an input unit 430.

[0020] The communication unit 310 is a communication interface that can transmit and receive data or information, and is, for example, a LAN module or a Wi-Fi (registered trademark) module.

[0021] The light source control unit 320 controls the operation of the light source 20. The control device 30 executes a predetermined program to cause the light source control unit 320 to function. For example, the light source control unit 320 controls the power on / off of the light source 20 based on user input information transmitted from the information communication terminal 40. The light source control unit 320 also adjusts the light intensity or color temperature of the light source 20 based on the user input information.

[0022] The optical element control unit 330 controls the optical element 10 to change the illumination mode, light distribution shape, and light distribution angle. The control device 30 executes a predetermined program to cause the optical element control unit 330 to function. For example, the optical element control unit 330 calculates a voltage to control the optical element 10 based on user input information transmitted from the information communication terminal 40, and inputs a signal including the calculated voltage to the liquid crystal cell 100. The illumination system 1 can change the gradation of light distribution depending on the illumination mode. Note that, in the following description, the degree of spread of emitted light in the illumination system is referred to as "gradation." The gradation can be set in multiple stages, ranging from the smallest spread of emitted light (no spread of emitted light, or light emitted from the light source is emitted as is) to the largest spread of emitted light. The gradation can be set to 8, 16, 32, 64, 128, 256, or the like. Alternatively, instead of gradation, a configuration can be applied in which the light spread state is set between 0% (no light spread, or light from the light source is irradiated as is) and 100% (maximum light spread).

[0023] The lighting mode may be, for example, a wide-angle lighting mode that illuminates a wide range like a downlight, or a narrow-angle lighting mode that illuminates a narrow range like a spotlight, but is not limited to these. Details of the gradation control of light distribution by the optical element control unit 330 will be described later.

[0024] The memory unit 340 is a storage capable of saving data or information. The memory unit 340 may be, for example, a hard disk drive (HDD), a solid state drive (SSD), a read only memory (ROM), a random access memory (RAM), or a flash memory. The memory unit 340 stores a plurality of weighting coefficients 341 corresponding to a plurality of lighting modes.

[0025] The communication unit 410 has the same configuration as the communication unit 310, and therefore a description thereof will be omitted.

[0026] The display unit 420 is a display interface that includes a screen and can display images on the screen. The display unit is, for example, a liquid crystal display device or an OLED display device.

[0027] The input unit 430 is a user interface through which a user can input data or information. The input unit 430 can receive user operations, such as a button, a keyboard, or a mouse. The input unit 430 can also generate user input information based on the user operations. The user input information can be, for example, lighting mode information including a lighting mode selected by the user, and gradation information including a gradation selected by the user. The input unit 430 may be a touch screen integrated with the display unit 420.

[0028] 2. Configuration of Optical Element 10 3A and 3B are schematic cross-sectional views showing the configuration of an illumination system 1 according to one embodiment of the present invention. Specifically, Fig. 3A is a cross-sectional view of optical element 10 taken along line A1-A2 in Fig. 1, and Fig. 3B is a cross-sectional view of optical element 10 taken along line B1-B2 in Fig. 1.

[0029] 3A and 3B, each of the first to fourth liquid crystal cells 100-1 to 100-4 includes a first substrate 110-1, a second substrate 110-2, a plurality of first transparent electrodes 120-1, a plurality of second transparent electrodes 120-2, a plurality of third transparent electrodes 120-3, a plurality of fourth transparent electrodes 120-4, a first alignment film 130-1, a second alignment film 130-2, a sealant 140, and a liquid crystal layer 150. The first transparent electrodes 120-1 and the second transparent electrodes 120-2 are alternately provided on the first substrate 110-1. That is, the plurality of first transparent electrodes 120-1 and the plurality of second transparent electrodes 120-2 are arranged in a comb-like pattern. Furthermore, a first alignment film 130-1 is provided on the first substrate 110-1 so as to cover the first transparent electrode 120-1 and the second transparent electrode 120-2. Third transparent electrodes 120-3 and fourth transparent electrodes 120-4 are provided alternately on the second substrate 110-2. That is, the plurality of third transparent electrodes 120-1 and the plurality of fourth transparent electrodes 120-4 are arranged in a comb-like pattern. Furthermore, a second alignment film 130-2 is provided on the second substrate 110-2 so as to cover the third transparent electrodes 120-3 and the fourth transparent electrodes 120-4. The first substrate 110-1 and the second substrate 110-2 are arranged so that the first transparent electrode 120-1 and the second transparent electrode 120-2 face the third transparent electrode 120-3 and the fourth transparent electrode 120-4, and are bonded together via a sealant 140 provided on the periphery of the first substrate 110-1 and the second substrate 110-2. A liquid crystal is sealed in the space surrounded by the first substrate 110-1 (more specifically, the first alignment film 130-1), the second substrate 110-2 (more specifically, the second alignment film 130-2), and the sealant 140, and a liquid crystal layer 150 is provided between the first substrate 110-1 and the second substrate 110-2.

[0030] An optically elastic resin layer 160 is provided between the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2. Similarly, an optically elastic resin layer 160 is provided between the second liquid crystal cell 100-2 and the third liquid crystal cell 100-3, and between the third liquid crystal cell 100-3 and the fourth liquid crystal cell 100-4. For example, an adhesive containing a light-transmitting acrylic resin can be used as the optically elastic resin layer 160. In other words, the optically elastic resin layer 160 can bond and fix two adjacent liquid crystal cells 100.

[0031] Each of the first substrate 110-1 and the second substrate 110-2 may be a rigid substrate having light-transmitting properties, such as a glass substrate, a quartz substrate, or a sapphire substrate. Alternatively, each of the first substrate 110-1 and the second substrate 110-2 may be a flexible substrate having light-transmitting properties, such as a polyimide resin substrate, an acrylic resin substrate, a siloxane resin substrate, or a fluororesin substrate.

[0032] Each of the first transparent electrode 120-1, the second transparent electrode 120-2, the third transparent electrode 120-3, and the fourth transparent electrode 120-4 functions as an electrode for forming an electric field in the liquid crystal layer 150. Each of the first transparent electrode 120-1, the second transparent electrode 120-2, the third transparent electrode 120-3, and the fourth transparent electrode 120-4 is made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO).

[0033] In the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2, the first transparent electrode 120-1 and the second transparent electrode 120-2 extend in the x-axis direction, and the third transparent electrode 120-3 and the fourth transparent electrode 120-4 extend in the y-axis direction. In the third liquid crystal cell 100-3 and the fourth liquid crystal cell 100-4, the first transparent electrode 120-1 and the second transparent electrode 120-2 extend in the y-axis direction, and the third transparent electrode 120-3 and the fourth transparent electrode 120-4 extend in the x-axis direction.

[0034] In the following description, the first transparent electrode 120-1 to the fourth transparent electrode 120-4 may be referred to as the transparent electrodes 120 when no particular distinction is made between them.

[0035] Each of the first alignment film 130-1 and the second alignment film 130-2 aligns the liquid crystal molecules in the liquid crystal layer 150 in a predetermined direction. The first alignment film 130-1 and the second alignment film 130-2 are made of a material such as polyimide resin. The first alignment film 130-1 and the second alignment film 130-2 may be given alignment characteristics by an alignment process such as a rubbing method or a photo-alignment method. The rubbing method is a method of rubbing the surface of the alignment film in one direction. The photo-alignment method is a method of irradiating the alignment film with linearly polarized ultraviolet light.

[0036] The first alignment film 130-1 is subjected to an alignment treatment so that the liquid crystal molecules on the first substrate 110-1 side of the liquid crystal layer 150 are aligned in a direction perpendicular to the extension direction of the first transparent electrode 120-1 and the second transparent electrode 120-2. The second alignment film 130-2 is subjected to an alignment treatment so that the liquid crystal molecules on the second substrate 110-2 side of the liquid crystal layer 150 are aligned in a direction perpendicular to the extension direction of the third transparent electrode 120-3 and the fourth transparent electrode 120-4. Therefore, in the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2, the long axes of the liquid crystal molecules on the first substrate 110-1 side are aligned in the y-axis direction, and the long axes of the liquid crystal molecules on the second substrate 110-2 side are aligned in the x-axis direction. In the third liquid crystal cell 100-3 and the fourth liquid crystal cell 100-4, the long axes of the liquid crystal molecules on the first substrate 110-1 side are aligned in the x-axis direction, and the long axes of the liquid crystal molecules on the second substrate 110-2 side are aligned in the y-axis direction. Note that, although the above description has been given assuming that the alignment direction of the liquid crystal molecules and the extension direction of the transparent electrode 120 are perpendicular to each other, the alignment direction of the liquid crystal molecules and the extension direction of the transparent electrode 120 may intersect at an angle other than perpendicular, for example, an angle between 85 degrees and 90 degrees.

[0037] An adhesive material containing epoxy resin or acrylic resin is used as the seal material 140. The adhesive material may be an ultraviolet curing type or a thermosetting type.

[0038] The liquid crystal layer 150 can refract light passing through it or change the polarization state of the light passing through it depending on the orientation state of the liquid crystal molecules. Nematic liquid crystals or the like are used as the liquid crystal for the liquid crystal layer 150. The liquid crystal described in this embodiment is a positive type, but a negative type can also be applied by changing the orientation direction of the liquid crystal molecules when no voltage is applied to the transparent electrode 120. In addition, the liquid crystal preferably contains a chiral agent that imparts a twist to the liquid crystal molecules.

[0039] [3. Electrode pattern of liquid crystal cell 100] 4A and 4B are schematic plan views showing electrode patterns of a liquid crystal cell 100 included in an optical element 10 of an illumination system 1 according to an embodiment of the present invention. Specifically, Fig. 4A is a plan view showing an electrode pattern formed on a first substrate 110-1 of a first liquid crystal cell 100-1, and Fig. 4B is a plan view showing an electrode pattern formed on a second substrate 110-2 of the first liquid crystal cell 100-1.

[0040] 4A, first connection pads 121-1 and second connection pads 121-2 are provided on a first substrate 110-1. A plurality of first transparent electrodes 120-1 are electrically connected to the first connection pads 121-1. A plurality of second transparent electrodes 120-2 are electrically connected to the second connection pads 121-2.

[0041] As shown in FIG. 4B, a third connection pad 121-3, a fourth connection pad 121-4, a first terminal 122-1, a second terminal 122-2, a third terminal 122-3, and a fourth terminal 122-4 are provided on the second substrate 110-2. The plurality of third transparent electrodes 120-3 are electrically connected to the third terminal 122-3. The plurality of fourth transparent electrodes 120-4 are electrically connected to the fourth terminal 122-4. The third connection pad 121-3 is electrically connected to the first terminal 122-1. The fourth connection pad 121-4 is electrically connected to the second terminal 122-2.

[0042] When the first substrate 110-1 and the second substrate 110-2 are bonded together, the first connection pad 121-1 and the second connection pad 121-2 overlap with the third connection pad 121-3 and the fourth connection pad 121-4, respectively. A conductive material such as silver paste is provided between the first connection pad 121-1 and the third connection pad 121-3, and the first connection pad 121-1 and the third connection pad 121-3 are electrically connected via the conductive material. Similarly, a conductive material is provided between the second connection pad 121-2 and the fourth connection pad 121-4, and the second connection pad 121-2 and the fourth connection pad 121-4 are electrically connected via the conductive material. Therefore, the first transparent electrode 120-1 and the second transparent electrode 120-2 on the first substrate 110-1 are electrically connected to the first terminal 122-1 and the second terminal 122-2, respectively.

[0043] The electrode pattern of the second liquid crystal cell 100-2 is the same as that of the first liquid crystal cell 100-1. The electrode pattern configurations of the third liquid crystal cell 100-3 and the fourth liquid crystal cell 100-4 are the same as that of the first liquid crystal cell 100-1, except that the extension direction of the transparent electrode 120 is rotated by 90°.

[0044] In the liquid crystal cell 100, the first terminal 122-1 to the fourth terminal 122-4 on the second substrate 110-2 are exposed from the first substrate 110-1. In each of the first to fourth liquid crystal cells 100-1 to 100-4, flexible printed circuits (FPCs) 170 are provided on the exposed first to fourth terminals 122-1 to 122-4 (see FIG. 1). The FPCs 170 are electrically connected to the control device 30. Therefore, the control device 30 can input signals to the first to fourth transparent electrodes 120-1 to 120-4 of the liquid crystal cell 100 via the FPCs 170, respectively, to control the optical element 10.

[0045] 4. Optical Properties of Liquid Crystal Cell 100 5A and 5B are schematic diagrams illustrating the optical characteristics of the liquid crystal cell 100 included in the optical element 10 of the lighting system 1 according to one embodiment of the present invention. Specifically, Fig. 5A shows the liquid crystal cell 100 in a state where no voltage is applied to the transparent electrode 120, and Fig. 5B shows the liquid crystal cell 100 in a state where a voltage is applied to the transparent electrode 120.

[0046] As shown in FIG. 5A, the liquid crystal molecules on the first substrate 110-1 side of the liquid crystal layer 150 are aligned in the y-axis direction, and the liquid crystal molecules on the second substrate 110-2 side of the liquid crystal layer 150 are aligned in the x-axis direction. Therefore, when no voltage is applied to any of the first transparent electrode 120-1 to the fourth transparent electrode 120-4, the liquid crystal molecules in the liquid crystal layer 150 are aligned so that they are twisted 90° in the c-axis direction as they move from the first substrate 110-1 to the second substrate 110-2. Furthermore, the polarization plane (polarization axis or direction of polarization components) of light passing through the liquid crystal layer 150 is rotated 90° according to the alignment of the liquid crystal molecules. More specifically, a P-polarized component incident on the liquid crystal cell 100 becomes an S-polarized component as it passes through the liquid crystal layer 150 of the liquid crystal cell 100, and an S-polarized component incident on the liquid crystal cell 100 becomes a P-polarized component. This transition of polarization components may be referred to as optical rotation.

[0047] On the other hand, when a voltage is applied so as to generate a potential difference between two adjacent transparent electrodes 120, an electric field (hereinafter referred to as a "transverse electric field") is generated between the two adjacent transparent electrodes 120, and the orientation of the liquid crystal molecules changes. As shown in FIG. 5B , the liquid crystal molecules in the liquid crystal layer 150 are oriented so as to be twisted 90° in the c-axis direction as they move from the first substrate 110-1 to the second substrate 110-2. The liquid crystal molecules near the first substrate 110-1 side are aligned in a convex arc shape relative to the first substrate 110-1 due to the transverse electric field between the first transparent electrode 120-1 and the second transparent electrode 120-2, and the liquid crystal molecules near the second substrate 110-2 side are aligned in a convex arc shape relative to the second substrate 110-2 due to the transverse electric field between the third transparent electrode 120-3 and the fourth transparent electrode 120-4. The liquid crystal molecules aligned in a convex arc shape have a refractive index distribution, and light having the same polarization direction as the orientation direction of the liquid crystal molecules is diffused. Furthermore, since the cell gap d, which is the distance between the first substrate 110-1 and the second substrate 110-2, is sufficiently larger than the distance between two adjacent transparent electrodes (for example, 10 μm≦d≦30 μm), the orientation of the liquid crystal molecules located near the center between the first substrate 110-1 and the second substrate 110-2 hardly changes.

[0048] The light emitted from the light source 20 includes 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"), but for convenience, the light emitted from the light source 20 will be described below as being divided into a first light 1000-1 having a P polarized component and a second light 1000-2 having an S polarized component.

[0049] The P-polarized component of the first light 1000-1 incident from the first substrate 110-1 side is different from the alignment direction of the liquid crystal molecules on the first substrate 110-1 side, and therefore the first light 1000-1 is not diffused (see (1) in FIG. 5B). Furthermore, the first light 1000-1 is optically rotated while passing through the liquid crystal layer 150, and the polarization component changes from a P-polarized component to an S-polarized component. The S-polarized component of the first light 1000-1 is different from the alignment direction of the liquid crystal molecules on the second substrate 110-2 side, and therefore the first light 1000-1 is not diffused (see (2) in FIG. 5B).

[0050] The S-polarized component of second light 1000-2 incident from the first substrate 110-1 side is aligned in the same direction as the liquid crystal molecules on the first substrate 110-1 side, so second light 1000-2 is diffused in the y-axis direction in accordance with the refractive index distribution of the liquid crystal molecules (see (3) in FIG. 5B). Furthermore, second light 1000-2 is optically rotated while passing through liquid crystal layer 150, and its polarization component changes from S-polarized component to P-polarized component. Since the P-polarized component of second light 1000-2 is aligned in the same direction as the liquid crystal molecules on the second substrate 110-2 side, second light 1000-2 is diffused in the x-axis direction in accordance with the refractive index distribution of the liquid crystal molecules (see (4) in FIG. 5B).

[0051] [5. Light distribution control] [5-1. Control of light distribution shape] By controlling the voltages applied to the first transparent electrodes 120-1 to fourth transparent electrodes 120-4 of the first liquid crystal cell 100-1 to fourth liquid crystal cell 100-4, respectively, the light distribution pattern of light passing through the optical element 10 can be changed.

[0052] 6A to 6C are timing charts of signals input to the transparent electrode 120 of the optical element 10 to control the light distribution pattern in the lighting system 1 according to one embodiment of the present invention. In the following description, for convenience, the High voltage is defined as +αV (or −βV), the High voltage is defined as −αV (or βV), and the intermediate voltage is defined as 0V. However, the High voltage, Low voltage, and intermediate voltage are not limited to these. The High voltage may be any voltage greater than the Low voltage and the intermediate voltage. The intermediate voltage may be any voltage between the High voltage and the Low voltage. For example, the High voltage, Low voltage, and intermediate voltage may be 30V, 0V, and 15V, respectively.

[0053] The voltage included in the signal input to the transparent electrode 120 is a square wave in which high voltages and low voltages are repeated, or a constant intermediate voltage, but is not limited to this.

[0054] 6A to 6C show a first signal S1, a second signal S2, a third signal S3, and a fourth signal. The first signal S1 is input to the first transparent electrodes 120-1 of the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2, and to the third transparent electrodes 120-3 of the third liquid crystal cell 100-3 and the fourth liquid crystal cell 100-4. The second signal S2 is input to the second transparent electrodes 120-2 of the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2, and to the fourth transparent electrodes 120-4 of the third liquid crystal cell 100-3 and the fourth liquid crystal cell 100-4. The third signal S3 is input to the third transparent electrodes 120-3 of the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 and the first transparent electrodes 120-1 of the third liquid crystal cell 100-3 and the fourth liquid crystal cell 100-4. The fourth signal S4 is input to the fourth transparent electrodes 120-4 of the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 and the second transparent electrodes 120-2 of the third liquid crystal cell 100-3 and the fourth liquid crystal cell 100-4.

[0055] In the timing chart shown in FIG. 6A, a transverse electric field is generated between two adjacent transparent electrodes 120 extending in the y-axis direction. In this case, liquid crystal molecules whose major axes are aligned in the x-axis direction are arranged in a convex arc shape. Therefore, light passing through the optical element 10 is diffused in the x-axis direction in each of the first liquid crystal cell 100-1 to the fourth liquid crystal cell 100-4. Therefore, in the timing chart shown in FIG. 6A, a linear light distribution spreading in the x-axis direction can be obtained.

[0056] In the timing chart shown in FIG. 6B, a transverse electric field is generated between two adjacent transparent electrodes 120 extending in the x-axis direction. In this case, liquid crystal molecules with their major axes aligned in the y-axis direction are arranged in a convex arc shape. Therefore, light passing through the optical element 10 is diffused in the y-axis direction in each of the first to fourth liquid crystal cells 100-1 to 100-4. Therefore, in the timing chart shown in FIG. 6B, a linear light distribution spreading in the y-axis direction can be obtained.

[0057] In the timing chart shown in FIG. 6C, a transverse electric field is generated between two adjacent transparent electrodes 120 extending in the y-axis direction and between two adjacent transparent electrodes 120 extending in the x-axis direction. In this case, not only the liquid crystal molecules on one substrate 110 side of the liquid crystal cell 100 whose major axes are aligned in the x-axis direction, but also the liquid crystal molecules on the other substrate 110 side of the liquid crystal cell 100 whose major axes are aligned in the y-axis direction are arranged in a convex arc shape. Therefore, light passing through the optical element 10 is diffused in the x-axis and y-axis directions in each of the first to fourth liquid crystal cells 100-1 to 100-4. Therefore, in the timing chart shown in FIG. 6C, when α=β, a circular light distribution can be obtained. When α<β, an elliptical light distribution with its major axis aligned in the x-axis direction can be obtained. When β>α, an elliptical light distribution with its major axis aligned in the y-axis direction can be obtained.

[0058] [5-2. Gradation control of light distribution angle] Changing the magnitude of the voltage applied to the transparent electrode 120 can change the degree of light diffusion in the liquid crystal cell 100. Therefore, by controlling the magnitude of the voltage applied to the first transparent electrode 120-1 to the fourth transparent electrode 120-4 of each of the first liquid crystal cell 100-1 to the fourth liquid crystal cell 100-4, it is possible to control the gradation of the light distribution angle of light passing through the optical element 10. Here, the definition of the light distribution angle will be described with reference to Figures 7A and 7B.

[0059] 7A and 7B are schematic diagrams illustrating the definitions of the light distribution angle and half width at half maximum in lighting system 1 according to one embodiment of the present invention. More specifically, Fig. 7B is a graph showing the change in illuminance with respect to the polar angle when light source 20 is provided at a polar angle of 0°, with the horizontal axis representing the polar angle in the x-axis direction and the vertical axis representing the illuminance on surface S illuminated by lighting system 1, when the state of Fig. 7A is viewed from the y-axis direction.

[0060] The light distribution of light emitted from the light source 20 is controlled by the optical element 10, and light having a predetermined light distribution pattern is projected onto the projection surface. The illuminance of light on the projection surface is greatest at the center (directly below the light source 20) and decreases with increasing distance from the center. The half-illuminance angle is essentially defined as the angle between a line perpendicular to the light source 20 and a line connecting the light source 20 and a point where the illuminance is 50% of the illuminance directly below the light source 20. In FIG. 7B, the half-illuminance angle is the polar angle at which the illuminance is 50% in an illuminance graph where the illuminance directly below the light source 20 is 100%. In this specification, the light distribution angle is equal to the half-illuminance angle and is sometimes referred to as the half width at half maximum (HWHM). In other words, the light distribution angle can be expressed as the half width at half maximum (θ°). Therefore, for convenience, the half width at half maximum will sometimes be used to describe the light distribution angle below. The full width at half maximum (FWHM) is twice the half width at half maximum.

[0061] Fig. 8 is a graph showing the correlation between the voltage applied to the transparent electrode 120 of the optical element 10 in the lighting system 1 according to one embodiment of the present invention and the half width at half maximum. Fig. 8 shows data (black circles in Fig. 8) measured in the fabricated lighting system 1 and its approximation curve.

[0062] As shown in Fig. 8, the half width at half maximum versus the voltage applied to the transparent electrode 120 shows a complex curve. For example, the function f(x) of the approximate curve shown in Fig. 8 can be expressed as the sum of two sigmoid functions, as shown in Equation (1).

[0063]

number

[0064] In equation (1), k1 and k2 are proportionality constants, and z is a predetermined coefficient.

[0065] Note that formula (1) is an example, and the function f(x) for calculating the half width at half maximum relative to the voltage x is not limited to formula (1). In particular, the constants in formula (1) may vary depending on the number of liquid crystal cells 100 included in the optical element 10, the type of light source 20, and the like. The function f(x) can be calculated based on measured data, and may be any function that indicates the correlation between the voltage x applied to the transparent electrode 120 of the liquid crystal cell 100 and the half width at half maximum.

[0066] In the gradation control of light distribution in lighting system 1, the light distribution angle can be changed by user operation. Here, the relationship between the light distribution angle and voltage is complex, as shown in the above-mentioned function f(x). Therefore, simply allocating voltage x evenly to the gradation level operated by the user may result in large or small changes in the light distribution angle depending on the gradation level, which may not match the user's operational feeling. Furthermore, it may be difficult to make fine adjustments to the light distribution angle depending on the gradation level. Therefore, lighting system 1 introduces a function g(p) that represents the correlation between gradation level p and light distribution angle, as shown in equation (2).

[0067]

number

[0068] In equation (2), a and c are arbitrary constants, and b is a weighting coefficient. Here, the constants a and c are a>0 and c>0, and the weighting coefficient b is b≧1. In the function g(p), the light distribution angle increases as the grayscale level p increases. The number of grayscale levels p, i.e., the number of grayscale levels, is, for example, 256 (grayscale levels 0 to 255), but is not limited to this. In addition, p max is the maximum number of the set gradation levels, and when the gradation level is 0 to 255, p max is 255. Depending on the number of gradations, p max For example, when the number of gradations is 16, 32, and 64 (all of which include 0 as the minimum gradation), p max The values ​​15, 31, and 63 are used, respectively. If the minimum gradation does not include 0, p maxIt goes without saying that the number of gradations is 16, 32, 64, or 256, etc.

[0069] When the orientation state is expressed as a percentage such as n%, g(n) can also be defined as in equation (3).

[0070]

number

[0071] As mentioned above, the light distribution angle and half width at half maximum are the same thing. In the following, to unify the names, the term half width at half maximum will be used for explanation. That is, both f(x) and g(p) are formulas for calculating half width at half maximum. Therefore, if f(x) = g(p), the voltage x for the gradation level p can be calculated. The constant c corresponds to the half width at half maximum when the gradation level is 0. That is, the constant c can be calculated from the half width at half maximum when the voltage x = 0V. Also, the maximum gradation level p max and maximum voltage x max Half width at half maximum A max Using this, A max =a·(p max / 255) b +c. Therefore, once the weighting coefficient b is determined, the constant a can be calculated.

[0072] As can be seen from equation (2), the weighting coefficient b is a value that determines the ratio of the amount of change in the half width at half maximum to the amount of change in the gradation level p. As the weighting coefficient b increases, the amount of change in the light distribution angle at lower gradation levels p decreases, and the amount of change in the light distribution angle at higher gradation levels p increases. In other words, as the weighting coefficient b increases, the number of gradations on the lower gradation side increases. Therefore, in this case, fine adjustments at small half widths at half maximum become easier. In the lighting system 1, when the lighting mode is a narrow-angle lighting mode, it is often used at a small light distribution angle rather than a large light distribution angle. In this case, a large weighting coefficient b is preferable. In this way, the lighting system 1 can change the weighting coefficient b depending on the application (lighting mode) used. Therefore, the storage unit 340 includes multiple weighting coefficients 341 corresponding to each of the multiple lighting modes. Note that the weighting coefficient b is not limited to a natural number.

[0073] Fig. 9 is a flowchart illustrating the gradation control process in the lighting system 1 according to one embodiment of the present invention. The flowchart shown in Fig. 9 includes steps S110 to S150, but the gradation control process may further include other steps.

[0074] In step S110, the communication unit 310 receives the lighting mode information transmitted from the information communication terminal 40. The lighting mode information is one piece of user input information, and is generated by the user operating the input unit 430 of the information communication terminal 40.

[0075] In step S120, the optical element control unit 330 determines the weighting coefficient b based on the illumination mode information. Specifically, the optical element control unit 330 determines the weighting coefficient b corresponding to the illumination mode information from among the multiple weighting coefficients 341 stored in the storage unit 340.

[0076] In step S130, the communication unit 310 receives the gradation information transmitted from the information communication terminal 40. The gradation information is one piece of user input information, and is generated by the user operating the input unit 430 of the information communication terminal 40.

[0077] In step S140, the optical element control unit 330 calculates a voltage to be applied to the transparent electrode 120 based on the grayscale information. Specifically, the optical element control unit 330 determines a grayscale level p based on the grayscale information. The optical element control unit 330 also calculates a voltage x based on the determined grayscale level p and the relational expression f(x)=g(p).

[0078] In step S150, the optical element control unit 330 inputs a signal including the calculated voltage x to the transparent electrode 120 of the liquid crystal cell 100.

[0079] As described above, in the lighting system 1, the optical element control unit 330 can calculate the voltages to be input to the first transparent electrodes 120-1 to 120-4 of each of the first liquid crystal cell 100-1 to the fourth liquid crystal cell 100-4 based on the gradation information and the weighting coefficient b.

[0080] [6. Differences in gradation due to differences in weighting coefficient b] [6-1. Weighting coefficient b=1] Fig. 10A is a graph showing the correlation between gray scale and half width at half maximum in lighting system 1 according to one embodiment of the present invention when weighting coefficient b = 1. Fig. 10B is a graph showing the correlation between gray scale and voltage applied to transparent electrode 120 in lighting system 1 according to one embodiment of the present invention when weighting coefficient b = 1.

[0081] FIG. 10A shows a graph of g(p)=ap+c in Equation (2) with weighting coefficient b=1. As can be seen from the graph in FIG. 10A, the amount of change in the half-width at half maximum relative to the amount of change in the grayscale level p is constant. However, the amount of change in the area of ​​the light distribution pattern on the projection surface is not constant. For example, when changing from grayscale level 15 to grayscale level 30, the amount of change in the half-width at half maximum is 1.65°, and the area change rate of the light distribution pattern is 1.95%. On the other hand, when changing from grayscale level 240 to grayscale level 255, the amount of change in the half-width at half maximum is 1.65°, but the area change rate of the light distribution pattern is 1.14%. In other words, when comparing the area change rates of the light distribution pattern, the change is larger at lower grayscale levels than at higher grayscale levels. This means that the amount of increase in area at lower grayscale levels is larger than the amount of increase in area at higher grayscale levels. Therefore, users are more likely to perceive the illumination as more widespread at lower grayscale levels than at higher grayscale levels.

[0082] 10B shows a graph of a relational expression indicating the correlation between the gradation level p calculated as f(x) = g(p) and the voltage x when the weighting coefficient b is 1. In the lighting system 1, the optical element control unit 330 can convert the gradation level p into the voltage x based on the relational expression shown in FIG.

[0083] [6-2. Weighting coefficient b=2] Fig. 11A is a graph showing the correlation between gray scale and half width at half maximum in lighting system 1 according to one embodiment of the present invention when weighting coefficient b = 2. Fig. 11B is a graph showing the correlation between gray scale and voltage applied to transparent electrode 120 in lighting system 1 according to one embodiment of the present invention when weighting coefficient b = 2.

[0084] FIG. 11A shows the relationship between g(p) and a 211A shows a graph of the half-width at half maximum (FWHM) vs. the change in grayscale level p. As can be seen from the graph in FIG. 11A, the change in the half-width at half maximum (FWHM) is not constant relative to the change in grayscale level p. The change in the half-width at half maximum (FWHM) varies more at higher grayscale levels than at lower grayscale levels. However, the change in the area of ​​the light distribution pattern on the projection surface is not as large as the change in the half-width at half maximum. For example, when changing from grayscale level 15 to grayscale level 30, the increase in the half-width at half maximum is 0.292°, and the area increase rate of the light distribution pattern is 1.23%. On the other hand, when changing from grayscale level 240 to grayscale level 255, the increase in the half-width at half maximum is 3.106°, and the area increase rate of the light distribution pattern is 1.30%. The area increase rate of the light distribution pattern is similar at lower and higher grayscale levels. Therefore, the user can perceive the illumination as spreading to the same extent at lower and higher grayscale levels.

[0085] 11B is a graph showing a relational expression indicating the correlation between the gray level p calculated as f(x) = g(x) and the voltage x when the weighting coefficient b is 2. In the lighting system 1, the optical element control unit 330 can convert the gray level p into the voltage x based on the relational expression shown in FIG.

[0086] [6-3. Weighting coefficient b=3] Fig. 12A is a graph showing the correlation between gray scale and half width at half maximum in lighting system 1 according to one embodiment of the present invention when weighting coefficient b = 3. Fig. 12B is a graph showing the correlation between gray scale and voltage applied to transparent electrode 120 in lighting system 1 according to one embodiment of the present invention when weighting coefficient b = 3.

[0087] FIG. 12A shows the relationship between g(p) and a 312A shows a graph of half-width at half maximum (FWHM) + c. As can be seen from the graph in FIG. 12A, the increase in half-width at half maximum with respect to the increase in gradation level p is not constant. Compared to the case where b=2, when b=3, the change in half-width at half maximum at lower gradation levels is small, and the change in half-width at half maximum at higher gradation levels is large. This allows the user to adjust the slight spread of the illumination at lower gradation levels.

[0088] 12B is a graph showing a relational expression indicating the correlation between the gradation level p calculated as f(x) = g(p) and the voltage x when the weighting coefficient b is 3. In the lighting system 1, the optical element control unit 330 can convert the gradation level p into the voltage x based on the relational expression shown in FIG.

[0089] The correlation between the gradation level p and the half-width at half maximum (FWHM) when the weighting coefficient b is 1, 2, or 3 has been explained above. However, as the weighting coefficient b increases, the number of gradations can be increased when the FWHM is small. For example, when the lighting mode is a narrow-angle lighting mode such as a spotlight, a large FWHM is not required, and fine adjustment with a small FWHM may be required. In this case, for example, by setting the weighting coefficient b to 3 and converting the gradation level p to voltage x, the number of gradations with a small FWHM increases, enabling fine adjustment of the gradation of the light distribution.

[0090] As described above, in the lighting system 1 according to this embodiment, by introducing equation (2) and calculating the voltage x to be applied by the optical element control unit 330 to the transparent electrode 120, the gradation can be controlled so that the light distribution angle monotonically increases (or decreases) based on the calculated voltage x. That is, the lighting system 1 easily controls the gradation of the light distribution. Furthermore, equation (2) includes a weighting coefficient b, and by changing the weighting coefficient b, it is possible to control the gradation of the light distribution in accordance with the application (lighting mode) used by the user. Therefore, the lighting system 1 can control the gradation of the light distribution in accordance with the lighting mode.

[0091] Second Embodiment A lighting system 1A according to one embodiment of the present invention will be described with reference to Fig. 13. In the following, when the configuration of the lighting system 1A is similar to that of the lighting system 1, the description of the configuration of the lighting system 1A may be omitted.

[0092] 13 is a block diagram illustrating a lighting system 1A according to one embodiment of the present invention. The control device 30 includes a communication unit 310, a light source control unit 320, an optical element control unit 330A, and a storage unit 340. The storage unit 340 stores a plurality of weighting coefficients 341 corresponding to a plurality of lighting modes. The storage unit 340 also stores a plurality of look-up tables (LUTs) 342A corresponding to the plurality of weighting coefficients 341.

[0093] In the lookup table 342A, the voltage x of the first transparent electrode 120-1 to the fourth transparent electrode 120-4 of each of the first liquid crystal cell 100-1 to the fourth liquid crystal cell 100-4 at each gradation level p, calculated from equations (1) and (2), is assigned. That is, in the lookup table 342A, the gradation level of the light distribution angle, the weighting coefficient, and the voltage x of the first transparent electrode 120-1 to the fourth transparent electrode 120-4 of each of the first liquid crystal cell 100-1 to the fourth liquid crystal cell 100-4 are associated with each other.

[0094] The optical element control unit 330A can generate signals for controlling the optical element 10 and input the generated signals to the first liquid crystal cell 100-1 to the fourth liquid crystal cell 100-4, thereby controlling the shape and gradation of the light distribution.

[0095] Specifically, the optical element control unit 330A determines a weighting coefficient b corresponding to the lighting mode information from among a plurality of weighting coefficients 341 stored in the storage unit 340, based on the lighting mode information transmitted from the information communication terminal 40. The optical element control unit 330A determines a gradation level based on the gradation information transmitted from the information communication terminal 40. The optical element control unit 330A acquires a lookup table corresponding to the weighting coefficient b from among a plurality of lookup tables 342A stored in the storage unit 340. The optical element control unit 330A acquires voltages of the first to fourth transparent electrodes 120-1 to 120-4 of the first to fourth liquid crystal cells 100-1 to 100-4, respectively, corresponding to the gradation level, based on the acquired lookup table. The optical element control unit 330A inputs a signal including the acquired voltage to the first transparent electrode 120-1 to the fourth transparent electrode 120-4 of each of the first liquid crystal cell 100-1 to the fourth liquid crystal cell 100-4, thereby controlling the light emitted from the light source 20 to have a light distribution with a gradation desired by the user.

[0096] As described above, in the lighting system 1A according to this embodiment, a plurality of lookup tables 342A are stored, and the optical element control unit 330A acquires a predetermined lookup table, thereby enabling the gradation to be controlled so that the light distribution angle increases (or decreases) based on the acquired lookup table. That is, the lighting system 1 facilitates gradation control of the light distribution. Furthermore, Equation (2) includes a weighting coefficient b, and by changing the weighting coefficient b, it is possible to control the gradation of the light distribution in accordance with the application (lighting mode) used by the user. Therefore, in the lighting system 1A, the gradation of the light distribution can be controlled in accordance with the lighting mode.

[0097] Third Embodiment A lighting system 1B according to one embodiment of the present invention will be described with reference to Fig. 14. In the following, when the configuration of the lighting system 1B is similar to the configuration of the lighting system 1, the description of the configuration of the lighting system 1B may be omitted.

[0098] 14 is a block diagram illustrating a lighting system 1B according to an embodiment of the present invention. The control device 30 includes a communication unit 310, a light source control unit 320, and an optical element control unit 330B. The information communication terminal 40 includes a communication unit 410, a display unit 420, an input unit 430, a calculation unit 440B, and a storage unit 450B. The storage unit 450B stores weighting coefficients 451B corresponding to a plurality of lighting modes.

[0099] The calculation unit 440B is, for example, a computer. The calculation unit 440B can generate gradation data necessary for controlling the optical element 10. Specifically, the calculation unit 440B determines a weighting coefficient b corresponding to the illumination mode information from among a plurality of weighting coefficients 451B stored in the storage unit 450B based on the illumination mode information generated by the input unit 430. The calculation unit 440B determines a gradation level based on the gradation information generated by the input unit 430. The calculation unit 440B calculates a voltage to be applied to the transparent electrode 120 based on the determined gradation level and the relational expression f(x) = g(x). The voltage is calculated for all of the first transparent electrodes 120-1 to fourth transparent electrodes 120-4 of each of the first liquid crystal cell 100-1 to fourth liquid crystal cell 100-4. The gradation data including the calculated voltage is transmitted to the control device 30 via the communication unit 410.

[0100] The optical element control unit 330B generates signals for controlling the optical element 10 based on the transmitted gradation data, and inputs the generated signals to the first liquid crystal cell 100-1 to the fourth liquid crystal cell 100-4, thereby controlling the shape and gradation of the light distribution.

[0101] As described above, in lighting system 1B according to this embodiment, a program is installed in user's information communication terminal 40, and calculation unit 440B calculates voltage x to be applied to transparent electrode 120 using equation (2). The calculated voltage x is transmitted to control device 30, and optical element control unit 330B can control the gradation so that the light distribution angle monotonically increases (or monotonically decreases) based on the transmitted voltage x. That is, lighting system 1A facilitates gradation control of light distribution.

[0102] It is understood that within the scope of the concept of the present invention, those skilled in the art may make various modifications and alterations, and that these modifications and alterations also fall within the scope of the present invention. For example, even if a person skilled in the art appropriately adds, deletes, or modifies the design of the above-described embodiments, or adds, omits, or modifies the conditions of steps, these modifications are also included within the scope of the present invention as long as they maintain the gist of the present invention.

[0103] Furthermore, other effects and advantages brought about by each embodiment that are clear from the description in this specification or that can be appropriately conceived by a person skilled in the art are naturally understood to be brought about by the present invention. [Explanation of symbols]

[0104] 1, 1A, 1B: lighting system, 10: optical element, 20: light source, 30: control device, 40: information and communication terminal, 100: liquid crystal cell, 110: substrate, 120: transparent electrode, 121: connection pad, 122: terminal, 130: first alignment film, 140: sealing material, 150: liquid crystal layer, 160: optical elastic resin layer, 170: flexible printed circuit board (FPCs), 310: communication unit, 320: light source control unit, 330, 330A: optical element control unit, 340: memory unit, 342A: look-up table, 410: communication unit, 420: display unit, 430: input unit, 440B: calculation unit, 450B: memory unit, 1000-1: first light, 1000-2: second light

Claims

1. A light source and a liquid crystal cell that changes the light distribution angle of the light emitted from the light source; a control device for controlling the gradation of the light distribution angle, The liquid crystal cell is a first substrate on which first transparent electrodes and second transparent electrodes each extending in a first direction are alternately provided; a second substrate on which third transparent electrodes and fourth transparent electrodes are alternately provided, each extending in a second direction intersecting the first direction; a liquid crystal layer between the first substrate and the second substrate; The control device a communication unit that receives gradation information of the light distribution angle from an information communication terminal; a storage unit that stores a weighting coefficient that associates a change in the gradation of the light distribution angle with a change in the light distribution angle; a control unit that calculates a first voltage to be input to the first transparent electrode, a second voltage to be input to the second transparent electrode, a third voltage to be input to the third transparent electrode, and a fourth voltage to be input to the fourth transparent electrode based on the gradation information and the weighting coefficient.

2. The lighting system of claim 1 , wherein the storage unit includes a plurality of the weighting factors corresponding to a plurality of lighting modes.

3. 2. The lighting system of claim 1, wherein the storage unit includes a lookup table in which gray levels of the light distribution angles, the weighting coefficients, the first voltages, the second voltages, the third voltages, and the fourth voltages are associated with each other.

4. The lighting system according to claim 3 , wherein the storage unit includes a plurality of the look-up tables corresponding to a plurality of the weighting coefficients.

5. The lookup table includes a first function f(x) that represents the correlation between the voltage x calculated based on the measurement data and the light distribution angle f, and a second function g(p)=a(p / p) that converts the gray level p into the light distribution angle g. ｍａｘ ) ｂ + c (where a and c are arbitrary constants, b is the weighting coefficient, and p ｍａｘ 4. The lighting system according to claim 3, wherein the voltage x corresponding to the gradation level p is associated with the gradation level p based on the fact that the light distribution angle g determined from the second function g(p) matches the light distribution angle f determined from the first function f(x) (g(x)=f(x)).

6. 6. The lighting system of claim 5, wherein the weighting factor b is greater than or equal to 1.

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