JP2017224462A - Illumination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination device which illuminates a diffusion cover in a uniform manner while suppressing local nonuniformity.SOLUTION: An illumination device comprises: multiple LED light sources which are disposed in annular rows; a substrate on which the LED light sources are mounted; wide-angle lenses covering the LED light sources; and a diffusion cover which covers the LED light sources and the wide-angle lenses and has a curved surface. The wide-angle lenses include: an outer wide-angle lens covering LED light sources in a row that is disposed outsides among the rows of the LED light sources; an inner wide-angle lens covering LED light sources in a row that is disposed insides among the rows of the LED light sources; and a middle wide-angle lens covering LED light sources in a row that is disposed between the row of the LED light sources corresponding to the outer wide-angle lens and the row of the LED light sources corresponding to the inner wide-angle lens among the rows of the LED light sources. Ratios of heights with respect to lateral widths of contours of the wide-angle lens become smaller in the order of the inner wide-angle lens, the middle wide-angle lens and the outer wide-angle lens.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lighting device.

  In recent years, LEDs (Light Emitting Diodes) have been increasingly used as light sources for lighting devices. LEDs have begun to be used in place of fluorescent tubes as light sources for ceiling-mounted indoor lighting devices. The LED lighting device is characterized by being mercury-free, and is an environment-friendly light source. Furthermore, as an LED illumination device, directivity may be imparted to light emitted from the LED. Patent Documents 1 to 4 disclose optical systems in which directivity is imparted to light emitted from an LED.

JP 2014-154461 A JP 2014-135233 A JP 2011-204397 A JP 2014-13744 A

  In a lighting device provided with a diffusion cover that scatters and spreads light emitted from an LED so as to cover the LED, it is desired that the diffusion cover shine uniformly from the viewpoint of design. Conventionally, LEDs are arranged in a wide range under the diffusion cover, and further, the light from the LEDs is spread by a lens arranged corresponding to the LED, so that the diffusion cover is uniformly illuminated. However, in recent years, the efficiency of LEDs has improved, and the number of LEDs required as a lighting device has decreased. Therefore, the distance between adjacent LEDs has increased, and a lens that emits light from individual LEDs in a wider range has become necessary. . On the other hand, a lens that emits light over a wide range may form local unevenness such as bright lines on the diffusion cover, which may impair the design. An object of this invention is to provide the illuminating device which suppresses a local nonuniformity and the whole diffusion cover shines uniformly.

  In order to solve the above problems, the LED light sources arranged in a plurality of annular rows, a substrate on which the LED light sources are mounted, a wide-angle lens covering the LED light sources, the LED light sources and the wide-angle lenses are covered, A diffusion cover having a curved surface, and the wide-angle lens includes an outer wide-angle lens that covers the LED light sources arranged on the outer side of the row of LED light sources, and an inner side of the row of LED light sources. An inner wide-angle lens that covers the LED light sources in the arranged row, and an LED light source row corresponding to the outer wide-angle lens and an LED light source row corresponding to the inner wide-angle lens in the LED light source row. A wide-angle lens covering the LED light sources in a row, and the ratio of the height to the lateral width of the outer shape of the wide-angle lens decreases in the order of the inner wide-angle lens, the middle-wide-angle lens, and the outer wide-angle lens.

  According to the present invention, the configuration of the lens and the lens group has the effect of suppressing local unevenness and irradiating the entire diffusing cover with light to provide a lighting device with good design.

The front view for demonstrating the structure of the illuminating device which concerns on the 1st Embodiment of this invention. Sectional drawing for demonstrating the structure of the illuminating device which concerns on the 1st Embodiment of this invention. The figure which shows the radiation intensity distribution of the lens of the illuminating device which concerns on the 1st Embodiment of this invention. (a) The figure which shows the radiant intensity ratio of the lens of the illuminating device concerning the 1st Embodiment of this invention (b) The figure which expanded ratio of radiant intensity 2 or less (a) Cross section of dotted line in (b) (b) Front view of inner wide-angle lens 4 (a) Sectional drawing of the dotted line of (b) (b) Front view of the medium wide-angle lens 5 (a) Cross section of dotted line in (b) (b) Front view of outer wide-angle lens 6 (a) The figure which shows the light radiate | emitted to polar angle (theta) from the light source when a diffusion cover is made into a plane substantially (b) The light radiate | emitted from the light source to polar angle (theta) when a diffusion cover is made into a curved surface approximately Illustration

<< First Embodiment >>
FIG. 1 is a front view for explaining the configuration of the illumination device according to the first embodiment of the present invention, and is a view of the substrate 2 on which the LED light source 3 is mounted as viewed from the normal direction of the substrate 2. . In the present embodiment, the substrate 2 is a substantially annular plate-shaped member. A surface of the substrate 2 on which the LED light source 3 is mounted is referred to as a mounting surface. The LED light sources 3 are arranged in a plurality of annular rows, and each LED light source 3 is configured to be covered by a wide angle lens (an inner wide angle lens 4, a middle wide angle lens 5, and an outer wide angle lens 6).

  Among the annular rows of LED light sources 3, the wide-angle lens that covers the LED light sources 3 in the rows arranged outside is the outer wide-angle lens 6, and the wide-angle lens that covers the LED light sources 3 in the rows arranged inside is the inner wide-angle lens 4. A wide-angle lens covering the LED light source 3 in a row disposed between them (a row of LED light sources 3 corresponding to the outer wide-angle lens 6 and a row of LED light sources 3 corresponding to the inner wide-angle lens 4) is a medium-wide-angle lens 5 And In this embodiment, the outer wide-angle lens 6 covers the LED light source 3 in the outermost row, the middle wide-angle lens 5 covers the LED light source 3 in the second row from the outside (third row from the inside), and the inner wide-angle lens 4 is the outermost row. In this configuration, the LED light sources 3 in the inner row and the next inner row (second row from the inner side) are covered. The distance from the center C of the substrate 2 to the center of each wide-angle lens increases in the order of the inner wide-angle lens 4, the middle wide-angle lens 5, and the outer wide-angle lens 6.

  FIG. 2 is a cross-sectional view of the illumination device according to the first embodiment. The said cross section is sectional drawing in the surface parallel to the normal line of the board | substrate 2 with which the LED light source 3 is mounted. As indicated by an arrow in FIG. 2, a direction in which the illumination device 1 mainly emits light is a front direction Z. The direction in which the lighting device 1 mainly emits light is, for example, a type of lighting device that is installed on the ceiling and illuminates the interior of the room, or the direction normal to the ceiling or the direction from the ceiling to the floor (directly below the lighting device 1). Direction) is the front direction Z. A direction substantially perpendicular to the front direction Z is defined as a side surface direction.

  The lighting device 1 has a frame 11 as a housing, and the frame 11 is made of, for example, iron. The substrate 2 is attached to a part of the flat surface 11A of the frame 11 by screws or the like. The frame 11 has a hollow portion, and a lighting circuit 9 for driving the LED light source 3 is installed in the hollow portion. The frame 11 is bent and inclined near the end 2E of the substrate 2 and has an inclined portion 11B. A diffusion cover 8 is attached to the frame 11. In the present embodiment shown in FIG. 2, the frame 11 is composed of two members, a member to which the substrate 2 is attached and a member to which the diffusion cover 8 is attached.

  The lighting device 1 is fixed to the ceiling 50 by a fixture 51. Due to the fixture 51, the LED light source 3 cannot be placed in the center of the lighting device 1. The center cover 10 is installed on the front direction Z side of the fixture 51 so that light does not enter the groove in which the fixture 51 is disposed. The light propagating toward the groove is reflected and scattered in the front direction Z by the center cover 10. The center cover 10 is preferably a member having a high reflectance. Further, since the inside of the substrate 2 and the frame 11 is covered with a white material using white paint, white resist, white sheet, or the like, the center cover 10 is preferably a member that also reflects white.

  In the present embodiment, the LED light sources 3 corresponding to the inner wide-angle lens 4, the middle wide-angle lens 5, and the outer wide-angle lens 6 are distinguished as necessary and referred to as LED light source 3A, LED light source 3B, and LED light source 3C, respectively. To. These LED light sources 3 may be LED light sources of the same type or color, or LED light sources of different types or colors. Examples of the LED light source 3 include a white LED module using a blue light emitting LED and a yellow phosphor. In this embodiment, the light source is an LED light source, but is not limited to an LED light source.

  The inner wide-angle lens 4, the middle wide-angle lens 5, and the outer wide-angle lens 6 are connected by a flat portion 7 to form a lens cover 12. In the present embodiment, the lens cover 12 is molded at once. The material of the lens cover 12 is a resin such as polycarbonate, polystyrene, or acrylic.

  In the present embodiment, the diffusion cover 8 has a shape that covers all the LED light sources 3 and the lens cover 12, and diffuses and reflects and transmits the light emitted from the LED light sources 3. For the sake of explanation, the diffusion cover 8 is divided into a front part 8A in which the normal line of the surface of the diffusion cover 8 is substantially directed in the front direction Z, and a side part in which the normal line of the surface of the diffusion cover 8 is substantially directed in the lateral direction. Roughly divided into 8B. The diffusion cover 8 is often a resin, and contains a diffusion material such as silica in the resin. The total light transmittance of the diffusion cover 8 can be controlled by the type and concentration of the diffusion material. The light incident on the diffusion cover 8 exits the illumination device 1 from the diffusion cover 8 with a certain scattering angle distribution. In the present invention, the shape of the diffusion cover 8 is not limited and may be a shape that does not cover all the LED light sources 3, and the diffusion cover 8 may not be provided with diffusibility.

  Next, a wide angle lens will be described. Generally, the luminous intensity distribution of the emitted light from the LED light source 3 is Lambertian (an angle θ from the normal (referred to as a polar angle) and luminous intensity (radiant intensity) that maximize the normal direction of the mounting surface. ) The relationship between I (θ) and the luminous intensity (radiant intensity) I (0) in the normal direction is as follows: I (θ) = I (0) cos θ). Here, the luminous intensity [cd] means a luminous intensity measured at a position sufficiently away from the LED light source 3 and the lens. Hereinafter, the luminous intensity (or radiation intensity) of the LED light source 3 is expressed as I (θ). The luminous intensity is an amount obtained by multiplying the spectral radiant intensity by the visibility and integrating the wavelength as a variable. In the present invention, any of them is not misunderstood, and therefore is treated as equivalent. For example, since the two are generally in a proportional relationship, when the angle θ is 80 degrees, if there is a light intensity peak, it means that the radiation intensity also has a peak at 80 degrees. In the case of Lambertian, the angle θ has a peak at an angle of 0 degrees.

The wide-angle lens is a lens that refracts when light emitted from the LED light source 3 enters and emits light so as to be in a wider range (angle). For example, when the luminous intensity of the light emitted from the wide-angle lens is I _L (θ) (or radiation intensity), the ratio R _I (the luminous intensity (or radiation intensity) of the lens with respect to the LED light source 3 at θ = 0 degree). 0) = (I _L (0) / I (0)) is a ratio of luminous intensity (or radiation intensity) at a certain angle θ (θ> 0) R _I (θ) = (I _L (θ) / I ( A lens that is smaller than θ)) is a wide-angle lens. In this embodiment, a lens that partially satisfies R _I (0) <R _I (θ) at an angle θ greater than at least 45 degrees is a wide-angle lens.

  FIG. 3 shows radiation intensity distributions calculated by simulation for the inner wide-angle lens 4, the middle wide-angle lens 5, and the outer wide-angle lens 6 of the present embodiment. The optical system used for the calculation was a system in which the LED light source 3 was covered with each wide-angle lens, and the radiation intensity of the emitted light from each wide-angle lens was measured. The vertical axis in FIG. 3 indicates the radiation intensity [W / sr], and the horizontal axis indicates the emission angle θ [deg]. A broken line, a chain line (one-dot chain line, a two-dot chain line), and a solid line are the radiation intensities of the inner wide-angle lens 4, the middle wide-angle lens 5, and the outer wide-angle lens 6, respectively. The dotted line is the radiation intensity of the LED light source 3. In FIG. 1, the shape of the medium-wide-angle lens 5 viewed from the front is drawn isotropically simplified. However, the shape is actually an ellipse, and the radiant intensity (5a, 5b) in the minor axis and major axis directions is also shown. Indicated. Each distribution has a peak. The angles θp corresponding to the peaks Ip of the inner wide-angle lens 4, the medium-wide-angle lens short axis 5 a and the major axis 5 b, and the outer wide-angle lens 6 are 61.5 degrees, 68.5 degrees, and 69, respectively. .5 degrees and 80.5 degrees, and the angle θp also increases as the lens position goes outside.

Figure 4 is a diagram showing the ratio R _I of the radiation intensity _(theta), the ratio R _{I (theta)} of the vertical axis the radiation intensity in the figure, the abscissa indicates the output angle θ [deg]. FIG. 4B is an enlarged view of the ratio of radiant intensity of 2 or less. Each lens is a wide-angle lens, and there is always a region where the radiation intensity ratio R _I (θ) is larger than R _I (0) at 45 degrees or more, and the radiation intensity ratio R _I (θp) at the angle θp. Is always larger than R _I (0).

  The shape and arrangement of the wide-angle lens of the present embodiment is a configuration in which the diffusion cover 8 shines uniformly, and a configuration that suppresses local unevenness that may occur locally on the diffusion cover, such as bright lines, when the wide-angle lens is used. But there is. These will be described sequentially.

  As shown in FIG. 2, the diffusion cover 8 has a curved cross-sectional configuration such that the distance from the LED light source 3 </ b> A is the largest at the center and approaches the LED light source 3 </ b> C toward the end of the lighting device 1. As an example of this embodiment, the vertical distance from the substrate 2 to the diffusion cover 8 is about 80 mm in the vicinity of the LED light source 3 in the center and about 60 mm at the end 2E. The illuminance distribution formed on the diffusion cover 8 by the light emitted from the wide-angle lens becomes wider and gentler as the distance between the wide-angle lens and the diffusion cover 8 increases. The LED light source 3C is a main light source that irradiates the diffusion cover 8 positioned outside the LED light source 3C in addition to the distance from the diffusion cover 8 being just above the LED light source 3C. Therefore, the outer wide-angle lens 6 corresponding to the LED light source 3C needs to be a lens that reduces the light emitted directly above and emits as much light as possible over a wide range. Therefore, the outer wide-angle lens 6 needs to spread light more than the inner wide-angle lens 4 having a large distance to the diffusion cover 8 and a narrow area to be irradiated with light.

  In the medium wide-angle lens 5, when the luminous intensity distributions of the inner wide-angle lens 4 and the outer wide-angle lens 6 are greatly different, local unevenness may occur on the diffusion cover 8. Therefore, in order to moderate the change in luminous intensity distribution, It is desirable that the performance of spreading the light be the performance between the inner wide-angle lens 4 and the outer wide-angle lens 5 to buffer the performance change.

  The LED light sources 3 are arranged in an annular row, and the distance between the LED light sources 3 in the radial direction from the center of the instrument toward the outside in the mounting surface is larger than the distance between the LED light sources 3 in the annular row. Therefore, the spread of light in the radial direction is important. Hereinafter, each wide-angle lens will be described with a focus on the spread of light in the radial direction.

  5A and 5B are diagrams for explaining the inner wide-angle lens 4. FIG. 5B is a front view, and FIG. 5A is a cross-sectional view taken along a dotted line in FIG. In the illumination device 1, the direction parallel to the dotted line is the radial direction.

  In this embodiment, the case of an LED light source having an outer shape of 3 × 5 mm is shown. The lens inner surface 4i facing the LED light source 3A is an elliptical surface, and the outer lens outer surface 4o is a surface that refracts light from the lens inner surface 4i in a predetermined direction. The dimensions of the inner wide-angle lens 4 are as follows: the inner surface height 4Hi and width 4Wi, the outer lens surface height 4H and width 4W, the lens center thickness (4H-4Hi), and the lens end thickness (4W-4Wi). And

  6A and 6B are diagrams for explaining the medium-wide-angle lens 5, FIG. 6B is a front view, and FIG. 6A is a cross-sectional view taken along the dotted line in FIG. 6B. In the illumination device 1, the direction parallel to the dotted line is the radial direction. When viewed from the front, the medium-wide-angle lens 5 has an elliptical shape having a short axis in the radial direction and a long axis in the direction perpendicular to the radial direction. The long axis is longer than the short axis by about 1 mm. Similar to the inner wide-angle lens, the lens inner surface 5i facing the LED light source 3B is an elliptical surface, and the outer lens outer surface 5o is a surface that refracts light from the lens inner surface 5i in a predetermined direction. The dimensions of the medium and wide-angle lens 5 are as follows: the inner surface height 5Hi and width 5Wi, the outer lens surface height 5H and width 5W, the lens center thickness (5H-5Hi), and the lens end thickness (5W-5Wi). And

  7A and 7B are diagrams for explaining the outer wide-angle lens 6. FIG. 7B is a front view, and FIG. 7A is a cross-sectional view taken along the dotted line in FIG. 7B. In the illumination device 1, the direction parallel to the dotted line is the radial direction. Similar to the inner wide-angle lens, the lens inner surface 6i facing the LED light source 3C is an elliptical surface, and the outer lens outer surface 6o is a surface that refracts light from the lens inner surface 6i in a predetermined direction. The dimensions of the outer wide-angle lens 6 are as follows: height 6Hi and width 6Wi of the lens inner surface, height 6H and width 6W of the lens outer surface, lens center thickness (6H-6Hi), lens end thickness (6W-6Wi). And In addition, when the external shape of the LED light source 3 is rectangular as in the present embodiment, the short axis direction of the LED light source 3 is substantially parallel to the radial direction, so This has the effect of spreading the emitted light. This is because the lens exhibits its original performance the closer the light source is to the point light source, the smaller the size of the light source in the radial direction, the greater the ability to spread the lens light in the radial direction. This is because it is easy.

  Examples of the dimensions of each lens are shown in the table below. For the medium and wide-angle lens 5, dimensions in the minor axis direction (radial radius direction) are shown. The medium and wide-angle lens 5 will be described by paying attention to the radial direction. In the present embodiment, the center of the outer surface of the wide-angle lens is a flat surface. The reason is as follows. If the center of the outer surface of the wide-angle lens is recessed and light from the vicinity of the center of the outer surface of the lens is emitted at a wide angle, if the center of the LED light source 3 and the center of the lens do not coincide with each other with high accuracy, And local unevenness occurs. Therefore, in the case of the lens cover 12 having a plurality of wide-angle lenses, the center of the outer surface of the wide-angle lens is set to the flat surface that is strongest against the center position deviation, thereby suppressing the occurrence of local unevenness. Play.

  In any of the wide-angle lenses, the inner surface of the lens is larger than the width, and the cross section is an ellipsoid that is long in the normal direction of the substrate 2. The larger the inclination of the inner surface of the lens near the lens center, the more the light can be spread. This will be described with reference to FIG. When light emitted at a certain angle θ reaches the inner surface of the lens, if the inclination of the tangential plane of the lens inner surface is larger than the inclination of the tangential plane when the lens inner surface is spherical, the light on the lens inner surface is centered on the lens. Refracts away from the surface.

  When the lens inner surface is spherical, the normal of the tangential plane is parallel to the light beam. However, in the case of the wide-angle lens of this embodiment, the normal 5Ni of the tangential plane is outside the angle θ of the light ray Ray5a as shown in the figure. Therefore, the angle of the light beam in the lens also becomes larger than the angle θ due to refraction, and the light spreads. By making the height of the inner surface of the lens larger than the width, the effect of spreading light is achieved. This effect is not limited to the elliptical inner surface of the lens, but can also be obtained by using a curve, a broken line, a combination thereof, or the like. Further, the ratio of the height to the lateral width of the lens inner surface facing the LED light source 3 of each lens is larger in the ratio of the outer wide-angle lens 6 than in the ratio of the inner wide-angle lens 4. This is because the outer wide-angle lens 6 significantly spreads light more than the inner wide-angle lens 4.

  However, the inner surface of the lens is preferably a smooth curved surface such as an elliptical surface. As smoothness, when the cross-sectional shape of the inner surface of the lens is approximated by a curve or a polygonal line, the first-order differentiation is continuous (the differential value from the positive side is substantially equal to the differential value from the negative side with respect to a certain point). It is desirable to be. This is because the wide-angle lens emits light in a predetermined direction with respect to the light from the point light source placed at the center, but the light emitting surface of the LED light source 3 has a size of about 3 mm and is not a complete point light source. Therefore, light emitted from a position deviated from the center of the light emitting surface deviates from a predetermined emission direction. When the lens inner surface shape (inclination) changes discontinuously at a certain point, when light enters from a position other than the lens center before and after the discontinuous point, the exit direction of the incident light from the lens depends on the incident position. Since the predetermined emission direction changes greatly and the light beams passing before and after the discontinuous point intersect after being emitted from the lens, the emitted light may form local unevenness on the diffusion cover 8. It is.

  The ratio of the height to the width of the lens outer surface (height / width) becomes smaller as the position of the lens becomes the outer side. That is, the inner, middle, and outer wide-angle lenses become smaller in this order. This is because, from the viewpoint of uniformity, the outer lens needs to spread light, and the lens that spreads light needs to widen the lens width as described later, and all the lenses are wide lenses. Since the necessary number of LED light sources 3 cannot be mounted on the substrate 2 due to the restriction of the lens, the inner wide-angle lens 4 which has no problem even if the width is reduced from the viewpoint of uniformity is made smaller, and the outer wide-angle lens 6 is made wider. This is because of the large lens.

  The middle wide-angle lens 5 is arranged to reduce the difference when the performance difference between the inner wide-angle lens 4 and the outer wide-angle lens 6 is large. For example, in FIG. 2, when the distance from the center of the substrate 2 to the end 2E is 200 mm and the distance from the center of the front surface 8A of the diffusion cover to the end is 300 mm, the outer wide-angle lens 6 is Since it is necessary to irradiate light in the range of about 100 mm to the end, the angle θp corresponding to the peak Ip of luminous intensity (radiation intensity) becomes a wide-angle lens having an angle larger than 75 degrees. On the other hand, the inner wide-angle lens 4 is a lens having an angle θp of about 60 degrees. In this case, if there is no medium wide-angle lens 5, the illuminance distribution formed by each lens on the diffusion cover 8 is different at the boundary between the inner wide-angle lens 4 and the outer wide-angle lens 6, which may cause local unevenness. . Therefore, in order to reduce the difference in illuminance distribution formed on the diffusion cover 8 by both, it is better to mount the medium-wide angle lens 5. In that case, it is better that the angle θp of the middle wide-angle lens 5 is between the angles θp of the inner wide-angle lens 4 and the outer wide-angle lens 6. For this purpose, the ratio of the height to the lateral width of the lens outer surface is determined by the lens The inner wide-angle lens 4, the middle-wide-angle lens 5, and the outer are reduced so that the unevenness of the diffusion cover 8 can be suppressed when the LED light source 3 is turned on. It is necessary to decrease in order of the wide-angle lens 6. Thereby, it becomes possible to suppress the occurrence of unevenness in the diffusion cover 8. The relationship between the ratio of the height to the width of the lens outer surface and the spread of light will be described. Rays Ray4 and Ray6 shown in FIGS. 5 (a) and 7 (b) indicate rays radiated from the center of the LED in a direction where the polar angle θ is 45 degrees and refracted by the wide-angle lens. The angle of incidence of the ray Ray6 on the outer surface of the outer wide-angle lens 6 (the angle of the normal 6No and the incident ray) than the angle of incidence of the ray Ray4 on the outer surface of the inner wide-angle lens 4 (normal 4No and the angle of the incident ray) ) Is larger. Therefore, the polar angle of the outgoing light beam emitted from the lens outer surface 6 is larger in the outer wide-angle lens 6 than in the inner wide-angle lens 4. That is, light is emitted at a wider angle.

  By increasing the incident angle of the light emitted at a certain polar angle θ to the lens outer surface, the light can be emitted in a wider range. When spreading the light compared to the case where the outer surface is spherical, the incident angle of the light emitted at a certain polar angle θ to the lens outer surface is increased compared to the case where the spherical surface is the outer surface, so that the outer surface is spherical. Can also spread the light. This is because the angle between the tangent plane where light emitted at a certain polar angle θ enters the lens outer surface and the surface (mounting surface) perpendicular to the normal of the substrate 2 is smaller than when the outer surface is a spherical surface. Means that. Therefore, as the lens emits light at a wider angle, the angle between the tangential plane and the mounting surface of the substrate 2 becomes smaller. The fact that the angle between the tangential plane at each position of the lens outer surface and the mounting surface of the substrate 2 is smaller than that when the outer surface is a spherical surface means that the lateral component of each surface element of the lens outer surface becomes larger. Is longer in the lateral direction than in the case of a spherical surface, that is, the width becomes longer. Accordingly, as the ratio of the height to the width of the lens outer surface (height / width) is reduced, the lens has an effect of spreading light.

  In addition, the ratio of the lens end thickness to the lens center thickness (lens end thickness / lens center thickness) increases as the lens position goes to the outside, that is, in order of the inner, middle, and outer wide-angle lenses. growing. This is because the lens thickness ratio also increases as the lens light spreading performance increases, due to the widening of the lens width.

  When two wide-angle lenses having an angle θp corresponding to a peak that differ by 10 degrees or more are used, the angle θp has a medium-wide angle lens 5 that falls between the angles θp of the two wide-angle lenses, and has a height with respect to the width of the lens outer surface. By reducing the ratio as the position of the lens moves outward, the illuminance of the entire diffusion cover 8 can be made uniform, and local unevenness can be suppressed.

  Similarly, it has a medium-wide-angle lens 5, and the ratio of the lens end wall thickness to the lens center wall thickness is increased as the position of the lens is increased, thereby making the entire illuminance of the diffusion cover 8 uniform. Furthermore, there is an effect of suppressing local unevenness.

  Next, suppression of local unevenness formed by the single lens on the diffusion cover 8 will be described in detail. The non-uniformity in which the LED interval is wide and the area immediately above the LED becomes bright and the adjacent LED becomes dark can be suppressed by spreading the light from the lens, and the lens shape that spreads the light is as described above. When attention is focused on a lens corresponding to one LED light source 3, the emitted light from the lens may form local unevenness on the diffusion cover 8. In particular, bright linear (curved) unevenness (bright line) may occur, and this is likely to occur with a wide-angle lens having a peak in the luminous intensity distribution. As a method of suppressing these bright lines, it is conceivable to provide a concave / convex shape (so-called “texture”) on the outer surface of the lens to suppress it by light scattering. To do. Furthermore, there is a problem in that light is lost by scattering and reflecting toward the surrounding substrate or the like due to the embossing and the efficiency is lowered.

  According to our experiments, it has been found that such local unevenness can be suppressed if the illuminance distribution formed on the diffusion cover 8 by the light emitted from the lens decreases monotonously as it moves away from directly above the LED light source 3. . Preferably, it should be lowered smoothly with increasing distance from the position directly above the LED light source 3. To be smooth, the first derivative of the illuminance distribution with respect to the position may be substantially continuous. Further, for example, if the illuminance distribution is a distribution that can be fitted with a monotonically decreasing curve such as a Gaussian distribution, unevenness depending on the discontinuity of the illuminance distribution does not occur.

  Therefore, even if the lens is a wide-angle lens, the illuminance distribution formed on the diffusion cover 8 by the single lens unit is monotonously reduced from directly above the LED light source 3, and preferably, the maximum value is directly above the LED light source 3. The effect of suppressing local unevenness can be obtained by using a structure that can be reduced or a distribution that can be fitted with a smooth arbitrary function such as a Gaussian distribution. Furthermore, since it is not necessary to give unevenness to the outer surface of the lens to suppress local unevenness, there is also an effect of reducing loss.

  In particular, the outer wide-angle lens 6 has such a shape that the illuminance on the diffusion cover 8 gradually attenuates as the distance from the LED light source 3 increases when the LED light source 3 is lit alone.

  The outer surface of the lens of the present embodiment is a surface that has a root mean square roughness smaller than the main wavelength (for example, 450 nm) of the LED light source 3 and is optically specular, and hardly scatters light.

  In particular, when the peak of luminous intensity is too large, the outer wide-angle lens 6 is bent so that the diffusion cover 8 is closer to the direction of the substrate 2 as it goes outward as shown in FIG. Bright lines may occur in the vicinity of the part of the diffusion cover 8 that reaches. The radiation intensity distribution that suppresses the bright line has the configuration shown in FIG. 3, and it can be seen that the peak Ip of the outer wide-angle lens 6 is smaller than any of the peaks Ip of the inner wide-angle lens 4 and the medium-wide-angle lens 5. As described above, since the luminous intensity distribution is approximately proportional to the radiant intensity distribution (the profile is similar), the peak of the luminous intensity distribution of the outer wide-angle lens 6 is the same as the luminous intensity distribution of either the inner wide-angle lens 4 or the middle-wide-angle lens 5. Smaller than the peak. Therefore, the characteristics and effects described below are established not only by the radiant intensity but also by the luminous intensity.

  The outer wide-angle lens 6 is a lens that emits light even at an emission angle of 80 degrees or more, but the emission angle dependency of the radiation intensity increases gently as compared with other distributions, and the peak Ip is a lens arranged on the inner side. It has a smaller configuration. The radiant intensity distribution of the outer wide-angle lens 6 is set such that the angle θp is larger than the distribution of all other lenses, and the peak Ip is smaller than the peak Ip of the other lenses, thereby spreading the light, and There is an effect of suppressing local unevenness. Furthermore, since it is not necessary to give unevenness to the outer surface of the lens to suppress local unevenness, there is also an effect of reducing loss. In other words, particularly in the case of a specular lens that does not impart an uneven shape to the lens outer surface, the angle θp of the outer wide-angle lens 6 is larger than the distribution of all other lenses in the radiation intensity distribution or luminous intensity distribution. Thus, the peak is made smaller than the peaks of the other lenses, so that the effect of spreading light and suppressing local unevenness is obtained. A mirror surface is a surface that is less scattered by unevenness. As a standard for a surface with less scattering due to unevenness, it can be said that the root mean square roughness is a surface smaller than the main wavelength (for example, 450 nm) of the LED light source 3, and when the root mean square roughness is less than 200 nm, it is almost scattered. Therefore, it can be said to be a mirror surface, and when it is less than 100 nm, the scattering is extremely small and it can be said to be a perfect mirror surface.

Here, the ability to spread light will be described again. From the radiation intensity ratio R _I (θ) shown in FIG. 4, the outer wide-angle lens 6 has a sufficiently large radiation intensity ratio with respect to the LED light source 3 at the angle θp, and the radiation intensity ratio at the angle θp is 3 It is the largest value among all kinds of wide-angle lenses. Here, the luminous intensity I _C (θ) of the LED light source, the luminous intensity I _CL (θ) when the LED light source 3 is covered with a wide-angle lens, and the luminous intensity ratio is RI _C (θ) = (I _CL (θ) / I _C (θ)), the luminous intensity ratio RI _C (θ) has almost the same distribution as the radiant intensity ratio. Therefore, the same can be said for the radiant intensity ratio. The lens 6 has a sufficiently large luminous intensity ratio, and the luminous intensity ratio at the angle θp is the largest value among the three types of lenses. That is, the luminous intensity distribution (radiant intensity distribution) of the outer wide-angle lens 6 is set so that the peak of the angle θp and the luminous intensity ratio (radiant intensity ratio) is larger than the distribution of other lenses, preferably all other lenses. By making the peak of the luminous intensity distribution (radiation intensity distribution) smaller than the peak of other lenses, the effect of spreading the light and suppressing local unevenness is exhibited. Furthermore, since it is not necessary to give unevenness to the outer surface of the lens to suppress local unevenness, there is also an effect of reducing loss. That is, when RI _C (θ) = (I _CL (θ) / I _C (θ)), the peak of the luminous intensity ratio increases in the order of the inner wide-angle lens 4, the middle wide-angle lens 5, and the outer wide-angle lens 6. Thus, the above-described effect is achieved. Further, the light intensity peak of the outer wide-angle lens 6 is lower than the light intensity peak of the inner wide-angle lens 4 or the middle wide-angle lens 5, so that a further effect is achieved. At this time, the outer wide-angle lens 6 has a shape that greatly spreads light, and is a wide-angle lens corresponding to an annular row having many LED light sources 3 on the outer side. Therefore, the lens outer surface 6o of the outer wide-angle lens is used as a mirror surface. And improving the performance of spreading light.

Further, when the radiation intensity ratio is RI (θ) = (I _L (θ) / I (θ)), the peak of the radiation intensity ratio is that of the inner wide-angle lens 4, the middle wide-angle lens 5, and the outer wide-angle lens 6. By increasing in order, the above-described effect is achieved. Furthermore, the peak of the radiation intensity of the outer wide-angle lens 6 is lower than the peak of the radiation intensity of the inner wide-angle lens 4 or the medium-wide-angle lens 5, so that a further effect is achieved. At this time, the outer wide-angle lens 6 has a shape that greatly spreads light, and is a wide-angle lens corresponding to an annular row having many LED light sources 3 on the outer side. Therefore, the lens outer surface 6o of the outer wide-angle lens is used as a mirror surface. And improving the performance of spreading light.

  Note that the illuminance distribution formed on the diffusion cover 8 by the lens having such a luminous intensity distribution is basically a distribution that monotonously decreases immediately above the LED light source.

  In FIG. 3, the ratio of the radiant intensity at angle θp to the radiant intensity at 0 ° polar angle (radiant intensity at angle θp / radiant intensity at 0 ° polar angle) is as follows. In the order of the wide-angle lens 6, they are 2.11, 4.27, and 2.80. The medium wide-angle lens ratio of 4.27 is close to the upper limit at which local unevenness does not occur. Therefore, it is desirable that the radiation intensity ratio of the angle θp with respect to the polar angle of 0 degree is less than 4.27. By making the said radiation intensity ratio less than 4.27, there exists an effect of suppressing a local nonuniformity. As will be described again, since the luminous intensity ratio and the radiant intensity ratio are substantially the same, by setting the luminous intensity ratio to less than 4.27, the same effect of suppressing local unevenness is obtained.

  Next, a profile preferable as an illuminance distribution formed on the diffusion cover 8 by the single wide-angle lens will be described. As described above, the illuminance of the diffusing cover 8 decreases monotonously with increasing distance from the LED light source, and it is desirable that the illuminance should be smoothly reduced. When a Gaussian distribution is used as such a distribution, there is an effect that it is possible to easily realize irradiation of light to the entire diffusion cover while suppressing local unevenness.

This will be described with reference to FIG. When the diffusion cover 8 is approximately flat, the distance from the LED light source 3A to the diffusion cover 8 is tz, and the distance from the central axis Cax of the inner wide-angle lens 4 is ρ, the illuminance distribution on the diffusion cover 8 is expressed as a distance. In the case of Gaussian distribution related to ρ (Exp (−1 / 2 * (ρ / σ) ² , σ is a constant representing spread)), the distance ρ that the light emitted from the light source to the polar angle θ should reach by the diffusion cover 8 Is given by Equation 1 below.

  If the inner surface of the lens is set to an arbitrary shape (in this embodiment, an elliptical surface) using Equation 1, the outer surface of the lens is uniquely determined. Even in a lens manufactured by this method assuming that the diffusion cover 8 is a flat surface, local unevenness does not occur if the curvature of the curved surface of the diffusion cover 8 is large. Therefore, when a certain plane is assumed and the illuminance distribution formed by a single lens is a Gaussian distribution, local unevenness is suppressed. The lens forming the Gaussian distribution satisfies the relationship of the formula (1). Note that even if the relationship between ρ and θ is not necessarily expressed by equation (1), the relationship between ρ and θ is determined, and therefore the luminous intensity distribution (radiation intensity distribution) of the lens emission light is determined, and the lens inner surface shape is determined. The lens outer surface is uniquely determined.

  Further, the above concept can be applied not only to a plane but also to a curved surface. This will be described with reference to FIG. Light is emitted from the LED light source 3A in the polar angle θ direction, and the distance from the central axis Cax of the inner wide-angle lens 4 to the light beam arrival position in the direction parallel to the substrate 2 is ρ, and the LED light source 3A in the normal direction of the substrate 2 Tz and ρ are given as functions of the angle δ, where tz is the distance between the light beam arrival position and tz, and the angle between the normal of the substrate 2 and the outgoing light beam from the lens outer surface 4o is δ. The relational expression is given by a differential equation of polar angle θ and angle δ reflecting the curved surface shape. If the relationship and the lens inner surface shape are set, the lens outer surface shape is uniquely determined. Accordingly, if the illuminance distribution is determined, the luminous intensity distribution of the lens (the relationship between the distance ρ and the polar angle θ and the relationship between the angle δ and the polar angle θ) is determined, and if the inner surface of the lens is set, the corresponding lens shape is determined. That is, for example, when an illuminance distribution that decreases smoothly as the distance from the LED light source reaches its maximum value is set, the corresponding lens shape is determined by setting the lens inner surface.

  8 (a) and 8 (b), a profile preferable as an illuminance distribution formed by a single wide-angle lens on the diffusion cover 8 and a method of manufacturing a lens that realizes the profile are shown as follows: LED light source 3A, inner wide-angle lens 4, diffusion cover 8; As described above, the relationship between the LED light source 3B and the LED light source 3C, the medium wide-angle lens 5 and the outer wide-angle lens 6, the diffusion cover 8 and the illuminance distribution formed thereon is the same. It is possible to produce a lens shape corresponding to.

  As described above, a part of the description of the present embodiment has described the characteristics of the radiation intensity and the effects of the characteristics using the radiation intensity [W / sr] of the light emitted from the wide-angle lens of the present embodiment. The same holds true for the luminous intensity [cd] of light emitted from the wide-angle lens of the present embodiment.

  Moreover, this invention is not limited to an LED light source, For example, the cyclic | annular row | line | column of a certain LED light source may be comprised with the LED light source from which a color and a kind differ.

DESCRIPTION OF SYMBOLS 1 ... Illuminating device 2 ... Board | substrate 3 ... LED light source 4 ... Inner wide angle lens 5 ... Medium wide angle lens 6 ... Outer wide angle lens 7 ... Flat part 8 ... Diffusion cover DESCRIPTION OF SYMBOLS 9 ... Lighting circuit 10 ... Center cover 11 ... Frame 12 ... Lens cover 50 ... Ceiling 51 ... Fixing tool

Claims (12)

An LED light source arranged in a plurality of annular rows, a substrate on which the LED light source is mounted, a wide-angle lens that covers the LED light source, a diffusion cover that covers the LED light source and the wide-angle lens and has a curved surface; Have
The wide-angle lens is
An outer wide-angle lens that covers the LED light sources arranged on the outer side of the LED light source row, an inner wide-angle lens that covers the LED light sources on the inner row of the LED light source rows, and the LED A medium wide-angle lens that covers the LED light sources arranged between the LED light source rows corresponding to the outer wide-angle lens and the LED light source rows corresponding to the inner wide-angle lens, among the light source rows;
The illumination device according to claim 1, wherein a ratio of a height to a lateral width of an outer shape of the wide-angle lens decreases in the order of the inner wide-angle lens, the middle wide-angle lens, and the outer wide-angle lens. In claim 1,
The illuminating device according to claim 1, wherein the outer wide-angle lens is shaped so that the illuminance on the diffusion cover gradually attenuates with distance from the LED light source when the LED light source is lit alone. In claim 1,
The lighting device according to claim 1, wherein the ratio of the height of the wide-angle lens to the lateral width of the inner surface facing the LED light source is larger than the ratio of the inner wide-angle lens. In claim 1,
The angle from the normal of the substrate is a polar angle θ, the radiation intensity I (θ) of the LED light source, and the radiation intensity I _L (θ) when the LED light source is covered with the wide-angle lens, and the radiation intensity ratio is When RI (θ) = (I _L (θ) / I (θ)), the peak of the radiation intensity ratio increases in the order of the inner wide-angle lens, the middle-wide-angle lens, and the outer wide-angle lens. A lighting device. In claim 4,
An illumination device, wherein an angle corresponding to the peak of the intensity ratio increases in the order of the inner wide-angle lens, the medium-wide-angle lens, and the outer wide-angle lens. In claim 1,
The center of the wide angle lens is a flat surface. In claim 1,
In the wide-angle lens, the ratio of the thickness of the end portion to the thickness of the central portion increases in the order of the inner wide-angle lens, the medium-wide-angle lens, and the outer wide-angle lens. In claim 1,
The angle from the normal of the substrate is the polar angle θ, the luminous intensity I _C (θ) of the LED light source, the luminous intensity I _CL (θ) when the LED light source is covered with the wide-angle lens, and the luminous intensity ratio is RI _C When (θ) = (I _CL (θ) / I _C (θ)), the peak of the luminous intensity ratio increases in the order of the inner wide-angle lens, the middle wide-angle lens, and the outer wide-angle lens. Lighting device. In claim 1 and claims 4 and 8,
An illumination device, wherein a peak of luminous intensity of the outer wide-angle lens is lower than a peak of luminous intensity of the inner wide-angle lens or the middle wide-angle lens. In claim 1, 4, 8,
In the luminous intensity distribution of the wide-angle lens, when the angle from the normal of the substrate is a polar angle θ, and the polar angle corresponding to the peak of luminous intensity is θp,
A lighting device, wherein a ratio of a luminous intensity at an angle θp to a luminous intensity at a polar angle of 0 degree (luminous intensity at a polar angle θp / luminous intensity at a polar angle of 0 degree) is lower than 4.27. In claim 1, the angle from the normal of the substrate is a polar angle θ,
In a plane parallel to the substrate and located on the wide-angle lens,
The origin is directly above the center of the wide-angle lens in the plane,
A light beam is emitted in the polar angle θ direction from the LED light source,
The distance between the position where the light beam reaches the plane and the origin is ρ,
When fitting the normalized illuminance distribution obtained by normalizing the illuminance distribution formed by the wide-angle lens in the plane with the maximum value using a constant σ with a Gaussian distribution represented by the following equation:

An illumination apparatus comprising the wide-angle lens in which a polar angle θ and a distance ρ satisfy a relationship of the following formula:

In claim 9,
The illumination device characterized in that the lens outer surface of the outer wide-angle lens is a mirror surface.

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