Lighting device
The integration of a funnel-type reflector and liquid crystal lens system in a lighting device addresses the size and collimation challenges of conventional fixtures, enabling a compact design with adjustable light shapes and beam angles.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- JAPAN DISPLAY INC
- Filing Date
- 2022-06-24
- Publication Date
- 2026-06-11
AI Technical Summary
Conventional lighting fixtures such as Z-lights and cylindrical floor lamps are large in size and difficult to use in small spaces, and obtaining collimated light from these fixtures is challenging, often requiring additional optical components that increase their length.
A lighting device utilizing a funnel-type reflector with a reflective surface and a liquid crystal lens configuration, where light is reflected and then emitted through a series of liquid crystal lenses to achieve collimation and shape change, reducing the device's length and allowing for compact design.
The solution enables a compact lighting device capable of emitting collimated light with adjustable beam angles and shapes, maintaining a sufficient distance from the work surface while minimizing the device's thickness.
Smart Images
Figure 0007872983000001 
Figure 0007872983000002 
Figure 0007872983000003
Abstract
Description
Technical Field
[0001] The present invention relates to a lighting device that is compact and can easily change the shape of the irradiated light.
Background Art
[0002] As lighting fixtures, there are various fixtures such as so-called Z-lights, desk lights with linearly arranged LEDs, and cylindrical floor lamps.
[0003] On the other hand, there is a demand for using a lighting device in which the emitted light is collimated. Patent Document 1 describes a lighting device that emits light from a light source as parallel light using a rod lens or the like. Cited Document 1 also describes a configuration in which light collimated by a rod lens or the like is used as a backlight for a liquid crystal valve (liquid crystal display device).
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0005] Conventionally used lighting fixtures such as so-called Z-lights, desk lights with linearly arranged LEDs, and cylindrical floor lamps are large in size and many are difficult to use in a small space. Also, it is difficult to obtain collimated light from these lighting fixtures.
[0006] Conventionally, in order to obtain collimated light, a rod lens or the like has been used. Generally, however, sufficient collimated light cannot be obtained with only a rod lens, so additional optical components such as lenses are required. Then, the length in the emission direction of the lighting device increases.
[0007] The objectives of this invention are to realize a lighting device that is compact and has a reduced length in the direction of light emission. Furthermore, to realize a lighting device that is compact while being able to reduce the beam angle of the emitted light. In addition, to realize a lighting device that can easily change the shape of the light spot. [Means for solving the problem]
[0008] The present invention solves the above problems, and the main specific means are as follows: a funnel-type reflector having a first hole in which a light source is placed and a second hole from which light is emitted, and a reflective surface connecting the first hole and the second hole, with the line connecting the center of the first hole and the center of the second hole being the first direction, a reflector facing the second hole of the funnel-type reflector, with the main surface of the reflective surface inclined at a first angle with respect to the first direction, and a liquid crystal lens facing the reflector, with the main surface of the incident surface inclined at a second angle with respect to the main surface of the reflector, wherein light emitted from the funnel-type reflector is reflected by the reflector and emitted from the liquid crystal lens. [Brief explanation of the drawing]
[0009] [Figure 1] This is a side view of a lighting device in a comparative example. [Figure 2] This is a plan view of the lighting device of Example 1. [Figure 3] This is a perspective view of the lighting fixture from above. [Figure 4] This is a perspective view of the lighting fixture from below. [Figure 5] A cross-sectional view showing the configuration of Example 1 is provided. [Figure 6] This is a perspective view of a funnel-shaped reflector. [Figure 7] This is a cross-sectional view illustrating the operation of a liquid crystal lens. [Figure 8] This is another cross-sectional view illustrating the operation of the liquid crystal lens. [Figure 9] This is yet another cross-sectional view illustrating the operation of the liquid crystal lens. [Figure 10] It is a cross-sectional view of the first liquid crystal lens. [Figure 11] It is a plan view showing the electrode shape of the first liquid crystal lens. [Figure 12] It is a perspective view showing the operations of the first liquid crystal lens and the second liquid crystal lens. [Figure 13] It is a cross-sectional view showing the state where the first liquid crystal lens and the second liquid crystal lens are laminated. [Figure 14] It is a perspective view showing the operations of the first liquid crystal lens, the second liquid crystal lens, the third liquid crystal lens, and the fourth liquid crystal lens. [Figure 15] It is a table showing various actions of the liquid crystal lens according to Example 1. [Figure 16] It is a plan view showing an electrode configuration according to another example of the liquid crystal lens. [Figure 17] It is a plan view of the lens element of the liquid crystal lens in FIG. 16. [Figure 18] It is a plan view showing the shape of incident light on the liquid crystal lens. [Figure 19] It is a cross-sectional view showing the state where the liquid crystal lens is performing a diverging action in a specific direction. [Figure 20] It is a cross-sectional view showing the case where there is no diverging action of the liquid crystal lens in a direction perpendicular to the specific direction shown in FIG. 19. [Figure 21] It is a chart when the liquid crystal lens is driven in a time-division manner. [Figure 22] It is a cross-sectional view and a graph showing the action of the liquid crystal lens according to Example 2. [Figure 23] It is a plan view showing the electrode configuration of the liquid crystal lens of Example 2. [Figure 24] It is a plan view showing another electrode configuration of the liquid crystal lens of Example 2. [Figure 25] It is a plan view and a cross-sectional view showing the action of the liquid crystal lens in Example 3. [Figure 26] It is a table showing examples of various actions of the liquid crystal lens according to Example 3. [Figure 27] It is a perspective view of the funnel-shaped reflector according to Example 3. [Figure 28]Figure 27 shows the funnel-shaped reflector viewed from the bottom direction (direction B). [Figure 29] This is a cross-sectional view AA in Figure 27. [Modes for carrying out the invention]
[0010] The present invention will be described in detail below with reference to examples. [Examples]
[0011] Figure 1 shows a lighting device as a comparative example. In Figure 1, the lighting device 1 is supported by an arm 2 from a base 3. The schematic shape of the lighting device 1 in Figure 1 is a rectangular parallelepiped with a cross-section of a square with a width d2 and a length d1. The basic configuration of the lighting device 1 in Figure 1 uses an LED as the light source, and the light from the LED is converted into parallel light by a funnel-type reflector with a parabolic curved inner wall.
[0012] The details of the funnel-type reflector will be explained later, but in order to obtain collimated light, the funnel-type reflector needs to have a predetermined length in the optical axis direction. In the length d1 of the illumination device 1 in Figure 1, the length d1 of the funnel-type reflector accounts for a large proportion. Therefore, in Figure 1, if we try to make the beam angle θ of the emitted light 4 as small as possible, the length of the illumination device 1 in the direction of emission increases. This leads to the problem that the distance h1 from the emission hole of the illumination device 1 to the work surface 31 cannot be sufficiently maintained.
[0013] Figure 2 is a schematic side view of Embodiment 1, which addresses the problems in the configuration of Figure 1. The difference between Figure 2 and Figure 1 is that the lighting device 1 attached to the arm 2 is oriented horizontally, and the emitted light 4 is emitted from an emitter positioned on the side of the lighting device 1. In order to emit the emitted light 4 from the side of the lighting device 1, a reflector tilted at 45 degrees with respect to the direction of light propagation is placed inside the lighting device 1 in Figure 2, and the outer shape of the lighting device 1 also has an inclined surface formed accordingly.
[0014] With the configuration shown in Figure 2, sufficient distance can be maintained from the lighting device 1 to the work surface 31. Furthermore, even if the length d3 of the lighting device 1 is increased to further reduce the beam angle θ of the emitted light 4, the width d4 of the lighting device 1 remains unchanged. Therefore, the distance h2 from the lighting device 1 to the work surface 31 remains unchanged.
[0015] Figure 3 is a perspective view of the lighting device 1 shown in Figure 2, viewed from an oblique upward direction. In Figure 3, the housing 5 of the lighting device 1 contains an LED, which is the light source, and a funnel-shaped reflector. Reflectors for changing the direction of light are placed in the inclined part of the outer shape. Figure 4 is a perspective view of Figure 3 from direction A. In other words, Figure 4 shows the shape of the bottom surface of the lighting device 1. In Figure 4, the circular light emission hole 6 is located on the bottom surface of the lighting device 1. Also, as will be explained later, a liquid crystal lens for changing the shape of the emitted light 4 is placed directly in front of the emission hole 6.
[0016] Figure 5 is a cross-sectional view showing the configuration of Embodiment 1, and is a cross-sectional view of the components arranged inside the housing 5. The general configuration of Figure 5 is as follows. In Figure 5, an LED 20, which is a light source, is fitted into the LED hole of the funnel-type reflector 10. The LED 20 is arranged on the LED substrate 21. The light emitted from the LED 20 is collimated in a direction parallel to the optical axis by the parabolic curved surface formed on the inner surface of the funnel-type reflector 10, and the light emitted from the funnel-type reflector 10 is directed towards the reflector 30.
[0017] The direction of the light is bent by 90 degrees by the reflector 30 and directed downwards in Figure 5. Depending on the application of the lighting device 1, the direction in which the light is bent does not have to be limited to 90 degrees. The direction in which the light is bent is determined by the inclination angle φ of the reflector 30 shown in Figure 5. The light 7 reflected by the reflector 30 enters the liquid crystal lens 100, undergoes lensing action by the liquid crystal lens 100, and then becomes emitted light 4, which is emitted from the exit hole of the lighting device. In Figure 5, the light that enters the liquid crystal lens undergoes divergence. The liquid crystal lens 100 in Figure 5 is composed of a set of four liquid crystal lenses.
[0018] In Figure 5, the angle φ between the main surface of the reflector 30 and the main surface of the liquid crystal lens 100 is 45 degrees, but this angle does not have to be limited to 45 degrees. Depending on the application of the lighting device, it may deviate from 45 degrees.
[0019] According to the configuration shown in Figure 5, the thickness of the lighting device in the direction of light emission can be reduced. Furthermore, by placing the liquid crystal lens 100 after the light has been bent by the reflector 30, rather than between the reflector 30 and the funnel-type reflector 10, the lensing effect of the liquid crystal lens 100 can be made more effective. In addition, the distance between the reflector 30 and the emission hole of the funnel-type reflector 10 can be reduced, increasing the degree of freedom in optical design.
[0020] Figure 6 is a perspective view of the funnel-type reflector 10. In Figure 5, the funnel-type reflector 10 is positioned horizontally, but in Figure 6, it is positioned vertically. The outer shape of the funnel-type reflector 10 is a rectangular parallelepiped. Inside the rectangular parallelepiped, a funnel-shaped recess is formed, and the wall surface of the recess is a parabolic curved surface 11. The shape of this recess is circular in the xy-plane, and the cross-section in the z-axis direction is parabolic. The light is collimated by the parabolic curved surface in a direction parallel to the z-axis. Note that the wall surface of the recess may also be configured so that only a portion of it is a parabolic curved surface.
[0021] In Figure 6, a hole 13 for the LED 20 is formed on the top surface of the rectangular prism. Small LEDs are commercially available that are as small as 1.5 mm square when viewed from above. The LED hole 13 only needs to be large enough in diameter to accommodate such a small LED. An emission hole 12 is formed on the bottom surface of the rectangular prism. The emission hole 12 is, for example, a circle with a diameter dd of about 6.5 mm.
[0022] The LED hole 13 and the emission hole 12 are connected by a parabolic curved surface 11. The light emitted from the LED 20 is collimated by the parabolic curved surface 11 and emitted from the emission hole 12. In Figure 6, the larger the ratio (hf / dd) between the diameter dd of the emission hole 12 and the height hf of the funnel-type reflector 10, the more collimated the light, i.e., the smaller the beam angle of the emitted light. (hf / dd) is sometimes called the aspect ratio.
[0023] The aspect ratio is preferably 2 or greater, more preferably 3 or greater, and even more preferably 4 or greater. In the configuration of the present invention shown in Figure 5, the funnel-type reflector 10 is used horizontally, so even if the aspect ratio is increased, the height of the lighting device does not change. Therefore, the h2 shown in Figure 2 can be maintained.
[0024] Returning to Figure 5, in this invention, the shape of the light emitted from the lighting device 1 is changed by the liquid crystal lens 100. In order to more accurately determine the shape of the light spot by the liquid crystal lens 100, it is desirable that the light incident on the liquid crystal lens 100 be as collimated as possible. The funnel-type reflector 10 has a small external shape but can emit light with a small beam angle, making it suitable for the optical configuration shown in Figure 5.
[0025] In Figure 5, the light emitted from the funnel-type reflector 10 is reflected by the reflector 30 and changes direction by 90 degrees before continuing its path. Experiments have confirmed that the orientation angle of the reflected light remains almost unchanged even after reflection by the reflector 30. In Figure 5, the angle of the main surface of the reflector 30 with respect to the optical axis is 45 degrees, but this can be changed depending on the application of the lighting device.
[0026] Light reflected by the reflector 30 enters the liquid crystal lens 100, and through the action of the liquid crystal lens 100, it can be changed into various light spot shapes as needed. The liquid crystal lens 100 is a set of four liquid crystal lenses: the first liquid crystal lens 110, the second liquid crystal lens 120, the third liquid crystal lens 130, and the fourth liquid crystal lens 140.
[0027] According to the configuration shown in Figure 5, the light incident on the liquid crystal lens 100 is collimated by the funnel-type reflector 10, and maintains a small light spot diameter even after being reflected by the reflector 30. Therefore, there is no need to increase the size of the liquid crystal lens 100. Each of the liquid crystal lenses 110, 120, 130, and 140 is composed of a TFT substrate and a counter substrate, and the thickness of each substrate is about 0.5 mm, so the thickness of one liquid crystal lens is about 1 mm, and when four liquid crystal lenses are stacked, the total thickness is about 4 mm.
[0028] Figure 7 is a cross-sectional view illustrating the principle of the liquid crystal lens 100. In Figure 7, collimated light is incident from the left side of the liquid crystal layer 300. In Figure 7, P represents the direction of deflection of the incident light. While the deflection direction of normal light is randomly distributed, liquid crystals have anisotropy in their refractive index, so Figure 7 shows the effect on light deflected in the P direction.
[0029] In Figure 7, the liquid crystal molecules 301 in the liquid crystal layer 300 are oriented by electrodes such that the tilt increases as they move toward the periphery of the liquid crystal layer 300. Since the liquid crystal molecules 301 have an elongated shape, and the effective refractive index in the direction of the long axis of the liquid crystal molecule 301 is greater than the effective refractive index in the direction of the short axis of the liquid crystal molecule 301, the refractive index increases toward the periphery of the liquid crystal layer 300, thus forming a convex lens. The dotted line in Figure 7 represents the optical wavefront WF, and f is the focal distance of the lens.
[0030] Because liquid crystals have anisotropic refractive index, forming a lens requires a second lens that acts on light polarized perpendicular to the direction of polarization of the light acted on by the first lens. Figure 8 is an exploded perspective view showing this lens configuration. In Figure 8, the parallelogram on the left represents the wavefront of light. That is, light polarized in the X and Y directions is incident on the liquid crystal layer 300. The first liquid crystal lens 110 acts on X-polarized light, and the second liquid crystal lens 120 acts on Y-polarized light.
[0031] In Figure 8, the initial orientation directions of the liquid crystal molecules 301 differ by 90 degrees between the first liquid crystal lens 110 and the second liquid crystal lens 120. The initial orientation of the liquid crystal molecules 301 is determined by the orientation direction of the alignment film within the liquid crystal lens. In other words, in Figure 8, the orientation directions of the alignment films on the substrates on the side where light is incident are perpendicular to each other.
[0032] Figure 9 shows the case where a concave lens is formed using liquid crystal lenses. In Figure 9, light with a wavefront WF parallel to the liquid crystal layer 300 and deflected in one direction is incident on the liquid crystal layer 300 from the left. In Figure 9, the liquid crystal molecules 301 in the liquid crystal layer 300 are most strongly oriented near the optical axis by the electrodes, and the orientation angle decreases towards the periphery. With this lens configuration due to liquid crystal orientation, the wavefront WF of the light that has passed through the liquid crystal layer 300 forms a curve as shown by the dotted line in Figure 9, thus forming a concave lens. Note that, as with Figure 8, two liquid crystal lenses are required even in the case of a concave lens.
[0033] Figure 10 is a detailed cross-sectional view of the liquid crystal lens 110. In Figure 10, a first electrode 112 is formed on the TFT substrate 111, and a first alignment film 113 is formed covering the first electrode 112. The orientation direction of the first alignment film 113 determines the polarization of the incident light that is affected by the liquid crystal lens. A second electrode 116 is formed on the inside of the opposing substrate 115, and a second alignment film 117 is formed covering the second electrode 116. The relationship between the orientation direction of the first alignment film 113 and the orientation direction of the second alignment film 117 is determined by the type of liquid crystal used. A liquid crystal layer 300 is sandwiched between the TFT substrate 111 and the opposing substrate 115.
[0034] The left side of Figure 11 is a plan view of the first electrode 112 formed on the first substrate 111. The first electrode 112 is a concentric circle. Lead wires 114 for applying voltage are connected to each circular electrode 112. The right side of Figure 11 is a plan view showing the shape of the second electrode 116 formed on the opposing substrate 115. The second electrode 116 is a planar electrode and is formed over almost the entire surface of the opposing substrate 115.
[0035] In Figure 11, lenses of various intensities can be formed by changing the voltage between the first electrode 112 and the second electrode 116. The examples in Figures 10 and 11 have the advantage that circular lenses can be easily formed because the first electrode 111 is formed in a concentric circle.
[0036] The liquid crystal lens 110 described in Figures 10 and 11 is a lens that acts in one direction, for example, with respect to polarized light PX. However, since the light from LED 10 is polarized in all directions, a liquid crystal lens is needed that acts at least with respect to light PY polarized perpendicular to PX.
[0037] Figure 12 is a perspective view showing this configuration. In Figure 12, when light LL from the LED is incident from the left, the light polarized in the PX direction by the first liquid crystal lens 110 is affected by the liquid crystal lens. Light polarized in the PY direction is not affected by the first liquid crystal lens 110. Light polarized in the PY direction is affected by the second liquid crystal lens 120. Light polarized in the PX direction is not affected by the second liquid crystal lens 120. As a result, both light polarized in the x direction and light polarized in the y direction can be affected by the liquid crystal lens.
[0038] Figure 13 is a cross-sectional view showing the stacked state of the first liquid crystal lens 110 and the second liquid crystal lens 120. The first liquid crystal lens 110 and the second liquid crystal lens 120 are bonded together with a transparent adhesive 200. In Figure 13, the electrode configuration of the second liquid crystal lens 120 is the same as that of the first liquid crystal lens 110. That is, in the second liquid crystal lens 120, a third electrode 122 is formed on the TFT substrate 121, and a third alignment film 123 is formed on top of it. A fourth electrode 126 is formed on the opposing substrate 125, and a fourth alignment film 127 is formed on top of it.
[0039] The difference between the second liquid crystal lens 120 and the first liquid crystal lens 110 lies in the orientation direction of the alignment film 123. In Figure 13, AL indicates the orientation direction of the alignment film 113. In Figure 13, the orientation direction of the first alignment film 113 formed on the TFT substrate 111 of the first liquid crystal lens 110 is, for example, the x-direction. The orientation direction of the third alignment film 123 formed on the TFT substrate 121 of the second liquid crystal lens 120 is, for example, the y-direction. In other words, both light polarized in the x-direction and light polarized in the y-direction can be affected by the two liquid crystal lenses 110 and 120.
[0040] The orientation direction of the second alignment film 117 formed on the opposing substrate 115 of the first liquid crystal lens 110, and the orientation direction of the fourth alignment film 127 formed on the opposing substrate 125 of the second liquid crystal lens 120, are determined by the type of liquid crystal used as the liquid crystal 300. In other words, the second alignment film 117 in the first liquid crystal lens 110 may be oriented in the same direction as the first alignment film 113, or it may be oriented perpendicular to it. The same applies to the relationship between the third alignment film 123 and the fourth alignment film 127 in the second liquid crystal lens 120.
[0041] By the way, since the light from LED 10 is polarized in all directions, if the liquid crystal lens acts only on the polarized light of PX or PY, it may not be able to achieve sufficient effect. In this case, as shown in Figure 14, for example, a liquid crystal lens 130 that acts on light P45 polarized at a 45-degree angle to the x-direction, and a liquid crystal lens 140 that acts on light P135 polarized at a 135-degree angle to the x-direction can be added.
[0042] Liquid crystal lenses can not only have the effect of converging and diverging, but also the effect of changing the shape of the light spot. The table shown in Figure 15 is a typical example. In Figure 15, 15A is the case where a small circular beam is converted to a large circular beam, 15B is the case where it is expanded only in the horizontal direction, 15C is the case where it is expanded only in the vertical direction, and 15D is the case where it is expanded in a cross shape.
[0043] While 15A can be addressed by the lens configuration shown in Figure 11, 15B, 15C, 15D, etc., cannot be addressed by the lens configuration shown in Figure 11. Figure 16 is a plan view of a liquid crystal lens 110 that can perform such functions. In Figure 16, the TFT substrate 111 and the opposing substrate 115 are bonded together at the periphery with a sealing material 150, and liquid crystal is sealed inside. The area where the TFT substrate 111 and the opposing substrate 115 overlap becomes the lens area 170.
[0044] The TFT substrate 111 is formed larger than the opposing substrate 115, and the portion of the TFT substrate 111 that does not overlap with the opposing substrate 115 is the terminal region 160. Driver ICs 165 and other components that drive the liquid crystal lens are located in the terminal region 160.
[0045] In the lens region 170 of Figure 16, scan lines 151 extend in the horizontal direction (x direction) and are arranged in the vertical direction (y direction). Signal lines 152 also extend in the vertical direction and are arranged in the horizontal direction. A lens element 153, including lens element electrodes (hereinafter simply referred to as element electrodes), is formed in the region enclosed by the scan lines 151 and signal lines 152. A voltage is applied between the element electrodes and a common electrode formed on the opposing substrate to orient the liquid crystal molecules in the desired direction and refract light.
[0046] Figure 17 is a plan view of the lens element 153. In Figure 17, the element electrode 154 is formed in the region enclosed by the scan line 151 and the signal line 152. A TFT (Thin Film Transformer) that is switched by the scan signal is formed between the element electrode 154 and the signal line 152. The TFT is formed by a gate electrode 210 branched from the scan line 151, a semiconductor film 211, a drain electrode 212 branched from the signal line 153, and a source electrode 123, with the source electrode 213 connected to the element electrode 154 via a through-hole 214. The other liquid crystal lenses 120, 130, and 140 have a similar configuration.
[0047] Figure 18 is a plan view showing the state in which light 7 from the reflector 30 is incident on the liquid crystal lens 100, as shown in Figure 5. A roughly circular beam of light 7 is incident on the rectangular liquid crystal lens 100. If the liquid crystal lens 100 is made to diverge in the x direction as shown in Figure 19, and no lensing action is applied in the y direction as shown in Figure 20, a horizontally elongated light spot like that in Figure 15B can be obtained. The white arrows in Figures 19 and 20 indicate the direction of light propagation.
[0048] On the other hand, in order to obtain a vertically elongated light spot using the liquid crystal lens 100, as shown in Figure 15C, the liquid crystal lens 100 should be made to diverge in the y-direction as shown in Figure 19, and not apply a lensing effect in the x-direction as shown in Figure 20.
[0049] However, obtaining a cross-shaped light spot, as shown in Figure 15D, using the liquid crystal lens 100 is difficult with the same method. Therefore, to obtain a light spot like that in Figure 15, a horizontal light spot in Figure 15B and a vertical light spot in Figure 15C can be displayed using time-division multiplexing. Figure 21 shows an example of time-division multiplexing to obtain a cross-shaped light spot. As shown in Figure 21, the horizontal spot is displayed during the first T1 interval, and the vertical spot is displayed during the subsequent T1 interval. T1 should be chosen to minimize flicker. [Examples]
[0050] The effects of the liquid crystal lens 100 are not limited to lensing effects such as divergence and convergence, but may also include cases where it is desired to deflect light. Below, we will describe the case in which two liquid crystal lenses acting on light polarized in a perpendicular direction are used as a pair. Each liquid crystal lens can be configured as described in Figures 16 and 17. Figure 22 is a cross-sectional view showing the effect of the first liquid crystal lens 110 of the pair of liquid crystal lenses.
[0051] Figure 22 is a diagram illustrating the principle of deflecting light to the left using a liquid crystal lens 110. In Figure 22, the upper diagram is a cross-sectional view of the liquid crystal lens 110. A first electrode 112 is formed on the first substrate 111 of the liquid crystal lens 110, and a first alignment film 113 is formed on top of it. A second electrode 116 is formed on the second substrate 115, and a second alignment film 117 is formed on top of it. A liquid crystal layer 300 exists between the first alignment film 113 and the second alignment film 117. The liquid crystal layer 300 is sealed with a sealing material 150.
[0052] When a voltage v is applied between the first electrode 112 and the second electrode 116 in Figure 22, such that the potential difference increases from left to right as shown in the lower graph of Figure 22, the orientation angle of the liquid crystal molecules 301 changes from place to place, and the effective birefringence Δn of the liquid crystal layer 300 changes as shown in the graph. Due to this configuration of the liquid crystal layer 300, light LL incident on the liquid crystal lens 110 from below is deflected to the left and emitted.
[0053] To refract the incident light to the right, the opposite of the case in Figure 22 is to apply a voltage to each electrode so that the potential difference gradually increases from right to left. In this case, the orientation angle of the liquid crystal molecules 301 changes from place to place, and the effective birefringence Δn of the liquid crystal layer 300 changes in the opposite direction to the lower graph in Figure 22, causing the light incident on the liquid crystal lens from below to be deflected to the right.
[0054] Figure 23 is a plan view showing the electrode configuration of the first liquid crystal lens 110, corresponding to Figure 22. Both the first electrode 112 and the second electrode 116 are formed from a transparent conductive film such as ITO (Indium Tin Oxide). The upper part of Figure 23 shows the shape of the second electrode 116 formed on the opposing substrate 115. The second electrode 116 is formed planarly across the entire second substrate 115.
[0055] The lower part of Figure 23 is the TFT substrate 111, on which striped electrodes 112 are formed. In Figure 23, the striped electrodes 112 extend in the y direction and are arranged in the x direction. When operating the liquid crystal lens 110, a voltage is applied to each striped electrode 112 sequentially from one end, increasing or decreasing. Note that, as shown in Figure 16, even when the element electrodes 154 are arranged in a matrix, the same effect as with striped electrodes can be obtained by applying the same voltage to element electrodes 154 arranged in one column or one row.
[0056] The electrode structure of the TFT substrate 111 and the opposing substrate 115 of the first liquid crystal lens 110 is the same for the second liquid crystal lens 120. The difference between the first liquid crystal lens 110 and the second liquid crystal lens 120 is that the orientation directions of the first alignment film 113 and the second alignment film 117 in the first liquid crystal lens 110 and the orientation directions of the first alignment film 123 and the second alignment film 127 in the second liquid crystal lens 120 are at a 90-degree angle to each other.
[0057] In other words, the relationship between the orientation directions of the first liquid crystal lens 110 and the second liquid crystal lens 120 is the same as that shown in Figure 12. Furthermore, the stacked structure of the first liquid crystal lens 110 and the second liquid crystal lens 120, the orientation directions of the first alignment film 113 and the third alignment film 123, the relationship between the second alignment film 117 and the first alignment film 114, and the relationship between the fourth alignment film 127 and the third alignment film 123 are the same as those explained in Figure 13.
[0058] The electrode configuration of the first liquid crystal lens 110 in Figure 23 is for the case where light is polarized in the left-right direction when viewed on a plane. Figure 24 shows the electrode configuration when light is polarized in the up-down direction when viewed on a plane. In Figure 24, the second electrode 116 formed on the opposing substrate 115 is planar in shape, the same as in Figure 23. The first electrode 112 formed on the TFT substrate 111 shown at the bottom of Figure 24 extends in the x direction and is arranged in the y direction. In other words, it is orthogonal to the first electrode 112 in Figure 23. Therefore, light can be polarized in the up-down direction by the same action as explained in Figure 22.
[0059] Thus, by using liquid crystal lenses with the electrode structure shown in Figure 23 and liquid crystal lenses with the electrode structure shown in Figure 24, light can be polarized vertically and horizontally when viewed on a plane. Furthermore, to achieve a more complete liquid crystal lens effect when polarizing light, four liquid crystal lenses can be used for each of the horizontal and vertical directions when viewed on a plane, as shown in Figure 14. [Examples]
[0060] In Example 1, the cross-section of the light 7 incident on the liquid crystal lens 100 is circular, as shown in Figure 18. Therefore, the light spot illuminating the illumination surface has an elongated oval shape, either horizontally or vertically. The liquid crystal lens 100 can diverge and converge with respect to the incident light, but it is relatively difficult to change its shape. The upper part of Figure 25 is a plan view when light 7 incident on the liquid crystal lens has a rectangular cross-section, and the lower part is a cross-sectional view of the emitted light 4 after the incident light 7 has been diverged by the liquid crystal lens 100.
[0061] The table in Figure 26 shows examples of how a rectangular beam of light 7 incident on the liquid crystal lens 100, as shown in Figure 25, can be transformed into various shapes by the action of the liquid crystal lens 100. The action of the liquid crystal lens 100 in Figure 26 is the same as that explained in Figure 15, but since the light 7 incident on the liquid crystal lens 100 is rectangular, the irradiated light 4 is a sharp rectangle. In Figure 26, 26A is the case where a small rectangular beam of light is converted into a large rectangle, 26B is the case where it is magnified only in the horizontal direction, 26C is the case where it is magnified only in the vertical direction, and 26D is the case where it is magnified in a cross shape.
[0062] Figure 27 is a perspective view of a funnel-type reflector 15 for supplying rectangular incident light to a liquid crystal lens 100. The difference between the funnel-type reflector 15 in Figure 27 and the funnel-type reflector 10 in Figure 6 is that the opening 17 and the LED hole 18 of the funnel-type reflector 15 are rectangular. This makes it possible to make the shape of the light emitted from the funnel-type reflector 15 rectangular.
[0063] Figure 28 is a bottom view of the funnel-type reflector 15 of Figure 27, viewed from direction B, i.e., from below. As shown in Figure 28, the opening 17 of the funnel-type reflector 15 is rectangular, and the emitted light has a shape corresponding to this rectangle. Figure 29 is a cross-sectional view AA of the funnel-type reflector 15 of Figure 27. The LED hole 18 and the opening 17 are connected by a curved surface 16 whose cross-section is parabolic in some respects. As a result, collimated light with a rectangular cross-section is emitted from the emission hole 17.
[0064] The aspect ratio, which is the ratio of the height of the funnel-type reflector 15 to the diameter of the exit hole 17, can be defined as follows: If the exit hole 17 is square, hf / (dx or dy); if the exit hole 17 is rectangular, hf / (the larger of dx or dy). The aspect ratio is preferably 2 or more, more preferably 3 or more, and even more preferably 4 or more.
[0065] As described above, according to the present invention, it is possible to obtain a lighting device that is compact and can arbitrarily change the spot shape of the emitted light. [Explanation of symbols]
[0066] 1...Lighting device, 2...Arm, 3...Base, 4...Projected light, 5...Housing, 6...Emission hole, 7...Incident light to liquid crystal lens, 10...Funnel-type reflector, 11...Parabola reflective surface, 12...Aperture, 13...Hole for LED, 15...Rectangular funnel-type reflector, 16...Parabola reflector, 17...Aperture, 18...Hole for LED, 20...LED, 21...LED substrate, 30...Reflector, 31...Light irradiation surface, 100...Liquid crystal lens, 110...First liquid crystal lens, 111...TFT substrate, 112...First electrode, 113...First alignment film, 114...Lead-out wiring, 115...Opposite substrate, 116...Second electrode, 117...Second alignment film, 120...Second liquid crystal lens, 121...TFT substrate, 122...Third electrode, 123...Third alignment layer, 125...Opposite substrate, 126...Fourth electrode, 127...Fourth alignment layer, 150...Sealing material, 151...Scanning line, 152...Signal line, 153...Lens element, 154...Element electrode, 160...Terminal region, 165...Driver IC, 170...Lens region, 210...Gate electrode, 211...Semiconductor film, 212...Drain electrode, 213...Source electrode, 214...Through hole, 300...Liquid crystal layer, 301...Liquid crystal molecule
Claims
1. A funnel-type reflector having a first hole in which a light source is placed, a second hole from which light is emitted, and a reflective surface connecting the first hole and the second hole, with the line connecting the center of the first hole and the center of the second hole being the first direction, A reflector facing the second hole of the funnel-type reflector, the reflector having a main surface of the reflecting surface inclined at a first angle with respect to the first direction, The liquid crystal lens is located opposite the reflector, and its incident surface is inclined at a second angle with respect to the main surface of the reflector. The outer shape of the aforementioned funnel-type reflector is a rectangular parallelepiped. The first hole is formed on the first face of the rectangular parallelepiped, The second hole is formed on the second surface of the rectangular parallelepiped, opposite the first surface. The first hole in the funnel-type reflector is smaller than the second hole. At least a portion of the curved surface connecting the first hole and the second hole is a parabolic surface. The second hole of the funnel-type reflector is circular. In the funnel-type reflector, the ratio of the diameter of the second hole to the distance between the first surface and the second surface of the funnel-type reflector is 2 or more. An illumination device characterized in that light emitted from the funnel-shaped reflector is reflected by the reflector and emitted from the liquid crystal lens.
2. The lighting device according to claim 1, characterized in that the first angle is 45 degrees.
3. The lighting device according to claim 1, characterized in that the second angle is 45 degrees.
4. A funnel-type reflector having a first hole in which a light source is placed, a second hole from which light is emitted, and a reflective surface connecting the first hole and the second hole, wherein the line connecting the center of the first hole and the center of the second hole is the first direction, A reflector facing the second hole of the funnel-type reflector, the reflector having a main surface of the reflecting surface inclined at a first angle with respect to the first direction, The liquid crystal lens is located opposite the reflector, and its incident surface is inclined at a second angle with respect to the main surface of the reflector. The outer shape of the aforementioned funnel-type reflector is a rectangular parallelepiped. The first hole is formed on the first face of the rectangular parallelepiped, The second hole is formed on the second surface of the rectangular parallelepiped, opposite the first surface. The first hole in the funnel-type reflector is smaller than the second hole. At least a portion of the curved surface connecting the first hole and the second hole is a parabolic surface. The second hole of the funnel-type reflector is square, The ratio of the length of the side of the second hole to the distance between the first surface and the second surface of the funnel-type reflector is 2 or more. An illumination device characterized in that light emitted from the funnel-shaped reflector is reflected by the reflector and emitted from the liquid crystal lens.
5. The lighting device according to claim 1, characterized in that the liquid crystal lens has a first liquid crystal lens, a second liquid crystal lens, a third liquid crystal lens, and a fourth liquid crystal lens.
6. The liquid crystal lens comprises a first liquid crystal lens, a second liquid crystal lens, a third liquid crystal lens, and a fourth liquid crystal lens. The lighting device according to claim 4, characterized in that the first liquid crystal lens, the second liquid crystal lens, the third liquid crystal lens, and the fourth liquid crystal lens act on light of different polarizations among the incident light.
7. A funnel-type reflector having a first hole in which a light source is placed, a second hole from which light is emitted, and a reflective surface connecting the first hole and the second hole, wherein the line connecting the center of the first hole and the center of the second hole is the first direction, A reflector facing the second hole of the funnel-type reflector, the reflector having a main surface of the reflecting surface inclined at a first angle with respect to the first direction, The liquid crystal lens is located opposite the reflector, and its incident surface is inclined at a second angle with respect to the main surface of the reflector. The liquid crystal lens comprises a first liquid crystal lens, a second liquid crystal lens, a third liquid crystal lens, and a fourth liquid crystal lens. The first liquid crystal lens, the second liquid crystal lens, the third liquid crystal lens, and the fourth liquid crystal lens have a divergent or converging effect with respect to incident light. An illumination device characterized in that light emitted from the funnel-shaped reflector is reflected by the reflector and emitted from the liquid crystal lens.
8. A funnel-type reflector having a first hole in which a light source is placed, a second hole from which light is emitted, and a reflective surface connecting the first hole and the second hole, wherein the line connecting the center of the first hole and the center of the second hole is the first direction, A reflector facing the second hole of the funnel-type reflector, the reflector having a main surface of the reflecting surface inclined at a first angle with respect to the first direction, The liquid crystal lens is located opposite the reflector, and its incident surface is inclined at a second angle with respect to the main surface of the reflector. The liquid crystal lens comprises a first liquid crystal lens, a second liquid crystal lens, a third liquid crystal lens, and a fourth liquid crystal lens. The first liquid crystal lens, the second liquid crystal lens, the third liquid crystal lens, and the fourth liquid crystal lens have a divergent effect in a specific direction, but do not diverge in a direction perpendicular to the specific direction. An illumination device characterized in that light emitted from the funnel-shaped reflector is reflected by the reflector and emitted from the liquid crystal lens.
9. The lighting device according to claim 8, characterized in that the first liquid crystal lens, the second liquid crystal lens, the third liquid crystal lens, and the fourth liquid crystal lens have a deflection effect in the specific direction.