JP2019220287A - Planar luminaire - Google Patents

Abstract

To provide a planar luminaire capable of emitting light uniformly even in a case where an emission surface is a bent surface.SOLUTION: A planar luminaire comprises a light source (an LED 31, a light bar 32) that emits light, and a light guide plate 5 that receives light from the light source and emits the light toward a predetermined direction. The light guide plate has: an end face 50 on which the light from the light source is made incident; a first main surface 51 intersecting with an end surface, which is an emission surface 5a for emitting light incident on the end surface; and a second main surface 52 intersecting with the end surface, which is a back surface 56 of the emission surface. The first main surface is a convex bent surface having a predetermined radius of curvature, and the second main surface extends in a direction gradually approaching the first main surface from a base end part having the end surface toward a tip part.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a planar lighting device.

  2. Description of the Related Art Conventionally, there is a spread illuminating device including a light source and a light guide plate for receiving light from the light source and emitting the light in a predetermined direction. The light guide plate of such a planar illumination device is formed of a plate having an end surface on which light from a light source is incident and a main surface serving as an exit surface for emitting light incident on the end surface.

  The main surface of the light guide plate is generally formed in a planar shape in order to uniformly emit light, but a light guide plate having a curved main surface is also known (see, for example, Patent Document 1). reference).

JP 2004-317976 A

  However, in order to emit light uniformly from the exit surface formed by the curved surface, a more precise optical design is required in terms of optical path design and arrangement.

  An object of the present invention is to provide a planar illumination device capable of uniformly emitting light even when the emission surface is a curved surface, in which the above is an example of the problem.

  In order to solve the above-described problem and achieve the object, a planar lighting device according to one embodiment of the present invention includes a light source that emits light, and a light guide plate that receives light from the light source and emits the light in a predetermined direction. And. The light guide plate includes an end surface on which light from the light source is incident, a first main surface that intersects the end surface with an exit surface for emitting light incident on the end surface, and a back surface of the exit surface. And a second main surface intersecting with the end surface. The first main surface is a convex curved surface having a predetermined radius of curvature, and the second main surface is the first main surface from the base end having the end surface toward the front end. The film is stretched in a direction gradually approaching the surface.

FIG. 1 is a front view schematically illustrating the spread illuminating apparatus according to the embodiment. FIG. 2 is an explanatory diagram corresponding to a cross-sectional view taken along line II-II of FIG. 1. FIG. 3 is a front view schematically showing a planar lighting device according to a modification. FIG. 4 is an explanatory diagram corresponding to a cross-sectional view taken along line VI-VI of FIG. FIG. 5 is an explanatory diagram illustrating a curved surface state of an emission surface of the light guide plate. FIG. 6A is an explanatory diagram illustrating a luminance distribution on an emission surface according to a radius of curvature. FIG. 6B is an explanatory diagram showing how to view the luminance distribution on the emission surface. FIG. 7 is a line graph showing the luminance distribution on the exit surface according to the radius of curvature. FIG. 8A is a schematic side view illustrating a cross-sectional shape of a light guide plate according to a first modification. FIG. 8B is a schematic side view illustrating a cross-sectional shape of a light guide plate according to a second modification.

  Hereinafter, embodiments for carrying out the present invention (hereinafter, referred to as “embodiments”) will be described in detail with reference to the accompanying drawings. The same components are denoted by the same reference numerals throughout the description of the embodiments.

  Hereinafter, a planar lighting device according to an embodiment will be described with reference to the drawings. It should be noted that the application of the planar lighting device is not limited by the embodiments described below. Further, it is necessary to keep in mind that the drawings are schematic, and the dimensional relationships of the respective elements, the ratios of the respective elements, and the like may be different from actual ones. Further, the drawings may include portions having different dimensional relationships and ratios.

  First, an outline of a spread illuminating apparatus according to an embodiment will be described with reference to FIGS. FIG. 1 is a front view schematically showing the spread illuminating apparatus according to the embodiment, and FIG. 2 is an explanatory view corresponding to a cross-sectional view taken along line II-II in FIG.

  As shown in FIG. 1, the spread illuminating apparatus 1 includes a housing frame 2, a light source 3, a prism bar 33, and a light guide plate 5. The spread illuminating apparatus 1 according to the present embodiment is used, for example, as a high-mount stop lamp (auxiliary brake light), which is one of tail lights of an automobile. In the present embodiment, the spread illuminating apparatus 1 is applied to a high-mount stop lamp. However, the planar illuminating apparatus 1 may be used for an in-vehicle illuminating lamp that illuminates a driver's seat or a passenger seat. In this case, two light guide plates 5 may be provided side by side to irradiate the driver's seat and the passenger's seat at the same time.

  The housing frame 2 is formed of a synthetic resin or metal in a frame shape, houses the light source 3, the prism bar 33, and holds the base end 53 of the light guide plate 5. That is, as shown in FIG. 2, the housing frame 2 has a groove 20 for holding the base end 53 of the light guide plate 5, and the groove 20 also serves as a storage section for storing the light source 3. As shown in FIG. 2, the groove 20 in which the light source 3 and the prism bar 33 are arranged includes a first wall 22a and a second wall 22b facing each other in the Z-axis direction, and a third wall serving as a bottom. 1, the first wall portion 22a is omitted in FIG. 1 for convenience.

  As shown in FIGS. 1 and 2, the light source 3 is, for example, a light source that emits light for emitting a high-mount stop lamp, and includes a pair of LEDs (Light Emitting Diode) 31, a light bar 32, and a prism bar. 33, and is configured as a linear light source. Although not shown, the light source 3 includes a board connected to a drive circuit and a power supply, and the LED 31 is mounted on the board. When the LED 31 is driven via the substrate, the light source 3 emits light.

  The LED 31, which is a point-like light source, has a light emitting surface 31a that emits light, and is provided at both ends of the light bar 32 such that the light emitting surface 31a faces light entering surfaces 32a formed at both ends of the light bar 32. Are located. As described above, the LED 31 emits light from the light emitting surface 31a toward the light incident surface 32a of the light bar 32.

  The light bar 32 is, for example, formed in a rod shape from a transparent material such as a polycarbonate resin, and is substantially orthogonal to the light incident surface 32a formed on both longitudinal end surfaces in the Y-axis direction with respect to the light incident surface 32a. It has a light exit surface 32b, which is a surface, and a reverse light exit surface 32c opposite to the light exit surface 32b. The light bar 32 converts light incident from the LED 31 that is a point light source into linear light, and emits the light toward the prism bar 33.

  The light incident surface 32a is an end surface of the light bar 32 formed in a rod shape facing the X-axis direction, and receives light emitted from the LED 31. The light exit surface 32b extends in the X-axis direction, is substantially perpendicular to the light entrance surface 32a, and is longer than the light entrance surface 32a, and emits light incident on the light entrance surface 32a. In addition, a plurality of prisms (not shown) are formed on the light exit surface 32b and the reverse light exit surface 32c.

  The prism bar 33 is disposed between the light exit surface 32b of the light bar 32 and the end surface 50 which is the light entrance surface of the light guide plate 5, and can control the light distribution. The prism bar 33 has a light entrance surface 33a facing the light exit surface 32b of the light bar 32, and a light exit surface 33b opposite to the light entrance surface 33a.

  The prism bar 33 has a plurality of prisms (not shown) formed on a light incident surface 33a, and a lenticular lens (not shown) formed on a light exit surface 33b.

  The planar lighting device 1 according to the present embodiment is configured such that the light source 3, which is the above-described linear light source, emits linear light from the light exit surface 33 b of the prism bar 33 to the end surface 50 of the light guide plate 5. 5 can emit planar light. That is, the light that has entered the light guide plate 5 from the light source 3 is guided inside and is emitted from the emission surface 5a formed on the main surface. Thus, the planar lighting device 1 can emit planar light from the light guide plate 5.

  The light guide plate 5 is made of, for example, a transparent material such as a polycarbonate resin, and has an end surface 50, a first main surface 51, and a second main surface 52, as shown in FIGS. Then, the base end portion 53 is held by the housing frame 2. Light emitted from the light source 3 is incident on an end face 50 formed on a base end portion 53 of the light guide plate 5, and after being guided, is emitted from an emission face 5 a formed on a first main surface 51. .

  That is, the light guide plate 5 includes an end surface 50 on which light from the light source 3 is incident, and an emission surface 5 a for emitting light incident on the end surface 50, and a first main surface 51 intersecting with the end surface 50. It has a second main surface 52 that is the back surface 5b of the emission surface 5a and intersects the end surface 50. In other words, the light guide plate 5 includes an end face 50, a first main surface 51 that is in contact with the end face 50 via the first intersection line 501, and a back face 5 b that faces the emission face 5 a, and It has a second main surface 52 that contacts the end surface 50 via a second intersection line 502 parallel to the line 501.

  The end surface 50 is an elongated rectangular surface facing the light source 3 in the groove 20 of the housing frame 2. The first principal surface 51 is a rectangular surface in plan view having a relatively largest area, and has a predetermined radius of curvature R centered on the point P as shown in FIG. Is a convex curved surface. The second main surface 52 is a surface which is formed in a rectangular shape in plan view similarly to the first main surface 51 and faces the first main surface 51, from the base end portion 53 having the end surface 50. It extends in a direction gradually approaching the first main surface 51 toward the tip end portion 54.

  That is, as shown in FIG. 2, a flat portion 55 that is fitted and held in the groove 20 of the housing frame 2 is formed in the base end portion 53 of the light guide plate 5. In the flat portion 55, the side of the first main surface 51 and the side of the second main surface 52 are both formed in a planar shape. An end surface 50 is formed on the start end side of the flat portion 55, and the emission surface 5a and the back surface 5b extend from the end side of the flat portion 55.

  Of a pair of surfaces 55a and 55b of the flat portion 55 facing each other in the Z-axis direction, it is assumed that an imaginary plane S extending horizontally in the Y-axis direction from the first surface 55a located on the emission surface side is assumed. The upper half portion of the light guide plate 5 having the virtual plane S as a virtual bottom surface is formed as a convex curved surface protruding in the positive direction of the Z axis. That is, the emission surface 5a is a curved surface that swells in the emission direction more than the first intersection line 501 where the first main surface 51 intersects the end surface 50. In addition, the curved surface forming the emission surface 5a is a curved surface that does not tangent to the virtual plane S.

  On the other hand, the lower half of the light guide plate 5 has a wedge shape formed by the imaginary plane S and the back surface 5b, and the thickness gradually decreases from the base end 53 to the tip end 54. That is, the back surface 5b extends in a direction approaching the emission surface 5a from the base end portion 53 having the end surface 50 to the tip end portion 54 where the first main surface 51 and the second main surface 52 intersect. .

  As described above, the emission surface 5a of the light guide plate 5 is formed by the end point of the flat portion 55 in the positive Y-axis direction (the boundary between the flat portion 55 and the emission surface 5a), the second main surface 52, and the virtual plane S. The line connecting the intersection is a curved surface formed by a curve that is convex from the virtual plane S in the light emission direction.

  On the other hand, the back surface 5b of the second main surface 52 opposed to the first main surface 51 has an end point in the positive Y-axis direction of the flat portion 55 (a boundary between the flat portion 55 and the back surface 5b) and the second main surface. It is a plane constituted by straight lines connecting the intersection of the plane 52 and the virtual plane S. That is, the back surface 5b extends in a direction approaching the emission surface 5a from the base end portion 53 toward the tip end portion 54 where the first main surface 51 and the second main surface 52 intersect.

  With the light guide plate 5 having such a configuration, light that enters the end face 50 from the light source 3 and travels straight in parallel with the virtual plane S reaches the back surface 5b without hitting the emission surface 5a, and is reflected by the back surface 5b. Is emitted from the emission surface 5a.

  In the light guide plate 5 having such a configuration, the light incident on the end face 50 from the light source 3 has its course changed by the back surface 5b and is emitted from the emission surface 5a. The back surface 5b may be provided with a prism portion capable of appropriately changing the light path.

  The planar lighting device 1 using such a light guide plate 5 can uniformly emit light even when the emission surface 5a is a curved surface. Therefore, the brake operation is performed by applying the planar illumination device 1 to a high-mount stop lamp of an automobile. This can be clearly notified to the following vehicle. In addition, by forming the emission surface 5a as a curved surface, for example, in the case of use in a vehicle, it is possible to provide the planar illumination device 1 having a shape conforming to a curved shape such as a rear glass of a vehicle.

  The planar lighting device 1 described above has a configuration in which the base end 53 of the light guide plate 5 is cantilevered by the housing frame 2 as shown in FIGS. 1 and 2. However, as shown in FIGS. 3 and 4, the light guide plate 5 can have a configuration in which not only the base end portion 53 but also the front end portion 54 can be held by the housing frame 2.

  FIG. 3 is a front view schematically showing a spread illuminating apparatus according to a modification, and FIG. 4 is an explanatory view corresponding to a cross-sectional view taken along line VI-VI of FIG. In FIGS. 3 and 4, the same elements as those described above are denoted by the same reference numerals, and description thereof is omitted.

  The housing frame 2 in the modified example is formed in a frame shape having an opening 21 as shown in FIGS. That is, the housing frame 2 is divided into a first groove 201 (FIG. 4) for holding the base end 53 of the light guide plate 5 and a second groove 202 (FIG. 4) for holding the front end 54 of the light guide plate 5. Configuration. The light guide plate 5 is held such that an emission surface 5 a for emitting light faces the opening 21. In FIG. 3, for convenience of explanation, the first wall portion 22a on the positive Z-axis direction side in the first groove portion 201 (FIG. 4) in which the light source 3 and the prism bar 33 are arranged is omitted.

  Further, the light guide plate 5 in the modified example has a flat surface 54a, 54b so that the front end portion 54 can be easily held by the housing frame 2 similarly to the base end portion 53. Since the distal end portion 54 of the light guide plate 5 in the modified example has a smaller thickness than the flat portion 55 of the base end portion 53, the spacer 23 is disposed in the second groove portion 202 as shown in FIG. In place of the arrangement of the spacers 23, one of the walls constituting the second groove 202 may be formed thick.

  By the way, as described above, the light exit surface 5a of the light guide plate 5 is a curved surface, but the radius of curvature R defining the curved surface is preferably 400 or more. That is, the exit surface 5a is preferably a curved surface having a radius of curvature R ≧ 400 mm.

  Here, the curvature of the light exit surface 5a of the light guide plate 5 will be described with reference to FIGS. FIG. 5 is an explanatory diagram showing a curved surface state of the emission surface 5a of the light guide plate 5. FIG. 6A is an explanatory diagram showing the luminance distribution on the exit surface 5a according to the radius of curvature, and FIG. 6B is an explanatory diagram showing how to view the luminance distribution on the exit surface 5a. FIG. 7 is a line graph showing the luminance distribution of the emission surface 5a according to the radius of curvature.

  When the light exit surface 5a has a different radius of curvature R, the shape of the light guide plate 5 in a side view is, as shown in FIG. 5, the larger the radius of curvature R, the more the Z-axis extends from the virtual plane S extending in the Y-axis direction. The projecting amount of the emission surface 5a in the direction is large. In FIG. 5, a flat surface is indicated by a solid line, a case with a radius of curvature R = 1000 mm is indicated by a dotted line, a case with a radius of curvature R = 500 mm is indicated by a broken line with a large pitch, and a case with a radius of curvature R = 400 mm is indicated by a chain line. The case where the radius of curvature R = 200 mm is indicated by a broken line with a small pitch, and the case where the radius of curvature R = 100 mm is indicated by a two-dot chain line.

  As shown in FIG. 6A, it has been experimentally found that the luminance distribution of the emission surface 5a changes according to the magnitude of the radius of curvature R (curvature). In FIG. 6A, the luminance distribution is schematically shown by the dot density. As shown in the drawing, the luminance distribution when the emission surface 5a is flat is the best, but it can be seen that as the curvature increases, the end side of the emission surface 5a becomes darker. This tendency is more remarkable as the curvature becomes larger. Here, when the radius of curvature R is 100 mm, the end side of the emission surface 5a is darkest. Here, the terminating end refers to the side of the distal end portion 54 in FIG. 1, FIG. 2, FIG. 3, and FIG.

  The brightness distribution that changes according to the radius of curvature R of the exit surface 5a is also apparent from FIG. As shown in the figure, if the radius of curvature R ≧ 400 mm, the luminance distribution of the emission surface 5a tends to be relatively close to a flat surface. Also in FIG. 7, a flat surface is indicated by a solid line, a case where the radius of curvature R = 1000 mm is indicated by a dotted line, a case where the radius of curvature R = 500 mm is indicated by a broken line with a large pitch, and a case where the radius of curvature R = 400 mm is indicated. The case where the radius of curvature R = 200 mm is indicated by a broken line with a small pitch, and the case where the radius of curvature R = 100 mm is indicated by a two-dot chain line.

  As described above, when the emission surface 5a is a curved surface having a radius of curvature R ≧ 400 mm, it can be seen that there is no significant change in luminance distribution as compared with the case of a flat surface. Therefore, it is possible to provide the planar illumination device 1 that can uniformly emit light while having the curved emission surface 5a.

  By the way, as shown in FIG. 6B, the luminance distribution is measured by measuring the luminance of the emission surface 5a in a state where the planar illumination device 1 is inclined 55 degrees toward the back surface 5b with respect to the emission direction H. That is, when the actual width of the emission surface 5a is 60 mm, the width of the emission surface 5a showing the luminance distribution is about 50 mm.

  Next, a modified example of the light guide plate 5 will be described with reference to the drawings. 8A and 8B are schematic side views showing the cross-sectional shapes of the light guide plates according to the first and second modifications. 8A and 8B, the same elements as those described above are denoted by the same reference numerals and description thereof will be omitted.

  As shown in FIG. 8A, the light guide plate 5 according to the first modification does not have the flat portion 55 at the base end portion 53, and the light exit surface 5a and the rear surface 5b are connected to the first main surface 51 and the second main surface 51b. Extend from the first intersection line 501 and the second intersection line 502 respectively intersecting with the end surface 50 toward the distal end portion 54. In the light guide plate 5 according to the second modification, the back surface 5b extends obliquely and linearly in a direction approaching the emission surface 5a from the base end portion 53 to the front end portion.

  As shown in FIG. 8B, the light guide plate 5 according to the second modified example has a flat portion 55 formed at the base end portion 53. Here, the light guide plate 5 is in contact with the end surface 50 via the first intersection line 501. While only the surface is formed flat, the front end portion of the second main surface 52 is a flat surface 541 in the front end portion 54. Even with such a configuration, when configuring the planar illumination device 1, the base end portion 53 and the distal end portion 54 of the light guide plate 5 are easily held by the housing frame 2.

  In the above-described modification, the back surface 5b is a flat surface. However, for example, the back surface 5b may be a curved surface that is concavely curved in the light emission direction.

  According to the above-described embodiment, the following planar illumination device 1 is realized.

  (1) A light source 3 that emits light, and a light guide plate 5 that receives light from the light source 3 and emits the light in a predetermined direction, wherein the light guide plate 5 has an end face 50 on which light from the light source 3 is incident. A first main surface 51 intersecting the end surface 50, which is an emission surface 5a for emitting light incident on the end surface 50, and a second main surface 52 intersecting the end surface 50, which is a back surface 5b of the emission surface 5a. The first main surface 51 is a convex curved surface having a predetermined radius of curvature R, and the second main surface 52 is directed from the base end portion 53 having the end surface 50 toward the front end portion 54. The planar illumination device 1 extends in a direction gradually approaching the first main surface 51 according to the following.

  According to such a spread illuminating device 1, light can be uniformly emitted even when the emission surface 5a is a curved surface.

  (2) The planar lighting device 1 according to (1), wherein the emission surface 5a is a curved surface that expands in the emission direction from a position where the first main surface 51 intersects the end surface 50 (first intersection line 501).

  According to the spread illuminating apparatus 1, light can be more uniformly emitted from the emission surface 5a by utilizing refraction of light by the back surface 5b.

  (3) In the above (1) or (2), the base end portion 53 has a flat portion 55 in which the first main surface 51 and the second main surface 52 are both flat. A planar lighting device 1 in which an end face 50 is formed at a start end side of a portion 55 and an emission surface 5a and a back surface 5b extend from an end side of a flat portion 55.

  According to the spread illuminating device 1, the light guide plate 5 can be firmly held by, for example, the housing frame 2.

  (4) The planar lighting device 1 according to any one of (1) to (3), including the housing frame 2 having the groove 20 for holding the light source 3 while sandwiching the base end 53 of the light guide plate 5.

  According to the spread illuminating apparatus 1, since the light source 3 can be accommodated and the light guide plate 5 can be firmly held, the entire apparatus can be made compact while maintaining optical functions.

  (5) In any one of the above (1) to (4), at least one of the first main surface 51 side and the second main surface 52 side of the front end portion 54 of the light guide plate 5 is flat. , Surface illumination device 1.

  According to the spread illuminating apparatus 1, the light guide plate 5 can be more reliably held by, for example, the housing frame 2.

  (6) The planar illumination device 1 according to any one of (1) to (5), wherein the emission surface 5a is a curved surface having a radius of curvature R ≧ 400 mm.

  According to such a spread illuminating device 1, even when the emission surface 5a is a curved surface, an optical design in the case where the emission surface 5a is a flat surface can be used, so that light can be uniformly emitted easily. be able to.

  In the embodiment described above, a resin having a high reflectance (for example, a white resin) may be used for the housing frame 2 around the LED 31 and near the light entrance surface 32a of the light bar 32. Thereby, the light efficiency can be improved. Further, for the housing frame 2 other than the above-described portions, a resin having a high absorption rate (for example, a black resin) may be used. Thereby, unnecessary light distribution can be reduced. That is, the housing frame 2 is preferably formed by two-color molding using a white resin and a black resin.

  In the above embodiment, the light source 3 is a linear light source using the LED 31 and the light bar 32. However, the configuration of the linear light source is not limited to the example described above. For example, a plurality of LEDs may be arranged in a line to form a linear light source.

  Further, the present invention is not limited by the above embodiments. The present invention also includes a combination of the above-described configurations as appropriate. Further, further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the above-described embodiments, and various modifications are possible.

  1 planar illumination device, 2 housing frame, 3 light sources, 5 light guide plates, 5a emission surface, 5b back surface, 20 groove portions, 51 first main surface, 52 second main surface, 53 base end portion, 54 tip end portion, 55 flat part, radius of curvature

Claims (6)

A light source for emitting light,
A light guide plate that receives light from the light source and emits light in a predetermined direction,
With
The light guide plate,
An end surface on which light from the light source is incident, a first main surface that intersects the end surface that is an emission surface that emits light incident on the end surface, and intersects the end surface that is a back surface of the emission surface. A second main surface,
The first main surface is a convex curved surface having a predetermined radius of curvature,
The planar illumination device, wherein the second main surface extends in a direction gradually approaching the first main surface from a base end portion having the end surface toward a distal end portion.   2. The spread illuminating apparatus according to claim 1, wherein the emission surface is a curved surface that expands in an emission direction from a position where the first main surface intersects with the end surface. 3. The base end,
Each of the first main surface side and the second main surface side has a flat portion that is a flat surface, the end surface is formed at the start end side of the flat portion, and the emission surface and the emission surface from the end side of the flat portion. The planar lighting device according to claim 1, wherein the back surface extends.   4. The spread illuminating apparatus according to claim 1, further comprising a housing frame that sandwiches the base end of the light guide plate and has a groove that accommodates the light source. 5.   The planar illumination according to any one of claims 1 to 4, wherein at least one of the first main surface side and the second main surface side of the front end portion of the light guide plate is a flat surface. apparatus. The emission surface is
The planar illumination device according to any one of claims 1 to 5, wherein the surface illumination device has a curved surface with a radius of curvature R ≧ 400 mm.

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