lighting equipment

Abstract

This lighting apparatus includes a light source, a light-emitting element, and a control device for controlling the light-emitting element, the control device including a signal generating circuit unit, a switch circuit unit that includes first through fourth output channels that are electrically connected to first through fourth transparent electrodes, respectively, of a liquid crystal cell of the light-emitting element, and a first signal line and a second voltage signal line that are connected to the signal generating circuit unit and the switch circuit unit and to each of which a voltage signal generated by the signal generating circuit unit is transmitted, the switch circuit unit being driven so that, in a first subframe period of a one-frame period, a first voltage signal line and a first output channel are placed in a conducting state, and a second signal line and a second output channel are placed in a conducting state, and the switch circuit unit being driven so that, in a second subframe period of a one-frame period, the first voltage signal line and a third output channel are placed in a conducting state, and the second signal line and a fourth output channel are placed in a conducting state.

Description

[Technical Field]

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

[0002] Conventionally, optical elements, known as liquid crystal lenses, have been known that utilize the phenomenon in which the refractive index of liquid crystal changes when the voltage applied to the liquid crystal is adjusted. Furthermore, development of lighting devices using light sources and liquid crystal lenses is progressing (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-117344 Summary of the Invention [Problem to be solved by the invention]

[0004] The optical element of the lighting device includes a control circuit for controlling the light distribution, which includes a digital-to-analog converter (DAC) and an amplifier (AMP) that occupy a large area. In conventional optical elements, a voltage signal is generated for each transparent electrode that applies voltage to the liquid crystal, and optical elements with a large number of transparent electrodes require a large number of DACs and AMPs. However, increasing the number of DACs and AMPs, which occupy a large area, increases the size of the control circuit and increases manufacturing costs. Therefore, there has been a demand for reducing the number of DACs and AMPs included in the control circuit and reduce manufacturing costs.

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

[0006] An illumination device according to one embodiment of the present invention includes a light source, an optical element including a first liquid crystal cell and a second liquid crystal cell that transmits light emitted from the light source in a variably diffused manner, and a control device connected to the optical element and controlling the optical element, wherein each of the first liquid crystal cell and the second liquid crystal cell includes a first substrate on which first transparent electrodes and second transparent electrodes extending in a first direction are alternately provided, a second substrate on which third transparent electrodes and fourth transparent electrodes extending in a second direction intersecting the first direction are alternately provided, and a liquid crystal layer between the first substrate and the second substrate, and the control device includes a first output channel electrically connected to the first transparent electrode of the first liquid crystal cell, a second output channel electrically connected to the second transparent electrode of the first liquid crystal cell, a third output channel electrically connected to the third transparent electrode of the first liquid crystal cell, and a fourth output channel electrically connected to the fourth transparent electrode of the first liquid crystal cell. the first liquid crystal cell and the second liquid crystal cell; a signal generation circuit section that generates a plurality of voltage signals to be input to the first transparent electrode, the second transparent electrode, the third transparent electrode, and the fourth transparent electrode of each of the first and second liquid crystal cells; and first and second voltage signal lines that are connected to the switch circuit section and the signal generation circuit section and transmit one of the generated plurality of voltage signals, wherein one frame period includes a first sub-frame period and a second sub-frame period, wherein the switch circuit section drives to bring the first voltage signal line and the first output channel into conduction and the second voltage signal line and the second output channel into conduction, and wherein the switch circuit section drives to bring the first voltage signal line and the third output channel into conduction and the second voltage signal line and the fourth output channel into conduction, and wherein

[0007] An illumination device according to one embodiment of the present invention includes a light source, an optical element including a first liquid crystal cell and a second liquid crystal cell that transmits light emitted from the light source in a variably diffused manner, and a control device connected to the optical element and controlling the optical element, wherein each of the first liquid crystal cell and the second liquid crystal cell includes a first substrate on which first transparent electrodes and second transparent electrodes extending in a first direction are alternately provided, a second substrate on which third transparent electrodes and fourth transparent electrodes extending in a second direction intersecting the first direction are alternately provided, and a liquid crystal layer between the first substrate and the second substrate; and a first output channel electrically connected to the first transparent electrode of the first liquid crystal cell, a second output channel electrically connected to the second transparent electrode of the first liquid crystal cell, a third output channel electrically connected to the third transparent electrode of the first liquid crystal cell, a fourth output channel electrically connected to the fourth transparent electrode of the first liquid crystal cell, a fifth output channel electrically connected to the first transparent electrode of the second liquid crystal cell, a sixth output channel electrically connected to the second transparent electrode of the second liquid crystal cell, and a seventh output channel electrically connected to the third transparent electrode of the second liquid crystal cell. a switch circuit section including an eighth output channel electrically connected to the first transparent electrode of the first liquid crystal cell and the fourth transparent electrode of the second liquid crystal cell; a signal generation circuit section that generates a plurality of voltage signals to be input to the first transparent electrode, the second transparent electrode, the third transparent electrode, and the fourth transparent electrode of each of the first liquid crystal cell and the second liquid crystal cell; and first, second, third, and fourth voltage signal lines that are connected to the switch circuit section and the signal generation circuit section and through which each of the generated voltage signals is transmitted, The first sub-frame period includes a first sub-frame period and a second sub-frame period, and in the first sub-frame period, the switch circuit section drives the first voltage signal line, the second voltage signal line, the third voltage signal line, and the fourth voltage signal line so as to be conductive with the first output channel, the second output channel, the third output channel, and the fourth output channel, respectively, and in the second sub-frame period, the switch circuit section drives the first voltage signal line, the second voltage signal line, the third voltage signal line, and the fourth voltage signal line so as to be conductive with the fifth output channel, the sixth output channel, the seventh output channel,and the eighth output channel. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram illustrating a configuration of an illumination device according to an embodiment of the present invention. [Figure 2] 1 is a block diagram showing a configuration of an illumination device according to an embodiment of the present invention. [Figure 3A] 1 is a schematic cross-sectional view showing a configuration of an illumination device according to an embodiment of the present invention. [Figure 3B] 1 is a schematic cross-sectional view showing a configuration of an illumination device 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 device 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 device 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 device 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 device according to one embodiment of the present invention. [Figure 6A] 4 is a timing chart showing voltage signals input to transparent electrodes of a liquid crystal cell to control light distribution in an illumination device according to an embodiment of the present invention. [Figure 6B] 4 is a timing chart showing voltage signals input to transparent electrodes of a liquid crystal cell to control light distribution in an illumination device according to an embodiment of the present invention. [Figure 6C] 4 is a timing chart showing voltage signals input to transparent electrodes of a liquid crystal cell to control light distribution in an illumination device according to an embodiment of the present invention. [Figure 7] 1 is a block diagram showing a configuration of an illumination device according to an embodiment of the present invention. [Figure 8]4 is a timing chart showing voltage signals input to transparent electrodes of a liquid crystal cell to control light distribution in an illumination device according to an embodiment of the present invention. [Figure 9] 1 is a block diagram showing a configuration of an illumination device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

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

[0010] 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.

[0011] 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.

[0012] 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.

[0013] First Embodiment An illumination device 1 according to one embodiment of the present invention will be described with reference to FIGS. 1 to 6C.

[0014] [1. Configuration of lighting device 1] 1 is a schematic diagram showing the configuration of an illumination device 1 according to one embodiment of the present invention. As shown in FIG. 1, the illumination device 1 includes an optical element 10, a light source 20, a control device 30, and a power supply 40.

[0015] 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.

[0016] The light source 20 can emit 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 emitted from the fourth liquid crystal cell 100-4. In the lighting device 1, the four liquid crystal cells 100 included in the optical element 10 control the diffusion and polarization of light, and can change the light distribution of the light emitted from the fourth liquid crystal cell 100-4. That is, the optical element 10 can transmit the light emitted from the light source 20 in a diffusible manner and control the light distribution. 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.

[0017] The control device 30 is connected to the optical element 10 and can control the optical element 10. 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). Although detailed description will be omitted, the control device 30 is also connected to the light source 20 and can control the light source 20. The configuration of the control device 30 will be described in detail later.

[0018] The power supply 40 is connected to the control device 30 and can supply power to the control device 30. That is, the power supply 40 can generate a predetermined voltage. For example, the power supply 40 can generate two voltages (e.g., 3.3 V and 30 V), but is not limited to this. The power supply 40 may also include a voltage that is GND (e.g., 0 V). For convenience, this specification may also refer to the case where a voltage is generated even in the case of GND.

[0019] 2 is a block diagram showing the configuration of a lighting device 1 according to one embodiment of the present invention. As shown in FIG. 2, the control device 30 includes a signal generating circuit unit 310, a switch circuit unit 320, a first voltage signal line 330-1, a second voltage signal line 330-2, and a timing control signal line 340.

[0020] The signal generation circuit unit 310 can perform arithmetic processing using data or information. Specifically, the signal generation circuit unit 310 can generate a plurality of voltage signals to be input to the liquid crystal cell 100 based on a predetermined program. The signal generation circuit unit 310 can also generate a timing control signal to control the switch circuit unit 320 in accordance with the voltage signals output from the signal generation circuit unit 310. The signal generation circuit unit 310 is, for example, an FPGA, but is not limited to this.

[0021] The signal generating circuit unit 310 and the switch circuit unit 320 are connected via a first voltage signal line 330-1 and a second voltage signal line 330-2. Therefore, two voltage signals out of the multiple voltage signals generated by the signal generating circuit unit 310 are input to the switch circuit unit 320 via the first voltage signal line 330-1 and the second voltage signal line 330-2. A digital-to-analog converter circuit (DAC) 331 and an amplifier circuit (AMP) 332 are connected to the first voltage signal line 330-1 and the second voltage signal line 330-2, respectively. Voltages of 3.3 V and 30 V are supplied to the DAC 331 and the AMP 332, respectively, from the power supply 40. The voltage signal output from the signal generating circuit unit 310 is converted into a digital signal by the DAC 331, and the voltage is amplified by the AMP 332 and input to the switch circuit unit 320. In the following description, it is assumed that the voltage signal output from the signal generating circuit unit 310 includes a voltage signal that has been converted into a digital signal by the DAC 331 and whose voltage has been amplified by the AMP 332.

[0022] The switch circuit unit 320 includes 16 output channels CH (first output channel CH1 to sixteenth output channel CH16). A timing control signal is input to the switch circuit unit 320 via a timing control signal line 340. The timing control signal includes information about two output channels CH that are electrically connected to the first voltage signal line 330-1 and the second voltage signal line 330-2. In other words, the timing control signal includes information about the output channel CH that is selected in accordance with two voltage signals input from the signal generation circuit unit 310 to the first voltage signal line 330-1 and the second voltage signal line 330-2. Based on the timing control signal, the switch circuit unit 320 can be driven to electrically connect the first voltage signal line 330-1 and the second voltage signal line 330-2 to two of the first output channel CH1 to the sixteenth output channel CH16. For example, the switch circuit unit 320 drives the first voltage signal line 330-1 and the second voltage signal line 330-2 so that they are electrically connected to the first output channel CH1 and the second output channel CH2, respectively. In this case, two voltage signals generated by the signal generation circuit unit 310 are input to the switch circuit unit 320 via the first voltage signal line 330-1 and the second voltage signal line 330-2 and output from the first output channel CH1 and the second output channel CH2. Note that in this case, the first voltage signal line 330-1 and the second voltage signal line 330-2 are not electrically connected to the third output channel CH3 to the sixteenth output channel CH16. In other words, the first voltage signal line 330-1 and the second voltage signal line 330-2 are not electrically connected to the third output channel CH3 to the sixteenth output channel CH16. In other words, each of the third output channel CH3 to the sixteenth output channel CH16 is in a high-impedance state. The switch circuit unit 320 is, for example, an analog switch circuit (ASW), but is not limited to this.

[0023] The first output channel CH1 to the fourth output channel CH4 are connected to the first liquid crystal cell 100-1 via flexible printed circuits (FPCs) 170 (see FIG. 1). The fifth output channel CH5 to the eighth output channel CH8 are connected to the second liquid crystal cell 100-2 via the FPCs 170. The ninth output channel CH9 to the twelfth output channel CH12 are connected to the third liquid crystal cell 100-3 via the FPCs 170. The thirteenth output channel CH13 to the sixteenth output channel CH16 are connected to the fourth liquid crystal cell 100-4 via the FPCs 170.

[0024] 2. Configuration of Optical Element 10 3A and 3B are schematic cross-sectional views showing the configuration of an illumination device 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.

[0025] 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. A first alignment film 130-1 is also provided on the first substrate 110-1 to cover the first transparent electrodes 120-1 and the second transparent electrodes 120-2. Third transparent electrodes 120-3 and fourth transparent electrodes 120-4 are alternately provided on the second substrate 110-2. 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 electrodes 120-1 and the second transparent electrodes 120-2 face the third transparent electrodes 120-3 and the fourth transparent electrodes 120-4, and are bonded together via a sealant 140 provided on the peripheries 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 sealing material 140, and a liquid crystal layer 150 is provided between the first substrate 110-1 and the second substrate 110-2.

[0026] 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.

[0027] 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.

[0028] 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).

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] [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 device 1 according to one 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. The first substrate 110-1 and the second substrate 110-2 are bonded together so that the electrode pattern shown in Fig. 4A faces the electrode pattern shown in Fig. 4B.

[0036] 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.

[0037] 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.

[0038] 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 electrode 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 electrode. Similarly, a conductive electrode 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 electrode. 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.

[0039] 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 extending direction of the transparent electrode 120 differs by 90°.

[0040] 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 liquid crystal cell 100-1 to the fourth liquid crystal cell 100-4, FPCs 170 are provided on the exposed first terminal 122-1 to the fourth terminal 122-4 (see FIG. 1).

[0041] The first to fourth output channels CH1 to CH4 are electrically connected to the first to fourth terminals 122-1 to 122-4 of the first liquid crystal cell 100-1 via FPCs 170. The fifth to eighth output channels CH5 to CH8 are electrically connected to the first to fourth terminals 122-1 to 122-4 of the second liquid crystal cell 100-2 via FPCs 170. The ninth to twelfth output channels CH9 to CH12 are electrically connected to the first to fourth terminals 122-1 to 122-4 of the third liquid crystal cell 100-3 via FPCs 170. The thirteenth to sixteenth output channels CH13 to CH16 are electrically connected to the first to fourth terminals 122-1 to 122-4 of the fourth liquid crystal cell 100-4 via FPCs 170. Therefore, the control device 30 can input voltage signals to each of the first transparent electrode 120-1 to the fourth transparent electrode 120-4 of the liquid crystal cell 100 via the FPCs 170, thereby controlling the optical element .

[0042] 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 device 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.

[0043] 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 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. Furthermore, the polarization plane (the polarization axis or the direction of the polarization component) of light transmitted through the liquid crystal layer 150 is rotated 90° in accordance with the alignment direction of the liquid crystal molecules. In other words, the light transmitted through the liquid crystal layer 150 (more specifically, the polarization component of the transmitted light) is optically rotated.

[0044] 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, 8 μm≦d≦50 μm, preferably 10 μm≦d≦30 μm, and more preferably 15 μm≦d≦25 μm), the electric field formed between the transparent electrodes 120 does not have much effect on the liquid crystal molecules located near the center between the first substrate 110-1 and the second substrate 110-2.

[0045] 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.

[0046] 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).

[0047] 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).

[0048] [5. Control of light distribution by lighting device 1] 6A to 6C are timing charts showing voltage signals input to the transparent electrodes 120 of the liquid crystal cells 100 to control the light distribution in the lighting device 1 according to one embodiment of the present invention. In the lighting device 1 according to this embodiment, predetermined voltage signals are sequentially input to the first transparent electrodes 120-1 to 120-4 of the first to fourth liquid crystal cells 100-1 to 100-4, respectively, to drive the liquid crystal cells 100 in a time-division manner. That is, in the lighting device 1, the light distribution of light passing through the optical element 10 can be controlled by driving the plurality of liquid crystal cells 100 in a time-division manner based on a single signal generating circuit unit 310. More specifically, in the lighting device 1 according to this embodiment, a plurality of liquid crystal cells 100 are connected to a switch circuit section 320, and a pair of an analog conversion circuit 331 and an amplifier circuit 332 is provided between the switch circuit section 320 and the signal generation circuit section 310, and the connection states between the analog conversion circuit 331 and the amplifier circuit 332 and the transparent electrodes 120 of each liquid crystal cell 100 are switched in a time-division manner via the switch circuit section 320, thereby enabling time-division driving of each liquid crystal cell 100. Specific examples of time-division driving will be described in detail below.

[0049] Figure 6A is a timing chart for controlling optical element 10 so that the light distribution shape is circular, Figure 6B is a timing chart for controlling optical element 10 so that the light distribution shape is linear and spreads in the x-axis direction, and Figure 6C is a timing chart for controlling optical element 10 so that the light distribution shape is linear and spreads in the y-axis direction.

[0050] 6A to 6C, the voltage signals output from the first to fourth output channels CH1 to CH4 are input to the first to fourth transparent electrodes 120-1 to 120-4 of the first liquid crystal cell 100-1, respectively. The voltage signals output from the fifth to eighth output channels CH5 to CH8 are input to the first to fourth transparent electrodes 120-1 to 120-4 of the second liquid crystal cell 100-2, respectively. The voltage signals output from the ninth to twelfth output channels CH9 to CH12 are input to the first to fourth transparent electrodes 120-1 to 120-4 of the third liquid crystal cell 100-3, respectively. The voltage signals output from the thirteenth to sixteenth output channels CH13 to CH16 are input to the first to fourth transparent electrodes 120-1 to 120-4 of the fourth liquid crystal cell 100-4, respectively.

[0051] In the lighting device 1, as shown in FIGS. 6A to 6C, one frame period is divided into eight sub-frame periods SF (first sub-frame period SF1 to eighth sub-frame period SF8).

[0052] [5-1. Circular light distribution] As shown in FIG. 6A, in the first subframe period SF1, a first voltage signal having a square wave is output from the first output channel CH1, and a second voltage signal having a square wave is output from the second output channel CH2. The phase of the first voltage signal is opposite to the phase of the second voltage signal. In other words, the phase of the first voltage signal is 180° different from the phase of the second voltage signal. Meanwhile, the third output channel CH3 to the sixteenth output channel CH16 are in a high-impedance state (High-Z).

[0053] During the first subframe period SF1, the first voltage signal and the second voltage signal generated by the signal generating circuit 310 are input to the switch circuit 320 via the first voltage signal line 330-1 and the second voltage signal line 330-2, respectively. The switch circuit 320 drives the first voltage signal line 330-1 and the second voltage signal line 330-2 so that they are electrically connected to the first output channel CH1 and the second output channel CH2, respectively. Therefore, during the first subframe period SF1, as described above, the first voltage signal and the second voltage signal are output from the first output channel CH1 and the second output channel CH2, respectively. Meanwhile, because the first voltage signal line 330-1 and the second voltage signal line 330-2 are electrically disconnected from the third output channel CH3 to the sixteenth output channel CH16, the third output channel CH3 to the sixteenth output channel CH16 are in a high-impedance state.

[0054] Therefore, in the first sub-frame period SF1, a high voltage or a low voltage is applied to each of the first transparent electrode 120-1 and the second transparent electrode 120-2 of the first liquid crystal cell 100-1. That is, in the first sub-frame period SF1, a transverse electric field is generated between the first transparent electrode 120-1 and the second transparent electrode 120-2 of the first liquid crystal cell 100-1.

[0055] During the second subframe period SF2, the third voltage signal having a square wave and the fourth voltage signal having a square wave generated by the signal generating circuit 310 are input to the switch circuit 320 via the first voltage signal line 330-1 and the second voltage signal line 330-2, respectively. Here, the phase of the third voltage signal is opposite to the phase of the fourth voltage signal. The switch circuit 320 drives the first voltage signal line 330-1 and the second voltage signal line 330-2 so that they are conductive with the third output channel CH3 and the fourth output channel CH4, respectively. Therefore, during the second subframe period SF2, the third voltage signal and the fourth voltage signal are output from the third output channel CH3 and the fourth output channel CH4, respectively. On the other hand, since the first voltage signal line 330-1 and the second voltage signal line 330-2 are in a non-conductive state with the first output channel CH1, the second output channel CH2, and the fifth output channel CH5 to the sixteenth output channel CH16, the first output channel CH1, the second output channel CH2, and the fifth output channel CH5 to the sixteenth output channel CH16 are in a high impedance state.

[0056] Therefore, in the second sub-frame period SF2, a high voltage or a low voltage is applied to each of the third transparent electrode 120-3 and the fourth transparent electrode 120-4 of the first liquid crystal cell 100-1. That is, in the second sub-frame period SF2, a horizontal electric field is generated between the third transparent electrode 120-3 and the fourth transparent electrode 120-4 of the first liquid crystal cell 100-1.

[0057] During the second sub-frame period SF2, the first output channel CH1 and the second output channel CH2 are in a high impedance state, and therefore the high voltage or low voltage applied to the first transparent electrode 120-1 and the second transparent electrode 120-2 of the first liquid crystal cell 100-1 is maintained by the capacitance of the liquid crystal in the liquid crystal layer 150. Therefore, even during the second sub-frame period SF2, a transverse electric field is maintained between the first transparent electrode 120-1 and the second transparent electrode 120-2 of the first liquid crystal cell 100-1.

[0058] The same is true for the third sub-frame period SF3 to the eighth sub-frame period. That is, in the third sub-frame period SF3 and the fourth sub-frame period SF4, a transverse electric field is generated between the first transparent electrode 120-1 and the second transparent electrode 120-2 of the second liquid crystal cell 100-2, and between the third transparent electrode 120-3 and the fourth transparent electrode 120-4 of the second liquid crystal cell 100-2. In the fifth sub-frame period SF5 and the sixth sub-frame period SF6, a transverse electric field is generated between the first transparent electrode 120-1 and the second transparent electrode 120-2 of the third liquid crystal cell 100-3, and between the third transparent electrode 120-3 and the fourth transparent electrode 120-4 of the third liquid crystal cell 100-3. In the seventh sub-frame period SF7 and the eighth sub-frame period SF8, a transverse electric field is generated between the first transparent electrode 120-1 and the second transparent electrode 120-2 of the fourth liquid crystal cell 100-4, and between the third transparent electrode 120-3 and the fourth transparent electrode 120-4 of the fourth liquid crystal cell 100-4.

[0059] During the third sub-frame period SF3 to the eighth sub-frame period SF8, the output channel CH from which no voltage signal is output is in a high impedance state, and therefore the capacitance of the liquid crystal in the liquid crystal layer 150 maintains the high or low voltage applied to the transparent electrode 120.

[0060] Therefore, the diffusion characteristics of the first to fourth liquid crystal cells 100-1 to 100-4 in one frame period are as shown in Table 1. In each of the first to eighth subframe periods SF1 to SF8, a horizontal electric field is generated between two adjacent transparent electrodes 120 on one substrate 110 side of the liquid crystal cell 100. However, because the high or low voltage applied to the transparent electrodes 120 is maintained by the capacitance of the liquid crystal in the liquid crystal layer 150, the first to fourth liquid crystal cells 100-1 to 100-4 have the diffusion characteristics shown in Table 1 in one frame period. In this case, the P-polarized component and the S-polarized component of the light emitted from the light source 20 are each diffused in the x-axis and y-axis directions by the optical element 10. Therefore, the light emitted from the light source 20 is controlled by the optical element 10 to have a circular light distribution. It should be noted that by changing the magnitude of the high voltage and low voltage applied to each transparent electrode 120, it is possible to control the light distribution to have an elliptical shape.

[0061] [Table 1]

[0062] The cycle of one frame period is 30 Hz to 120 Hz, preferably 60 Hz. When the cycle of one frame period is in the above range, the voltage applied to the transparent electrode 120 can be maintained by the capacitance of the liquid crystal in the liquid crystal layer 150.

[0063] [5-2. Linear light distribution spreading in the x-axis direction] As shown in FIG. 6B, during the first subframe period SF1, a first voltage signal and a second voltage signal having an intermediate voltage (a voltage between a high voltage and a low voltage) generated by the signal generating circuit 310 are input to the switch circuit 320 via the first voltage signal line 330-1 and the second voltage signal line 330-2, respectively. The intermediate voltage is a fixed voltage, and the phase of the first voltage signal is the same as the phase of the second voltage signal. The switch circuit 320 drives the first voltage signal line 330-1 and the second voltage signal line 330-2 so that they are electrically connected to the first output channel CH1 and the second output channel CH2, respectively. Therefore, during the first subframe period SF1, the first voltage signal and the second voltage signal are output from the first output channel CH1 and the second output channel CH2, respectively. On the other hand, since the first voltage signal line 330-1 and the second voltage signal line 330-2 are in a non-conductive state with the third output channel CH3 to the sixteenth output channel CH16, the third output channel CH3 to the sixteenth output channel CH16 are in a high impedance state.

[0064] Therefore, in the first sub-frame period SF1, an intermediate voltage is applied to each of the first transparent electrode 120-1 and the second transparent electrode 120-2 of the first liquid crystal cell 100-1. In this case, the first transparent electrode 120-1 and the second transparent electrode 120-2 are at the same potential, and no transverse electric field is generated between the first transparent electrode 120-1 and the second transparent electrode 120-2.

[0065] The second sub-frame period SF2 shown in FIG. 6B is similar to the second sub-frame period SF2 shown in FIG. 6A, and therefore a description thereof will be omitted.

[0066] Therefore, in the second sub-frame period SF2, a high voltage or a low voltage is applied to each of the third transparent electrode 120-3 and the fourth transparent electrode 120-4 of the first liquid crystal cell 100-1. That is, in the second sub-frame period SF2, a transverse electric field is generated between the third transparent electrode 120-3 and the fourth transparent electrode 120-4 of the first liquid crystal cell 100-1.

[0067] During the second sub-frame period SF2, the first output channel CH1 and the second output channel CH2 are in a high-impedance state, and therefore the intermediate voltage applied to the first transparent electrode 120-1 and the second transparent electrode 120-2 of the first liquid crystal cell 100-1 is maintained by the capacitance of the liquid crystal in the liquid crystal layer 150. Therefore, during the first sub-frame period SF1 and the second sub-frame period SF2, a transverse electric field is generated only between the third transparent electrode 120-3 and the fourth transparent electrode 120-4 of the first liquid crystal cell 100-1.

[0068] The same is true for the third sub-frame period SF3 to the eighth sub-frame period. That is, in the third sub-frame period SF3 and the fourth sub-frame period SF4, a transverse electric field is generated only between the third transparent electrode 120-3 and the fourth transparent electrode 120-4 of the second liquid crystal cell 100-2. In the fifth sub-frame period SF5 and the sixth sub-frame period SF6, a transverse electric field is generated only between the first transparent electrode 120-1 and the second transparent electrode 120-2 of the third liquid crystal cell 100-3. In the seventh sub-frame period SF7 and the eighth sub-frame period SF8, a transverse electric field is generated only between the first transparent electrode 120-1 and the second transparent electrode 120-2 of the fourth liquid crystal cell 100-4.

[0069] During the third sub-frame period SF3 to the eighth sub-frame period SF8, the output channel CH to which no voltage signal is output is in a high impedance state, so the capacitance of the liquid crystal in the liquid crystal layer 150 maintains the high voltage, low voltage, or intermediate voltage applied to the transparent electrode 120.

[0070] Therefore, the diffusion characteristics of the first to fourth liquid crystal cells 100-1 to 100-4 in one frame period are as shown in Table 2. In each of the second sub-frame period SF2, the fourth sub-frame period SF4, the fifth sub-frame period SF5, and the seventh sub-frame period SF7, a horizontal electric field is controlled to be generated between two adjacent transparent electrodes 120 on one substrate 110 side of the liquid crystal cell 100. In each of the first sub-frame period SF1, the third sub-frame period SF3, the sixth sub-frame period SF6, and the eighth sub-frame period SF8, an intermediate voltage is controlled to be applied to the two transparent electrodes 120 on the other substrate 110 side of the liquid crystal cell 100. However, because the capacitance of the liquid crystal in the liquid crystal layer 150 maintains the high voltage, low voltage, or intermediate voltage applied to the transparent electrode 120, the first to fourth liquid crystal cells 100-1 to 100-4 have the diffusion characteristics shown in Table 2 during one frame period. In this case, the P-polarized component and the S-polarized component of the light emitted from the light source 20 are each diffused only in the x-axis direction by the optical element 10. Therefore, the light emitted from the light source 20 is controlled by the optical element 10 to have a linear light distribution that spreads in the x-axis direction.

[0071] [Table 2]

[0072] The high voltage, low voltage, and intermediate voltage are +15 V, -15 V, and 0 V, respectively, but are not limited to these. The high voltage, low voltage, and intermediate voltage may be +30 V, 0 V, and +15 V, respectively. Note that the above voltage values ​​are merely examples and are not limited to these.

[0073] [5-3. Linear light distribution spreading in the y-axis direction] The first sub-frame period SF1 shown in FIG. 6C is similar to the first sub-frame period SF1 shown in FIG. 6A, and therefore a description thereof will be omitted.

[0074] Therefore, in the first sub-frame period SF1, a high voltage or a low voltage is applied to each of the first transparent electrode 120-1 and the second transparent electrode 120-2 of the first liquid crystal cell 100-1. That is, in the first sub-frame period SF1, a transverse electric field is generated between the first transparent electrode 120-1 and the second transparent electrode 120-2 of the first liquid crystal cell 100-1.

[0075] 6C , during the second subframe period SF2, the third voltage signal and fourth voltage signal having an intermediate voltage generated by the signal generation circuit 310 are input to the switch circuit 320 via the first voltage signal line 330-1 and the second voltage signal line 330-2, respectively. The switch circuit 320 drives the first voltage signal line 330-1 and the second voltage signal line 330-2 so that they are electrically connected to the third output channel CH3 and the fourth output channel CH4, respectively. Therefore, during the second subframe period SF2, the third voltage signal and the fourth voltage signal are output from the third output channel CH3 and the fourth output channel CH4, respectively. On the other hand, since the first voltage signal line 330-1 and the second voltage signal line 330-2 are in a non-conductive state with the first output channel CH1, the second output channel CH2, and the fifth output channel CH5 to the sixteenth output channel CH16, the first output channel CH1, the second output channel CH2, and the fifth output channel CH5 to the sixteenth output channel CH16 are in a high impedance state.

[0076] Therefore, in the second sub-frame period SF2, an intermediate voltage is applied to each of the third transparent electrode 120-3 and the fourth transparent electrode 120-4 of the first liquid crystal cell 100-1. In this case, the third transparent electrode 120-3 and the fourth transparent electrode 120-4 are at the same potential, and no transverse electric field is generated between the third transparent electrode 120-3 and the fourth transparent electrode 120-4.

[0077] During the second sub-frame period SF2, the first output channel CH1 and the second output channel CH2 are in a high impedance state, and therefore the high or low voltage applied to the first transparent electrode 120-1 and the second transparent electrode 120-2 of the first liquid crystal cell 100-1 is maintained by the capacitance of the liquid crystal in the liquid crystal layer 150. Therefore, during the first sub-frame period SF1 and the second sub-frame period SF2, a transverse electric field is generated only between the first transparent electrode 120-1 and the second transparent electrode 120-2 of the first liquid crystal cell 100-1.

[0078] The same is true for the third sub-frame period SF3 to the eighth sub-frame period SF8. That is, in the third sub-frame period SF3 and the fourth sub-frame period SF4, a transverse electric field is generated only between the first transparent electrode 120-1 and the second transparent electrode 120-2 of the second liquid crystal cell 100-2. In the fifth sub-frame period SF5 and the sixth sub-frame period SF6, a transverse electric field is generated only between the third transparent electrode 120-3 and the fourth transparent electrode 120-4 of the third liquid crystal cell 100-3. In the seventh sub-frame period SF7 and the eighth sub-frame period SF8, a transverse electric field is generated only between the third transparent electrode 120-3 and the fourth transparent electrode 120-4 of the fourth liquid crystal cell 100-4.

[0079] During the third sub-frame period SF3 to the eighth sub-frame period SF8, the output channel CH to which no voltage signal is output is in a high impedance state, so the capacitance of the liquid crystal in the liquid crystal layer 150 maintains the high voltage, low voltage, or intermediate voltage applied to the transparent electrode 120.

[0080] Therefore, the diffusion characteristics of the first liquid crystal cell 100-1 to the fourth liquid crystal cell 100-4 in one frame period are as shown in Table 3. In each of the first sub-frame period SF1, the third sub-frame period SF3, the sixth sub-frame period SF6, and the eighth sub-frame period SF8, a horizontal electric field is controlled to be generated between two adjacent transparent electrodes 120 on one substrate 110 side of the liquid crystal cell 100. In each of the second sub-frame period SF2, the fourth sub-frame period SF4, the fifth sub-frame period SF5, and the seventh sub-frame period SF7, an intermediate voltage is controlled to be applied to the two transparent electrodes 120 on the other substrate 110 side of the liquid crystal cell 100. However, because the capacitance of the liquid crystal in the liquid crystal layer 150 maintains the high voltage, low voltage, or intermediate voltage applied to the transparent electrode 120, the first to fourth liquid crystal cells 100-1 to 100-4 have the diffusion characteristics shown in Table 3 during one frame period. In this case, the P-polarized component and the S-polarized component of the light emitted from the light source 20 are each diffused only in the y-axis direction by the optical element 10. Therefore, the light emitted from the light source 20 is controlled by the optical element 10 to have a linear light distribution that spreads in the y-axis direction.

[0081] [Table 3]

[0082] As described above, in controlling light distribution by the lighting device 1 according to this embodiment, one frame is divided into a plurality of subframe periods SF. In each subframe period SF, the output channel of the switch circuit unit 320 is switched in accordance with two voltage signals input from the signal generation circuit unit 310 to a pair of voltage signal lines 330 (a first voltage signal line 330-1 and a second voltage signal line), and two voltage signals are input to each of two adjacent transparent electrodes 120. Therefore, the number of voltage signal lines 330 can be reduced more than the number of transparent electrodes 120, and as a result, the number of DACs and AMPs can be reduced. Therefore, in the lighting device 1, the control device 30 can be made smaller and manufacturing costs can be reduced.

[0083] Second Embodiment An illumination device 1A according to one embodiment of the present invention will be described with reference to Figures 7 and 8. Note that when the configuration of illumination device 1A is the same as that of illumination device 1, the description of the configuration of illumination device 1A may be omitted.

[0084] [1. Configuration of lighting device 1A] Fig. 7 is a block diagram showing the configuration of an illumination device 1A according to one embodiment of the present invention. As shown in Fig. 7, the illumination device 1A includes an optical element 10, a light source 20, a control device 30A, and a power supply 40. The control device 30A includes a signal generation circuit section 310, a switch circuit section 320A, a first voltage signal line 330-1, a second voltage signal line 330-2, a third voltage signal line 330-3, a fourth voltage signal line 330-4, and a timing control signal line 340.

[0085] The signal generating circuit section 310 and the switch circuit section 320A are connected via a first voltage signal line 330-1 to a fourth voltage signal line 330-4. Therefore, four voltage signals out of the multiple voltage signals generated by the signal generating circuit section 310 are input to the switch circuit section 320 via the first voltage signal line 330-1 to the fourth voltage signal line 330-4.

[0086] The switch circuit unit 320A can drive the first voltage signal line 330-1 to the fourth voltage signal line 330-4 and the first output channel CH1 to the sixteenth output channel CH16 based on the timing control signal so that they are electrically connected to each other. For example, the switch circuit unit 320A can drive the first voltage signal line 330-1 to the fourth voltage signal line 330-4 and the first output channel CH1 to the fourteenth output channel CH4 based on the timing control signal so that they are electrically connected to each other. Note that at this time, the first voltage signal line 330-1 to the fourth voltage signal line 330-4 and the fifth output channel CH5 to the sixteenth output channel CH16 are not electrically connected to each other. That is, each of the fifth output channel CH5 to the sixteenth output channel CH16 is in a high impedance state.

[0087] [2. Control of light distribution by lighting device 1A] 8 is a timing chart showing voltage signals input to the transparent electrodes 120 of the liquid crystal cells 100 to control the light distribution in an illumination device 1A according to one embodiment of the present invention. In the illumination device 1A according to this embodiment, predetermined voltage signals are sequentially input to the first transparent electrodes 120-1 to 120-4 of the first to fourth liquid crystal cells 100-1 to 100-4, respectively, to drive the liquid crystal cells 100 in a time-division manner. That is, in the illumination device 1A, the light distribution of light passing through the optical element 10 can be controlled by driving the plurality of liquid crystal cells 100 in a time-division manner based on a single signal generating circuit unit 310. More specifically, in the lighting device 1A according to this embodiment, a plurality of liquid crystal cells 100 are connected to a switch circuit section 320A, and two pairs of analog conversion circuits 331 and amplifier circuits 332 are provided between the switch circuit section 320A and the signal generation circuit section 310, and the connection states between the analog conversion circuits 331 and the amplifier circuits 332 and the transparent electrodes 120 of each liquid crystal cell 100 are switched in a time-division manner via the switch circuit section 320A, thereby enabling time-division driving of each liquid crystal cell 100. Specific examples of time-division driving will be described in detail below.

[0088] 8 is a timing chart for controlling optical element 10 so that the light distribution shape is circular. However, in lighting device 1A, the light distribution shape controlled by optical element 10 is not limited to this. As with lighting device 1, lighting device 1A can also have a light distribution shape that has a linear shape spreading in the x-axis direction or the y-axis direction.

[0089] In the lighting device 1A, as shown in FIG. 8, one frame period is divided into four sub-frame periods (first sub-frame period SF1 to fourth sub-frame period SF4).

[0090] During the first subframe period SF1, the first to fourth voltage signals having rectangular waves generated by the signal generation circuit 310 are input to the switch circuit 320A via the first to fourth voltage signal lines 330-1 to 330-4, respectively. Here, the phase of the first voltage signal is opposite to that of the second voltage signal, and the phase of the third voltage signal is opposite to that of the fourth voltage signal. The switch circuit 320 drives the first to fourth voltage signal lines 330-1 to 330-4 so that they are electrically connected to the first to fourth output channels CH1 to CH4, respectively. Therefore, during the first subframe period SF1, the first to fourth voltage signals are output from the first to fourth output channels CH1 to CH4, respectively. On the other hand, since the first voltage signal line 330-1 to the fourth voltage signal line 330-4 and the fifth output channel CH5 to the sixteenth output channel CH16 are in a non-conductive state, the fifth output channel CH5 to the sixteenth output channel CH16 are in a high impedance state.

[0091] Therefore, in the first sub-frame period SF1, a high voltage or a low voltage is applied to each of the first transparent electrode 120-1 to the fourth transparent electrode 120-4 of the first liquid crystal cell 100-1. That is, in the first sub-frame period SF1, a transverse electric field is generated between the first transparent electrode 120-1 and the second transparent electrode 120-2 of the first liquid crystal cell 100-1, and between the third transparent electrode 120-3 and the fourth transparent electrode 120-4 of the first liquid crystal cell 100-1.

[0092] During the second subframe period, the fifth to eighth voltage signals having rectangular waves generated by the signal generation circuit 310 are input to the switch circuit 320A via the first to fourth voltage signal lines 330-1 to 330-4, respectively. Here, the phase of the fifth voltage signal is opposite to that of the sixth voltage signal, and the phase of the seventh voltage signal is opposite to that of the eighth voltage signal. The switch circuit 320 drives the first to fourth voltage signal lines 330-1 to 330-4 so that they are electrically connected to the fifth to eighth output channels CH5 to CH8, respectively. Therefore, during the second subframe period SF2, the fifth to eighth voltage signals are output from the fifth to eighth output channels CH5 to CH8, respectively. On the other hand, since the first voltage signal line 330-1 to the fourth voltage signal line 330-4 are in a non-conductive state with the first output channel CH1 to the fourth output channel CH4 and the ninth output channel CH9 to the sixteenth output channel CH16, the first output channel CH1 to the fourth output channel CH4 and the ninth output channel CH9 to the sixteenth output channel CH16 are in a high impedance state.

[0093] Therefore, in the second sub-frame period SF2, a high voltage or a low voltage is applied to each of the first transparent electrode 120-1 to the fourth transparent electrode 120-4 of the second liquid crystal cell 100-2. That is, in the second sub-frame period SF2, a transverse electric field is generated between the first transparent electrode 120-1 and the second transparent electrode 120-2 of the second liquid crystal cell 100-2, and between the third transparent electrode 120-3 and the fourth transparent electrode 120-4 of the second liquid crystal cell 100-2.

[0094] During the second sub-frame period SF2, the first output channel CH1 to the fourth output channel CH4 are in a high impedance state, and therefore the high or low voltage applied to the first transparent electrode 120-1 to the fourth transparent electrode 120-4 of the first liquid crystal cell 100-1 is maintained by the capacitance of the liquid crystal in the liquid crystal layer 150. Therefore, even during the second sub-frame period SF2, a transverse electric field is maintained between the first transparent electrode 120-1 and the second transparent electrode 120-2 of the first liquid crystal cell 100-1, and between the third transparent electrode 120-3 and the fourth transparent electrode 120-4 of the first liquid crystal cell 100-1.

[0095] The same is true for the third sub-frame period SF3 and the fourth sub-frame period SF4. That is, in the third sub-frame period SF3, a transverse electric field is generated between the first transparent electrode 120-1 and the second transparent electrode 120-2 of the third liquid crystal cell 100-3, and between the third transparent electrode 120-3 and the fourth transparent electrode 120-4 of the third liquid crystal cell 100-3. In the fourth sub-frame period SF4, a transverse electric field is generated between the first transparent electrode 120-1 and the second transparent electrode 120-2 of the fourth liquid crystal cell 100-4, and between the third transparent electrode 120-3 and the fourth transparent electrode 120-4 of the fourth liquid crystal cell 100-4.

[0096] Even during the third sub-frame period SF3 and the fourth sub-frame period SF4, the output channel CH to which no voltage signal is output is in a high impedance state, and the high or low voltage applied to the transparent electrode 120 is maintained by the capacitance of the liquid crystal in the liquid crystal layer 150.

[0097] Therefore, the diffusion characteristics of the first to fourth liquid crystal cells 100-1 to 100-4 in one frame period are as shown in Table 1. In this case, the P-polarized component and the S-polarized component of the light emitted from the light source 20 are each diffused in the x-axis direction and the y-axis direction by the optical element 10. Therefore, the light emitted from the light source 20 is controlled by the optical element 10 to have a circular light distribution. Note that by changing the magnitude of the High voltage and the Low voltage applied to each transparent electrode 120, the light can also be controlled to have an elliptical light distribution.

[0098] As described above, in controlling light distribution by the lighting device 1A according to this embodiment, one frame is divided into multiple subframe periods SF. In each subframe period SF, the output channel of the switch circuit unit 320 is switched in response to two voltage signals input from the signal generation circuit unit 310 to two pairs of voltage signal lines 330 (first voltage signal line 330-1 to fourth voltage signal line), and two voltage signals are input to each of two adjacent transparent electrodes 120. In this way, even when controlling light distribution using multiple pairs of voltage signal lines 330, the number of voltage signal lines 330 can be reduced compared to the number of transparent electrodes 120, and as a result, the number of DACs and AMPs can be reduced. Therefore, in the lighting device 1A, the control device 30A can be made smaller and manufacturing costs can be reduced.

[0099] <Third embodiment> An illumination device 1B according to one embodiment of the present invention will be described with reference to Fig. 9. When the configuration of illumination device 1B is similar to that of illumination device 1, the description of the configuration of illumination device 1B may be omitted.

[0100] Fig. 9 is a block diagram showing the configuration of an illumination device 1B according to one embodiment of the present invention. As shown in Fig. 9, the illumination device 1B includes an optical element 10, a light source 20, a control device 30B, and a power supply 40. The control device 30B includes a signal generation circuit section 310B, a switch circuit section 320, a first voltage signal line 330-1, a second voltage signal line 330-2, and a timing control signal line 340.

[0101] The signal generating circuit unit 310B includes a DAC. That is, the signal generating circuit unit 310B has a built-in DAC, and the voltage signal output from the signal generating circuit unit 310B is a digital signal. Therefore, each of the first voltage signal line 330-1 and the second voltage signal line 330-2 does not include a DAC.

[0102] As described above, the lighting device 1B according to this embodiment does not include a DAC that occupies a large area on each of the first voltage signal line 330-1 and the second voltage signal line 330-2. Therefore, the lighting device 1B can reduce the number of DACs, and as a result, the manufacturing cost can be reduced.

[0103] 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.

[0104] 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]

[0105] 1, 1A, 1B: lighting device, 10: optical element, 20: light source, 30, 30A, 30B: control device, 40: power supply, 100: liquid crystal cell, 110: substrate, 120: transparent electrode, 121: connection pad, 122: terminal, 130: alignment film, 140: sealing material, 150: liquid crystal layer, 160: optical elastic resin layer, 170: flexible printed circuit board (FPCs), 310, 310B: signal generation circuit section, 320, 320A: switch circuit section, 330: voltage signal line, 331: digital-to-analog conversion circuit (DAC), 332: amplifier circuit (AMP), 340: timing control signal line, 1000-1: first light, 1000-2: second light, CH: output channel, SF: subframe period

Claims

1. A light source and an optical element including a first liquid crystal cell and a second liquid crystal cell, which transmits light emitted from the light source in a variably diffused manner; a control device connected to the optical element and controlling the optical element, Each of the first liquid crystal cell and the second liquid crystal cell comprises: a first substrate on which first transparent electrodes and second transparent electrodes extending in a first direction are alternately provided; a second substrate on which third transparent electrodes and fourth transparent electrodes extending in a second direction intersecting the first direction are alternately provided; a liquid crystal layer between the first substrate and the second substrate; The control device a switch circuit section including a first output channel electrically connected to the first transparent electrode of the first liquid crystal cell, a second output channel electrically connected to the second transparent electrode of the first liquid crystal cell, a third output channel electrically connected to the third transparent electrode of the first liquid crystal cell, and a fourth output channel electrically connected to the fourth transparent electrode of the first liquid crystal cell; a signal generating circuit unit that generates a plurality of voltage signals to be input to the first transparent electrode, the second transparent electrode, the third transparent electrode, and the fourth transparent electrode of each of the first liquid crystal cell and the second liquid crystal cell; a first voltage signal line and a second voltage signal line connected to the switch circuit unit and the signal generating circuit unit, each of which transmits one of the generated voltage signals; one frame period includes a first sub-frame period and a second sub-frame period, during the first subframe period, the switch circuit unit is driven to bring the first voltage signal line and the first output channel into conduction and bring the second voltage signal line and the second output channel into conduction; a lighting device, wherein, during the second sub-frame period, the switch circuit unit is driven so that the first voltage signal line and the third output channel are electrically connected, and the second voltage signal line and the fourth output channel are electrically connected.

2. during the first subframe period, the third output channel and the fourth output channel are in a high impedance state; The lighting device of claim 1 , wherein the first output channel and the second output channel are in a high impedance state during the second sub-frame period.

3. the switch circuitry further includes a fifth output channel electrically connected to the first transparent electrode of the second liquid crystal cell, a sixth output channel electrically connected to the second transparent electrode of the second liquid crystal cell, a seventh output channel electrically connected to the third transparent electrode of the second liquid crystal cell, and an eighth output channel electrically connected to the fourth transparent electrode of the second liquid crystal cell; the one frame period further includes a third sub-frame period and a fourth sub-frame period, during the third subframe period, the switch circuit unit is driven to bring the first voltage signal line and the fifth output channel into conduction and bring the second voltage signal line and the sixth output channel into conduction; 2. The lighting device according to claim 1, wherein, during the fourth subframe period, the switch circuit unit is driven to bring the first voltage signal line and the seventh output channel into conduction, and bring the second voltage signal line and the eighth output channel into conduction.

4. during the third subframe period, the first output channel, the second output channel, the third output channel, the fourth output channel, the seventh output channel, and the eighth output channel are in a high impedance state; 4. The lighting device of claim 3, wherein, during the fourth sub-frame period, the first output channel, the second output channel, the third output channel, the fourth output channel, the fifth output channel, and the sixth output channel are in a high impedance state.

5. 5. The lighting device according to claim 1, wherein, during the first sub-frame period, a phase of a first voltage signal input to the first transparent electrode of the first liquid crystal cell is opposite to a phase of a second voltage signal input to the second transparent electrode of the first liquid crystal cell.

6. 6. The lighting device according to claim 5, wherein, during the second sub-frame period, a phase of a third voltage signal input to the third transparent electrode of the first liquid crystal cell is opposite to a phase of a fourth voltage signal input to the fourth transparent electrode of the first liquid crystal cell.

7. 6. The lighting device according to claim 5, wherein, during the second sub-frame period, a phase of a third voltage signal input to the third transparent electrode of the first liquid crystal cell is the same as a phase of a fourth voltage signal input to the fourth transparent electrode of the first liquid crystal cell.

8. A light source and an optical element including a first liquid crystal cell and a second liquid crystal cell, which transmits light emitted from the light source in a variably diffused manner; a control device connected to the optical element and controlling the optical element, Each of the first liquid crystal cell and the second liquid crystal cell comprises: a first substrate on which first transparent electrodes and second transparent electrodes extending in a first direction are alternately provided; a second substrate on which third transparent electrodes and fourth transparent electrodes extending in a second direction intersecting the first direction are alternately provided; a liquid crystal layer between the first substrate and the second substrate; The control device a switch circuit unit including a first output channel electrically connected to the first transparent electrode of the first liquid crystal cell, a second output channel electrically connected to the second transparent electrode of the first liquid crystal cell, a third output channel electrically connected to the third transparent electrode of the first liquid crystal cell, a fourth output channel electrically connected to the fourth transparent electrode of the first liquid crystal cell, a fifth output channel electrically connected to the first transparent electrode of the second liquid crystal cell, a sixth output channel electrically connected to the second transparent electrode of the second liquid crystal cell, a seventh output channel electrically connected to the third transparent electrode of the second liquid crystal cell, and an eighth output channel electrically connected to the fourth transparent electrode of the second liquid crystal cell; a signal generating circuit unit that generates a plurality of voltage signals to be input to the first transparent electrode, the second transparent electrode, the third transparent electrode, and the fourth transparent electrode of each of the first liquid crystal cell and the second liquid crystal cell; a first voltage signal line, a second voltage signal line, a third voltage signal line, and a fourth voltage signal line connected to the switch circuit unit and the signal generating circuit unit, each of which transmits one of the generated voltage signals; one frame period includes a first sub-frame period and a second sub-frame period, during the first subframe period, the switch circuit unit drives the first voltage signal line, the second voltage signal line, the third voltage signal line, and the fourth voltage signal line so as to be conductive with the first output channel, the second output channel, the third output channel, and the fourth output channel, respectively; during the second sub-frame period, the switch circuit unit drives the first voltage signal line, the second voltage signal line, the third voltage signal line, and the fourth voltage signal line so as to be electrically connected to the fifth output channel, the sixth output channel, the seventh output channel, and the eighth output channel, respectively.

9. during the first subframe period, the fifth output channel, the sixth output channel, the seventh output channel, and the eighth output channel are in a high impedance state; The lighting device of claim 8 , wherein the first output channel, the second output channel, the third output channel, and the fourth output channel are in a high impedance state during the second sub-frame period.

10. 10. The lighting device according to claim 8, wherein, during the first sub-frame period, a phase of a first voltage signal input to the first transparent electrode of the first liquid crystal cell is opposite to a phase of a second voltage signal input to the second transparent electrode of the first liquid crystal cell, and a phase of a third voltage signal input to the third transparent electrode of the first liquid crystal cell is opposite to a phase of a fourth voltage signal input to a fourth transparent electrode of the first liquid crystal cell.

11. 10. The lighting device according to claim 8, wherein, during a first subframe period, a phase of a first voltage signal input to the first transparent electrode of the first liquid crystal cell is opposite to a phase of a second voltage signal input to the second transparent electrode of the first liquid crystal cell, and a phase of a third voltage signal input to the third transparent electrode of the first liquid crystal cell is the same as a phase of a fourth voltage signal input to the fourth transparent electrode of the first liquid crystal cell.

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