Lighting device

Abstract

This lighting device includes a light source device having a light source, and a light distribution device. The light distribution device includes: an optical element including at least one liquid crystal cell on the light source; a control device; a smoothing circuit; a shift register; and a light distribution power supply circuit. The light distribution power supply circuit is configured to input, to the shift register and the smoothing circuit, a light distribution control signal based on a pulse width modulation method for designating the degree of diffusion of light from the light source by the optical element. The control device is configured to supply an output signal based on a pulse amplitude modulation method to at least one liquid crystal cell on the basis of the light distribution control signal processed by the shift register.

Description

lighting equipment

[0001] One embodiment of the present invention relates to a lighting device, for example, a lighting device that controls light distribution by utilizing the orientation of liquid crystals.

[0002] A liquid crystal lens is an optical element that utilizes the fact that the refractive index of the liquid crystal layer changes by controlling the orientation of the liquid crystal through controlling the voltage applied to the liquid crystal. By placing this optical element over a light source and controlling the refractive index of the liquid crystal layer, it is possible to diffuse the light from the light source, thereby providing a lighting device with controllable light distribution (see, for example, Patent Document 1).

[0003] International Publication No. 2022 / 176684

[0004] An object of one embodiment of the present invention is to provide a lighting device having a novel structure, for example, a lighting device that can be installed at low cost and that can control light distribution.

[0005] One embodiment of the present invention is a lighting device. The lighting device includes a light source device having a light source, and a light distribution device. The light distribution device includes an optical element including at least one liquid crystal cell on the light source, a control device, a smoothing circuit, a shift register, and a light distribution power supply circuit. The light distribution power supply circuit is configured to input a pulse-width modulated light distribution control signal that specifies the degree of diffusion of light from the light source by the optical element to the shift register and the smoothing circuit. The control device is configured to supply a pulse-amplitude modulated output signal to the at least one liquid crystal cell based on the light distribution control signal processed by the shift register.

[0006] One embodiment of the present invention is an illumination device. The illumination device includes a light source device having a light source, and a light distribution device. The light distribution device includes an optical element including at least one liquid crystal cell on the light source, a control device, and a light distribution power supply circuit. The light distribution power supply circuit is configured to input a pulse-width modulated light distribution control signal to the control device, the pulse-width modulated light distribution control signal specifying the degree of diffusion of light from the light source by the optical element. The control device is configured to supply a pulse-width modulated output signal to the liquid crystal cell based on the light distribution control signal.

[0007] 1 is a functional block diagram of a lighting device according to an embodiment of the present invention; 2 is a schematic perspective view of a portion of a lighting device according to an embodiment of the present invention; 3 is a schematic end view of an optical element of a lighting device according to an embodiment of the present invention; 4 is a schematic end view of an optical element of a lighting device according to an embodiment of the present invention; 5 is a schematic end view illustrating the diffusion of light by an optical element of a lighting device according to an embodiment of the present invention; 6 is a schematic view illustrating the diffusion of light by an optical element of a lighting device according to an embodiment of the present invention; 7 is a schematic diagram illustrating the operation of a lighting device according to an embodiment of the present invention; 8 is a functional block diagram of a light distribution device of a lighting device according to an embodiment of the present invention; 9 is a functional block diagram of a lighting device according to an embodiment of the present invention; 10 is a schematic view of a portion of a lighting device according to an embodiment of the present invention; 11 is a functional block diagram of a lighting device according to an embodiment of the present invention; 12 is a schematic view illustrating the operation of a lighting device according to an embodiment of the present invention;

[0008] Hereinafter, various embodiments 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 spirit of the present invention, and should not be construed as being limited to the description of the embodiments exemplified below.

[0009] In order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. In this specification and each drawing, elements having the same function as those described in the previous drawings may be given the same reference numerals, and duplicated explanations may be omitted. This reference numeral is used to collectively represent multiple identical or similar structures, and when these are individually represented, a hyphen and a natural number are added after the reference numeral.

[0010] In this specification and claims, when expressing an aspect of placing another structure on top of a certain structure, the term "on top" is used, unless otherwise specified, to include both a case in which another structure is placed directly on top of a certain structure so as to be in contact with the certain structure, and a case in which another structure is placed above a certain structure via yet another structure.

[0011] In this specification and claims, the expression that two structures are "orthogonal" includes not only a state in which the two structures intersect perpendicularly (90°), but also a state in which the two structures intersect at an angle of 90°±10°. The expression that two structures are "parallel" includes a state in which the extension directions of the two structures form an angle of 0°±10°.

[0012] First Embodiment In this embodiment, a lighting device 100 according to one embodiment of the present invention will be described.

[0013] 1. Overall Configuration of the Illumination Device Fig. 1 is a functional block diagram of an illumination device 100. As shown in Fig. 1, the illumination device 100 includes a light source device 200 and a light distribution device 110. The light source device 200 has a light source 210 and is configured to supply light emitted from the light source 210 to the light distribution device 110. The light distribution device 110 is configured to diffuse the light from the light source 210, thereby arbitrarily controlling the illumination range of the light. These components will be described in detail below.

[0014] 2. Light Source Device The light source device 200 includes a light source 210, a dimming power supply circuit 204 electrically connected to the light source 210, and a dimming controller 202. The light source 210 is configured to emit visible light of a given wavelength and includes one or more light-emitting elements, such as light-emitting diodes (LEDs) or cold-cathode tubes. The dimming power supply circuit 204 is connected to an external power supply, such as a commercial power supply. There are no restrictions on the configuration of the dimming power supply circuit 204, as long as it is configured to convert the external power supply into a light source drive signal for driving the light source 210 and supply the light source 210 with the light source drive signal. More specifically, the dimming power supply circuit 204 is configured to convert the external power supply, which is an AC signal, into a pulse-width modulated light source drive signal having a constant amplitude and supply the light source 210 with the light source drive signal. The frame period of the light source drive signal has a frequency of 30 Hz to 120 Hz, preferably 60 Hz to 120 Hz. The intensity of the light emitted from the light source 210 is determined by the duty ratio (high potential period / frame period) of the light source drive signal.

[0015] The dimming controller 202 controls the dimming power supply circuit 204, thereby controlling the intensity of light emitted from the light source 210. That is, the dimming controller 202 determines the duty ratio of a light source drive signal, and the dimming power supply circuit 204 generates a light source drive signal in accordance with this duty ratio and supplies it to the light source 210. The dimming controller 202 is provided with, for example, a slider or a dial, and the intensity of light from the light source 210 (i.e., the duty ratio of the light source drive signal) is controlled by the amount the slider is slid or the amount the dial is rotated. The dimming controller 202 and the dimming power supply circuit 204 are installed, for example, on a wall or a pillar near where the lighting device 100 is installed.

[0016] The dimming controller 202 may further be configured to control the color of light from the light source 210. For example, if the light source 210 is configured with red, green, and blue light-emitting elements, the dimming controller 202 may be configured to individually control the intensities of light from these light-emitting elements. By appropriately controlling the intensities of light from the red, green, and blue light-emitting elements, light of any color can be obtained from the light source 210.

[0017] 1 , the light distribution device 110 has an optical element 130, a control device 120 for controlling the optical element 130, a light distribution power supply circuit 114, a smoothing circuit 116, a shift register 118, and a light distribution controller 112. The control device 120 is electrically connected to the optical element 130, the smoothing circuit 116, and the shift register 118, and the light distribution power supply circuit 114 is connected to the smoothing circuit 116 and the shift register 118. The light distribution power supply circuit 114 is connected to the light distribution controller 112 and is controlled by the light distribution controller 112.

[0018] In the functional block diagram shown in FIG. 1 , two circuit groups including a smoothing circuit 116, a shift register 118, a light distribution power supply circuit 114, and a light distribution controller 112 are connected to the control device 120. That is, a circuit group including a first light distribution power supply circuit 114-1, a first smoothing circuit 116-1, a first shift register 118-1, and a first light distribution controller 112-1, and a circuit group including a second light distribution power supply circuit 114-2, a second smoothing circuit 116-2, a second shift register 118-2, and a second light distribution controller 112-2 are connected to the control device 120. This is to individually diffuse light from the light source device 200 in two mutually orthogonal directions (hereinafter referred to as the x direction and the y direction), as will be described later. One circuit group supplies a signal for light diffusion in one direction (e.g., the x direction) to the control device 120, and the other circuit group supplies a signal for light diffusion in the other direction (e.g., the y direction) to the control device 120. Therefore, if light diffusion in the x and y directions is to be controlled collectively rather than individually, or if light is to be diffused only in either the x or y direction, only one circuit group needs to be connected to the control device 120.

[0019] 3-1. Optical Element FIG. 2 shows a schematic perspective view of a portion of the lighting device 100. The optical element 130 is disposed on the light source 210 so as to transmit light emitted by the light source 210. The optical element 130 includes at least one liquid crystal cell 140 disposed on the light source 210. The number of liquid crystal cells 140 included in the optical element 130 may be two or more. In the optical element 130 shown in FIG. 2, four liquid crystal cells (a first liquid crystal cell 140-1, a second liquid crystal cell 140-2, a third liquid crystal cell 140-3, and a fourth liquid crystal cell 140-4) are disposed on the light source 210 in this order from the light source 210 side. Each liquid crystal cell 140 is connected to a connector 132 such as a flexible printed circuit (FPC) board, and is connected to the control device 120 via the connector 132. This allows the optical element 130 to be controlled by the control device 120. In the following description, an illumination device 100 having an optical element 130 including four liquid crystal cells 140 will be described as an example. The direction from the light source 210 to the optical element 130 is defined as the z direction, which is perpendicular to the x direction and the y direction.

[0020] Light emitted from the light source 210 is incident on the first liquid crystal cell 140-1, passes through the second liquid crystal cell 140-2 and the third liquid crystal cell 140-3, and is emitted from the fourth liquid crystal cell 140-4. As will be described later, in the lighting device 100, the diffusion of light is controlled by the liquid crystal cell 140 included in the optical element 130, and the light distribution of the light emitted from the optical element 130 can be changed. In other words, the light from the light source 210 can be processed to arbitrarily change the shape of the surface (irradiation surface) on which the light irradiates an object.

[0021] 3 and 4 show schematic diagrams of the end faces of the optical element 130 taken along the dashed line A-A' and the dashed line B-B' perpendicular to the dashed line A-A' in FIG. 2, respectively. As shown in these figures, each of the first to fourth liquid crystal cells 140-1 to 140-4 includes a first substrate 142 and a second substrate 144 facing each other, with a plurality of first electrodes 146-1, a plurality of second electrodes 146-2, a plurality of third electrodes 146-3, a plurality of fourth electrodes 146-4, a first alignment film 148-1, and a second alignment film 148-2 provided between them. The plurality of first electrodes 146-1 and the plurality of second electrodes 146-2 are provided on the first substrate 142, and a first alignment film 148-1 is formed on these electrodes. The plurality of third electrodes 146-3 and the plurality of fourth electrodes 146-4 are provided under the second substrate 144 and are disposed between the second substrate 144 and the second alignment film 148-2. In each liquid crystal cell 140, the first substrate 142 and the second substrate 144 are fixed to each other by a sealant 152, and a liquid crystal layer 150 is sealed in a space surrounded by the first substrate 142, the second substrate 144, and the sealant 152. An adhesive 154 that transmits visible light is provided between adjacent liquid crystal cells 140, thereby fixing the adjacent liquid crystal cells 140 to each other. For example, an acrylic resin adhesive or an epoxy resin adhesive can be used as the adhesive 154.

[0022] (1) Substrate The first substrate 142 and the second substrate 144 are configured to transmit at least visible light of the light emitted by the light source 210. For example, the first substrate 142 and the second substrate 144 may be made of a light-transmitting substrate such as a glass substrate or a quartz substrate. The first substrate 142 and the second substrate 144 may contain a light-transmitting polymer such as polyimide, polyamide, polycarbonate, acrylic resin, or polysiloxane. The multiple liquid crystal cells 140 are preferably arranged on the light source 210 such that the normal to the first substrate 142 and the second substrate 144 is in the z direction and the main surface is in the xy plane.

[0023] (2) Electrodes Each of the electrodes 146 functions as an electrode for forming a transverse electric field in the liquid crystal layer 150. The electrodes 146 are made of a conductive oxide that transmits visible light, such as indium tin oxide (ITO) or indium zinc oxide (IZO). Alternatively, the electrodes 146 may contain a metal such as aluminum, tantalum, molybdenum, or tungsten, or an alloy thereof. However, to ensure transparency to visible light, it is preferable to form the electrodes 146 in a mesh shape with a plurality of openings.

[0024] As can be seen from Figures 3 and 4, the first electrodes 146-1 and the second electrodes 146-2 are arranged in stripes, parallel to each other, and alternately. Therefore, one second electrode 146-2 is arranged between adjacent first electrodes 146-1, and one first electrode 146-1 is arranged between adjacent second electrodes 146-2. Similarly, the third electrodes 146-3 and the fourth electrodes 146-4 are also arranged in stripes, parallel to each other, and alternately. Therefore, one fourth electrode 146-4 is arranged between adjacent third electrodes 146-3, and one third electrode 146-3 is arranged between adjacent fourth electrodes 146-4. However, the direction in which the first electrode 146-1 and the second electrode 146-2 extend intersects or is perpendicular to the direction in which the third electrode 146-3 and the fourth electrode 146-4 extend.

[0025] Here, between the first liquid crystal cell 140-1 and the second liquid crystal cell 140-2, the extension directions of the first electrode 146-1 and the second electrode 146-2 are the same, and the extension directions of the third electrode 146-3 and the fourth electrode 146-4 are also the same. This relationship is also the same between the third liquid crystal cell 140-3 and the fourth liquid crystal cell 140-4. However, between the second liquid crystal cell 140-2 and the third liquid crystal cell 140-3, the extension directions of the first electrode 146-1 (or the second electrode 146-2) are orthogonal to each other, and the extension directions of the third electrode 146-3 (or the fourth electrode 146-4) are also orthogonal to each other. Although not shown, when the optical element 130 is composed of two liquid crystal cells 140, the optical element 130 may be configured so that the extension directions of the first electrodes 146-1 (or second electrodes 146-2) are the same between these liquid crystal cells 140, and the extension directions of the third electrodes 146-3 (or fourth electrodes 146-4) are also the same between these liquid crystal cells 140. In the following description, as shown in Figures 3 and 4, the extension direction of the first electrode 146-1 and second electrode 146-2 of the first liquid crystal cell 140-1 is defined as the y direction, and the extension direction of the third electrode 146-3 and fourth electrode 146-4 is defined as the x direction.

[0026] (3) Alignment Film In each liquid crystal cell 140, a first alignment film 148-1 covers the plurality of first electrodes 146-1 and the plurality of second electrodes 146-2, and a second alignment film 148-2 covers the plurality of third electrodes 146-3 and the plurality of fourth electrodes 146-4. The alignment film 148 includes a polymer such as polyimide. Each alignment film 148 is given alignment characteristics by an alignment process such as a rubbing method or a photoalignment method, and thereby functions to align the liquid crystal molecules contained in the liquid crystal layer 150 in a certain direction. Hereinafter, the direction in which the alignment film 148 aligns the liquid crystal molecules so that their longitudinal directions are aligned is referred to as the alignment direction.

[0027] In each liquid crystal cell 140, the alignment direction of the first alignment film 148-1 is perpendicular to the direction in which the first electrode 146-1 and the second electrode 146-2 extend. Similarly, the alignment direction of the second alignment film 148-2 is perpendicular to the direction in which the third electrode 146-3 and the fourth electrode 146-4 extend. Therefore, in each liquid crystal cell 140, the alignment directions of the first alignment film 148-1 and the second alignment film 148-2 are perpendicular to each other.

[0028] (4) Liquid Crystal Layer 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 crystals for the liquid crystal layer 150. The liquid crystals may be either positive or negative type. The liquid crystal layer 150 preferably contains a chiral agent that imparts a twist to the liquid crystals.

[0029] (5) Light Diffusion Light diffusion using the optical element 130 will be described with reference to Figures 5 and 6. Figures 5 and 6 are schematic end views for explaining the optical characteristics of one liquid crystal cell 140, and correspond to the states where a voltage is not applied to the electrode 146 and where a voltage is applied, respectively. In the figures, liquid crystal molecules contained in the liquid crystal layer 150 are schematically represented by circles or ellipses.

[0030] As shown in FIG. 5 , in accordance with the orientation direction of the alignment film 148, the liquid crystal molecules on the first substrate 142 side of the liquid crystal layer 150 are aligned in the x direction, and the liquid crystal molecules on the second substrate 144 side of the liquid crystal layer 150 are aligned in the y direction. Therefore, in a no-electric-field state in which no voltage is applied to any of the first electrode 146-1 to the fourth electrode 146-4, the liquid crystal molecules in the liquid crystal layer 150 are aligned so as to be twisted 90° in the xy plane as they move from the first substrate 142 to the second substrate 144. 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 orientation 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.

[0031] When a voltage is applied to the first electrode 146-1 to the fourth electrode 146-4 so as to generate a potential difference between adjacent electrodes 146, a transverse electric field is generated between the two adjacent electrodes 146. As a result, as shown in FIG. 6 , the liquid crystal molecules in the liquid crystal layer 150 are aligned so as to be twisted 90° in the xy plane as they move from the first substrate 142 to the second substrate 144. At the same time, the liquid crystal molecules near the first substrate 142 side are aligned in a convex arc shape relative to the first substrate 142 due to the transverse electric field between the first electrode 146-1 and the second electrode 146-2, and the liquid crystal molecules near the second substrate 144 side are aligned in a convex arc shape relative to the second substrate 144 due to the transverse electric field between the third electrode 146-3 and the fourth electrode 146-4. The liquid crystal molecules aligned in a convex arc shape have a refractive index distribution, and light having a polarization axis that is the same as the alignment direction of the liquid crystal molecules is diffused. Furthermore, since the cell gap d, which is the distance between the first substrate 142 and the second substrate 144, is sufficiently larger than the distance between two adjacent transparent electrodes (for example, 8 μm≦d≦50 μm, more preferably 10 μm≦d≦30 μm, and even more preferably 15 μm≦d≦25 μm), the electric field formed between the electrodes 146 does not have much effect on the liquid crystal molecules located near the center between the first substrate 142 and the second substrate 144.

[0032] The light emitted from the light source 210 includes a polarized component in the x direction (P polarized component) and a polarized component in the y direction (S polarized component). However, for convenience, the light emitted from the light source 210 will be described below as being divided into light Lp having a P polarized component and light Ls having an S polarized component.

[0033] Because the polarization plane of light Lp incident from the first substrate 142 side is the same as the orientation direction of the liquid crystal molecules on the first substrate 142 side, light Lp is diffused in the x direction in accordance with the refractive index distribution of the liquid crystal molecules (see (1) in FIG. 6). Furthermore, light Lp is optically rotated as it passes through the liquid crystal layer 150, and its polarization component changes from a P-polarized component to an S-polarized component. Because the polarization plane of the S-polarized component of light Lp is the same as the orientation direction of the liquid crystal molecules on the second substrate 144 side, light Lp is diffused in the y direction in accordance with the refractive index distribution of the liquid crystal molecules (see (2) in FIG. 6).

[0034] On the other hand, the polarization plane of light Ls incident from the first substrate 142 side is different (perpendicular) to the orientation direction of the liquid crystal molecules on the first substrate 142 side, so light Ls is not diffused (see (3) in FIG. 6). Furthermore, light Ls is optically rotated as it passes through the liquid crystal layer 150, and its polarization component changes from an S-polarized component to a P-polarized component. The P-polarized component of light Ls is different (perpendicular) to the orientation direction of the liquid crystal molecules on the second substrate 144 side, so light Ls is not diffused (see (4) in FIG. 6).

[0035] In this way, by passing light through one liquid crystal cell 140, one polarization component is selectively diffused. In other words, light can be diffused in one direction. Although not shown, light Ls passing through the first liquid crystal cell 140-1 can be diffused in the x and y directions by the second liquid crystal cell 140-2 using the same principle. Therefore, by using two overlapping liquid crystal cells 140, all polarization components can be diffused in the x and y directions. Furthermore, the degree of diffusion (diffusion rate) can be changed by changing the voltage applied to the electrodes 146. Therefore, by stacking multiple liquid crystal cells 140 and controlling the voltage applied to each electrode 146, light can be diffused as desired in the x and y directions. As a result, the shape of the surface illuminated by light from the light source 210 can be changed into various shapes, such as a circle or an ellipse.

[0036] 3-2. Light distribution power supply circuit and light distribution controller The light distribution power supply circuit 114 is connected to an external power supply (not shown) such as a commercial power supply. There are no restrictions on the configuration of the light distribution power supply circuit 114, as long as it is configured to convert the external power supply, which is an AC signal, into a light distribution control signal of pulse width modulation type having a constant amplitude and supply it simultaneously to the smoothing circuit 116 and the shift register 118. The cycle of the frame period of the light distribution control signal is 30 Hz or more and 120 Hz or less, preferably 60 Hz or more and 120 Hz or less. The degree of light diffusion is determined by the duty ratio of the light distribution control signal (high potential period / frame period).

[0037] Like the dimming power supply circuit 204, the light distribution power supply circuit 114 outputs a light distribution control signal using a pulse-width modulation method. The amplitude of the light distribution control signal may be the same as the amplitude of the light source drive signal. Therefore, the light distribution power supply circuit 114 may have the same configuration as the dimming power supply circuit 204. In other words, circuits with the same circuit configuration, circuit layout, standards, size, specifications, etc. may be used for the light distribution power supply circuit 114 and the dimming power supply circuit 204. Therefore, an existing circuit that can be used as the dimming power supply circuit 204, or a dimming power supply circuit 204 used in an existing lighting device, can be used as the light distribution power supply circuit 114. This contributes to reducing the manufacturing costs and installation costs of the lighting device 100.

[0038] The light distribution controller 112 controls the light distribution power supply circuit 114, thereby controlling the degree of light diffusion. That is, the light distribution controller 112 determines the duty ratio of the light distribution control signal generated by the light distribution power supply circuit 114, and the light distribution power supply circuit 114 generates the light distribution control signal according to this duty ratio and supplies it to the smoothing circuit 116 and the shift register 118. Like the dimming controller 202, the light distribution controller 112 is provided with a slider, dial, or the like, and the degree of light diffusion is controlled by the amount of sliding of the slider or the amount of rotation of the dial. As shown in FIG. 1 , two light distribution controllers 112 may be provided to separately control light diffusion in the x and y directions. Only one light distribution controller 112 may be provided to simultaneously control only one of the x and y directions. The light distribution controller 112 may also have the same configuration as the dimming controller 202. That is, controllers with the same circuit configuration, circuit layout, standards, size, specifications, etc. may be used for the light distribution controller 112 and the dimming controller 202. Therefore, an existing controller that can be used as the dimming controller 202, or an already installed dimming controller 202, can be used as the light distribution controller 112. This contributes to reducing the manufacturing costs and installation costs of the lighting device 100. The light distribution controller 112 and the light distribution power supply circuit 114 are also installed, for example, on a wall or a pillar.

[0039] 3-3. Smoothing Circuit and Shift Register Since known circuit configurations can be appropriately applied to the smoothing circuit 116 and the shift register 118, detailed explanations will be omitted. Briefly, the smoothing circuit 116 includes a diode, a capacitance element, a resistor, etc., and is configured to rectify the light distribution control signal output from the light distribution power supply circuit 114 and convert it into a DC signal or a pseudo DC power supply. The smoothing circuit 116 converts the light distribution control signal into a different voltage (V １ , V ２ (V １ >V ２ )) and inputs them as a power supply to the control device 120. In this way, the control device 120 is driven.

[0040] The shift register 118 includes a plurality of flip-flops, and is configured to reduce the amplitude of the light distribution control signal while maintaining its duty ratio, as shown in FIG. 7. This allows the light distribution control signal to be converted into an input signal (PMW) having a potential suitable for driving a signal generating circuit unit 122 (to be described later) and the like. ｘ , P.M.W. ｙ ) and input to the control device 120. The voltage of the input signal may be the same as the voltage of the light source drive signal, for example, 3.1V.

[0041] 3-4. Control Device A functional block diagram of the control device 120 is shown in FIG. 8. The control device 120 controls the voltage V １ and V ２ It is driven by a voltage V １ and V ２ , for example, 3.3 V and 30 V, respectively. The control device 120 is further configured to generate an output signal based on the light distribution control signal output by the light distribution power supply circuit 114, and supply the output signal to the liquid crystal cell 140 of the optical element 130. Specifically, the control device 120 determines the voltage (i.e., amplitude) of the pulse amplitude modulated output signal to be applied to the electrode 146 of the liquid crystal cell 140 based on the duty ratio of the input signal input from the shift register 118, and supplies the output signal to the electrode 146.

[0042] As described above, the lighting device 100 can be configured to diffuse light from the light source 210 in two directions (x direction and y direction) separately. For this reason, a circuit group including the first light distribution power supply circuit 114-1, the first smoothing circuit 116-1, and the first shift register 118-1 generates a voltage V １ｘ and the input signal (PWM Ｘ ) is supplied, and a voltage V for diffusing light in the other direction (for example, the y direction) is generated by a circuit group including a second light distribution power supply circuit 114-2, a second smoothing circuit 116-2, and a second shift register 118-2. １ｙ and the input signal (PWM ｙ To reiterate, when the light from the light source 210 is to be diffused in two directions at once, or when the light is to be diffused in only one direction, only one circuit group is used to supply the voltage V １ , V ２ and the input signal PWM may be supplied to the control device 120.

[0043] As shown in FIG. 8 , the control device 120 includes a signal generating circuit unit 122 and a voltage applying unit 124. The signal generating circuit unit 122 is an integrated circuit having a calculation function, and operates based on a predetermined program. The signal generating circuit unit 122 is configured, for example, by 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 the like. The signal generating circuit unit 122 may include a random access memory (RAM) as well as a non-volatile memory such as a flash memory or a read-only memory. The signal generating circuit unit 122 applies a voltage V １ , and performs arithmetic processing on the input signals input from the shift register 118 to calculate the voltage to be applied to the electrodes 146 of each liquid crystal cell 140 .

[0044] The voltage application unit 124 includes a plurality of pairs of digital-analog conversion circuits 126 and amplifier circuits 128, each corresponding to an electrode 146 of the liquid crystal cell 140. In other words, one channel (ch) is formed by a pair of digital-analog conversion circuits 126 and amplifier circuits 128, and each electrode 146 is connected to the channel formed by the pair of digital-analog conversion circuits 126 and amplifier circuits 128. This allows voltages to be supplied independently to each electrode 146. The digital-analog conversion circuits 126 are connected to the signal generation circuit unit 122 by a serial bus such as a serial peripheral interface (SPI). The digital-analog conversion circuits 126 and amplifier circuits 128 each receive a voltage V １ and V ２ is supplied, which drives the digital-to-analog conversion circuit 126 and the amplifier circuit 128.

[0045] The signal output from the signal generating circuit 122 is converted into a digital signal by the digital-to-analog conversion circuit 126, amplified by the amplifier circuit 128, and supplied to the electrode 146 as a pulse amplitude modulation output signal having a constant pulse width. The voltage (i.e., amplitude) of the output signal is set, for example, in the range of 10 V to 50 V. The amplitude of the output signal supplied to the electrode 146 is determined by the duty ratio of the light distribution control signal output from the light distribution power supply circuit 114. Furthermore, to prevent burn-in of the liquid crystal cell 140, the liquid crystal cell 140 is driven so that the applied voltage is reversed every frame. Therefore, as schematically shown in FIG. 7 , the polarity of the output signal is reversed every frame with respect to a reference potential (e.g., ground potential).

[0046] As described above, in the lighting device 100, the light source drive signal for driving the light source 210 and the light distribution control signal for operating the control device 120 are both pulse-width modulated signals. Even if a pulse-width modulated signal is used as the light distribution control signal, the light distribution device 110 can be operated by using the smoothing circuit 116 and the shift register 118 to convert the light distribution control signal into a power supply for operating the control device 120 and an input signal for driving the optical element 130, respectively. Therefore, the dimming power supply circuit 204 and the light distribution power supply circuit 114 can have the same configuration, and the dimming controller 202 and the light distribution controller 112 can also have the same configuration. By utilizing these characteristics, a dimming power supply circuit used in a lighting device that does not have the light distribution device 110 or an existing lighting device that does not have the light distribution device 110 installed can be used as the light distribution power supply circuit 114 of the light distribution device 110. Similarly, a dimming controller 202 used in a lighting device that does not have a light distribution device 110 or an existing lighting device that does not have a light distribution device 110 mounted thereon can be utilized as the light distribution controller 112 of the light distribution device 110. Therefore, for example, when mounting the light distribution device 110 on an existing lighting device that does not have a light distribution device, the installation is simplified, and as a result, the installation period and installation costs can be shortened.

[0047] Due to these features, the dimming controller 202 of the light source device 200 and the light distribution controller 112 of the light distribution device 110 can be arranged in an integrated control unit 206, as shown in the functional block diagram of Fig. 9 . Alternatively, the dimming power supply circuit 204 of the light source device 200 and the light distribution power supply circuit 114 of the light distribution device 110 can be arranged in an integrated control unit 206. Alternatively, the dimming controller 202 of the light source device 200 and the light distribution controller 112 of the light distribution device 110, as well as the dimming power supply circuit 204 of the light source device 200 and the light distribution power supply circuit 114 of the light distribution device 110 can be arranged in an integrated control unit 206. In this case, as schematically shown in Fig. 10 , one control unit 206 can be arranged on a pillar or a wall, and the dimming controller 202, the light distribution controller 112, the dimming power supply circuit 204, and the light distribution power supply circuit 114 can be incorporated into this control unit 206. This makes it possible to control not only the brightness of the lighting device 100 but also the light diffusion in one or two directions using a single control unit 206. Furthermore, the mechanism for controlling the lighting device 100 can be arranged compactly.

[0048] Second Embodiment In this embodiment, a lighting device 102 having a different configuration from the lighting device 100 described in the first embodiment will be described. Descriptions of configurations that are the same as or similar to the configuration described in the first embodiment may be omitted.

[0049] One of the differences between the lighting device 102 and the lighting device 100 is that the lighting device 102 does not have a smoothing circuit, as shown in the functional block diagram of Figure 11. The light distribution power supply circuit 114 receives a voltage V １ , V ２ and inputs it directly to the control device 120. The control device 120 operates when the potential of the light distribution control signal is High and stops operating when it is Low. Note that the light distribution device 110 of the lighting device 102 does not need to include the shift register 118, or the light distribution device 110 may be configured so that the light distribution control signal is input to the control device 120 via the shift register 118, similar to the lighting device 100.

[0050] In the lighting device 102, the light distribution control signal is also processed in the signal generation circuit unit 122. However, unlike the lighting device 100, the signal generation circuit unit 122 generates a pulse-width modulated output signal having a constant pulse amplitude, which is then digital-to-analog converted, amplified, and supplied to the liquid crystal cell 140 of the optical element 130. The output signal and the light distribution control signal have the same duty ratio. Therefore, the degree of diffusion is determined by the duty ratio of the output signal. Furthermore, the signal generation circuit unit 122 uses an internal clock to perform calculations on the light distribution control signal so that the output signal switches between high and low at a frequency higher than that of the light distribution control signal during the period when the control device 120 is driven (i.e., during the period when the light distribution control signal is high). The frequency of the output signal may be selected, for example, from 1 kHz to 10 kHz. Therefore, as shown in FIG. 12 , during the period when the pulse-width modulated light distribution control signal is high, the output signal reverses polarity at a high frequency with respect to a reference potential (e.g., ground potential). On the other hand, since the control device 120 does not operate during the period when the light distribution control signal is Low, the potential of the output signal becomes the reference potential.

[0051] In the lighting device 102 according to this embodiment, the light source drive signal for driving the light source 210 and the light distribution control signal for operating the control device 120 are both pulse-width modulated signals. Therefore, the dimming power supply circuit 204 and the light distribution power supply circuit 114 can have the same configuration, and the dimming controller 202 and the light distribution controller 112 can also have the same configuration. Therefore, as in the first embodiment, the dimming controller 202 of the light source device 200 and the light distribution controller 112 of the light distribution device 110 can be arranged in an integrated control unit 206. Furthermore, the dimming power supply circuit 204 of the light source device 200 and the light distribution power supply circuit 114 of the light distribution device 110 can also be arranged in an integrated control unit 206. Therefore, the mechanism for controlling the lighting device 100 can be arranged compactly. Furthermore, similar effects can be obtained, such as simplifying the work required for installing the lighting device 102 and mounting the light distribution device 110 on an existing lighting device, shortening the installation time, and reducing the installation cost.

[0052] The above-described embodiments of the present invention can be combined as appropriate as long as they are not mutually inconsistent. Furthermore, even if a person skilled in the art appropriately adds or deletes components or modifies designs, or adds or omits processes or modifies conditions based on the embodiments, such combinations are included within the scope of the present invention as long as they include the gist of the present invention.

[0053] Even if there are other effects and advantages different from those brought about by the aspects of each of the above-mentioned embodiments, those that are clear from the description in this specification or that can be easily predicted by a person skilled in the art are naturally understood to be brought about by the present invention.

[0054] 100: lighting device, 102: lighting device, 110: light distribution device, 112: light distribution controller, 112-1: first light distribution controller, 112-2: second light distribution controller, 114: light distribution power supply circuit, 114-1: first light distribution power supply circuit, 114-2: second light distribution power supply circuit, 116: smoothing circuit, 116-1: first smoothing circuit, 116-2: second smoothing circuit, 118: shift register, 118-1: first shift register, 118-2: second shift register, 120: control device, 122: signal generation circuit section, 124: voltage application section, 126: digital-to-analog conversion circuit, 128: amplification circuit, 130: Optical element, 132: connector, 140: liquid crystal cell, 140-1: first liquid crystal cell, 140-2: second liquid crystal cell, 140-3: third liquid crystal cell, 140-4: fourth liquid crystal cell, 142: first substrate, 144: second substrate, 146: electrode, 146-1: first electrode, 146-2: second electrode, 146-3: third electrode, 146-4: fourth electrode, 148: alignment film, 148-1: first alignment film, 148-2: second alignment film, 150: liquid crystal layer, 152: sealing material, 154: adhesive, 200: light source device, 202: dimming controller, 204: dimming power supply circuit, 206: control unit, 210: light source

Claims

1. A lighting device comprising a light source device having a light source, and a light distribution device, wherein the light distribution device has an optical element including at least one liquid crystal cell on the light source, a control device, a smoothing circuit, a shift register, and a light distribution power supply circuit, wherein the light distribution power supply circuit is configured to input a pulse width modulated light distribution control signal that specifies the degree of diffusion of light from the light source by the optical element to the shift register and the smoothing circuit, and the control device is configured to supply a pulse amplitude modulated output signal to the at least one liquid crystal cell based on the light distribution control signal processed by the shift register.

2. The lighting device according to claim 1, wherein the at least one liquid crystal cell has: a plurality of first electrodes and a plurality of second electrodes arranged alternately in stripes; a liquid crystal layer on the plurality of first electrodes and the plurality of second electrodes; and a plurality of third electrodes and a plurality of fourth electrodes arranged alternately in stripes and intersecting the plurality of first electrodes and the plurality of second electrodes on the liquid crystal layer.

3. The lighting device described in claim 2, wherein the at least one liquid crystal cell includes a first liquid crystal cell, a second liquid crystal cell, a third liquid crystal cell, and a fourth liquid crystal cell arranged from the light source side, and the direction in which the multiple first electrodes of the first liquid crystal cell and the second liquid crystal cell extend intersects with the direction in which the multiple first electrodes of the third liquid crystal cell and the fourth liquid crystal cell extend.

4. The lighting device according to claim 1, wherein the smoothing circuit is configured to generate two different voltages from the light distribution control signal and supply them to the control device.

5. The lighting device according to claim 1, wherein the light source device further comprises a dimming power supply circuit that supplies a pulse-width modulated signal to the light source.

6. The lighting device according to claim 5, wherein the light distribution power supply circuit and the light control power supply circuit have the same structure.

7. The lighting device of claim 5, wherein the light distribution power supply circuit and the dimming power supply circuit are disposed within an integrated control unit.

8. The lighting device of claim 1, wherein the light distribution device further comprises a light distribution controller configured to control a duty ratio of the light distribution control signal output by the light distribution power supply circuit.

9. The lighting device according to claim 8, wherein the light source device further comprises: a dimming power supply circuit that supplies a pulse-width modulated light source drive signal to the light source; and a dimming controller configured to control the duty ratio of the light source drive signal, and the light distribution controller and the dimming controller have the same structure.

10. The lighting device of claim 9, wherein the light distribution controller and the dimming controller are located in an integrated control unit.

11. A lighting device comprising a light source device having a light source, and a light distribution device, wherein the light distribution device has an optical element including at least one liquid crystal cell on the light source, a control device, and a light distribution power supply circuit, wherein the light distribution power supply circuit is configured to input a pulse-width modulated light distribution control signal to the control device that specifies the degree of diffusion of light from the light source by the optical element, and the control device is configured to supply a pulse-width modulated output signal to the at least one liquid crystal cell based on the light distribution control signal.

12. The lighting device according to claim 11, wherein the duty ratio of the light distribution control signal and the duty ratio of the output signal are the same.

13. The lighting device according to claim 11, wherein the frequency of the output signal is higher than the frequency of the light distribution control signal.

14. The lighting device of claim 11, wherein the at least one liquid crystal cell has: a plurality of first electrodes and a plurality of second electrodes arranged alternately in stripes; a liquid crystal layer on the plurality of first electrodes and the plurality of second electrodes; and a plurality of third electrodes and a plurality of fourth electrodes arranged alternately in stripes and intersecting the plurality of first electrodes and the plurality of second electrodes on the liquid crystal layer.

15. The lighting device described in claim 14, wherein the at least one liquid crystal cell includes a first liquid crystal cell, a second liquid crystal cell, a third liquid crystal cell, and a fourth liquid crystal cell arranged from the light source side, and the direction in which the multiple first electrodes of the first liquid crystal cell and the second liquid crystal cell extend intersects with the direction in which the multiple first electrodes of the third liquid crystal cell and the fourth liquid crystal cell extend.

16. The lighting device according to claim 11, wherein the light distribution device further comprises a shift register configured to receive the light distribution control signal, adjust the amplitude of the light distribution control signal, and input the adjusted signal to the control device.

17. The lighting device according to claim 11, wherein the light source device further comprises a dimming power supply circuit that supplies a pulse-width modulated signal to the light source.

18. The lighting device of claim 17, wherein the light distribution power supply circuit and the light dimming power supply circuit have the same structure.

19. The lighting device of claim 18, wherein the light distribution power circuit and the dimming power circuit are disposed within an integrated control unit.

20. The lighting device of claim 11, wherein the light distribution device further comprises a light distribution controller configured to control a duty cycle of the light distribution control signal output by the light distribution power supply circuit.

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