Lighting device

Abstract

A lighting device (1) is provided with: a light source device (10) which emits parallel light (Lp) along a Z direction; a liquid crystal panel (20) on which the parallel light (Lp) is incident; and a lens plate (30) on which the parallel light (Lp) transmitted through the liquid crystal panel (20) is incident. In the lens plate (30), a plurality of rectangular convex lenses (31) are arranged in a matrix when viewed along the Z direction. The liquid crystal panel (20) has a plurality of divided regions (Rd) which overlap the convex lens (31) when viewed along a predetermined direction. Each of the plurality of divided regions (Rd) includes a plurality of pixels (Px).

Description

Lighting device

[0001] The present disclosure relates to a lighting device.

[0002] Patent Document 1 discloses a cutter spotlight capable of changing the shape of a light-transmitting spot (illumination range) illuminated by the lighting device, as an example of a lighting device. The lighting device of Patent Document 1 includes a light source, an objective lens, a mask plate disposed between the light source and the objective lens and having a circular window, and a cutter device covering the circular window. The cutter device includes a plurality of light shielding plates that cover the circular window from the periphery of the circular window. The shape of the illumination range is adjusted by the plurality of light shielding plates covering the circular window. The shape of the illumination range is, for example, a polygonal shape.

[0003] Japanese Utility Model Publication No. 63-22011

[0004] In the lighting device of the above-mentioned Patent Document 1, it is necessary to replace or move the light shielding plate to change the shape of the illumination range, so adjustment of the shape of the illumination range is relatively difficult. On the other hand, for such lighting devices, there is a demand for accurately adjusting the shape of the illumination range.

[0005] The present disclosure has been made in view of the above, and an object of the present disclosure is to provide a lighting device capable of accurately adjusting the shape of an illumination range.

[0006] The lighting device of the present disclosure includes: a light source device that emits parallel light along a predetermined direction; a liquid crystal panel on which the parallel light is incident; and a lens plate on which the parallel light transmitted through the liquid crystal panel is incident, wherein the lens plate has a plurality of rectangular convex lenses arranged in a matrix when viewed along the predetermined direction, the liquid crystal panel has a plurality of divided regions overlapping the convex lenses when viewed along the predetermined direction, and each of the plurality of divided regions includes a plurality of pixels.

[0007] Figure 1 is a diagram showing the configuration of an illumination device according to an embodiment of the present disclosure. Figure 2 is a plan view of the liquid crystal panel shown in Figure 1. Figure 3 is a partially enlarged plan view of the liquid crystal panel shown in Figure 2. Figure 4 is a cross-sectional view of the liquid crystal panel along the line IV-IV shown in Figure 2. Figure 5 is a plan view of the lens plate shown in Figure 1. Figure 6 is a partially enlarged plan view of the lens plate shown in Figure 5. Figure 7 is a cross-sectional view of the lens plate along the line VII-VII shown in Figure 6. Figure 8 is a schematic diagram showing a single convex lens and the illumination range when the light emitted from the single convex lens is irradiated onto the screen. Figure 9 is a schematic diagram showing the state in which parallel light emitted from a light source device passes through the liquid crystal panel and is refracted by the lens plate. Figure 10 is a plan view of the screen showing the illumination range when the illumination device illuminates the screen.

[0008] Embodiments for implementing this disclosure will be described in detail with reference to the drawings. This disclosure is not limited to the embodiments described below. Furthermore, the components described below include those that are easily conceivable to those skilled in the art, and those that are substantially the same. In addition, the components described below can be combined as appropriate.

[0009] Furthermore, the disclosure is merely an example, and any modifications that a person skilled in the art could easily conceive of while maintaining the intent of the disclosure are naturally included within the scope of this disclosure. In addition, drawings may schematically represent the width, thickness, shape, etc. of each part in order to clarify the explanation, but these are merely examples and do not limit the interpretation of this disclosure. Moreover, in this specification and each drawing, elements similar to those described above in previously shown drawings are denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.

[0010] The X, Y, and Z directions shown in the drawings are orthogonal to each other. In the X direction, the side indicated by the arrow is the +X side, and the opposite side is the -X side. In the Y direction, the side indicated by the arrow is the +Y side, and the opposite side is the -Y side. In the Z direction, the side indicated by the arrow is the +Z side, and the opposite side is the -Z side. Note that the X, Y, and Z directions are examples, and this disclosure is not limited to these directions.

[0011] Figure 1 shows the configuration of an illumination device 1 according to an embodiment of the present disclosure. The illumination device 1 is adjustable in shape of the illumination range. The illumination device 1 comprises a light source device 10, a liquid crystal panel 20, and a lens plate 30. The light source device 10, the liquid crystal panel 20, and the lens plate 30 are arranged in this order along the Z direction.

[0012] In Figure 1, the light source device 10, the liquid crystal panel 20, and the lens plate 30 are spaced apart from each other. However, the light source device 10 (specifically the light source lens 12, which will be described later) and the liquid crystal panel 20 may be in contact, or the liquid crystal panel 20 and the lens plate 30 may be in contact. This allows for miniaturization of the lighting device 1.

[0013] The light source device 10 emits parallel light Lp along the Z direction (corresponding to the "predetermined direction"). The light source device 10 comprises a light source 11 and a light source lens 12.

[0014] The light source 11 is, for example, an LED (Light Emitting Diode). The light source 11 emits light Lr toward the light source lens 12.

[0015] The light source lens 12 refracts the light source Lr and emits it as parallel light Lp along the Z direction. The shape of the light source lens 12 is approximately conical. The light source lens 12 has a conical surface 12a that refracts the light source Lr in the Z direction. The light source lens 12 also has a convex lens portion 12b that refracts the light source Lr in the Z direction. The light source lens 12 may be a collimating lens or a Fresnel lens.

[0016] Figure 2 is a plan view of the liquid crystal panel 20 shown in Figure 1. The liquid crystal panel 20 shown in Figure 2 is a view of the liquid crystal panel 20 as seen from the +Z side along the Z direction. Figure 3 is a partially enlarged plan view of the liquid crystal panel 20 shown in Figure 2.

[0017] Parallel light Lp is incident on the liquid crystal panel 20 from the -Z side. The liquid crystal panel 20 is a vertical electric field type (for example, a TN (Twisted Nematic) type) liquid crystal panel. The liquid crystal panel 20 adjusts the illumination range of the illumination device 1 in the effective area Re (details will be described later).

[0018] As shown in Figure 2, the effective region Re is divided into multiple rectangular sub-regions Rd. The shapes of the multiple sub-regions Rd are identical. The multiple sub-regions Rd are arranged in a matrix. In addition, multiple pixels Px are arranged in a matrix within the effective region Re. As shown in Figure 3, each of the multiple sub-regions Rd contains multiple pixels Px.

[0019] Figure 4 is a cross-sectional view of the liquid crystal panel 20 along the IV-IV line shown in Figure 2.

[0020] The liquid crystal panel 20 comprises a first substrate 21, a second substrate 22, and a liquid crystal layer 23. The first substrate 21 and the second substrate 22 are light-transmitting and face each other in the Z direction.

[0021] The first substrate 21 is positioned on the -Z side of the second substrate 22. Multiple pixel electrodes Ep and the first alignment film AL1 are arranged on the +Z side surface of the first substrate 21.

[0022] Multiple pixel electrodes Ep correspond to multiple pixels Px. In the Z direction, one pixel electrode Ep overlaps with one pixel Px, and multiple pixel electrodes Ep are arranged in a matrix. The pixel electrodes Ep are rectangular plate-shaped in plan view. Multiple pixel electrodes Ep are arranged between the first substrate 21 and the first alignment film AL1.

[0023] The first alignment film AL1 is in contact with the liquid crystal layer 23. The first alignment film AL1 is a horizontal alignment film having an alignment direction perpendicular to the Z direction.

[0024] A common electrode Ec and a second orientation film AL2 are arranged on the -Z side of the second substrate 22.

[0025] The common electrode Ec faces multiple pixel electrodes Ep in the Z direction. The common electrode Ec is positioned between the second substrate 22 and the second alignment film AL2.

[0026] The second alignment film AL2 is in contact with the liquid crystal layer 23. The second alignment film AL2 is a horizontal alignment film having an alignment direction perpendicular to the Z direction and the alignment direction of the first alignment film AL1.

[0027] The liquid crystal layer 23 is located between the first substrate 21 and the second substrate 22 and contains a plurality of liquid crystal molecules LM. The plurality of liquid crystal molecules LM contained in the liquid crystal layer 23 are in a twisted orientation due to the first alignment film AL1 and the second alignment film AL2 when there is no potential difference between the common electrode Ec and the plurality of pixel electrodes Ep.

[0028] The liquid crystal panel 20 further comprises a first polarizing plate 24 and a second polarizing plate 25.

[0029] The first polarizing plate 24 is positioned on the -Z side of the first substrate 21. The transmission axis of the first polarizing plate 24 is parallel to the orientation direction of the first alignment film AL1. Parallel light Lp is incident on the liquid crystal panel 20 from the -Z side of the first polarizing plate 24.

[0030] The second polarizing plate 25 is positioned on the +Z side of the second substrate 22. The transmission axis of the second polarizing plate 25 is parallel to the orientation direction of the second alignment film AL2. Parallel light Lp that has passed through the liquid crystal panel 20 is emitted from the +Z side of the second polarizing plate 25.

[0031] Next, the operation of the liquid crystal panel 20 will be described. The liquid crystal panel 20 can select to transmit or block parallel light Lp for each pixel Px. In this embodiment, the liquid crystal panel 20 is a so-called normally white liquid crystal panel in which the light transmittance is maximized when no voltage is applied to the pixel electrode Ep.

[0032] If no voltage is applied to the pixel electrode Ep corresponding to a single pixel Px, there is no potential difference between the pixel electrode Ep and the common electrode Ec. In this case, no electric field is generated in the liquid crystal layer 23 at a single pixel Px, and the long axis of the liquid crystal molecule LM remains perpendicular to the Z direction.

[0033] In this case, the parallel light Lp incident on the liquid crystal panel 20 passes through the first polarizing plate 24 and becomes linearly polarized light parallel to the transmission axis of the first polarizing plate 24. When this linearly polarized light passes through the liquid crystal layer 23, its polarization direction is rotated by the liquid crystal molecules LM, becoming linearly polarized light parallel to the transmission axis of the second polarizing plate 25, and it passes through the second polarizing plate 25. In other words, in a single pixel Px, if no voltage is applied to the pixel electrode Ep corresponding to that pixel Px, the parallel light Lp from the light source device 10 passes through the liquid crystal panel 20.

[0034] On the other hand, when a voltage is applied to the pixel electrode Ep corresponding to a single pixel Px, a potential difference is generated between the pixel electrode Ep and the common electrode Ec. In this case, an electric field is generated in the liquid crystal layer 23 at a single pixel Px, causing the liquid crystal molecules LM to tilt.

[0035] In this case, linearly polarized light that passes through the first polarizing plate 24 is not rotated in the polarization direction by the liquid crystal layer 23 and is blocked without passing through the second polarizing plate 25. In other words, when a voltage is applied to the pixel electrode Ep at one pixel Px, the parallel light Lp from the light source device 10 is blocked without passing through the liquid crystal panel 20.

[0036] Figure 5 is a plan view of the lens plate 30 shown in Figure 1. The lens plate 30 shown in Figure 5 is a view of the lens plate 30 along the Z direction. Figure 6 is a partially enlarged plan view of the lens plate 30 shown in Figure 5.

[0037] Parallel light Lp that has passed through the liquid crystal panel 20 is incident on the lens plate 30. The lens plate 30 has a plurality of convex lenses 31. The convex lenses 31 refract the parallel light Lp that has passed through the liquid crystal panel 20 and emit light Ls. The emitted light Ls illuminates the object.

[0038] Each of the multiple convex lenses 31 has a rectangular shape when viewed along the Z direction. In this embodiment, the shape of the convex lens 31 when viewed along the Z direction is square, but it goes without saying that it is not limited to a square. The convex lens 31 has two parallel first sides S1a and two first diagonals S1b when viewed along the Z direction.

[0039] The plurality of convex lenses 31 are arranged in a matrix when viewed along the Z direction. In addition, when the lens plate 30 is viewed along the Z direction, the number of convex lenses 31 included in the effective irradiation range He of the light source device 10 (the range in which the light source device 10 emits the parallel light Lp) is 70 or more. In this case, the brightness can be uniformized in the illumination range of the illumination device 1.

[0040] In addition, the plurality of convex lenses 31 correspond to the plurality of divided regions Rd. Specifically, one convex lens 31 overlaps one divided region Rd when viewed along the Z direction. The peripheral edge of one convex lens 31 overlaps the peripheral edge of one divided region Rd when viewed along the Z direction. As described above, the liquid crystal panel 20 has a plurality of divided regions Rd overlapping the convex lenses 31 when viewed along the Z direction.

[0041] FIG. 7 is a cross-sectional view of the lens plate 30 taken along line VII-VII shown in FIG. 6. The optical axis Ax of the convex lens 31 is along the Z direction. The convex lens 31 has an incident surface 31a and an exit surface 31b that face opposite to each other in the Z direction.

[0042] The parallel light Lp transmitted through the liquid crystal panel 20 is incident on the incident surface 31a. The incident surface 31a has a convex shape protruding toward the -Z side. The exit surface 31b emits exit light Ls. The exit surface 31b has a convex shape protruding toward the +Z side. In addition, the shapes of the incident surface 31a and the exit surface 31b are defined as follows.

[0043] FIG. 8 is a schematic diagram showing one convex lens 31 and an irradiation range when the exit light Ls of the one convex lens 31 irradiates the screen Sc.

[0044] The screen Sc shown in FIG. 8 is a planar shape orthogonal to the Z direction. The first irradiation range Hs1 is a range where the exit light Ls of one convex lens 31 irradiates the screen Sc when the parallel light Lp is incident on the entire incident surface 31a of the one convex lens 31.

[0045] The first irradiation range Hs1 has a second side S2a and a second diagonal S2b corresponding to the first side S1a (FIG. 6) and the first diagonal S1b (FIG. 6) of the convex lens 31. Further, the first angle α is the maximum diffusion angle of the convex lens 31 in the direction along the first side S1a. The second angle β is the maximum diffusion angle of the convex lens 31 in the direction along the first diagonal S1b.

[0046] The first angle α and the second angle β are defined such that the first ratio of the first diagonal S1b to the first side S1a is equal to the second ratio of the second diagonal S2b to the second side S2a. Accordingly, the shape of the peripheral edge of the first irradiation range Hs1, which is formed when the outgoing light Ls from one convex lens 31 irradiates the screen Sc, can be accurately approximated to an enlarged shape of the peripheral edge of the one convex lens 31 when viewed along the Z direction.

[0047] Next, the operation of the lighting device 1 will be described.

[0048] FIG. 9 is a schematic diagram showing a state where parallel light Lp emitted from a light source device 10 transmits through a liquid crystal panel 20 and is refracted by a lens plate 30.

[0049] First, the case where the liquid crystal panel 20 does not block the parallel light Lp will be described. In this case, no voltage is applied to all pixel electrodes Ep, and the parallel light Lp emitted from the light source device 10 transmits through all pixels Px. The parallel light Lp transmitted through the liquid crystal panel 20 is incident on each of the plurality of convex lenses 31 on the lens plate 30.

[0050] When the lens plate 30 is viewed along the Z direction as described above, one convex lens 31 overlaps with one divided region Rd of the liquid crystal panel 20. Therefore, the parallel light Lp emitted from one divided region Rd is incident on one convex lens 31.

[0051] The parallel light Lp incident on the convex lens 31 is refracted at an incident surface 31a and an exit surface 31b, exits from the exit surface 31b as outgoing light Ls, and passes through a focal point P of the convex lens 31. In other words, the convex lens 31 refracts the parallel light Lp to diffuse it, and emits the diffused light as the outgoing light Ls. The plurality of outgoing light beams Ls respectively emitted from the plurality of convex lenses 31 overlap each other.

[0052] Figure 10 is a plan view of the screen Sc, showing the illumination range when the lighting device 1 illuminates the screen Sc. The screen Sc shown in Figure 10 is planar and perpendicular to the Z direction. The lighting device 1 and the screen Sc are sufficiently far apart.

[0053] As described above, the emitted light Ls from each of the multiple convex lenses 31 is irradiated onto the screen Sc. Therefore, the screen Sc has multiple first illumination ranges Hs1 (Figure 8) corresponding to the multiple convex lenses 31. The multiple first illumination ranges Hs1 on the screen Sc substantially overlap each other. The area that includes all of these multiple first illumination ranges Hs1 corresponds to the first illumination range H1 illuminated by the illumination device 1. The first illumination range H1 corresponds to the area illuminated by the illumination device 1 when the liquid crystal panel 20 does not block the parallel light Lp.

[0054] As described above, the multiple first illumination ranges Hs1 (Figure 8) corresponding to the multiple convex lenses 31 in the screen Sc substantially overlap each other. Therefore, the shape of the first illumination range H1 is substantially the same as the enlarged shape of one convex lens 31 when viewed along the Z direction.

[0055] Furthermore, as described above, one convex lens 31 diffuses and emits parallel light Lp emitted from one divided region Rd. Moreover, when one convex lens 31 is viewed along the Z direction, the one convex lens 31 and one divided region Rd overlap. Therefore, the shape of the first illumination range H1 is approximately the same as the enlarged shape of one divided region Rd.

[0056] Next, we will describe the case where the liquid crystal panel 20 blocks a portion of the parallel light Lp. When the user sets the illumination range of the lighting device 1 to a desired shape, the liquid crystal panel 20 is controlled to transmit parallel light Lp through the pixels Px corresponding to the desired shape. In other words, among the multiple pixels Px, the parallel light Lp is blocked from pixels Px other than the pixels Px corresponding to the desired shape.

[0057] For example, when the illumination device 1 illuminates a second illumination range H2, which corresponds to a part of the +Y side of the first illumination range H1 in the screen Sc shown in Figure 10, parallel light Lp is transmitted through multiple pixels Px in the transmission range Ht (Figure 3) corresponding to the second illumination range H2 in each of the multiple divided regions Rd. The transmission range Ht is a part of the -Y side of the divided region Rd.

[0058] In each of the multiple divided regions Rd, no voltage is applied to the multiple pixels Px located within the transmission range Ht. As a result, parallel light Lp is transmitted within the transmission range Ht. On the other hand, in each of the multiple divided regions Rd, a voltage is applied to the multiple pixels Px located outside the transmission range Ht. As a result, parallel light Lp is blocked outside the transmission range Ht.

[0059] Parallel light Lp emitted from the transmission range Ht of one divided region Rd is refracted by one convex lens 31 as described above and emitted as emitted light Ls. In this case, the range in which the emitted light Ls from the one convex lens 31 illuminates the screen Sc corresponds to the second illumination range Hs2, which is a part of the +Y side of the first illumination range Hs1 shown in Figure 8. The shape of the second illumination range Hs2 is almost the same as the shape of an expanded transmission range Ht of one divided region Rd.

[0060] Furthermore, the multiple second illumination ranges Hs2 corresponding to the multiple convex lenses 31 in the screen Sc substantially overlap each other. The area encompassing all of these multiple second illumination ranges Hs2 is placed in the second illumination range H2 illuminated by the illumination device 1. The shape of the second illumination range H2 is substantially the same as an enlarged version of the shape of one transmission range Ht.

[0061] In this way, by controlling the transmission and blocking of parallel light Lp at each of the multiple pixels Px, the shape of the transmission range Ht and the shape of the illumination range of the illumination device 1 can be changed. Therefore, the shape of the illumination range of the illumination device 1 can be easily changed, and the shape of the illumination range can be adjusted with high precision.

[0062] Furthermore, if, as shown in Figure 7, light Li tilted relative to parallel light Lp is incident on the incident surface 31a, it is conceivable that the light Li will travel to the convex lens 31 (convex lens 131) adjacent to the convex lens 31 into which the light Li is incident, as indicated by the dashed arrow. When the light Li travels to the convex lens 131 and is refracted at the exit surface 131a of the convex lens 131 and exits, it does not pass through the focal point P of the convex lens 31, falls outside the first illumination range Hs1, and becomes so-called stray light.

[0063] Therefore, as described above, the incident surface 31a of the convex lens 31 is formed in a convex shape, and as shown by the solid arrow, the light Li is refracted at the incident surface 31a so as to travel toward the focal point P. This suppresses the light from traveling toward the convex lens 131, thereby suppressing stray light.

[0064] Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments. The contents disclosed in the embodiments are merely examples, and various modifications are possible without departing from the spirit of the present invention. Appropriate modifications made without departing from the spirit of the present invention naturally fall within the technical scope of the present invention. At least one of various omissions, substitutions, and modifications of components can be made without departing from the gist of each of the embodiments and modifications described above.

[0065] For example, the liquid crystal panel 20 may be a so-called normally black liquid crystal panel, which has the lowest light transmittance when no voltage is applied to the pixel electrode Ep.

[0066] Furthermore, the liquid crystal panel 20 may be a vertical electric field method other than the TN method (for example, the VA (Vertical Alignment) method). Also, the liquid crystal panel 20 may be a transmissive liquid crystal display using a horizontal electric field method such as the FFS (Fringe Field Switching) method or the IPS (In Plane Switching) method.

[0067] Furthermore, in the convex lens 31, one of the incident surface 31a and the exit surface 31b may be a flat surface.

[0068] Furthermore, any other effects and advantages brought about by the embodiments described herein that are obvious from this specification or that can be appropriately conceived by those skilled in the art are naturally provided for by this disclosure.

[0069] 1 Illumination device 10 Light source device 20 Liquid crystal panel 21 First substrate 22 Second substrate 23 Liquid crystal layer 30 Lens plate 31 Convex lens 31a Incident surface 31b Exit surface Ec Common electrode Ep Pixel electrode Lp Parallel light Ls Exit light Px Pixel Rd Divided region S1a First side S1b First diagonal S2a Second side S2b Second diagonal α First angle β Second angle

Claims

1. An illumination device comprising: a light source device that emits parallel light along a predetermined direction; a liquid crystal panel into which the parallel light is incident; and a lens plate into which the parallel light that has passed through the liquid crystal panel is incident, wherein the lens plate has a plurality of rectangular convex lenses arranged in a matrix when viewed along the predetermined direction, and the liquid crystal panel has a plurality of divided regions that overlap with the convex lenses when viewed along the predetermined direction, and each of the plurality of divided regions contains a plurality of pixels.

2. The lighting device according to claim 1, wherein the liquid crystal panel comprises a first substrate and a second substrate facing each other, a plurality of pixel electrodes disposed on the first substrate and corresponding to a plurality of pixels, a common electrode disposed on the second substrate and facing the plurality of pixel electrodes, and a liquid crystal layer between the first substrate and the second substrate.

3. The lighting device according to claim 1, wherein the convex lens has two first sides and one first diagonal that are parallel to each other when viewed along the predetermined direction, and when the parallel light is incident on the entire incident surface of one of the convex lenses, the area illuminated by the emitted light of one of the convex lenses on a planar screen perpendicular to the predetermined direction is rectangular in shape, having a second side corresponding to the first side and a second diagonal corresponding to the first diagonal, and the first angle, which is the maximum diffusion angle in the direction along the first side of the convex lens, and the second angle, which is the maximum diffusion angle in the direction along the first diagonal, are determined such that the first ratio of the first diagonal to the first side is equal to the second ratio of the second diagonal to the second side.

4. The lighting device according to claim 1, wherein the convex lens has an incident surface into which the parallel light is incident and an exit surface from which the exit light is emitted, and the incident surface and the exit surface are each convex.

Images