Lighting device

Abstract

The present application provides a kind of lighting device, can utilize one lighting device switching overall illumination and local illumination.Light emitting device is characterized in that, on the first light guide plate (13) of circular plate shape with first main surface and first back and with first hole in the center, the second light guide plate (14) of circular plate shape with second main surface and second back and with second hole in the center is arranged, the reflective sheet (12) is arranged on the first back side of the first light guide plate (13), the liquid crystal lens (100) is arranged on the second main surface side of the second light guide plate (14), a plurality of first LED (20) is arranged along the circumference on the side of the first hole of the first light guide plate (13), a plurality of second LED (20) is arranged along the circumference on the side of the second hole of the second light guide plate (14), and the first LED (20) and the second LED (20) are arranged staggered in azimuth direction.

Description

Technical Field

[0001] This invention relates to a lighting device that has both overall lighting and local lighting functions. Background Technology

[0002] Light-emitting diodes (LEDs) are increasingly being used in lighting devices. LEDs have high luminous efficiency, which helps reduce power consumption. However, LEDs are point light sources; therefore, they need to be converted into surface light sources for use in lighting devices.

[0003] Patent document 1 describes a configuration that converts a point light source into a surface light source capable of achieving overall illumination by arranging LEDs on the outer wall of a circular light guide plate.

[0004] Patent document 2 describes a configuration that uses a liquid crystal lens to control the shape of a light beam.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: JP 2011-159435

[0008] Patent Document 2: US2019 / 0025657A1 Summary of the Invention

[0009] Indoor lighting fixtures are typically designed to illuminate the entire room (hereafter referred to as general lighting). While this is suitable for illuminating the whole room, it is difficult to achieve when you want to illuminate only a part of the room while darkening the rest (hereafter referred to as local lighting). To achieve local lighting, additional lighting fixtures are required.

[0010] The objective of this invention is to provide a lighting device capable of switching between general lighting and local lighting using a single lighting device.

[0011] The present invention is proposed to solve the above-mentioned problems, and its main specific means are as follows.

[0012] (1) A lighting device, characterized in that a second light guide plate having a second main surface and a second back surface and a second hole in the center is disposed on a first light guide plate having a first main surface and a first back surface and a first hole in the center, a reflector is disposed on the first back surface side of the first light guide plate, a liquid crystal lens is disposed on the second main surface side of the second light guide plate, a plurality of first LEDs are disposed circumferentially on the side surface of the first hole of the first light guide plate, a plurality of second LEDs are disposed circumferentially on the side surface of the second hole of the second light guide plate, and the first LEDs and the second LEDs are staggered in the azimuth direction.

[0013] (2) The lighting device according to (1) is characterized in that a first prism array extending radially and arranged circumferentially is formed on the first main surface of the first light guide plate, a second prism array forming concentrically in the circumferential direction is formed on the first back surface of the first light guide plate, a third prism array extending radially and arranged circumferentially is formed on the second main surface of the second light guide plate, and a fourth prism array forming concentrically in the circumferential direction is formed on the second back surface of the second light guide plate.

[0014] (3) The lighting device according to (2) is characterized in that the cross-section of the first prism array and the third prism array is an isosceles triangle, and the cross-section of the second prism array and the fourth prism array is a scalene triangle.

[0015] (4) The lighting device according to (1) is characterized in that the liquid crystal lens has a beam-gathering effect on the incident light.

[0016] (5) The lighting device according to (1) is characterized in that the liquid crystal lens has a diverging effect on the incident light.

[0017] (6) The lighting device according to (1) is characterized in that the liquid crystal lens causes the direction of the incident light to change.

[0018] (7) The lighting device according to (1) is characterized in that the liquid crystal lens causes the direction of the incident light to change to the inner circumferential direction. Attached Figure Description

[0019] Figure 1 It is a cross-sectional view of a lighting device used for local lighting in an existing example.

[0020] Figure 2 It is a cross-sectional view of using an existing lighting device for localized lighting of other parts.

[0021] Figure 3It is a cross-sectional view of overall lighting using an existing lighting fixture.

[0022] Figure 4 It is a cross-sectional view showing the state of general lighting using a lighting device configured on a wall, as in an existing example.

[0023] Figure 5 This is a cross-sectional view showing an example of localized lighting using the lighting device of the present invention.

[0024] Figure 6 This is a cross-sectional view showing an example of overall lighting using the lighting device of the present invention.

[0025] Figure 7 This is a perspective top view of the lighting device of the present invention.

[0026] Figure 8 yes Figure 7 AA sectional view.

[0027] Figure 9 This is an exploded perspective view of the lighting device of the present invention.

[0028] Figure 10 yes Figure 9 BB cross-sectional view.

[0029] Figure 11 This is a top view showing the first light guide plate and the second light guide plate overlapping.

[0030] Figure 12 This is a top view of the first light guide plate.

[0031] Figure 13 yes Figure 12 CC section view.

[0032] Figure 14 yes Figure 12 DD sectional view.

[0033] Figure 15 These are the brightness contour lines on the surface of the light guide plate.

[0034] Figure 16 This is a top view comparing the first light guide plate and the second light guide plate.

[0035] Figure 17 This is a top view showing the state in which the first light guide plate and the second light guide plate are arranged in an overlapping configuration.

[0036] Figure 18 This is a perspective view showing the configuration of the LEDs.

[0037] Figure 19 This is an example of a convex lens constructed from a liquid crystal lens.

[0038] Figure 20 It is a 3D image of a liquid crystal lens composed of two images.

[0039] Figure 21 This is an example of a concave lens constructed from a liquid crystal lens.

[0040] Figure 22 This is an example of using a liquid crystal lens to deflect a light beam.

[0041] Figure 23 This is another example of using a liquid crystal lens to deflect a light beam.

[0042] Figure 24 This is a cross-sectional view of the first example of a liquid crystal lens.

[0043] Figure 25 This is a top view of the first and second electrodes of the liquid crystal lens in the first example.

[0044] Figure 26 This is a cross-sectional view of the liquid crystal lens in the second example.

[0045] Figure 27 This is a top view of the first and second electrodes of the liquid crystal lens in the second example.

[0046] Figure 28 This is a cross-sectional view of the liquid crystal lens in the third example.

[0047] Figure 29 This is a top view of the first and second electrodes of the liquid crystal lens in the third example.

[0048] Figure 30 This is a cross-sectional view of the liquid crystal lens in the fourth example.

[0049] Figure 31 This is a top view of the first and second electrodes of the liquid crystal lens in the fourth example.

[0050] Figure 32 This is a cross-sectional view showing the use of two liquid crystal lenses.

[0051] Figure 33 This is a cross-sectional view showing the use of four liquid crystal lenses.

[0052] Figure 34 This is a cross-sectional view of a liquid crystal lens constructed using a liquid crystal lens and a polarizer.

[0053] The reference numerals in the attached figures are explained as follows:

[0054] 10 Lighting device; 11 Frame; 12 Reflector; 13 Lower light guide plate; 14 Upper light guide plate; 20 LED; 21 Flexible wiring substrate for LED; 100 Liquid crystal lens; 101 First substrate; 102 First electrode; 103 Second substrate; 104 Second electrode; 105 Sealing material; 106 Lead wire; 110 First liquid crystal lens; 111 Shaft of frame; 112 Flange of frame; 120 Second liquid crystal lens; 130 Third liquid crystal lens; 140 Fourth liquid crystal lens; 200 Bonding material; 250 Polarizer; 1000 Light spot; 2000 Table; 2100 Chair Detailed Implementation

[0055] Figures 1-3 This is a cross-sectional view illustrating an example of a lighting device that can achieve both localized and general lighting using existing technology. Figures 1-3 In this system, multiple lighting devices with very small beam angles are used to switch between localized and general lighting. Figure 1 In the case where it is desired to illuminate only the corner of the room (1000), only the lighting fixtures facing the angled direction are turned on. Additionally, in the case where it is desired to illuminate only the center of the room containing the table 2000 and chair 2100, while darkening other areas, only the downward-facing lighting fixtures are turned on.

[0056] On the other hand, if the goal is to brighten the entire room, all three lighting fixtures 10 are turned on. That is, because the beam angle of each lighting fixture is very small, multiple lighting fixtures with different lighting directions are needed to illuminate the entire room. Because... Figures 1-3 This is a sectional view of the room, so it will appear different when viewed from above. Figures 1-3 The cross-section of the room at right angles also needs to be illuminated, each time. In fact, a total of 5 lighting fixtures are needed.

[0057] Figure 4 This is a sectional view of the room showing the lighting fixture 10 mounted on the wall. Figure 4 In the diagram, the area indicated by the dashed line represents the area illuminated by the lighting device. This method is highly design-oriented, but it is difficult to apply to general lighting or spot lighting.

[0058] Figure 5 as well as Figure 6 This is a cross-sectional view illustrating the effect of the lighting device 10 of the present invention as described in the embodiment. A feature of the present invention is that it is possible to switch between general lighting and local lighting by changing the direction of the light spot 1000 using a single lighting device 10. Figure 5 This is a cross-sectional view illustrating an example of localized lighting. Figure 5 The example in the middle is a localized lighting system where the central part of the room is darkened while only the corners are brightened.

[0059] Figure 6 This is an example of using the lighting device 10 of the present invention for general lighting to brighten the entire room. Figure 6 In this process, light with a large beam angle emitted from the left half of the lighting device 10 and light with a large beam angle emitted from the right half of the lighting device 10 are combined to form overall lighting. Furthermore, Figure 6 It is a sectional view, so the structure of the lighting device 10 appears to be divided into a left half and a right half, but when viewed from above, the structure of the lighting device 10 is continuous.

[0060] The following examples illustrate the implementation. Figure 5 as well as Figure 6 The specific configuration of the lighting device of the present invention is shown.

[0061]

Example 1

[0062] Figure 7 This is a perspective top view of the lighting device 10 in Embodiment 1. Figure 8 yes Figure 7 AA section view. Furthermore, in Figure 7 , Figure 8 In subsequent drawings, the lighting fixture's enclosure, etc., are omitted. Figure 7 In the center, the top part is a rectangular liquid crystal lens, below which is the main body of a circular illumination device. Figure 7 In the middle, the frame has a T-shaped cross-section (see reference). Figure 8 A light guide plate pair 15, consisting of two circular light guide plates, is inserted into the shaft 111 of the frame. Furthermore, a flexible LED wiring substrate 21, in which LEDs 20 serving as light sources are arranged, is wound around the shaft 111 of the frame. That is, in Figure 7 In the process, light from LED20 is propagated from the inside of the light guide plate 15 to the outside and is radiated towards the top of the main surface, i.e., the side of the liquid crystal lens 100. Figure 7 The illumination device shown, including the liquid crystal lens 100, is, for example, a square with a side length of 100 mm. Figure 7 In this case, the shape of the liquid crystal lens 100 is rectangular, but it can also be made circular in the same way as the light guide plate, as needed.

[0063] Figure 8 yes Figure 7 AA section view. In Figure 8 In the frame 11, a reflective sheet 12, a lower light guide plate 13, and an upper light guide plate 14 are sequentially stacked on the flange 112. These optical components have circular grooves cut out near the center and are inserted into the shaft 111 of the frame 11. Then, a liquid crystal lens 100 is mounted on the upper light guide plate 13.

[0064] exist Figure 8 In this design, a flexible wiring substrate 21, on which LEDs 20 are mounted, is attached around the axis 111 of the frame 11. A portion of the flexible wiring substrate 21 passes through a notch formed in a portion of the flange 112 of the frame 11 and extends toward the back side of the frame 11. Since LEDs generate heat, the frame 11 is preferably made of metal to facilitate heat dissipation. Heat from the LEDs is dissipated from the flange 112 of the frame 11 via the axis 111 of the frame.

[0065] exist Figure 8 In this embodiment, a reflective sheet 12 is disposed on the flange 112. The reflective sheet 12 can be, for example, an ESR (Enhanced Specular Reflector) manufactured by 3M. The thickness is, for example, about 70 μm. A feature of this embodiment is that a lower light guide plate 13 serving as a first light guide plate and an upper light guide plate 14 serving as a second light guide plate are disposed on the reflective sheet 12. LEDs 20 are disposed corresponding to the inner side surfaces of each light guide plate 13, 14.

[0066] The arrows illustrate examples of the light paths from each LED 20 to the light guide plates 13 and 14. The light incident on the upper light guide plate 14 and the lower light guide plate 13 undergoes repeated reflections at the interfaces of the light guide plates, tending towards the upward side, i.e., the emission surface. Figure 8 In this configuration, reflection also occurs at the interface between the upper light guide plate 14 and the lower light guide plate 13. Therefore, compared to the case where the light guide plate is a single sheet, it can more effectively direct the light towards the emission surface. The detailed configuration of the light guide plate will be explained later.

[0067] Another feature of this embodiment is that, Figure 6 as well as Figure 8 As shown, by arranging multiple LEDs 20 along the inner walls of the holes in the upper light guide plate 14 and the lower light guide plate 13, the power consumption of each LED 20 is suppressed, the temperature rise of each LED 20 is suppressed, and the luminous efficiency of the LEDs 20 is prevented from decreasing.

[0068] Another feature of the present invention is that the liquid crystal lens 100 is disposed on the upper light guide plate 14. Figure 8 In the above light guide plate 14, light emitted from the normal direction of the main surface of the upper light guide plate is emitted outward at a direction of θ1 = 45 degrees and enters the liquid crystal lens 100. The light is deflected by the liquid crystal lens 100 and emitted in a direction of θ2 = 22 degrees relative to the normal direction of the main surface of the liquid crystal lens. Figure 8 The liquid crystal lens 100 has the function of deflecting light from the upper light guide plate.

[0069] In other words, when the liquid crystal lens 100 is set to ON, as described above, the light from the illumination device is emitted in a direction at an angle of θ2 = 22 degrees relative to the normal direction of the main surface of the liquid crystal lens 100. On the other hand, when the liquid crystal lens is set to OFF, the light from the illumination device is emitted in a direction at an angle of θ1 = 45 degrees relative to the normal direction of the main surface of the liquid crystal lens 100. Then, by changing the voltage applied to the liquid crystal lens 100, θ2 can be varied to various values. In addition, the liquid crystal lens 100 can also function to converge or diverge the light from the upper light guide plate 14. The configuration of the liquid crystal lens 100 will be described later.

[0070] Figure 9 Is Figure 8 The exploded three-dimensional diagram illustrating the structure is shown in the image. Figure 9 In the middle, a flexible wiring substrate 21 equipped with LEDs 20 is attached around the axis 111 of the frame 11. Figure 10 yes Figure 9 The BB section view is a detailed section view near axis 111 of frame 11. Figure 10 In this configuration, the LED 20 mounted on the flexible wiring substrate 21 is arranged in two layers, positioned opposite to the inner walls of the upper light guide plate 14 and the lower light guide plate 13. The LED 20 is at a high temperature, but the heat from the LED 20 is released through the very thin flexible wiring substrate 21 to the axis 111 of the frame 11, for example, which is made of metal.

[0071] Return to Figure 9 A reflector 12, a lower light guide plate 13, and an upper light guide plate 14 are inserted into the axis 111 of the frame 11. Figure 11 This is a top view of the upper light guide plate 14 and the lower light guide plate 13. The lower light guide plate 13 and the upper light guide plate 14 have patterned regions 131 and 141 with prism arrays and unpatterned regions 132 and 142 without prism arrays. When the lower light guide plate 13 and the upper light guide plate 14 are overlapped, the patterned region 131 of the lower light guide plate 13 coincides with the unpatterned region 142 of the upper light guide plate 14, or the unpatterned region 132 of the lower light guide plate 13 coincides with the patterned region 141 of the upper light guide plate 14.

[0072] Figure 12 This is a top view showing the configuration of the prism array in the lower light guide plate 13. Figure 12 In the light guide plate 13, regions 131 with prism arrays and regions 132 without prism arrays are arranged alternately along the circumference. The prism array formed on the upper side (hereinafter also referred to as the main surface side) of the light guide plate 13 is radially arranged, while the prism array formed on the lower side (hereinafter also referred to as the back side) of the light guide plate 13 is concentric. Then, the LED 20 is arranged opposite to the inner surface of the region with the prism array.

[0073] Figure 13 yes Figure 12 The CC cross-sectional view shows the prism array formed on the main surface side of the light guide plate 13. The prism array on the main surface side is a pattern extending radially from the center. Therefore, the prism spacing pt varies depending on the location. The thickness tg of the light guide plate is, for example, 1.5 mm. The height ht of the prism array is, for example, 0.05 mm, and the apex angle θt is, for example, 90 degrees.

[0074] Figure 14 yes Figure 12 The DD cross-sectional view is a cross-sectional view showing the prism array formed on the back side of the light guide plate 13. The prism array on the back side is a pattern formed in concentric circles. Figure 14 The prism in the image has a cross-section that is an scalene triangle, meaning the outer side is longer than the inner side. That is, in... Figure 14 The prism array formed in the middle constitutes a structure that directs light from the LED upwards at a certain angle relative to the main surface of the light guide plate. However, Figure 14 The prism array shown cannot deflect light from the LED relative to the main surface of the light guide plate in the vertical direction.

[0075] exist Figure 14 In the prism, the angle θb1 of the prism's cross-section is, for example, 15 degrees, and the angle θb2 is, for example, 85 degrees. These angles are determined based on the necessary angle of inclination of the light (e.g., Figure 8 The angle θb is set by θ1. The spacing pb between the concentric circles is, for example, 0.1 μm, the height hb of the prism is, for example, 0.02 μm, and the apex angle θb is, for example, 80 degrees. The height hb of the prism formed on the back surface is smaller than the height ht of the prism formed on the main surface. The angle θb2 is preferably between 80 and 90 degrees; the closer it is to 90 degrees, the more collimated the light emitted from the light guide plate can be, resulting in less diffusion. The apex angle θb can be changed based on angles θb2 and θb1. The light distribution is adjusted by fixing the angles and spacing pb of the prisms and changing the height hb.

[0076] The above describes the lower light guide plate 13, but the upper light guide plate 14 can also use a light guide plate of the exact same shape. As long as the upper light guide plate 13 and the lower light guide plate 14 are offset in the azimuth direction during assembly, so that the patterned area of ​​the upper light guide plate 14 corresponds to the unpatterned area of ​​the lower light guide plate 13.

[0077] Figure 15 This is a top view showing the brightness of the main surface of the light guide plate 13 when the LEDs 20 disposed on the inner wall of the light guide plate 13 are lit. Figure 15In the light guide plate 13, the LED 20 is configured corresponding to the pattern area 131 of the light guide plate 13. Using the reflector 12 and the prism array formed on the main surface and back surface of the light guide plate 13, the light from the LED 20 disposed on the side of the hole in the light guide plate 13 is emitted from the main surface of the light guide plate 13 in the pattern area 131.

[0078] Figure 15 In the diagram, b1, b2, and b3 represent contour lines of brightness, with b1 being the brightest area. Figure 11 The characteristic is that the light from the LED20 is directed to the corresponding patterned area 131 of the light guide plate 13 and emitted. That is, by utilizing the prism array formed on the main surface and the back surface of the light guide plate 13, the light from the LED20 is efficiently focused onto the main surface side of the patterned area 131. The same operation is performed in the upper light guide plate 14.

[0079] Figure 16 This is a top view showing the brightness distribution on the main surfaces of the upper light guide plate 14 and the lower light guide plate 13 when the LED 20 is lit. Figure 16 In the upper light guide plate 14 and the lower light guide plate 13, the bright part of the shadow line area, that is, the part where LED 20 is configured. Figure 16 The upper side shows the LED 20 of the upper light guide plate 14 and the LED 20 arranged in the upper light guide plate 14. Figure 16 The LEDs 20 on the lower light guide plate 13 shown on the lower side are all different LEDs.

[0080] Figure 17 This refers to the brightness distribution when the upper light guide plate 14 and the lower light guide plate 13 are arranged in an overlapping configuration. The upper light guide plate 14 and the lower light guide plate 13 are arranged in such a way that a very bright area from which light is emitted from the LED 20 overlaps with a very dark area from which light is not emitted from the LED 20, so that light is emitted substantially uniformly from the main surface of the light guide plate 14.

[0081] Figure 18 This is a perspective view showing the arrangement of LEDs 20 disposed on the inner walls of the lower light guide plate 13 and the upper light guide plate 14. The LEDs 20 are arranged in a circumferential shape, with the upper LEDs 20 and the lower LEDs 20 arranged differently from each other in the azimuth direction. By setting it in this way, more LEDs 20 can be disposed, thus suppressing the power consumption of each LED 20 and suppressing heat generation.

[0082] The light emitted from the main surface of the second light guide plate is like... Figure 8As shown, the light is emitted in a direction inclined outward in the vertical direction relative to the main surface of the second light guide plate. The light emitted from the second light guide plate has a predetermined beam distribution angle by utilizing the characteristics of the first light guide plate, the second light guide plate, etc. One of the features of the present invention is that by arranging a liquid crystal lens on the second light guide plate, the direction of the emitted light is changed; furthermore, the beam distribution angle is changed by utilizing the converging or diverging effect of the liquid crystal lens.

[0083] Figure 19 This is a cross-sectional view illustrating the principle of a liquid crystal lens. Figure 19 In the middle, collimated light is incident from the left side of the liquid crystal layer 300. Figure 19 In this context, P refers to the direction of deflection of the incident light. Normally, the direction of light deflection is randomly distributed, but liquid crystals exhibit anisotropy in their refractive index; therefore, Figure 19 This illustrates the effect on light that has been deflected in the P direction.

[0084] exist Figure 19 In the liquid crystal layer 300, liquid crystal molecules 301 are oriented by electrodes such that their tilt increases as they move towards the periphery of the liquid crystal layer 300. The liquid crystal molecules 301 have an elongated shape, and the effective refractive index along the long axis of the liquid crystal molecules 301 is greater than the effective refractive index along the short axis of the liquid crystal molecules 301. Therefore, the refractive index becomes greater towards the periphery of the liquid crystal layer 300, thereby forming a convex lens. Figure 19 The dashed line in the image represents the wavefront WF, and f is the focusing distance of the lens.

[0085] Liquid crystals exhibit anisotropy in refractive index; therefore, in order to form a lens, a second lens is required. This second lens acts on light that is deflected in a direction perpendicular to the deflection direction of the light passing through the first lens. Figure 20 This is an exploded three-dimensional view showing the lens configuration. Figure 20 In the image, the parallelogram on the left represents the wavefront of light. That is, light deflected in the x and y directions is incident on the liquid crystal layer. The first liquid crystal lens 110 acts on X-polarized light, and the second liquid crystal lens 120 acts on Y-polarized light.

[0086] exist Figure 20 In the first liquid crystal lens 110 and the second liquid crystal lens 120, the initial orientation directions of the liquid crystal molecules 301 are 90 degrees different. The initial orientation of the liquid crystal molecules 301 is determined by the orientation direction of the alignment film within the liquid crystal lens. That is to say, in Figure 20 In the two liquid crystal lenses, the orientation directions of the alignment films in the substrate on the light incident side are perpendicular to each other.

[0087] Figure 21 This refers to the case where a concave lens is formed using a liquid crystal lens. Figure 21In the image, the wavefront WF is parallel to the liquid crystal layer 300, and light deflected in one direction enters the liquid crystal layer 300 from the left. Figure 21 In the liquid crystal layer 300, the liquid crystal molecules 301 are oriented at a maximum angle near the optical axis via electrodes, and the orientation angle decreases as they move towards the periphery. Using a lens configuration based on this liquid crystal orientation, the wavefront WF of light passing through the liquid crystal layer 300 becomes... Figure 21 The dashed line represents a curve that forms a concave lens. Furthermore, the situation regarding concave lenses is also similar to... Figure 20 As shown, two liquid crystal lenses are also required.

[0088] Figure 22 This diagram illustrates the principle of deflecting light to the left using a liquid crystal lens. Figure 22 The upper part of the figure is a cross-sectional view of the liquid crystal lens 100. A first electrode 102 is formed on a first substrate 101 of the liquid crystal lens 100, and a second electrode 104 is formed on a second substrate 103. A liquid crystal layer 300 exists between the first electrode 102 and the second electrode 104. The liquid crystal layer 300 is sealed by a sealing material 105. Figure 22 In this design, instead of using two liquid crystal lenses, a polarizer 250 is used, thus reducing the number of liquid crystal lenses to one.

[0089] exist Figure 22 Between the first electrode 102 and the second electrode 104, as Figure 22 As shown in the curve on the lower side, when a voltage v is applied that increases in potential difference from left to right, the orientation angle of the liquid crystal molecules 301 changes according to different locations, and the effective birefringence Δn of the liquid crystal layer 300 changes curvilinearly. Using this configuration of the liquid crystal layer 300, light LL incident from the lower side is deflected to the left and emitted towards the liquid crystal lens 100.

[0090] Figure 23 This diagram illustrates the principle of light being deflected to the right by the liquid crystal lens 100. Figure 23 In the diagram above, apart from the method of applying voltage between the first electrode 102 and the second electrode 104, the method is similar to... Figure 22 Same. Figure 23 Between the first electrode 102 and the second electrode 104, such as Figure 23 As shown in the curve on the lower side, when a voltage v is applied that decreases in potential difference from left to right, the orientation angle of the liquid crystal molecules 301 changes according to different locations, and the effective birefringence Δn of the liquid crystal changes in a curved manner. Through this configuration of the liquid crystal layer 300, the light LL incident on the liquid crystal lens 100 is deflected to the right.

[0091] Figure 24 This is a cross-sectional view showing a first example of the structure of an actual liquid crystal lens. Figure 24In this structure, a first electrode 102 is disposed on a first substrate 101, a second electrode 104 is disposed on a second substrate 103, and a liquid crystal layer 300 is sandwiched between the first substrate 101 and the second substrate 103. An alignment film is formed covering the first electrode 102 and the second electrode 104, but... Figure 24 The alignment film is omitted in the figure. The same applies to the following figures. The initial alignment direction of the liquid crystal molecules 301 is determined by alignment treatments such as rubbing the alignment film.

[0092] exist Figure 24 In this configuration, the initial orientation direction of the liquid crystal molecules 301 on the first substrate 101 side is 90 degrees to the initial orientation direction of the liquid crystal molecules 301 on the second substrate 103 side, forming a so-called TN (Twisted Nematic) type liquid crystal lens. The first electrode 102 extends along the x-direction, and the second electrode 104 extends along the y-direction. However, the liquid crystal lens 100 is not necessarily limited to a TN type liquid crystal.

[0093] Figure 25 The diagram on the left is a top view of the first electrode 102 formed on the first substrate 101. Figure 25 The diagram on the right is a top view of the second electrode 104 formed on the second substrate 103. The first electrode 102 extends along the x-direction, and the second electrode 104 extends along the y-direction. At the intersection of the first electrode 102 and the second electrode 104, the liquid crystal molecules 301 are oriented according to voltage. That is, various functions of a liquid crystal lens can be achieved depending on the method of applying voltage to the first electrode 102 and the second electrode 104.

[0094] Figure 26 This is a cross-sectional view showing a second example of the configuration of an actual liquid crystal lens 100. Figure 26 In the first substrate 101, a striped first electrode 102 is disposed on the first substrate 101, a planar second electrode 104 is disposed on the second substrate 103, and a liquid crystal layer 300 is sandwiched between the first substrate 101 and the second substrate 103. Figure 27 The left side of the figure is a top view of the first electrode 102 formed on the first substrate 101, which extends along the x direction. Figure 27 The diagram on the right is a top view of the second electrode 104 formed on the second substrate 103, and the second electrode 104 is planar. In the second example, various liquid crystal lens functions can also be achieved by utilizing the voltage applied between the first electrode 102 and the second electrode 104.

[0095] Figure 28 This is a cross-sectional view showing a third example of the actual configuration of the liquid crystal lens 100. Figure 28In the first substrate 101, a striped first electrode 102 is disposed on the first substrate 101, and an electrode is disposed on the second substrate 103. Figure 29 The figure on the left is a top view of the first electrode 102 formed on the first substrate 101, which extends along the x-direction. Figure 29 The diagram on the right only depicts the second substrate 103; the second electrode is not present.

[0096] The third example is a transverse electrical boundary liquid crystal lens where the liquid crystal is driven solely by the first electrode 102 formed on the first substrate 101. That is, the liquid crystal molecules 301 are oriented using the potential difference between adjacent striped first electrodes 102, thereby forming a lens. By varying the voltage between the striped electrodes of the first electrode 102, various types of lenses can be constructed.

[0097] Figure 30 This is a cross-sectional view showing a fourth example of the actual configuration of the liquid crystal lens 100. Figure 30 In the first substrate 101, a concentric first electrode 102 is disposed on the first substrate 101, a planar second electrode 104 is disposed on the second substrate 103, and a liquid crystal layer 300 is sandwiched between the first substrate 101 and the second substrate 103. Figure 31 The left-hand diagram is a top view of the first electrode 102 formed on the first substrate 101. The first electrode 102 is a concentric circle. Each of the circular electrodes is connected to a winding electrode 106 for applying voltage. Figure 31 The diagram on the right shows that a second electrode is formed in a planar shape on the second substrate 103.

[0098] exist Figure 31 In this example, by varying the voltage between the first electrode 102 and the second electrode 104, lenses of various intensities can be formed. The fourth example is characterized in that the first electrode 102 is formed in concentric circles, thus making it easy to form a circular lens.

[0099] Figures 24-31 Both are constructed using a single liquid crystal lens. However, since liquid crystals can control the polarization of light in only one direction, it is necessary to use two liquid crystal lenses as a group using actual liquid crystal lenses. Figure 32 This is a cross-sectional view of the case where the first liquid crystal lens 110 and the second liquid crystal lens 120 are overlapped using bonding material 200.

[0100] exist Figure 32In this configuration, the first liquid crystal lens 110 is a TN liquid crystal, with a first electrode 102 formed on a first substrate 101 and a second electrode 104 formed on a second substrate 103, forming a configuration in which a liquid crystal layer 300 is sandwiched between the first substrate 101 and the second substrate 103. The second liquid crystal lens 120 has the same configuration. While the first and second liquid crystal lenses have the same configuration, the light distribution direction AL of the alignment film on the first substrate 101 in the first liquid crystal lens 110 intersects the light distribution direction AL of the alignment film on the first substrate 101 in the second liquid crystal lens 120 at a 90-degree angle. In other words, the first liquid crystal lens 110 acts on polarized light polarized in a first direction relative to the incident light, and the second liquid crystal lens 120 acts on polarized light polarized in a second direction perpendicular to the first direction of the incident light.

[0101] In cases where two liquid crystal lenses cannot fully utilize the lens function or deflection function, four liquid crystal lenses can be used. Figure 33 This is an example of combining four liquid crystal lenses using bonding material 200. Figure 33 In the middle, a first liquid crystal lens 110, a second liquid crystal lens 120, a third liquid crystal lens 130, and a fourth liquid crystal lens 140 are stacked from the bottom side. The configuration of the first liquid crystal lens 110 and the second liquid crystal lens 120 is as follows: Figure 32 As explained in the description. The third liquid crystal lens 130 and the fourth liquid crystal lens 140 are also the same as the first liquid crystal lens 110 or the second liquid crystal lens 120.

[0102] exist Figure 33 In the first liquid crystal lens 110, the alignment direction AL of the alignment film formed on the first substrate 101 is perpendicular to the light distribution direction AL of the alignment film formed on the first substrate 101 of the second liquid crystal lens 120, and the alignment direction AL of the alignment film formed on the first substrate 101 of the third liquid crystal lens 130 is perpendicular to the light distribution direction AL of the alignment film formed on the first substrate 101 of the fourth liquid crystal lens 140.

[0103] Furthermore, the orientation direction of the alignment film of the first to fourth liquid crystal lenses can also be... Figure 33 Other combinations. Furthermore, each liquid crystal lens does not need to be limited to TN liquid crystal.

[0104] Figure 34 This configuration aims to utilize only one liquid crystal lens 100. Figure 34 In the middle, a polarizer 250 is attached below the first liquid crystal lens 110. The structure and function of the first liquid crystal lens 110 are as follows: Figures 24-27 As explained in the previous section, liquid crystals only act on light in a specific deflection direction; therefore, it is necessary to direct the deflected light onto the first liquid crystal lens 110.

[0105] Figure 34 The diagram illustrates how polarizer 250 is disposed on the first substrate 101 of the first liquid crystal lens 110, allowing polarized light controllable by liquid crystal to be incident on the first liquid crystal lens 110. However, when polarizer 250 is used, light polarized in a direction perpendicular to the transmission axis of polarizer 250 cannot be transmitted. Therefore, the light that cannot be transmitted through polarizer 250 is reflected by the light guide plate 14 side, and then reflected again by the light guide plate 14 side. This rotates the polarization axis of the light, allowing it to be reused. By using a deflecting reflector in this way, the light utilization efficiency can be improved.

[0106] As explained above, according to the present invention, both general illumination and local illumination can be achieved using a single lighting device. Furthermore, by using a liquid crystal lens, the position and beam angle of the light spot can be freely varied during local illumination.

Claims

1. An illumination device characterized by comprising: a first light guide plate having a first main surface and a first back surface and being circular-plate-shaped with a first hole in the center, a second light guide plate having a second main surface and a second back surface and being circular-plate-shaped with a second hole in the center, disposed on the first light guide plate, a reflection sheet disposed on the first back surface side of the first light guide plate, a liquid crystal lens disposed on the second main surface side of the second light guide plate, a plurality of first LEDs disposed on the side of the first hole of the first light guide plate in the circumferential direction, and a plurality of second LEDs disposed on the side of the second hole of the second light guide plate in the circumferential direction, the first LEDs and the second LEDs being disposed apart in the azimuthal direction, a first prism array extending radially in a radial pattern and arranged in the circumferential direction being formed on the first main surface of the first light guide plate, and a second prism array formed in a concentric circle pattern in the circumferential direction being formed on the first back surface of the first light guide plate, a third prism array extending radially in a radial pattern and arranged in the circumferential direction being formed on the second main surface of the second light guide plate, and a fourth prism array formed in a concentric circle pattern in the circumferential direction being formed on the second back surface of the second light guide plate.

2. The illumination device according to claim 1, characterized in that: the cross section of the first prism array and the third prism array is an isosceles triangle, and the cross section of the second prism array and the fourth prism array is a scalene triangle.

3. The illumination device according to claim 2, characterized in that: the length of the side of the scalene triangle in the outer peripheral direction of the first light guide plate and the second light guide plate is longer than the length of the side in the inner peripheral direction.

4. The illumination device according to claim 1, characterized in that: the first light guide plate has a first region in which a fan-shaped region is radially opposite to the first LEDs, and a second region in which a fan-shaped region is not radially opposite to the first LEDs, the first prism array and the second prism array are formed in the first region and not formed in the second region, the second light guide plate has a third region in which a fan-shaped region is radially opposite to the second LEDs, and a fourth region in which a fan-shaped region is not radially opposite to the second LEDs, the third prism array and the fourth prism array are formed in the third region and not formed in the fourth region.

5. The illumination device according to claim 4, characterized in that: the first region of the first light guide plate and the fourth region of the second light guide plate coincide with each other when viewed from above.

6. The illumination device according to claim 1, characterized in that: the illumination device further comprises a frame having a circular-plate-shaped flange, and a shaft formed near the center of the circular plate and protruding in a cylindrical shape near the center of the circular plate, the reflection sheet, the first light guide plate, and the second light guide plate are placed on the flange in this order, the plurality of first LEDs and the plurality of second LEDs are attached around the shaft.

7. The illumination device according to claim 1, characterized in that: the liquid crystal lens has a converging effect on incident light.

8. The illumination device according to claim 1, wherein the liquid crystal lens has a diverging effect on the incident light.

9. The illumination device according to claim 1, wherein the liquid crystal lens changes the direction of the light with respect to the incident light.

10. The illumination device according to claim 1, wherein the liquid crystal lens changes the direction of the light with respect to the incident light to the inner circumferential direction.

Images