Lighting device

Abstract

To provide a lighting device that is a thin type, has a small orientation angle and little leakage light, and can accurately control a light beam using a liquid crystal lens.SOLUTION: A lighting device includes: a reflection cylinder 10 including a reflecting mirror inside thereof; and a liquid crystal lens assembly in which liquid crystal lenses 100, 200, 300, 400 are stacked in a vertical direction relative to an emission surface of the reflection cylinder 10 on a side of the emission surface. The liquid crystal lens assembly includes a light-shielding film 40 formed in a parallel direction relative to the emission surface of the reflection cylinder 10 and regulating an emission region of light from the liquid crystal lens assembly.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to a lighting device that is thin, has a small light distribution angle, and can reduce light leakage to the periphery.

Background Art

[0002] Even in the case of a lighting device, for example, when it is desired to be used as a spotlight, a light source with high directivity, that is, a light source with a small light distribution angle, is required. Conventionally, a configuration that forms parallel light using a parabolic mirror has been used for such a light source. However, such a light source requires depth and it is difficult to miniaturize or thin the lighting device.

[0003] When thinning a lighting device using the above-described light source, it is difficult to reduce the light distribution angle. Furthermore, there arises a problem that leakage light with a very large emission angle is generated.

[0004] There are cases where it is desired to control the emitted light using a liquid crystal lens, but in this case as well, it is difficult to control the leakage light with a large emission angle. As an example of using a plurality of stacked liquid crystal panels, Patent Document 1 can be cited. Further, Patent Document 2 describes a configuration in which a liquid crystal lens is used in various optical devices.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] When obtaining parallel light using a parabolic mirror, if the depth of the parabolic mirror is not increased, there will be a large amount of light component with a large angle to the optical axis (hereinafter also called radiant light), making it difficult to obtain a sharp spot. To reduce radiant light dispersion, the depth of the parabolic mirror must be increased, which in turn increases the depth of the lighting device.

[0007] Furthermore, there are cases where it is desirable to control the convergence, divergence, and deflection of emitted light using liquid crystal lenses or the like. However, it is difficult to control emitted light with lenses when the angle with respect to the optical axis is large.

[0008] The object of the present invention is to realize a lighting device with a small depth that can produce a sharp spot light with a small divergence angle. Another object of the present invention is to realize a lighting device that can efficiently control light using a liquid crystal lens when a liquid crystal lens is placed on the light-emitting surface of the lighting device. [Means for solving the problem]

[0009] The present invention solves the above problems, and the main specific means are as follows.

[0010] (1) A lighting device comprising a reflecting cylinder having a reflecting mirror inside, and a liquid crystal lens assembly having a plurality of liquid crystal lenses stacked on the emission surface side of the reflecting cylinder, wherein the liquid crystal lens assembly is formed in a direction parallel to the emission surface of the reflecting cylinder and has a light-shielding film that defines the light emission area from the liquid crystal lens assembly.

[0011] (2) The lighting device according to (1), characterized in that, when viewed in a plane, the outer shape of the liquid crystal lens is rectangular and the emission area is circular.

[0012] (3) The lighting device according to (1), characterized in that the plurality of liquid crystal lenses consist of two lenses.

[0013] (4) The lighting device according to (1), characterized in that the plurality of liquid crystal lenses are four in number.

[0014] (5) The lighting device according to (1), characterized in that the liquid crystal lens has a configuration in which liquid crystal is sandwiched between a first substrate and a second substrate, and the light-shielding film is a film formed on the surface of the first substrate or the second substrate opposite to the surface on which the liquid crystal is located.

[0015] (6) The lighting device according to (1), characterized in that the liquid crystal lens has a configuration in which liquid crystal is sandwiched between a first substrate and a second substrate, and the light-shielding film is a film formed on the liquid crystal side of the first substrate or the second substrate.

[0016] (7) The lighting device according to (1), wherein the liquid crystal lens has a configuration in which liquid crystal is sandwiched between a first substrate and a second substrate, the first substrate and the second substrate are bonded together with a black sealing material, and the black sealing material also serves as the light-shielding film.

[0017] (8) The lighting device according to (1), characterized in that the light-shielding film is composed of a black adhesive material that adheres the plurality of liquid crystal lenses to each other. [Brief explanation of the drawing]

[0018] [Figure 1] This is a cross-sectional view illustrating the operation of a lighting device using a reflecting tube with a parabolic mirror. [Figure 2] Figure 1 is a perspective view. [Figure 3] Figure 1 shows the illuminance distribution of the light spot produced by the lighting device. [Figure 4] This is a cross-sectional view illustrating the operation of a lighting device using a tall reflector tube. [Figure 5] Figure 4 shows the illuminance distribution of the light spot produced by the lighting device. [Figure 6] This is a cross-sectional view illustrating the operation of a lighting device that uses a light-shielding tube with an internal light-absorbing wall together with a reflecting tube. [Figure 7] Figure 6 is a perspective view. [Figure 8]It is the illuminance distribution of the light spot by the lighting device of FIG. 6. [Figure 9] It is a cross-sectional view showing the operation of the lighting device when a plurality of liquid crystal lenses are placed in the configuration of FIG. 6. [Figure 10] It is a perspective view of FIG. 9. [Figure 11] It is a cross-sectional view of Example 1. [Figure 12] It is a perspective view of FIG. 11. [Figure 13] It is a plan view of the liquid crystal lens of Example 1. [Figure 14] It is a cross-sectional view of the liquid crystal lens of Example 1. [Figure 15] It is the illuminance distribution of the light spot by the lighting device of Example 1 shown in FIG. 11. [Figure 16] It is a configuration example of a convex lens by a liquid crystal lens. [Figure 17] It is a perspective view of a liquid crystal lens composed of two sheets. [Figure 18] It is a configuration example of a concave lens by a liquid crystal lens. [Figure 19] It is a cross-sectional view of a liquid crystal lens. [Figure 20] It is a plan view showing electrodes formed on a TFT substrate and a counter substrate in a liquid crystal lens. [Figure 21] It is a schematic diagram showing an example of light control by four liquid crystal lenses. [Figure 22] It is a plan view of the liquid crystal lens of Example 2. [Figure 23] It is a cross-sectional view of the liquid crystal lens of Example 2. [Figure 24] It is a plan view of the liquid crystal lens of Example 3. [Figure 25] It is a cross-sectional view of the liquid crystal lens of Example 3. [Figure 26] It is a plan view of the liquid crystal lens of Example 4. [Figure 27] It is a cross-sectional view of FIG. 26. [Figure 28] It is a plan view of a liquid crystal lens according to another example of Example 4. [Figure 29] It is a cross-sectional view of FIG. 28. [Figure 30] This is a plan view of Example 5. [Figure 31] This is a cross-sectional view of Figure 30. [Figure 32] This is a plan view of another example of Example 5. [Figure 33] This is a cross-sectional view of Figure 32. [Figure 34] This is a plan view of yet another example of Example 5. [Figure 35] This is a cross-sectional view of Figure 34. [Modes for carrying out the invention]

[0019] Figure 1 is a cross-sectional view of a lighting device using a reflector tube 10 having a parabolic mirror inside, and Figure 2 is a perspective view thereof. The lighting devices in Figures 1 and 2 are, for example, floodlights for spotlights. In Figure 1, an LED 20, which is the light source, is positioned in the center of the bottom of the reflector tube 10. The diameter D1 of the light-emitting surface of the parabolic mirror inside the reflector tube 10 in Figure 1 is, for example, 6.5 mm, and the height H1 of the reflector tube is, for example, 4 mm.

[0020] The light from LED20 is divergent light with a wide beam angle characteristic. This divergent light is reflected by a parabolic mirror to form parallel light LL parallel to the optical axis. However, a certain range of light is not reflected by the parabolic mirror and is emitted outwards. This light LD (hereinafter also called emitted light) has a large angle with the optical axis and causes blurring of the light spot.

[0021] Figure 2 is a perspective view of Figure 1. As shown in Figure 2, the light-emitting part of the parabolic mirror inside the reflecting cylinder 10 is circular. In Figure 2, the LED 20 is omitted. In Figure 2, the light reflected by the parabolic mirror becomes parallel light LL parallel to the optical axis, while the light LD that is not reflected by the parabolic mirror and is directly emitted to the outside causes blurring of the light spot.

[0022] Figure 3 shows the illuminance distribution when a light spot is projected onto a screen 1000 mm away from the light source. The upper part of Figure 13 is a plan view showing the spot shape, and the dotted circles are contour lines of illuminance. In Figure 13, the horizontal axis X (mm) represents the horizontal diameter of the spot, and the vertical axis Y (mm) represents the vertical diameter of the spot.

[0023] The lower part of Figure 3 is a graph showing the illuminance distribution. The horizontal axis X (mm) represents the horizontal position, with the center of the light spot set to zero. The vertical axis (lx) represents the illuminance LUX corresponding to each position. As clearly shown in the lower part of Figure 3, the illuminance distribution of the light spot has a relatively large tail. In other words, the blurring of the light spot is large.

[0024] Figure 4 shows a lighting device having a reflector tube 10 to address this issue. In Figure 4, an LED 20, which is the light source, is positioned in the center of the bottom surface of the reflector tube 10. In Figure 4, the height H2 of the reflector tube 10 is 39.3 mm, and the diameter D2 of the emission surface of the parabolic mirror inside the reflector tube 10 is 13 mm. The aspect ratio H1 / D1 in Figure 1 is 0.615, and the aspect ratio H2 / D2 in Figure 5 is 3.038. The ratio of the height of the reflector tube 10 to the diameter of the emitted light from the parabolic mirror in Figure 5 is much larger than in the case of Figure 1.

[0025] As a result, as indicated by the arrows in Figure 5, most of the light emitted from the reflector tube 10 becomes parallel light LL, which is parallel to the optical axis. Figure 5 is an example of a light spot when using the reflector tube 10 from Figure 4. The measurement conditions are the same as in Figure 3. That is, the light spot on a screen 1000 mm away from the lighting device was evaluated. In both the upper and lower figures of Figure 5, the horizontal and vertical axes are the same as those explained in Figure 3. Comparing Figure 5 and Figure 3, the light spot in Figure 5 is much sharper. That is, in the upper figure of Figure 5, the diameter of the light spot is small, and in the illuminance distribution in the lower figure of Figure 5, there is almost no tail of the distribution.

[0026] However, the configuration shown in Figure 4 has the problem of having a long height H2 of the reflector tube 10. Therefore, it cannot be used when a lighting device with a small depth is required.

[0027] Figure 6 shows a configuration to address this issue, in which a light-shielding cylinder 30 is placed on the exit side of the reflecting cylinder 10 in Figures 1 and 2 to reduce synchrotron radiation LD and increase the proportion of parallel light LL. Figure 7 is a perspective view of Figure 6. The light-shielding cylinder 30 has a cylindrical light-transmitting region formed inside a rectangular prism. The exit surface of the light-shielding cylinder is circular, and the inner wall of the light-shielding cylinder 30 is made of a black light-absorbing material.

[0028] In Figure 6, the light emitted from the light source LED 20 is emitted along the optical axis, and the light reflected by the parabolic mirror is also emitted along the optical axis, becoming parallel light LL. In Figure 1, the synchrotron radiation LD that causes the light spot to blur is incident on the inner wall of the light-shielding cylinder 30 in Figure 6. Since the inner wall of the light-shielding cylinder 30 is made of a light-absorbing material, this light does not escape to the outside. The diameter D3 of the emission surface of the light-shielding cylinder 30 is 6.5 mm, the same as the diameter D1 of the emission surface of the parabolic mirror inside the reflecting cylinder 10.

[0029] Therefore, in Figure 6, the synchrotron radiation LD emitted from the emission surface has a small angle with the optical axis and a small light intensity. Figure 8 is an example of a light spot when using the reflector tube 30 in Figure 6. The measurement conditions are the same as in Figure 3. In other words, it evaluates the light spot on a screen 1000 mm away from the lighting device. In both the upper and lower figures of Figure 8, the horizontal and vertical axes are the same as those explained in Figure 3. Comparing Figure 8 and Figure 3, Figure 8 shows a sharper light spot. That is, in the upper figure of Figure 8, the diameter of the light spot is small, and in the illuminance distribution in the lower figure of Figure 8, the base of the distribution is smaller compared to the case of Figure 3.

[0030] In Figure 6, the overall height of the lighting device is determined by the sum of the height H1 of the reflector tube 10 and the height H3 of the light-shielding tube 30. However, in the configuration of Figure 6, to improve the effectiveness of the light-shielding tube 30, the height H3 of the light-shielding tube 30 must be increased. However, increasing H1+H3 is difficult when manufacturing a thin lighting device. In the end, there is a trade-off between the height of the lighting device and the improvement in the light spot diameter when using the light-shielding tube 30. Nevertheless, combining the reflector tube 10 and the light-shielding tube 30 is more efficient in improving the distribution of the light spot than addressing the issue solely by increasing the height of the reflector tube 10.

[0031] Incidentally, there are times when it is necessary to focus, diverge, or deflect emitted light using lenses or the like. In this case, using liquid crystal lenses has the advantage that the lens effect can be changed relatively freely by changing the voltage applied to the electrodes.

[0032] Figure 9 is a cross-sectional view showing the configuration of the lighting device 1, in which a liquid crystal lens assembly 2, consisting of four liquid crystal lenses 100, 200, 300, and 400, is placed on the output surface of the light-shielding cylinder 30, as in the configuration of Figure 6. Figure 10 is a perspective view of Figure 9. In Figure 9, four liquid crystal lenses 100, 200, 300, and 400 are placed on top of the light-shielding cylinder 30. The configuration and function of the liquid crystal lenses will be explained later. Each liquid crystal lens 100, 200, 300, and 400 is bonded to a TFT substrate on which the first electrode is formed and to an opposing substrate on which the second electrode is formed by a sealing material 50. Each liquid crystal lens 100, 200, 300, and 400 is bonded to each other by a transparent adhesive or the like.

[0033] In Figure 10, 50 represents the sealing material 50 in each liquid crystal lens, and is not formed on the surface of the liquid crystal lens. Generally, the sealing material 50 is formed with the smallest possible width in order to maximize the effective area of ​​the liquid crystal lens. The sealing material 50 may be made of a transparent material or it may be made of black material.

[0034] In Figure 9, the thickness of each liquid crystal lens 100, 200, 300, and 400 is approximately 1 mm, so the total thickness of the four liquid crystal lenses (liquid crystal lens assembly 2) is approximately 4 mm. In Figure 9, if the height H1 of the reflector tube 10 is 4 mm, the height H2 of the light-shielding tube 30 is 4 mm, and the total height H4 of the four liquid crystal lenses is 4 mm, then the total height of the lighting device is 12 mm.

[0035] In Figure 9, in addition to the light emitted from LED 20 along the optical axis, the light reflected by the parabolic mirror inside the reflecting tube 10 constitutes parallel light LL. Furthermore, light emitted from LED 20 along the optical axis and within a certain angular range is absorbed by the light-shielding tube 30. Light LD (synchrotron radiation) that is not reflected by the antiparabolic mirror and is not absorbed by the light-shielding tube 30 also enters the liquid crystal lens.

[0036] In other words, two types of light are incident on the liquid crystal lens. However, the liquid crystal lens cannot act in the same way on these two types of light. In this case, the liquid crystal lens is designed to act on parallel light LL. That is, it cannot provide the desired control over synchrotron radiation LD.

[0037] To increase the amount of parallel light LL that can be precisely controlled by the liquid crystal lens, and to decrease the amount of synchrotron radiation LD that cannot be precisely controlled, it is necessary to increase the height H1 of the reflecting tube 10 or the height H3 of the light-shielding tube 30. This makes it difficult to meet the requirement for a thin lighting device.

[0038] The embodiments of the present invention described below overcome the above-mentioned problems and enable the realization of a thin lighting device that can obtain a desired spot shape. Furthermore, the present invention uses a liquid crystal lens, which enables precise control of the light spot. [Examples]

[0039] Figure 11 is a cross-sectional view showing Embodiment 1, and Figure 12 is a perspective view of Figure 11. In Figure 11, a liquid crystal lens assembly 2, consisting of liquid crystal lenses 100, 200, 300, and 400, is placed on top of a reflecting cylinder 10. In Figure 11, the function of the reflecting cylinder 10 is the same as that described in Figure 1. Note that the reflecting mirror inside the reflecting cylinder 10 does not have to be a parabolic mirror; any reflecting mirror that forms parallel light is acceptable. The difference between the liquid crystal lens in Figure 11 and the liquid crystal lens shown in Figure 9 is that a light-shielding film 40 is formed on each liquid crystal lens.

[0040] In Figure 11, the presence of the light-shielding film 40 prevents the emission of radiant light greater than or equal to an angle θ from the optical axis from the liquid crystal lens 400. In other words, the presence of the light-shielding film 40 prevents the emission of light that cannot be controlled by the liquid crystal lenses 100, 200, 300, and 400. Therefore, the proportion of light emitted from the liquid crystal lenses that is controlled by the liquid crystal lenses 100, 200, 300, and 400 increases, making it possible to obtain a light spot close to the design value.

[0041] Figure 12 is a perspective view of Figure 11. In Figure 12, the outer shapes of the liquid crystal lenses 100, 200, 300, and 400 are rectangular, but the emission area 5 is circular. The emission area 5 is defined by the light-shielding film 40. As shown in Figure 12, the width of the light-shielding film 40 is particularly large in the diagonal direction of the liquid crystal lenses 100, 200, 300, and 400. Therefore, the effect of the present invention is particularly large in the diagonal direction of the liquid crystal lenses.

[0042] Figure 13 is a plan view of the liquid crystal lens shown in Figure 11, and Figure 14 is a cross-sectional view AA of Figure 13. Figures 13 and 14 show only the first liquid crystal lens 100 and the second liquid crystal lens 200. The external structure of liquid crystal lens 3 and liquid crystal lens 4 is the same as that of liquid crystal lens 1 and liquid crystal lens 2.

[0043] Figure 13 is a plan view of the second liquid crystal lens 200. In Figure 13, the emission area 5 is circular and is defined by the light-shielding film 40. The light-shielding film 40 blocks the divergent light LD from the light emitted from the reflecting tube 10, and emits only the light LL that can be precisely controlled by the liquid crystal lens, or light that makes a small angle with light LL. The frame 50 in Figure 13 is a sealing material 50 for bonding the TFT substrate 100 and the opposing substrate 200. The width of the sealing material 50 is very small compared to the light-shielding film 40.

[0044] The light-shielding film 40 in Figure 13 can be, for example, a light-shielding material applied to the outer surface of the opposing substrate 200. For example, graphite can be dissolved in epoxy resin and screen printed. There are many types of epoxy resins, including resins that cure at low temperatures. UV-curing resins can also be used. Furthermore, since the graphite film is conductive, a reference potential can be applied as needed. Alternatively, another insulating black resin can be applied. Hereafter, the light-shielding film 40 in Figures 13 and 14 may be referred to as the exterior light-shielding film 40. Note that printing is not limited to screen printing; inkjet printing may also be used.

[0045] Figure 14 is a cross-sectional view of Figure 13. In Figure 14, the first liquid crystal lens 100 and the second liquid crystal lens 200 are bonded together by a transparent adhesive 90. In Figure 14, taking the first liquid crystal lens 100 as an example, liquid crystal 500 is sandwiched between a TFT substrate 110 and a counter substrate 120. Electrodes and alignment films are formed on the inside of the TFT substrate 110 and the counter substrate 120, which will be explained later. A feature of Figure 14 is that a light-shielding film 40 is formed on the outside of the counter substrates 120 and 220, thereby preventing the emission of synchrotron radiation LDs with a large angle to the optical axis. The third liquid crystal lens 300 and the fourth liquid crystal lens 400 have a similar configuration. This makes it possible to obtain a light beam with a small light distribution angle. Note that, as shown in Figure 13, the width of the light-shielding film 40 is large in the diagonal direction. In other words, the present invention is particularly effective in the diagonal direction in rectangular liquid crystal lenses.

[0046] The outer light-shielding film 40 in Figures 13 and 14 is formed on the opposing substrates 120 and 220, but it may also be formed on the TFT substrates 110 and 210, or on both the opposing substrates 120 and 220 and the TFT substrates 110 and 210. In this case as well, the method for forming the outer light-shielding film 40 is the same as described above.

[0047] Figure 15 shows examples of light spots in the configurations shown in Figures 11, 13, and 14. The measurement conditions are the same as in Figure 3. That is, the light spot on a screen 1000 mm away from the lighting device was evaluated. In both the upper and lower figures of Figure 15, the horizontal and vertical axes are the same as those explained in Figure 3. Comparing Figure 15 with Figure 3, Figure 15 shows a sharper light spot. In other words, in the upper figure of Figure 15, the diameter of the light spot is smaller, and in the illuminance distribution in the lower figure of Figure 15, the base of the distribution is smaller compared to the case of Figure 3.

[0048] Comparing the illuminance distribution of the light spot in Figure 15 with that of the light spot shown in Figure 8, they are almost identical. In other words, although the light-shielding tube 30 is not used in Figure 11, an illuminance distribution equivalent to that obtained when the light-shielding tube 30 is used can be obtained by using a liquid crystal lens with a light-shielding film. The advantage of Figure 11 compared to Figure 6 is that in Figure 11, the effect of the liquid crystal lens can be applied to a light spot with the same illuminance distribution as in Figure 6.

[0049] Figure 16 is a cross-sectional view illustrating the principle of a liquid crystal lens. In Figure 16, polarized light is incident from the left side of the liquid crystal layer 500. In Figure 16, P represents the direction of polarization of the incident light. While the polarization direction of normal light is randomly distributed, liquid crystals only act on polarized light, so Figure 16 shows the effect on light polarized in the P direction.

[0050] In Figure 16, the liquid crystal molecules 501 in the liquid crystal layer 500 are oriented by electrodes such that the tilt increases as they move toward the periphery of the liquid crystal layer 500. Since the liquid crystal molecules 501 have an elongated shape, and the effective refractive index in the direction of the long axis of the liquid crystal molecule 501 is greater than the effective refractive index in the direction of the short axis of the liquid crystal molecule 501, the refractive index increases toward the periphery of the liquid crystal layer 500, thus forming a convex lens. The dotted line in Figure 16 represents the optical wavefront WF, and f is the focal distance of the lens.

[0051] Since liquid crystals only act on polarized light, forming a lens requires a second lens that acts on polarized light polarized perpendicular to the direction of polarization of the polarized light acted on by the first lens. Figure 17 is an exploded perspective view showing this lens configuration. In Figure 17, 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 500. The first liquid crystal lens 100 acts on X-polarized light, and the second lens 200 acts on Y-polarized light.

[0052] In Figure 17, the initial orientation directions of the liquid crystal molecules 501 differ by 90 degrees between the first liquid crystal lens 100 and the second liquid crystal lens 200. The initial orientation of the liquid crystal molecules 501 is determined by the orientation direction of the alignment film within the liquid crystal lens. In other words, in Figure 17, the orientation directions of the alignment films on the substrates on the side where light is incident are perpendicular to each other.

[0053] In Figure 17, the transparent regions 5 of the first liquid crystal lens 100 and the second liquid crystal lens 200 are circular. This transparent region 5 is defined by the light-shielding film 40 formed on the first liquid crystal lens 100 and the second liquid crystal lens 200.

[0054] Figure 18 shows the case where a concave lens is formed using liquid crystal lenses. In Figure 17, light with a wavefront WF parallel to the liquid crystal layer 500 and deflected in one direction is incident on the liquid crystal layer 500 from the left. In Figure 17, the liquid crystal molecules 501 in the liquid crystal layer 500 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 500 forms a curve as shown by the dotted line in Figure 25, thus forming a concave lens. Note that, as with the concave lens, two liquid crystal lenses are required, as shown in Figure 17.

[0055] Figure 19 is a detailed cross-sectional view of the liquid crystal lens 100. In Figure 19, a first electrode 111 is formed on the TFT substrate 110, and a first alignment film 112 is formed covering the first electrode 111. The orientation direction of the first alignment film 112 determines the polarization of the incident light that is affected by the liquid crystal lens. A second electrode 121 is formed on the inside of the opposing substrate 120, and a second alignment film 122 is formed covering the second electrode 121. The relationship between the orientation direction of the first alignment film 112 and the orientation direction of the second alignment film 122 is determined by the type of liquid crystal used. A liquid crystal layer 500 is sandwiched between the TFT substrate 110 and the opposing substrate 120.

[0056] The left side of Figure 20 is a plan view of the first electrode 111 formed on the first substrate 110. The first electrode 111 is a concentric circle. Lead wires 115 for applying voltage are connected to each circular electrode 111. The right side of Figure 20 is a plan view showing the shape of the second electrode 122 formed on the opposing substrate 120. The second electrode 122 is a planar electrode and is formed over almost the entire surface of the opposing substrate 120.

[0057] In Figure 20, lenses of various intensities can be formed by changing the voltage between the first electrode 111 and the second electrode 122. The examples in Figures 19 and 20 have the advantage that circular lenses can be easily formed because the first electrode 111 is formed in a concentric circle. Note that the liquid crystal structure described in Figures 19 and 20 is an example, and other electrode structures can be used to constitute the liquid crystal lens. The other liquid crystal lenses 200, 300, and 400 also have the same structure as liquid crystal lens 100, except for the orientation direction of the alignment film.

[0058] Figure 21 is a schematic diagram showing, indicated by white arrows, which directions of polarization the first liquid crystal lens 100 to the fourth liquid crystal lens 400 act on when light is incident on the liquid crystal lens. In Figure 21, the first liquid crystal lens 100 acts on light PX polarized in the x direction, the second liquid crystal lens 200 acts on light PY polarized in the y direction, the third liquid crystal lens 300 acts on light P45 polarized at a 45-degree angle from the x direction, and the fourth liquid crystal lens 400 acts on light P135 polarized at a 135-degree angle from the x direction. This makes it possible to apply the liquid crystal lenses to light polarized in almost all directions.

[0059] Note that the order of liquid crystal lenses 100, 200, 300, and 400 relative to the direction of light propagation does not have to be limited to the order shown in Figure 21. Figure 21 shows an example using four liquid crystal lenses, but it is also possible to use two. In this case, it is sufficient to use two liquid crystal lenses from 100 to 400 whose deflection directions are perpendicular to each other.

[0060] The following embodiments disclose various forms of light-shielding films formed on liquid crystal lenses in the present invention. In the following embodiments, two liquid crystal lenses are described, but the same applies to four lenses. In the case of four lenses, two sets of liquid crystal lenses described below can be stacked. However, the orientation direction of the alignment film follows the configuration described in Figure 21. [Examples]

[0061] Figure 22 is a plan view of the liquid crystal lens of Example 2, and Figure 23 is a cross-sectional view of Figure 22. The basic structure of the liquid crystal lenses in Figures 22 and 23 is the same as that described in Figures 13 and 14. The difference between Figures 22 and 23 and Figures 13 and 14 is that the light-shielding film is an internal light-shielding film 60 formed of a black matrix, rather than an external light-shielding film 40.

[0062] The black matrix is ​​a technically established technology in liquid crystal display devices, and there is an advantage in being able to use this established technology to form the internal light-shielding film 60 using the black matrix. The effect of forming the internal light-shielding film 60 on the liquid crystal lens is the same as the effect in Example 1. The internal light-shielding film 60 using the black matrix may be formed on the TFT substrate 110 side, or it may be formed on both the opposing substrate 120 side and the TFT substrate 110 side.

[0063] Although the interior light-shielding film 60 described above is formed in the same way as a so-called black matrix, it can also be formed from a film of metal or other materials after suppressing reflection, if necessary. [Examples]

[0064] Figure 24 is a plan view of the liquid crystal lens of Example 3, and Figure 25 is a cross-sectional view of Figure 24. The basic structure of the liquid crystal lenses in Figures 24 and 25 is the same as that described in Figures 13 and 14. The difference between Figures 24 and 25 and Figures 13 and 14 is that, for example, in the first liquid crystal lens 100, the sealing material 55 that bonds the TFT substrate 110 and the opposing substrate 120 is different from the usual one; its width is made very large to create a light-shielding film 55.

[0065] In this case, a black resin is used as the sealant 55. Conventional sealants are very narrow and are applied using a dispenser. However, as shown in Figure 23, the sealant 55 in this embodiment is applied over a wide area, making it more suitable for application by inkjet printing or screen printing. The viscosity of the black resin should be adjusted to be suitable for inkjet printing or screen printing. The same applies to the second liquid crystal lens 200 to the fourth liquid crystal lens 400. [Examples]

[0066] Figure 26 is a plan view of the liquid crystal lens of Example 4, and Figure 27 is a cross-sectional view of Figure 26. The basic structure of the liquid crystal lenses in Figures 26 and 27 is the same as that described in Figures 13 and 14. The difference between Figures 26 and 27 and Figures 13 and 14 is that the light-shielding film is not the outer light-shielding film 40, but rather the black adhesive material 80 that adheres the first liquid crystal lens 100 and the second liquid crystal lens.

[0067] The adhesive material 80, formed in the shape of the light-shielding film shown in Figure 26, is attached to the opposing substrate 120 of the first liquid crystal lens 100 and bonded to the second liquid crystal lens 200. A black adhesive tape 80 may be used as the black adhesive material 80. The black adhesive tape 80 can be the same type as the black adhesive tape used to bond the liquid crystal display panel and the backlight in a liquid crystal display device. The bonding of the second liquid crystal lens 200 to the third liquid crystal lens 300 and the bonding of the third liquid crystal lens 300 to the fourth liquid crystal lens 400 is done in the same manner.

[0068] In Figure 26, the area where the black adhesive tape 80 is absent is a space 95. Space 95 is a light transmission region 5. In space 95, the loss of transmitted light due to reflection caused by the difference in refractive index between the glass and the space can be a problem. In such cases, as shown in Figures 28 and 29, a transparent adhesive 90 with a refractive index close to that of the glass can be used between the first liquid crystal lens 100 and the second liquid crystal lens 200. The other configurations in Figures 28 and 29 are the same as in Figures 26 and 27. The bonding between the second liquid crystal lens 200 and the third liquid crystal lens 300, and the bonding between the third liquid crystal lens 300 and the fourth liquid crystal lens 400 are also the same. [Examples]

[0069] The configurations of Examples 1 to 4 can be used in combination. This is because using multiple light-shielding means together can sometimes prevent adverse effects on projected light due to stray light.

[0070] Figures 30 and 31 show examples of combining Example 4 and Example 1. Figures 32 and 33 show examples of combining Example 4 and Example 2. Figures 34 and 35 show examples of combining Example 4 and Example 3. These three combinations are merely examples, and other combinations of each example are possible as needed.

[0071] Incidentally, if you want to make the spot diameter of the light even sharper than that of the lighting devices using liquid crystal lenses described in Examples 1 to 5, you can use a light-shielding cylinder 30 in combination, as explained in Figures 6 and 7. In this case, the height of the light-shielding cylinder 30 will be added, so the depth of the lighting device will increase. Therefore, a balance must be struck between the requirements for the light spot and the required depth of the lighting device. [Explanation of symbols]

[0072] 5…Transmitting area, 10…Reflecting tube, 20…LED, 30…Light-shielding tube, 40…Outer light-shielding film, 50…Sealing material, 55…Light-shielding film that also serves as a sealant, 60…Black matrix for light-shielding film, 80…Black adhesive for light-shielding film, 90…Transparent adhesive, 95…Space, 100…First liquid crystal lens, 110…TFT substrate, 111…First electrode, 112…First alignment film, 115…Outer wiring, 120…Opposite substrate, 121…Second electrode, 122…Second alignment film, 200…Second liquid crystal lens, 210…TFT substrate, 220…Opposite substrate, 300…Third liquid crystal lens, 310…TFT substrate, 320…Opposite substrate, 400…Fourth liquid crystal lens, 410…TFT substrate, 420…Opposite substrate, 500…Liquid crystal layer, 501…Liquid crystal molecule, LL…Parallel light, LD…Synchrotron radiation, PX, PY, P45, P135…Polarization direction of light

Claims

1. A lighting device comprising a reflecting cylinder having a reflector inside, and a liquid crystal lens assembly having multiple liquid crystal lenses stacked on the emission side of the reflecting cylinder, The liquid crystal lens assembly is formed in a direction parallel to the emission surface of the reflecting cylinder and has a light-shielding film that defines the light emission region from the liquid crystal lens assembly. The lighting device is characterized in that the light-shielding film is composed of a black adhesive material that adheres the plurality of liquid crystal lenses to each other.

2. The lighting device according to claim 1, characterized in that, when viewed in a planar view, the outer shape of the liquid crystal lens is rectangular and the emission area is circular.

3. The lighting device according to claim 1, characterized in that the plurality of liquid crystal lenses are two.

4. The lighting device according to claim 1, characterized in that the plurality of liquid crystal lenses are four in number.

5. The lighting device according to claim 1, characterized in that the liquid crystal lens has a configuration in which liquid crystal is sandwiched between a first substrate and a second substrate, and the light-shielding film is a film formed on the surface of the first substrate or the second substrate opposite to the surface on which the liquid crystal is located.

6. The lighting device according to claim 1, characterized in that the liquid crystal lens has a configuration in which liquid crystal is sandwiched between a first substrate and a second substrate, and the light-shielding film is a film formed on the liquid crystal side of the first substrate or the second substrate.

7. The aforementioned liquid crystal lens has a configuration in which liquid crystal is sandwiched between a first substrate and a second substrate. The lighting device according to claim 1, characterized in that the first substrate and the second substrate are bonded together with a black sealing material, and the black sealing material also serves as the light-shielding film.

8. The lighting device according to claim 1, characterized in that, when viewed in a planar view, a transparent resin is formed between the plurality of liquid crystal lenses on the inside of the light-shielding film.

9. The lighting device according to claim 1, characterized in that the reflecting mirror formed inside the reflecting cylinder is a parabolic mirror.

10. The lighting device according to claim 1, characterized in that a light-shielding cylinder having a light-absorbing layer inside is placed between the reflecting cylinder and the liquid crystal lens assembly.

Images