Lighting device

Abstract

This lighting device (100) comprises an optical element (120) and a light source device (110) positioned below the optical element (120). The optical element (120) has a liquid crystal cell and a plurality of light-shielding films (146). The light source device (110) has a housing (112) and a light source (114) inside the housing, and is configured to irradiate the optical element (120) with light. The liquid crystal cell has a substrate (124), a plurality of lower electrodes (126) positioned on the substrate and arranged in a stripe shape, a first alignment film (128) on the plurality of lower electrodes, a liquid crystal layer (130) on the first alignment film, a second alignment film (132) on the liquid crystal layer, an upper electrode (134) positioned on the second alignment film and overlapping the plurality of lower electrodes (126), a counter substrate (136) on the upper electrode, and a first polarizing plate (122) and a second polarizing plate (140) positioned below the substrate (124) and on the counter substrate (136), respectively. The plurality of light-shielding films (146) are arranged in a stripe shape and overlap the plurality of lower electrodes (126). The extension direction of the plurality of lower electrodes (126) is parallel to the extension direction of the plurality of light-shielding films (146).

Description

lighting equipment

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

[0002] There are known lighting devices that utilize the fact that the refractive index of a liquid crystal layer is changed by controlling the orientation of the liquid crystal by controlling the voltage applied to the liquid crystal. For example, Patent Document 1 discloses a lighting device that has a light source and a dome-shaped liquid crystal section that covers the light source. In this lighting device, the light transmittance of the liquid crystal section is controlled for each area by controlling the voltage applied to the liquid crystal section, thereby allowing the illuminated surface to be changed as desired.

[0003] JP 2018-73661 A

[0004] An object of one embodiment of the present invention is to provide a lighting device having a novel structure. For example, an object of one embodiment of the present invention is to provide a lighting device at low cost that can arbitrarily change the position, shape, and size of the illumination surface.

[0005] One embodiment of the present invention is an illumination device. The illumination device includes an optical element and a light source device positioned below the optical element. The optical element includes a liquid crystal cell and multiple light-shielding films. The light source device includes a housing and a light source within the housing, configured to irradiate the optical element with light. The liquid crystal cell includes a substrate, multiple lower electrodes positioned on the substrate and arranged in a stripe pattern, a first alignment film on the multiple lower electrodes, a liquid crystal layer on the first alignment film, a second alignment film on the liquid crystal layer, an upper electrode positioned on the second alignment film and overlapping the multiple lower electrodes, a counter substrate on the upper electrode, and a first polarizer and a second polarizer positioned below the substrate and above the counter substrate, respectively. The multiple light-shielding films are arranged in a stripe pattern and overlap the multiple lower electrodes. The extension direction of the multiple lower electrodes is parallel to the extension direction of the multiple light-shielding films.

[0006] One embodiment of the present invention is an illumination device. The illumination device includes an optical element and a light source device located below the optical element. The optical element includes a liquid crystal cell and multiple light-shielding films. The light source device includes a housing and a light source within the housing, and is configured to irradiate the optical element with light. The liquid crystal cell includes a polarizer, a substrate on the polarizer, multiple lower electrodes located on the substrate and arranged in a stripe pattern, an alignment film on the multiple lower electrodes, a liquid crystal layer on the alignment film, and an opposing substrate on the liquid crystal layer. Multiple light-shielding films are sandwiched between the polarizer and the substrate. The extension direction of the multiple lower electrodes is parallel to the extension direction of the multiple light-shielding films.

[0007] 1 is a schematic exploded perspective view of a lighting device according to an embodiment of the present invention; a schematic end view of a lighting device according to an embodiment of the present invention; a schematic exploded perspective view of a portion of a lighting device according to an embodiment of the present invention; a schematic top view of a lower electrode of a lighting device according to an embodiment of the present invention; a schematic top view of a light-shielding film of a lighting device according to an embodiment of the present invention; a schematic end view illustrating an operation of a lighting device according to an embodiment of the present invention; a schematic view illustrating an operation of a lighting device according to an embodiment of the present invention; a schematic end view illustrating an operation of a lighting device according to an embodiment of the present invention; a schematic end view illustrating an operation of a lighting device according to an embodiment of the present invention; a schematic view of an irradiation surface illustrating an operation of a lighting device according to an embodiment of the present invention; a schematic end view of a lighting device according to an embodiment of the present invention; a schematic end view of a lighting device according to an embodiment of the present invention; a schematic end view of a lighting device according to an embodiment of the present invention; a schematic end view of a portion of a lighting device according to an embodiment of the present invention; a schematic end view illustrating an arrangement of lower electrodes in a lighting device according to an embodiment of the present invention; a schematic end view illustrating an arrangement of lower electrodes in a lighting device according to an embodiment of the present invention. 1 is a schematic end view showing an arrangement of lower electrodes in a lighting device according to one embodiment of the present invention. FIG. 2 is a schematic end view of a portion of a lighting device according to one embodiment of the present invention. FIG. 3 is a schematic end view of a portion of a lighting device according to one embodiment of the present invention. FIG. 4 is a schematic end view of a lighting device according to one embodiment of the present invention. FIG. 5 is a schematic developed perspective view of a portion of a lighting device according to one embodiment of the present invention. FIG. 6 is a schematic end view illustrating the operation of a lighting device according to one embodiment of the present invention. FIG. 7 is a schematic end view illustrating the operation of a lighting device according to one embodiment of the present invention. FIG. 8 is a schematic end view illustrating the operation of a lighting device according to one embodiment of the present invention. FIG. 9 is a schematic end view illustrating the operation of a lighting device according to one embodiment of the present invention.

[0008] Hereinafter, various embodiments of the present invention will be described with reference to the drawings, etc. However, the present invention can be embodied in various forms without departing from the spirit of the present invention, and should not be construed as being limited to the description of the embodiments exemplified below.

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

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

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

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

[0013] 1. Configuration of the Illumination Device FIG. 1 is a schematic exploded perspective view showing the overall configuration of an illumination device 100. As shown in FIG. 1, the illumination device 100 includes a light source device 110 and an optical element 120 on the light source device 110. As will be described later, the optical element 120 basically includes a liquid crystal cell and a plurality of light-shielding films 146. In FIG. 1, the light source device 110 and the optical element 120 are shown separated from each other, but they are fixed to each other by an adhesive or the like (not shown). For ease of viewing, some components of the optical element 120 are omitted from FIG. 1.

[0014] 1-1. Light Source Device As shown in FIG. 2, which is a schematic diagram of an end surface along the dashed line A-A' in FIG. 1, the light source device 110 includes a housing 112 and a light source 114 disposed within the housing 112. The housing 112 supports the optical element 120 disposed thereon and is configured so that light emitted isotropically from the light source 114 irradiates substantially the entire optical element 120. For this reason, a recess 112a is formed in the housing 112 (see FIG. 1), and the light source 114 is disposed within this recess 112a. There are no restrictions on the material from which the housing 112 may be constructed; for example, the housing 112 may be constructed from wood, resins such as polypropylene and polylactic acid, glass, or metals such as aluminum, copper, iron, and stainless steel. To efficiently utilize the light from the light source 114, it is preferable that the surface 112b of the recess 112a in which the light source 114 is disposed has a high reflectivity for visible light. For this reason, when the housing 112 is made of a material with low reflectivity for visible light, such as wood, resin, or glass, it is preferable that the surface 112b be covered with a metal with high reflectivity for visible light, such as aluminum, so that not only the light that is directly incident on the optical element 120 from the light source 114 but also the light that is reflected by the surface 112b and then incident on the optical element 120 can be used as illumination.

[0015] The light source 114 includes one or more light-emitting elements. Examples of light-emitting elements include inorganic light-emitting diodes (OLEDs). There are no restrictions on the color of light emitted from the light source 114. For this reason, the light source 114 may be configured using one or more white-emitting light-emitting elements, or may be configured to emit light of various colors by combining red, green, and blue light-emitting elements. Note that, because the light from the light source 114 travels isotropically, the light includes not only a component traveling perpendicular to the optical element 120 from the light source 114 (in the normal direction of the substrate 124 described below), but also a component that is obliquely incident on the optical element 120 (see the dotted arrow in FIG. 2 ).

[0016] 1-2. Optical Element The optical element 120 is a component that transmits light from the light source device 110 and controls the direction of travel and spread of the light. By using the optical element 120, it is possible to process the light from the light source device 110 and form an irradiation surface (a surface on which the light irradiates an object) of any shape and size. The optical element 120 basically comprises a liquid crystal cell and a plurality of light-shielding films 146.

[0017] (1) Liquid Crystal Cell The liquid crystal cell basically comprises a substrate 124, a plurality of lower electrodes 126, a first alignment film 128, a liquid crystal layer 130, a second alignment film 132, an upper electrode 134, an opposing substrate 136, a first polarizing plate 122, and a second polarizing plate 140.

[0018] The substrate 124 and the counter substrate 136 are configured to transmit light from the light source device 110 and to provide mechanical strength to the liquid crystal cell. Therefore, both the substrate 124 and the counter substrate 136 are configured to contain glass or a resin such as polyimide or polycarbonate so as to transmit visible light. The substrate 124 and the counter substrate 136 may be flexible. The substrate 124 is provided to cover the light source device 110 and close the recess 112a.

[0019] The first polarizing plate 122 and the second polarizing plate 140 are respectively disposed below the substrate 124 and above the opposing substrate 136. The first polarizing plate 122 and the second polarizing plate 140 are disposed in a crossed Nicol relationship, so that their light transmission axes are perpendicular to each other.

[0020] 1 and 2 , the plurality of lower electrodes 126 are arranged in a striped pattern on the substrate 124. On the other hand, the upper electrode 134 facing the lower electrodes 126 is a single electrode that is provided so as to overlap with the plurality of lower electrodes 126. Although not shown, in order to prevent impurities from entering from the substrate 124, a protective insulating film may be provided between the plurality of lower electrodes 126 and the substrate 124 and / or between the opposing substrate 136 and the upper electrode 134. The protective insulating film may be composed of one or more films containing a silicon-containing inorganic compound such as silicon oxide or silicon nitride.

[0021] Both the lower electrode 126 and the upper electrode 134 are configured to transmit visible light. For this reason, the lower electrode 126 and the upper electrode 134 are made of a light-transmitting conductive oxide such as indium-tin oxide (ITO) or indium-zinc oxide (IZO). Although not shown, the multiple lower electrodes 126 are connected to a drive circuit via wiring and configured to be supplied with potentials independently. Therefore, it is possible to supply different potentials to, for example, two adjacent lower electrodes 126. Meanwhile, a constant potential (reference potential) is supplied to the upper electrode 134. The potential supplied to the lower electrode 126 and the upper electrode 134 may be a DC potential or a pulsed AC potential (for example, a rectangular pulsed potential).

[0022] The first alignment film 128 and the second alignment film 132 are provided to cover the plurality of lower electrodes 126 and upper electrodes 134, respectively. The substrate 124 and the opposing substrate 136 are fixed to each other by a sealant 138, and the liquid crystal layer 130 is sealed in a space formed by the sealant 138, the first alignment film 128, and the second alignment film 132. The first alignment film 128 and the second alignment film 132 contain a resin such as polyimide and are configured to align the liquid crystal molecules contained in the liquid crystal layer 130 in a specific direction. For this reason, the first alignment film 128 and the second alignment film 132 are subjected to an alignment treatment such as a rubbing treatment, or are formed using photoalignment. The directions in which the first alignment film 128 and the second alignment film 132 align the liquid crystal molecules (the long axis directions of the liquid crystal molecules when aligned by the influence of the alignment film, hereinafter referred to as the alignment directions) are perpendicular to each other. That is, the first alignment film 128 and the second alignment film 132 are provided so as to be in a crossed Nicol relationship with each other.

[0023] There are no restrictions on the structure of the liquid crystal molecules that make up the liquid crystal layer 130. Therefore, the liquid crystal molecules may be nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, or chiral smectic liquid crystal. The thickness of the liquid crystal layer 130 is appropriately set, for example, in the range of 2 μm to 5 μm. By selecting a thickness within this range, a sufficiently large electric field (vertical electric field) can be formed in the liquid crystal layer 130. Although not shown, spherical spacers or columnar spacers may be arranged in the liquid crystal layer 130 to maintain a constant distance between the first alignment film 128 and the second alignment film 132 (i.e., the thickness of the liquid crystal layer 130).

[0024] There is no restriction on the operating mode of the liquid crystal cell described above, and it may be in either TN mode or VA mode.

[0025] (2) Light-Shielding Film The multiple light-shielding films 146 are configured to block light so as to block a portion of the light from the light source device 110. Preferably, the multiple light-shielding films 146 are configured to have low absorptivity and high reflectivity for the light from the light source device 110. This allows the light from the light source device 110 to be reflected within the liquid crystal cell and the housing 112 and ultimately extracted to the outside, which contributes to efficient use of light from the light source 114 and suppresses heat generation due to light absorption. Therefore, the multiple light-shielding films 146 are preferably configured to contain a metal such as aluminum, silver, molybdenum, titanium, or tantalum. Note that a resin with a dispersed black pigment may also be used, although this reduces light utilization efficiency.

[0026] 1 and 2 , in the lighting device 100, the plurality of light-shielding films 146 are formed on the support substrate 144 (below the support substrate 144 in FIG. 2 ), and the support substrate 144 is fixed to the counter substrate 136 by an adhesive layer 142. On the other hand, the second polarizing plate 140 is provided on the support substrate 144. Therefore, in the lighting device 100, the plurality of light-shielding films 146 are disposed between the counter substrate 136 and the second polarizing plate 140.

[0027] 3A is a schematic perspective view showing the arrangement of the plurality of lower electrodes 126, the upper electrode 134, and the plurality of light-shielding films 146. As can be seen from FIG. 3A, the plurality of light-shielding films 146 are also arranged in a stripe pattern, similar to the lower electrodes 126. The extension direction of the plurality of light-shielding films 146 is parallel to that of the plurality of lower electrodes 126. However, the width, spacing, and pitch differ between the lower electrodes 126 and the light-shielding films 146. Specifically, as shown schematically in FIGS. 3B and 3C, the width w １ is the width w of the plurality of light-shielding films 146 ２ For example, the width w １ is 2 μm or more and 1.5 mm or less, while the width w ２ The distance d between adjacent lower electrodes 126 is 95 μm or more and 50 mm or less. １ is the distance d between adjacent light-shielding films 146 ２ For example, the distance d １ is 3 μm or more and 10 μm or less, while the spacing d ２Therefore, the pitch p of the plurality of lower electrodes 126 is 5 μm or more and 5 mm or less. １ The pitch p of the plurality of light-shielding films 146 ２ For example, the former is 5 μm or more and 1.5 mm or less, and the latter is 100 μm or more and 60 mm or less.

[0028] 2. Control of the Illumination Surface by the Illumination Device The following describes the control of the illumination surface using the illumination device 100. As described above, the first alignment film 128 and the second alignment film 132 are arranged in a crossed Nicol relationship. Therefore, for example, when the liquid crystal cell is driven in TN mode, when no electric field exists in the liquid crystal layer 130, linearly polarized light from the light source device 110 passing through the first polarizer 122 is rotated by 90° as it passes through the liquid crystal layer 130, and its polarization axis becomes parallel to the light transmission axis of the second polarizer 140. Therefore, this linearly polarized light is transmitted through the second polarizer 140 (see the arrow in FIG. 4A ). At this time, some of the linearly polarized light is blocked by the light-shielding film 146. However, since the light from the light source 114 is not collimated but travels approximately isotropically before entering the optical element 120, light passing through the adjacent light-shielding film 146 is also diffused. As a result, the width w of the light-shielding film 146 ２ and interval d ２ Although it depends on the distance between the illumination device 100 and the illumination surface, as shown in FIG. 4B, the illumination surface A has a substantially uniform illuminance distribution that does not reflect the arrangement of the light-shielding film 146 but reflects the shape of the illumination device 100. ０ can be given.

[0029] On the other hand, although not shown, a potential difference is applied between all of the lower electrodes 126 and the upper electrodes 134 to generate a vertical electric field in the liquid crystal layer 130, causing the liquid crystal molecules to stand up. Therefore, linearly polarized light passing through the first polarizer 122 is not optically rotated in the liquid crystal layer 130, and maintains its polarization axis perpendicular to the light transmission axis of the second polarizer 140. Therefore, the light from the light source device 110 is blocked by the second polarizer 140 and does not illuminate the surface.

[0030] In this way, the liquid crystal layer 130 functions as an optical switch that can be switched between a light transmitting state (ON) and a light blocking state (OFF). By using a plurality of light blocking films 146 in cooperation with the optical switch function of the liquid crystal layer 130, it is possible to process the light from the light source device 110 and create irradiation surfaces of various shapes and sizes.

[0031] For example, as shown in FIG. 5A, a vertical electric field is generated between the upper electrode 134 and a part of the lower electrode 126. In the example shown in FIG. 5A, the liquid crystal cell is driven so that a vertical electric field is generated in a part 130a of the liquid crystal layer 130, and a vertical electric field is not generated in the other part 130b. When the liquid crystal cell is driven in this manner, the part 130b where no vertical electric field exists acts as a slit. In other words, it is possible to form a plurality of virtual light sources in a stripe shape under the light-shielding film 146. As a result, light passing through the light-shielding film 146 from the virtual light sources in a stripe shape forms an elongated irradiation surface A parallel to the extension direction of the lower electrode 126. １ (FIG. 5C). Irradiation surface A １ The number and width of the light-shielding films 146 can be controlled by appropriately selecting the lower electrode 126 that generates the vertical electric field and adjusting its potential. The light-shielding films 146 also function as slits that block part of the light from the stripe-shaped light source.

[0032] Furthermore, by shifting the portion 130b where the vertical electric field is generated in a direction perpendicular to the extension direction of the lower electrode 126 (FIG. 5B), the irradiation surface can also be shifted (irradiation surface A in FIG. 5C). ２ (See Fig. 1). That is, by using a liquid crystal cell, stripe-shaped virtual light sources having any width and number can be formed, and the position of the stripe-shaped light sources relative to the plurality of light-shielding films 146 functioning as fixed slits can be changed, and as a result, the traveling direction of light emitted from the virtual light sources can be changed. In summary, the lighting device 100 can form any number of irradiation surfaces having various shapes and sizes (widths), and can also change the positions of the surfaces.

[0033] 3. Modifications The structure of the lighting device 100 is not limited to the above-described structure and can be modified in various ways. For example, as shown in FIG. 6A , the light-shielding film 146 may be formed on the counter substrate 136 so as to be in contact with the counter substrate 136 and the second polarizing plate 140. In this case, the light-shielding film 146 may be formed on the counter substrate 136 using an inkjet method, a sputtering method, a chemical vapor deposition (CVD) method, or the like before injecting the liquid crystal layer 130 or before fixing the counter substrate 136 and the substrate 124. In this case, the light-shielding film 146 can be formed using alignment markers provided on the counter substrate 136 and / or the substrate 124, thereby improving the alignment accuracy.

[0034] 6B , the light-shielding film 146 may be disposed on the second polarizing plate 140. In this case, the second polarizing plate 140 is provided on the counter substrate 136, and a support substrate 144 on which the light-shielding film 146 is provided is bonded to the second polarizing plate 140 using an adhesive layer 142. In such a structure, most of the external light can be blocked by the light-shielding film 146, and therefore, photodegradation of the second polarizing plate 140 and the components forming the liquid crystal cell can be suppressed.

[0035] Alternatively, as shown in FIG. 6C , the light-shielding film 146 may be disposed below the liquid crystal cell, i.e., below the first polarizing plate 122. Similar to the example shown in FIG. 6B , in this case, the first polarizing plate 122 is provided on the substrate 124, and the support substrate 144 provided with the light-shielding film 146 is bonded to the first polarizing plate 122 using the adhesive layer 142. In this structure, the light-shielding film 146 can block most of the light from the light source 114, thereby suppressing heat generation and deterioration due to light absorption by the first polarizing plate 122. Note that in this configuration, the light-shielding film 146 apparently forms multiple stripe-shaped virtual light sources with fixed widths, and the liquid crystal cell forms slits on top of these, with variable widths, number, and positions. Therefore, the same effects as described above can be obtained.

[0036] As described above, in the lighting device 100, a striped virtual light source is formed by utilizing the vertical electric field generated in the liquid crystal layer 130. Therefore, the distance d between adjacent lower electrodes 126 is １ When the distance d increases, a sufficient vertical electric field cannot be formed in the liquid crystal layer 130 between the adjacent lower electrodes 126, causing light leakage. １ There is a limit to how much the distance between adjacent lower electrodes 126 can be reduced. Therefore, the lower electrodes 126 may be arranged in two layers, thereby reducing the apparent distance between adjacent lower electrodes 126. Specifically, as shown in FIG. 7A, multiple lower electrodes 126 are arranged alternately in different layers. That is, among the lower electrodes 126 arranged in a stripe pattern, odd-numbered lower electrodes 126-1 are arranged in the lower layer on the substrate 124 side, and even-numbered lower electrodes 126-2 are arranged in the upper layer on the liquid crystal layer 130 side. An interlayer insulating film 148 containing a silicon-containing inorganic compound such as silicon nitride or silicon oxide or a polymer such as epoxy resin or acrylic resin may be arranged between the upper and lower layers to prevent electrical conduction between the lower electrodes 126 arranged in the upper and lower layers. By adopting such an arrangement, the apparent distance between adjacent lower electrodes 126-1 and 126-2 can be reduced to 0 μm, as shown in FIG. 7B. The lower electrodes 126-1 and 126-2 arranged in the upper and lower layers may not overlap in the vertical direction (normal direction of the substrate 124) (FIG. 7C), or may overlap partially (FIG. 7D).

[0037] Alternatively, as shown in FIG. 8A , an auxiliary light-shielding film 150 for preventing light leakage may be disposed on the liquid crystal layer 130. The auxiliary light-shielding film 150 may be formed using a material that can be used for the light-shielding film 146. The auxiliary light-shielding film 150 is disposed in a stripe pattern so as to overlap the region between adjacent lower electrodes 126 in the vertical direction. The auxiliary light-shielding film 150 may be disposed between the counter substrate 136 and the upper electrode 134, or as shown in FIG. 8B , between the upper electrode 134 and the liquid crystal layer 130. In the former case, an overcoat 152 covering the auxiliary light-shielding film 150 may be further disposed, or the auxiliary light-shielding film 150 may be disposed so as to contact the upper electrode 134. Furthermore, an insulating film (not shown) may be disposed between the auxiliary light-shielding film 150 and the counter substrate 136. In the latter case, the auxiliary light-shielding film 150 and the upper electrode 134 may be in contact with each other, or an insulating film (not shown) may be disposed between them.

[0038] Second Embodiment In this embodiment, a lighting device 160 having a different structure from the lighting device 100 described in the first embodiment will be described. Descriptions of configurations that are the same as or similar to those described in the first embodiment may be omitted.

[0039] 1. Liquid Crystal Cell Structure One difference between the lighting device 160 and the lighting device 100 is the structure of the liquid crystal cell. Specifically, as shown in FIG. 9A , the lighting device 160 provided on the light source device 110 includes a liquid crystal cell and multiple light-shielding films 146, similar to the lighting device 100. However, the total number of polarizers in the lighting device 160 is one, and a first polarizer 122 is positioned between the light source device 110 and the liquid crystal layer 130. Furthermore, the liquid crystal layer 130 does not function as an optical switch but functions as a lenticular lens. Therefore, the liquid crystal cell is configured so that the contribution of the horizontal electric field generated between adjacent lower electrodes 126 in the liquid crystal layer 130 is greater than the contribution of the vertical electric field. More specifically, the thickness of the liquid crystal layer 130 is increased, for example, to a thickness of 10 μm or more and 100 μm or less. By selecting a thickness within this range, not only can a large vertical electric field be generated but also high light transmittance of the liquid crystal layer 130 can be maintained.

[0040] For this reason, in the lighting device 160, a first polarizing plate 122 is disposed below the support substrate 144, and a plurality of light-shielding films 146 are provided on the support substrate 144. The support substrate 144 and the substrate 124 are fixed to each other by an adhesive layer 142 or the like. No polarizing plate is provided on the counter substrate 136. Although not shown, similar to the lighting device 100, a plurality of light-shielding films 146 may be provided below the support substrate 144 so as to be in contact with the support substrate 144.

[0041] 9B , the light transmission axis of the first polarizing plate 122 is disposed perpendicular to the extension direction of the plurality of lower electrodes 126. The first alignment film 128 is also disposed so that its alignment direction is perpendicular to the extension direction of the plurality of lower electrodes 126. The first alignment film 128 and the second alignment film 132 are in a crossed Nicol relationship.

[0042] 2. Control of Illumination Surface by Illumination Device When no electric field is generated in the liquid crystal layer 130, i.e., when no potential is applied to the lower electrodes 126 and upper electrodes 134, or when the same potential is applied to all lower electrodes 126 and upper electrodes 134, the liquid crystal molecules are oriented according to the orientation directions of the first alignment film 128 and the second alignment film 132. Therefore, the liquid crystal molecules are oriented according to the orientation direction on the first alignment film 128 side and rotate in-plane as they approach the second alignment film 132. The orientation directions on the first alignment film 128 side and the second alignment film 132 side are perpendicular to each other. Therefore, as shown in FIG. 10 , linearly polarized light passing through the first alignment film 128 is rotated 90° by passing through the liquid crystal layer 130. In the illumination device 160, because no polarizer is provided above the liquid crystal layer 130, the rotated linearly polarized light passes through the upper electrode 134 and the opposing substrate 136 and is extracted to the outside (see the arrows in the figure).

[0043] Here, similarly to the first embodiment, the plurality of light-shielding films 146 arranged in a stripe pattern function as slits that partially block light. However, as described above, since light from the light source 114 travels isotropically, the light passing between the light-shielding films 146 spreads as it passes through the liquid crystal layer 130, etc., although this depends on the distance from the lighting device 160 and the pitch and width of the light-shielding films 146. Therefore, when the liquid crystal cell is not driven, an illuminated surface with a substantially uniform illuminance can be provided.

[0044] Next, a case will be described in which the liquid crystal cell is driven to make the liquid crystal layer 130 function as a lenticular lens. In the lighting device 160, a transverse electric field is formed by periodically changing the potential supplied to the plurality of lower electrodes 126, thereby forming a refractive index distribution in the liquid crystal layer 130 and forming a plurality of semi-cylindrical liquid crystal lenses extending in the extension direction of the lower electrodes 126. Therefore, the entire liquid crystal layer 130 functions as a lenticular lens.

[0045] As an example, as shown in FIGS. 11A and 11B, four consecutive lower electrodes 126 (electrodes E １ From electrode E ４ ) as one unit, the liquid crystal cell is driven so that the potential applied to these is periodically changed. １ , E ２ , E ３ The potential applied to the electrode E is decreased in this order. ３ , E ２ , E １ The potential is increased in the order of electrode E. １ The largest pulsed AC potential (±aV) was applied to electrode E １ Electrode E adjacent to ２ and E ４ a moderate pulsed AC potential (±bV, a>b) at electrode E ２ and E ４ Electrode E between ３By driving the liquid crystal cell in this way, a horizontal electric field is generated between the lower electrodes 126, and the tilt angle of the liquid crystal molecules also changes periodically. １ The tilt angle is maximum on the electrode to which the smallest potential is applied (here, electrode E ３ ) the tilt angle is minimum and is substantially the same as the alignment direction of the first alignment film 128. ２ and E ４ The tilt angle of the upper liquid crystal molecules is between these two (see the ellipse in FIG. 11A). By orienting the liquid crystal molecules in this way, a semicircular arc-shaped refractive index distribution is periodically formed on the lower electrode 126 side of the liquid crystal layer 130. As a result, multiple semicylindrical liquid crystal lenses are formed in the liquid crystal layer 130, and the liquid crystal layer 130 functions as a lenticular lens for light components parallel to the direction of the refractive index distribution.

[0046] As described above, the light transmission axis of the first polarizer 122 is perpendicular to the direction in which the lower electrode 126 extends, and therefore coincides with the direction of the refractive index distribution. Therefore, linearly polarized light that passes through the first polarizer 122 and passes between adjacent light-shielding films 146 is affected by the refractive index distribution of the liquid crystal layer 130. Therefore, as shown in FIG. 11A , for example, by appropriately adjusting the potential supplied to the lower electrode 126 to form a refractive index distribution that covers the space between adjacent light-shielding films 146, it is possible to condense the linearly polarized light that passes between the light-shielding films 146. As a result, as shown in FIG. 12A , an elongated irradiation surface A parallel to the direction in which the lower electrode 126 extends is formed. ３ can be given.

[0047] The potential applied to the lower electrode 126 can be adjusted as appropriate. Therefore, for example, by supplying a potential to the lower electrode 126 according to the timing chart shown in FIG. 13, the position of the semicircular arc-shaped refractive index distribution can be shifted in a direction perpendicular to the direction in which the lower electrode 126 extends. According to the timing chart shown in FIG. 13, the refractive index distribution shown in FIG. 11A is realized in the first period. On the other hand, in the second period, the potential applied to the lower electrode 126 is in the following order: E２ >E １ = E ３ >E ４

[0048] 14, when the first period is changed to the second period, the alignment state of the liquid crystal molecules is shifted by one pitch of the lower electrode 126. This shift causes a shift in the semicircular arc-shaped refractive index distribution, which is schematically shown by the dashed line in FIG. 15, and as a result, the refraction pattern of the light that has passed through the light-shielding films 146 changes, and the traveling direction of the light changes (see the dotted arrows in FIG. 15). As a result, as schematically shown in FIG. 12B, the illumination surface A given by the first period ３ shifts, and the irradiation surface A ４ Although not shown, by appropriately changing the pattern and magnitude of the potential applied to the lower electrode 126, the focal length and focal position of the lenticular lens formed by the liquid crystal layer 130 can be changed, and therefore the traveling direction of light and the shape and size of the irradiated surface can also be controlled arbitrarily.

[0049] In summary, in the illumination device 160, fixed slits are formed on the light source device 110 by the multiple light-shielding films 146, creating multiple striped virtual light sources. A lenticular lens, whose focal position, focal length, or width (the length perpendicular to the direction in which the lower electrodes 126 extend) can be changed, is created on this virtual light source by using liquid crystal cells. This allows the traveling direction of light passing between the multiple light-shielding films 146 to be changed, and the shape, size, and position of the illumination surface formed by this light to be freely controlled.

[0050] 3. Modifications As in the first embodiment, various modifications can be made to the configuration of the illumination device 160. For example, as shown in FIG. 16A , the illumination device 160 may be configured so that the first polarizing plate 122 is positioned between the light-shielding film 146 and the liquid crystal layer 130. In this case, after the first polarizing plate 122 is attached to the lower surface of the substrate 124, the support substrate 144 on which the light-shielding film 146 is formed may be fixed to the first polarizing plate 122 using an adhesive layer 142 or the like. By adopting this configuration, it is possible to suppress deterioration of the first polarizing plate 122 due to light from the light source 114.

[0051] 16B, the upper electrode 134 does not have to be provided. As described above, the refractive index distribution in the liquid crystal layer 130 is generated by the transverse electric field formed by the potential applied to the lower electrode 126, and this transverse electric field is mainly formed on the lower electrode 126 side of the liquid crystal layer 130. Therefore, the liquid crystal layer 130 can function as a lenticular lens even without providing the upper electrode 134 for forming the longitudinal electric field.

[0052] Alternatively, as shown in Figure 16C, the second alignment film 132 does not have to be provided. Because the refractive index distribution is mainly formed on the lower electrode 126 side of the liquid crystal layer 130, the direction of the refractive index distribution is determined by the alignment direction of the first alignment film 128. Furthermore, because no polarizing plate is provided on the liquid crystal layer 130, the optical rotation within the liquid crystal layer 130 does not affect the illuminated surface. Therefore, even without providing the second alignment film 132, a refractive index distribution can be formed in a fixed direction, and the liquid crystal layer 130 can function as a lenticular lens.

[0053] As described above, in the lighting device 100, 160 according to one embodiment of the present invention, the flat optical element 120 is provided on the light source device 110. Therefore, the liquid crystal cell is not required to have a three-dimensional shape, and light distribution can be controlled by the liquid crystal cell configured using the substrate 124 and opposing substrate 136 having a flat upper surface, which are commonly used in display devices, and the plurality of light-shielding films 146. Furthermore, this can prevent the lighting device from becoming large, and it is also possible to install the optical element 120 in an existing light source. Therefore, it is possible to provide the optical element 120 and a lighting device including the same at low cost.

[0054] The above-described embodiments of the present invention can be combined as appropriate as long as they are not mutually inconsistent. Furthermore, even if a person skilled in the art appropriately adds or deletes components or modifies the design of a display device of each embodiment, or adds or omits processes or modifies conditions, such a display device is included in the scope of the present invention as long as it includes the gist of the present invention.

[0055] Even if there are other effects and advantages different from those brought about by the aspects of each of the above-mentioned embodiments, those that are clear from the description in this specification or that can be easily predicted by a person skilled in the art are naturally understood to be brought about by the present invention.

[0056] 100: lighting device, 110: light source device, 112: housing, 112a: recess, 112b: surface, 114: light source, 120: optical element, 122: first polarizing plate, 124: substrate, 126: lower electrode, 128: first alignment film, 130: liquid crystal layer, 132: second alignment film, 134: upper electrode, 136: opposing substrate, 138: sealing material, 140: second polarizing plate, 142: adhesive layer, 144: supporting substrate, 146: light-shielding film, 148: interlayer insulating film, 150: auxiliary light-shielding film, 152: overcoat, 160: lighting device

Claims

1. An illumination device comprising: an optical element having a liquid crystal cell and a plurality of light-shielding films; and a light source device located below the optical element, having a housing and a light source within the housing, and configured to irradiate light onto the optical element, wherein the liquid crystal cell has: a substrate; a plurality of lower electrodes located on the substrate and arranged in a stripe pattern; a first alignment film on the plurality of lower electrodes; a liquid crystal layer on the first alignment film; a second alignment film on the liquid crystal layer; an upper electrode located on the second alignment film and overlapping the plurality of lower electrodes; a counter substrate on the upper electrode; and a first polarizing plate and a second polarizing plate located below the substrate and above the counter substrate, respectively; the plurality of light-shielding films are arranged in a stripe pattern and overlap the plurality of lower electrodes; and the extension direction of the plurality of lower electrodes is parallel to the extension direction of the plurality of light-shielding films.

2. The lighting device according to claim 1, wherein the plurality of light-shielding films are sandwiched between the opposing substrate and the second polarizing plate.

3. The lighting device according to claim 2, wherein the plurality of light-shielding films are in contact with the opposing substrate and the second polarizing plate.

4. The lighting device according to claim 1, wherein the plurality of light-shielding films are located on the second polarizing plate.

5. The lighting device according to claim 1, wherein the plurality of light-shielding films are located below the first polarizing plate.

6. The lighting device according to claim 1, wherein the upper electrode and the plurality of lower electrodes are both light-transmitting.

7. The lighting device according to claim 1, wherein the width of each of the plurality of lower electrodes is smaller than the width of each of the plurality of light-shielding films.

8. The lighting device according to claim 1, wherein the pitch of the plurality of lower electrodes is smaller than the pitch of the plurality of light-shielding films.

9. The lighting device according to claim 1, wherein the plurality of light-shielding films contain a metal selected from the group consisting of aluminum, silver, molybdenum, titanium, and tantalum.

10. The lighting device according to claim 1, wherein the plurality of lower electrodes are configured to be independently supplied with a potential.

11. An illumination device comprising: an optical element having a liquid crystal cell and a plurality of light-shielding films; and a light source device located below the optical element, having a housing and a light source within the housing, and configured to irradiate light onto the optical element, wherein the liquid crystal cell has: a polarizing plate; a substrate on the polarizing plate; a plurality of lower electrodes located on the substrate and arranged in a stripe pattern; an alignment film on the plurality of lower electrodes; a liquid crystal layer on the alignment film; and an opposing substrate on the liquid crystal layer, wherein the plurality of light-shielding films are sandwiched between the polarizing plate and the substrate, and the extension direction of the plurality of lower electrodes is parallel to the extension direction of the plurality of light-shielding films.

12. The lighting device of claim 11, wherein the total number of polarizing plates is one.

13. The lighting device according to claim 11, wherein the liquid crystal layer has a thickness of 15 μm or more and 100 μm or less.

14. The lighting device according to claim 11, wherein all of the plurality of lower electrodes are light-transmitting.

15. The lighting device according to claim 11, wherein the width of each of the plurality of lower electrodes is smaller than the width of each of the plurality of light-shielding films.

16. The lighting device according to claim 11, wherein the pitch of the plurality of lower electrodes is smaller than the pitch of the plurality of light-shielding films.

17. The lighting device according to claim 11, wherein the plurality of light-shielding films include a metal selected from the group consisting of aluminum, silver, molybdenum, titanium, and tantalum.

18. The lighting device according to claim 11, wherein the plurality of lower electrodes are configured to be independently supplied with a potential.

19. The lighting device according to claim 11, wherein the extension direction of the plurality of lower electrodes is perpendicular to the alignment direction of the alignment film.

20. The lighting device according to claim 11, wherein the light transmission axis of the polarizing plate is parallel to the alignment direction of the alignment film.

Images