JP2012119094A - Lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting system of an indirect illumination formula endowed with high light extraction efficiency.SOLUTION: A plurality of LEDs 1 (light sources) are arranged in a given array direction. Each of the plurality of LEDs 1 emits light toward a given range with a given emission direction nearly vertical to the array direction as a center. Rod lenses 3 (refracting parts) taking on nearly a cylindrical shape refract and transmit light emitted by the LEDs 1 and are arranged nearly in parallel with the array direction. A reflection sheet 5 (a diffusion reflection part) taking on nearly a plane shape diffuses and reflects light refracted and transmitted at the rod lenses 3 and is arranged nearly in parallel with the array direction as well as the emission direction, with a distance between the reflection sheet 5 and a center axis 3C of each rod lens 3 set shorter than that between the reflection sheet 5 and each of the plurality of LEDs 1.

Description

  The present invention relates to an indirect illumination type illumination device using a light source such as a light emitting diode.

Compared with conventional light sources such as fluorescent lamps and incandescent lamps, light emitting diodes (hereinafter referred to as “LEDs”) have a long life. In recent years, LEDs have begun to be used as light sources for ceiling lighting devices in public buildings such as office buildings, commercial facilities, schools, and hospitals as the luminous efficiency and luminous flux have improved. Usually, a luminous flux of several thousand [lm] is required for one lighting device, whereas the luminous flux per LED is about 100 [lm]. For this reason, a plurality of LEDs are mounted on one lighting device.
Since the LED is small and has a small light emitting area, it has high luminance. That is, the LED is dazzling. Therefore, when used on the ceiling of an office or the like, there is a method in which a diffusive cover is provided in front of the LED in order to reduce glare. As the light passing through the cover is diffused, the glare of the LED is alleviated.
For example, in the case of a cover in which the surface on which the light from the LED is incident, the surface on which the light is emitted, or both of them is a textured surface, the surface roughness of the textured surface is made rougher, thereby diffusing the cover. Can be increased. Or if it is a cover which knead | mixed the diffusion material, the diffusibility of a cover can be improved by making the density | concentration of a diffusion material high. Thereby, the glare of LED can be reduced more.
Alternatively, there is a method in which the dazzling per LED is kept low by arranging a large number of 0.1 W class low output LEDs in an array.
In addition, as a more suitable method that is friendly to the eyes of people working in offices, etc., a method using a light guide plate in which the LED is not directly visible from the outside, or light from the LED is once applied to a white plate or sheet to diffusely reflect it. There is an indirect illumination system that softly illuminates the space with scattered light.

JP 2007-87658 A JP 2009-252737 A

In a method using a diffusion cover, if the diffusibility of the diffusion cover is increased in order to alleviate the glare of the LED, the ratio of the light back-scattered to the LED side by the diffusion cover increases, so the light extraction efficiency decreases. . Here, the light extraction efficiency is defined as (total luminous flux emitted from the illumination device) / (total luminous flux emitted from all LEDs).
If the light extraction efficiency is low, the number of LEDs mounted on the lighting device must be increased in order to satisfy the required room brightness, that is, illuminance. Currently, LEDs are still more expensive than the conventional light sources such as fluorescent lamps and incandescent bulbs, and the number of LEDs increases in cost.
The method of arranging a large number of low-power LEDs in an array form is considerably expensive because the LED cost for obtaining the same luminous flux is about twice that of using a high-power LED of 1W class or higher. Become.
The method using a light guide plate generally has a low light extraction efficiency of about 80%. The indirect illumination method has a lower extraction efficiency. Again, it is necessary to increase the number of LEDs.
The present invention has been made, for example, in order to solve the above-described problems, and an object thereof is to provide an indirect illumination type illumination device having high light extraction efficiency.

The lighting device according to the present invention includes:
A light source unit, a refraction unit, and a diffuse reflection unit;
The light source unit has a plurality of light sources arranged side by side in a predetermined arrangement direction,
Each of the plurality of light sources emits light toward a predetermined range centered on a predetermined radiation direction substantially perpendicular to the arrangement direction,
The refraction part is substantially cylindrical, refracts and transmits light emitted from the light source part, and is arranged substantially parallel to the arrangement direction.
The diffuse reflection portion is substantially planar, diffusely reflects the light refracted and transmitted by the refracting portion, and is arranged substantially parallel to the arrangement direction and the radiation direction. The distance from the central axis is shorter than the distance between the diffuse reflection part and the plurality of light sources.

  According to the illumination device according to the present invention, (1) indirect illumination friendly to human eyes can be realized (2) with high light extraction efficiency, and (3) inexpensive and simple.

FIG. 3 is an exploded perspective view showing an example of the structure of the LED lighting device 10 according to the first embodiment. FIG. 3 is a cross-sectional side view showing an example of a cross section in the short-side direction X of the LED lighting device 10 according to the first embodiment. FIG. 4 is a partially enlarged side sectional view showing an example of a state in which light emitted from the LED 1 in the first embodiment is transmitted through a rod lens 3. Side surface sectional drawing which shows the LED lighting apparatus of a comparative example. The graph figure showing the required minimum value of distance s calculated | required by experiment. The figure for demonstrating the conditions from which the light which injected into the rod lens 3 radiate | emits in the direction parallel to the reflective sheet. The figure for demonstrating a mode that the incident angle 511 in the incident point 501 changes when the light which the rod lens 3 outputs changes in the position of the emission point 502, and advances to a parallel direction with respect to the reflective sheet 5. FIG. The figure for demonstrating another condition which the light emission point 503 of LED1 should satisfy | fill. FIG. 9 is a partially enlarged side sectional view showing an example of the shape of a reflector 4 in the second embodiment. The partially expanded side view sectional drawing which shows the shape of the reflector 4 of a comparative example. The graph which shows the relationship between (theta) ₀ and (theta) ₁ calculated | required from Formula (11). The figure for demonstrating the optical path of the light radiate | emitted after reflecting once inside the rod lens 3. FIG. FIG. 13 is a diagram for explaining how the position of the irradiation point 505 changes when the position of the incident point 501 is changed without changing the radiation angle 517 in FIG. 12. The figure which shows an example of the relationship between the radiation angle 517 and the distance 521. FIG. The figure which shows an example of the relationship between the radiation angle 517 where the distance 521 becomes constant, and the position of the incident point 501. The figure for demonstrating the conditions which the position of the light emission point 503 of LED1 should satisfy | fill. The graph which shows the relationship between eccentricity (DELTA) and distance D, and the extraction efficiency of light. The graph which shows the relationship between diameter (phi) and distance D, and the extraction efficiency of light. The graph which shows the relationship between parameter (alpha) and the extraction efficiency of light. The graph which shows the relationship between parameter (alpha) and the extraction efficiency of light. The figure for demonstrating the relationship between the reflective point 562 in the reflective sheet 5, and the extraction efficiency of light. FIG. 4 is a side view sectional view showing another example of the structure of the LED lighting device 10. The side view sectional drawing which shows another example of the structure of the LED lighting apparatus 10. FIG. The side view sectional drawing which shows another example of the structure of the LED lighting apparatus 10. FIG.

Embodiment 1 FIG.
The first embodiment will be described with reference to FIGS.

FIG. 1 is an exploded perspective view showing an example of the structure of the LED lighting device 10 according to this embodiment.
FIG. 2 is a cross-sectional side view showing an example of a cross section in the lateral direction X of the LED lighting device 10 in this embodiment.
The LED illumination device 10 (illumination device) includes two substrates 2, two rod lenses 3, two reflectors 4, a reflection sheet 5, a case 6, and a housing 7.
A plurality of LEDs 1 are mounted on the substrate 2 (light source unit). Each LED 1 (light source) emits light toward a range (predetermined emission range) centered on a front direction (predetermined emission direction) substantially perpendicular to the substrate 2. The LED 1 emits light toward a range where the angle between the direction in which light is actually emitted and the front direction is less than 90 degrees, for example, and has a light distribution characteristic that the light becomes weaker as the angle increases. The plurality of LEDs 1 are arranged and mounted in a straight line at equal intervals, for example.
The substrate 2 is formed of, for example, a metal such as aluminum, or a plate material such as glass epoxy resin or ceramic. A circuit pattern for mounting the LED 1 is printed on the surface of the substrate 2. In addition, the circuit pattern provided on the board | substrate 2, the connector for supplying electric power to LED1, etc. are abbreviate | omitting illustration. The substrate 2 is arranged in a direction in which the direction in which the LEDs 1 are arranged substantially coincides with the longitudinal direction Y of the LED lighting device 10, and is fixed to the case 6, for example. That is, the plurality of LEDs 1 are arranged side by side in a direction (predetermined arrangement direction) that coincides with the longitudinal direction Y of the LED lighting device 10. The two substrates 2 are arranged facing each other. The two substrates are arranged substantially in parallel. The front direction of the LED 1 mounted on the one substrate 2 and the front direction of the LED 1 mounted on the other substrate 2 are just opposite directions, and almost in front of each LED 1 mounted on the one substrate 2. Each LED 1 mounted on the other substrate 2 is located.
The rod lens 3 (refractive part) is formed of a transparent material that transmits light emitted from the LED 1, such as a transparent resin such as acrylic or polycarbonate, or glass. The refractive index of the material of the rod lens 3 is, for example, not less than 1.4 and not more than 1.7. The rod lens 3 has a cylindrical shape. The cylindrical surface 3 </ b> A (side surface) of the rod lens 3 is processed into a mirror shape and transmits light in the forward direction. Both end surfaces 3B (bottom surfaces) of the rod lens 3 are processed into a mirror surface shape or a satin surface shape, and transmit light in a regular or diffuse manner. The two rod lenses 3 respectively correspond to the two substrates 2 and are arranged close to the corresponding substrates 2. The central axis 3C of the rod lens 3 is arranged substantially parallel to the arrangement direction of the LEDs 1. The rod lens 3 is not located in front of the LED 1 but the center axis 3C is shifted to the reflection sheet 5 side (the bottom surface 6A side of the case 6). That is, the rod lens 3 is eccentric with respect to the optical axis of the LED 1.
The reflector 4 is formed of a resin that diffuses and reflects light, such as white polycarbonate. The surface of the reflector 4 is processed into a matte surface shape or a mirror surface shape. The reflector 4 is disposed on the side of the surface of the substrate 2 where the LED 1 is mounted. The reflector 4 is provided with openings 4A corresponding to the respective LEDs 1. The reflector 4 includes inclined surfaces 4B and 4C, inner cylindrical surfaces 4D and 4E, and a flange 4F on the light output side of the opening 4A. The shapes of the inner cylindrical surfaces 4D and 4E are curved surfaces along the cylindrical surface 3A of the rod lens 3. The inclined surface 4B is a flat surface in contact with the cylindrical surface 3A of the rod lens 3 and continuous from the inner cylindrical surface 4D. The inclined surface 4C is a flat surface in contact with the cylindrical surface 3A of the rod lens 3 and continuing from the inner cylindrical surface 4E. The inclined surfaces 4B and 4C are disposed at positions that do not block the light emitted from the LED 1 from entering the rod lens 3. The inclined surfaces 4 </ b> B and 4 </ b> C diffuse and reflect light emitted from the LED 1 in a direction not directly incident on the rod lens 3, and enter the rod lens 3, whereby the luminous efficiency of the LED illumination device 10. To increase. The flange 4F (outer light shielding portion) projects over the rod lens 3. The rod lens 3 is located between the flange 4F and the reflection sheet 5.
Moreover, the reflector 4 is provided with annular portions 4G at both ends. The annular portion 4G has an annular shape and holds the rod lens 3 inside. The shape of the annular portion 4G may be other shapes as long as the rod lens 3 can be held. Further, the annular portion 4G may be a separate member separated from the reflector 4 so that the reflector 4 can be manufactured by injection molding. Alternatively, the reflector 4 does not hold the rod lens 3, but the rod lens 3 is held by another configuration, such as fixing the end surface 7B of the housing 7 and the end surface 3B of the rod lens 3 with screws or the like. May be.

The case 6 has a U-shape formed by bending a flat plate-like member such as a steel plate or aluminum, and has a bottom surface 6A and two end surfaces 6B. The end surface 6B is located at both ends in the short side direction of the bottom surface 6A and is substantially perpendicular to the bottom surface 6A. The two end faces 6B are substantially parallel to each other.
The substrate 2, the rod lens 3, and the reflector 4 on which the LED 1 is mounted are a set, and one set is disposed on the left and right sides of the case 6 so as to face each other. The board | substrate 2 and the reflector 4 are attached to the end surface 6B of the case 6 by screwing etc., for example.
The case 6 may be made of a material having high thermal conductivity such as aluminum so as to have a role as a heat radiating plate and to release heat generated in the LED 1.

The reflection sheet 5 is, for example, a white sheet, and diffuses and reflects light with a high reflectance. The reflection sheet 5 is installed on the bottom surface 6 </ b> A of the case 6. The reflection sheet 5 is fixed to the case 6 by, for example, adhesion or screwing. The reflection sheet 5 is folded so that the end in the longitudinal direction Y is along the end surface 7 </ b> B of the housing 7. The reflection sheet 5 has a U-shape, similar to the case 6, but the direction of the U-shape is a direction orthogonal to the case 6.
The housing 7 has, for example, a rectangular parallelepiped box shape, and one surface is open. The housing 7 houses a case 6 on which the LED 1, the substrate 2, the rod lens 3, the reflector 4, and the reflection sheet 5 are mounted, a power supply (not shown) that supplies power for turning on the LED 1, and the like. Note that the upper surface portion of the case 6 and the opening 10 </ b> A emitted from the LED lighting device 10 may be configured to cover a transparent cover for preventing internal dirt and facilitating cleaning.

  Next, the behavior of light rays in the LED lighting device 10 will be described.

  FIG. 3 is a partially enlarged side sectional view showing an example of a state in which light emitted from the LED 1 in this embodiment is transmitted through the rod lens 3.

  The size of the light emitting surface 1A of the LED 1 is, for example, about several mm. A light ray group emitted from an arbitrary point on the light emitting surface 1A is refracted in the direction of the reflection sheet 5 because the rod lens 3 is eccentric with respect to the LED 1. In this figure, a group of light rays emitted from two points on both ends of the light emitting surface 1A are drawn.

  As shown in this figure, there is almost no light emitted from the rod lens 3 directly to the outside through the opening 10A. Since the light beam emitted from the LED 1 is once diffusely reflected by the reflection sheet 5, the LED 1 is not directly visible to a person working in an office or the like. Thereby, the indirect illumination which softly illuminates space with scattered light is implement | achieved.

FIG. 4 is a cross-sectional side view showing an LED lighting device of a comparative example.
In addition, the same code | symbol is attached | subjected to the part which is common in the LED lighting apparatus 10 in this embodiment, and description is abbreviate | omitted.

  As a comparative example, an example in which the rod lens 3 is not provided is shown. Since the light of the LED 1 is directly emitted from the opening 10A and does not become indirect illumination, it is necessary to lengthen the flange 4F of the reflector 4 in order to shield the light of the LED 1. For this reason, the opening 10A is narrowed. Thereby, most of the light emitted by the LED 1 is repeatedly reflected and attenuated between the ridge 4F, the inclined surface 4C, and the reflection sheet 5, so that the light extraction efficiency is about 70%.

  In contrast, in the LED illumination device 10 according to this embodiment, the eccentric rod lens 3 refracts the light incident on the rod lens 3 from the LED 1 in the direction of the reflection sheet 5 as described above. For this reason, the portion of the flange 4F can be shortened, and the opening 10A can be widened. Thereby, the repetitive reflection between the ridge 4F and the reflection sheet 5 is suppressed, and a high light extraction efficiency of 85% or more can be obtained.

  The rod lens 3 has a circular cross section, and has a shorter focal length than the one-side flat and one-side convex cylinder lens. The short focal length means that the refractive power of the lens is high, and even if the distance between the LED 1 and the lens is narrow, the light from the LED 1 can be refracted toward the reflecting sheet 5. Therefore, the rod lens 3 having a circular cross section can be disposed as close to the LED 1 as possible. For this reason, compared with the case where a cylinder lens is used, the taking-in angle of the light from LED1 in the rod lens 3 becomes large. Thereby, high light extraction efficiency can be realized.

  Instead of the rod lens 3 having a circular cross section, a lens having a short focal length and a high refractive power may be used. For example, a configuration using a lens having an elliptical cross section with a small flatness and a nearly circular shape may be used, or a configuration using both convex lenses having a substantially circular cross section may be used.

  As described above, according to the LED illumination device 10 in this embodiment, the light extraction is performed by providing the rod lens 3 that is eccentric with respect to the optical axis of the LED 1 on the front surface of the LEDs 1 that are linearly arranged. Highly efficient indirect lighting can be realized.

Moreover, since the LED illuminating device 10 in this embodiment uses the round bar material formed with transparent resin or glass as the rod lens 3, it can be manufactured cheaply and simply. Since the rod lens 3 has a circular cross section, it has a rotationally symmetric shape. Therefore, unlike a lens that is not rotationally symmetric, such as a cylinder lens, it is not necessary to manage the angle during assembly. Thereby, the LED lighting apparatus 10 can be manufactured easily and manufacturing cost can be suppressed low.
Moreover, since the light extraction efficiency is high, the necessary brightness can be obtained even if the number of LEDs 1 mounted on the LED lighting device 10 is small. Since the number of the LEDs 1 can be suppressed, the manufacturing cost can be further reduced and energy saving can be realized.
According to the LED illumination device 10 in this embodiment, (1) indirect illumination that is kind to human eyes can be realized (2) with high light extraction efficiency, and (3) inexpensive and simple.

  Next, the amount of eccentricity of the rod lens 3 with respect to the LED 1 will be described.

  As shown in FIG. 3, in order to refract the light from the LED 1 toward the reflection sheet 5, the rod lens 3 is not arranged in front of the LED 1 but is eccentric to the reflection sheet 5 side. If the amount of eccentricity Δ is too small, the light of the LED 1 that has passed through the rod lens 3 directly passes through the opening 10A and is emitted to the outside. Therefore, the amount of eccentricity Δ is used to realize indirect illumination. A necessary minimum value exists.

  Here, the amount of eccentricity Δ is between the optical axis L (see FIG. 3) of the LED 1 and a plane (horizontal plane H) (see FIG. 3) passing through the central axis 3C of the rod lens 3 and parallel to the optical axis L. Distance. Further, the diameter of the rod lens 3 is φ, the width of the light emitting surface 1A of the LED 1 is d, the distance from the light emitting surface 1A to the rod lens 3 is t, and the distance from the end of the light emitting surface 1A on the reflecting sheet 5 side to the horizontal plane H is Let s. The width d is the width of the light emitting surface 1A in the direction perpendicular to the reflection sheet 5 (see FIG. 3). The width of the light emitting surface 1A in the horizontal direction with respect to the reflection sheet 5 may be the same as or different from the width d.

  As can be seen from the comparison between the solid line and the broken line shown in FIG. 3, the necessary minimum value of the eccentricity Δ is that the light emitted from the end of the light emitting surface 1 </ b> A on the reflection sheet 5 side is the rod lens 3. It is determined by whether or not it proceeds toward the reflective sheet 5 after passing through. The required minimum value of the eccentricity Δ varies depending on φ and t. The amount of eccentricity Δ can be expressed as Δ = s + d / 2, and since d is a fixed value, s actually has a necessary minimum value.

  Using an acrylic material with a refractive index of 1.49 as the material of the rod lens 3, the distance t from the light emitting surface 1 </ b> A to the rod lens 3 and the diameter φ of the rod lens are changed to perform an experiment, and the reflecting sheet of the light emitting surface 1 </ b> A The required minimum value of the distance s from the end on the 5 side to the horizontal plane H was determined.

FIG. 5 is a graph showing a necessary minimum value of the distance s obtained by experiments.
Thus, the necessary minimum value of s increases as φ increases or t decreases. And the relationship is approximately linear. From this figure, the following relational expression (1) was approximately obtained.

  (Required minimum value of s) = 0.09 × φ−0.56 × t + 0.1 (1)

  That is, as shown in the following formula (2), if the amount of eccentricity Δ is equal to or greater than a value obtained by adding d / 2 to the necessary minimum value of s, the light from the LED 1 passes directly through the opening 10A. Indirect illumination is realized without being emitted to the outside.

  Δ ≧ d / 2 + 0.09 × φ−0.56 × t + 0.1 (2)

  If the amount of eccentricity Δ of the rod lens 3 with respect to the LED 1 is set so as to satisfy this equation (2), indirect illumination can be realized.

FIG. 6 is a diagram for explaining the conditions under which light incident on the rod lens 3 is emitted in a direction parallel to the reflection sheet 5.
When the incident angle 511 at which the light is incident on the rod lens 3 at the incident point 501 is θ _i , the refractive index of the rod lens 3 (relative refractive index to air) is n, and the refractive angle 512 at the incident point 501 is θ _t , Snell's From the law, sin (θ _i ) = n · sin (θ _t ).
Since the rod lens 3 is a cylindrical shape, the incident angle 513 at the exit point 502 is equal to the refraction angle 512 at the incident point 501, a theta _t. Further, according to Snell's law, the refraction angle 514 at the exit point 502 is θ _i .
If the angle 515 formed by the direction of the exit point 502 viewed from the central axis 3C of the rod lens 3 and the plane 522 (horizontal plane H) parallel to the reflective sheet 5 is θ _i equal to the refraction angle 514 at the exit point 502. The light emitted from the rod lens 3 travels in a direction parallel to the reflection sheet 5. At this time, an angle 516 formed by the direction of the incident point 501 viewed from the center axis 3C of the rod lens 3 and the plane 522 (horizontal plane H) parallel to the reflection sheet 5 is 2θ _t −θ _i .

When the incident angle 511 of the light incident on the incident point 501 is θ _i , the light emitted from the rod lens 3 travels in a direction parallel to the reflecting sheet 5, and therefore strikes the rod lens 3 on the opposite side, and LED illumination It is not emitted directly out of the device 10. On the other hand, when the incident angle 511 of the light incident on the incident point 501 is larger than θ _i , the light emitted from the rod lens 3 travels away from the reflection sheet 5. Therefore, when the light emitting point of the LED 1 is in the area 531 indicated by hatching, the light emitted from the LED 1 may be directly emitted outside the LED lighting device 10.

FIG. 7 is a diagram for explaining how the incident angle 511 at the incident point 501 changes when the light emitted from the rod lens 3 travels in the direction parallel to the reflecting sheet 5 by changing the position of the emission point 502. It is.
As described above, the incident angle 511 at the incident point 501 when the light emitted from the rod lens 3 travels in the direction parallel to the reflective sheet 5 varies depending on the position of the incident point 502, and accordingly, the region 531. Also changes. A hatched area 532 is a union of the areas 531. That is, the points included in the region 532 are included in the region 531 at any emission point 502. When the light emitting point of the LED 1 is in the region 532, the light emitted from the LED 1 may be directly emitted outside the LED lighting device 10. Therefore, the light emitting point of the LED 1 needs to exist in a region above the envelope 541.

  When the envelope 541 in the case where the refractive index n is 1.49 is obtained, it matches the above experimental result.

  In the range where the refractive index n is 1.45 to 1.65, the curve C approximating the envelope 541 can be represented by the following equations (3) to (6), for example.

C: Y = a ₁ / (X + a ₀ ) + a ₂ / (X + a ₀ ) ² (3)
^{_{a 0 = 0.5560-1.287 (n-1.5}} ) +1.944 (n-1.5) 2 -6.43 (n-1.5) 3 ··· (4)
a ₁ = −0.1215 + 0.425 (n−1.5) −0.374 (n−1.5) ² +1.212 (n−1.5) ³ (5)
^{_{a 2 = 0.0959-0.628 (n-1.5}} ) +1.864 (n-1.5) 2 -3.70 (n-1.5) 3 ··· (6)
However, Y is a quotient obtained by dividing the necessary minimum value of the distance s by the diameter φ of the rod lens 3. X is a quotient obtained by dividing the distance t by the diameter φ of the rod lens 3. a ₀ , a ₁ , and a ₂ are parameters of the curve C. n is the refractive index of the rod lens 3.

  When this curve C is used, the condition that the eccentricity Δ of the rod lens 3 with respect to the LED 1 should be satisfied can be expressed by the following equation (7).

Δ ≧ d / 2 + φ · [a ₁ / (t / φ + a ₀ ) + a ₂ / (t / φ + a ₀ ) ² ] (7)

FIG. 8 is a diagram for explaining another condition that the light emitting point 503 of the LED 1 should satisfy.
The light emitted from the light emitting point 503 becomes weaker as the radiation angle 517 between the direction in which the light is emitted and the optical axis L increases. Therefore, the angle θ ₀ is set based on the light distribution characteristics of the LED 1. θ ₀ is an angle at which the emission angle 517 is not emitted in a direction larger than θ ₀ or the emitted light is weak and can be ignored.
When the light emitting point 503 exists at a position where the light emitted from the light emitting point 503 at a radiation angle 517 of θ ₀ is refracted by the rod lens 3 and travels in a direction parallel to the reflecting sheet 5, the light emitting point 503 is present. The light emitted in the direction in which the radiation angle 517 is larger than θ ₀ is refracted by the spherical aberration of the rod lens 3, travels away from the reflection sheet 5, and may be emitted directly out of the LED illumination device 10. There is. However, as described above, the light emitted from the light emitting point 503 in the direction in which the emission angle 517 is larger than θ ₀ does not exist or can be ignored. Therefore, the light emitted from the light emitting point 503 is not directly emitted outside the LED lighting device 10. On the other hand, when the light emitting point 503 is present in the hatched region 533, the light emitted from the light emitting point 503 may be directly emitted outside the LED illumination device 10. Therefore, the light emitting point 503 needs to exist outside the region 533 (the upper left range of the region 533 in the drawing).

  From this condition, a condition to be satisfied by the amount of eccentricity Δ of the rod lens 3 with respect to the LED 1 can be expressed by the following equation (8).

(2t + φ) · sin (θ ₀ ) − (2Δ−d) · cos (θ ₀ ) ≦ φ · sin (θ _i ) (8)

As described above, the incident angle 511 at the incident point 501 and the refraction angle 514 at the exit point 502 are both θ _i , and the refraction angle 512 at the incident point 501 and the incident angle 513 at the exit point 502 are both θ _t . Also, the angle 515 is equal to θ _i , and the angle 516 is equal to 2θ _t −θ _i . Therefore, the radiation angle 517 is 2θ _i −2θ _t .
Therefore, when the radiation angle 517 is θ ₀ , the condition that the incident angle 511 at the incident point 501 becomes θ _i can be expressed by the following equation (9).

_{sin (θ i) = n ·} sin (θ 0/2) / √ [1 + n 2 + 2n · cos (θ 0/2)] ··· (9)

  Therefore, the condition to be satisfied by the eccentricity Δ of the rod lens 3 with respect to the LED 1 can be expressed by the following equation (10).

Δ ≧ d / 2 + (2t + φ) · tan (θ 0) -φ · n · sin (θ 0/2) / {cos (θ 0) · √ [1 + n 2 + 2n · cos (θ 0/2)]} · (10)

  By arranging the LED 1 at a position where neither the region 532 nor the region 533 has a light emitting point, the light emitted from the LED 1 is prevented from being directly emitted to the outside of the LED lighting device 10, and hits the reflection sheet 5 to be diffusely reflected. Indirect illumination with bright light can be realized.

The LED lighting device 10 in this embodiment includes a rod lens 3 having a substantially circular cross section in front of the LED 1.
The center of the rod lens 3 is not on the optical axis of the LED 1 but is eccentric.
On the side where the center of the rod lens 3 is eccentric, a reflective material (reflective sheet 5) that diffusely reflects the light of the LED 1 is provided.

  Thereby, the LED illumination device of the indirect illumination system which has high light extraction efficiency can be realized.

  In this embodiment, the LED illumination device 10 has a diameter of the rod lens 3, φ, a width of the light emitting surface 1A of the LED 1, d, a distance from the light emitting surface 1A of the LED 1 to the rod lens 3, and the rod lens. 3 and the surface parallel to the optical axis L of the LED 1 is H, and the eccentric amount Δ of the rod lens defined by the distance between the optical axis L of the LED 1 and the surface H is , Δ ≧ d / 2 + 0.09 × φ−0.56 × t + 0.1 is satisfied.

  Thereby, it is possible to prevent the direct light from the LED 1 refracted by the rod lens 3 from being emitted outside the lighting device.

Embodiment 2. FIG.
The second embodiment will be described with reference to FIGS.
In addition, about the part which is common in Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

FIG. 9 is a partially enlarged side sectional view showing an example of the shape of the reflector 4 in this embodiment.
In the reflector 4 in this embodiment, the inclined surface 4C (inner light shielding portion) is not a plane in contact with the cylindrical surface 3A of the rod lens 3, but a ridge line (intersection line) having a predetermined angle with the inner cylindrical surface 4E. ) Is formed. The ridgeline formed by the inclined surface 4C and the inner cylindrical surface 4E is parallel to the central axis 3C of the rod lens 3, for example, on a surface (horizontal plane H) that passes through the central axis 3C of the rod lens 3 and is parallel to the reflection sheet 5. To position.
Further, in the reflector 4, the front end position of the flange 4F (outer light shielding portion) in the short direction X is such that the end of the cylindrical surface 3A on the opening 10A side, that is, the cylindrical surface 3A and the horizontal plane H intersect on the opening 10A side. It extends to the position to do. That is, when viewed from a direction perpendicular to the reflection sheet 5, the flange 4F projects to a position where the rod lens 3 is almost completely invisible.

  FIG. 10 is a partially enlarged side sectional view showing the shape of the reflector 4 of the comparative example.

In the first embodiment, among the light emitted from the LED 1, the light emitted in the direction with the radiation angle larger than θ ₀ does not exist or can be ignored, and the LED 1 is arranged. However, depending on the light distribution characteristics of LED 1, θ ₀ may be large, and LED 1 may not be placed at a position that satisfies the condition represented by Equation (10) described in Embodiment 1. In this case, as indicated by the optical path P, light is incident on the cylindrical surface 3A of the rod lens 3 at a shallow angle and emitted in a direction with a shallow angle close to a direction parallel to the reflecting sheet 5 (horizontal direction). However, there is a possibility that the light is emitted to the outside of the LED lighting device 10.
Further, as indicated by the optical path Q, there is also light emitted from the rod lens 3 after being once reflected on the inner surface side of the cylindrical surface 3A of the rod lens 3. Since such light travels in a direction close to the vertical direction of the reflection sheet 5 (the front direction of the LED lighting device 10), if the ridge 4F is short, it may be emitted to the outside of the LED lighting device 10.

  The light beam that follows the optical path P and the optical path Q is emitted to the outside from the opening 10 </ b> A without hitting the reflection sheet 5. Since the light beam that follows the optical path P and the optical path Q has never been diffusely reflected by the reflector 4 or the reflection sheet 5, it can be said to be direct light from the LED 1. For this reason, when the LED illumination device 10 is viewed from a shallow angle, a bright bright spot due to the optical path P is seen at the lower edge of the cylindrical surface 3A, and when the LED illumination device 10 is viewed from the front, the edge of the cylindrical surface 3A is observed. A bright spot due to the optical path Q may be visible.

  On the other hand, in the LED illumination device 10 in this embodiment, in the rod lens 3, the light incident on the cylindrical surface 3A on the reflective sheet 5 side from the horizontal plane H is shielded by the inclined surface 4C and diffusely reflected. The light emitted from the LED 1 is prevented from following an optical path such as the optical path P. Further, the ridge 4F blocks and diffusely reflects a light beam that follows an optical path such as an optical path Q emitted in a direction close to the front of the LED lighting device 10.

  Thus, the cross-sectional shape of the reflector 4 is such that the intersection of the inclined surface 4C and the inner cylindrical surface 4E is located on the horizontal plane H (plane 522) passing through the central axis 3C of the rod lens 3, and the lateral direction of the flange 4F Direct light from the LED 1 can be prevented by making the tip position of X extend to a position where the cylindrical surface 3A and the horizontal plane H intersect on the opening 10A side.

  With reference to FIG. 8, the position of the intersection line between the inclined surface 4C and the inner cylindrical surface 4E will be described.

The incident point 501 where the light emitted from the light emitting point 503 enters the rod lens 3 toward the direction in which the radiation angle 517 is θ ₀ is parallel to the reflecting sheet 5 and the direction viewed from the central axis 3C of the rod lens 3. It is assumed that the light emitted from the rod lens 3 travels in a direction parallel to the reflection sheet 5 when the angle 516 formed with the flat surface 522 is θ ₁ .
When the emission point is in the region 533, the incident point where the light emitted toward the direction in which the emission angle 517 is θ ₀ is incident on the rod lens 3 is lower than the incident point 501, and the rod lens 3 The angle formed between the direction in which the incident point is viewed from the central axis 3 </ b> C and the plane 522 parallel to the reflection sheet 5 is larger than θ ₁ . In that case, the light emitted in the direction in which the radiation angle 517 is θ ₀ is emitted from the rod lens 3 in the direction away from the reflection sheet 5.
Therefore, the inclined surface 4C blocks the light emitted in the direction in which the emission angle 517 is θ ₀ when the emission point is in the region 533 so that it does not enter the rod lens 3. Good. That is, the position of the ridge line formed between the inclined surface 4C and the inner cylindrical surface 4E is the angular 516 may be a position of the incident point is theta ₁ or less. Although the corner 516 may be less than theta _1, so that the light also to shield do not need to be shielded. Accordingly, the position of the ridge line formed between the inclined surface 4C and the inner cylindrical surface 4E is found with the configuration angle 516 is the position of the incident point is theta _1, the luminous efficiency of the LED illumination apparatus 10 is the highest, desirable.

Since the angle 516 is equal to 2θ _t −θ _i and the radiation angle 517 is equal to 2θ _i −2θ _t , θ ₁ can be obtained by the following equation (11) when the radiation angle 517 is θ ₀ .

θ ₁ = θ _i −θ ₀ (11)
However, (theta) _i is the value calculated | required by Formula (9) demonstrated in Embodiment 1. FIG.

FIG. 11 is a graph showing the relationship between θ ₀ and θ ₁ obtained from equation (11).
The horizontal axis represents θ ₀ [degrees]. The vertical axis represents θ ₁ [degrees]. n is the refractive index of the rod lens 3.
As shown in this figure, the required θ ₁ varies depending on the refractive index n of the rod lens 3 and the angle θ ₀ determined by the light distribution characteristics of the LED ₁ . As the refractive index n of the rod lens 3 is large, the required theta ₁ is reduced. That is, it is necessary to increase the amount of light shielded by the inclined surface 4C. Also, the larger θ ₀ is, the smaller the required θ ₁ is. For example, when the refractive index of the rod lens 3 is 1.49 and θ ₀ is 83 degrees, the necessary θ ₁ is about 0 degrees. That is, the ridgeline formed by the inclined surface 4 </ b> C and the inner cylindrical surface 4 </ b> E may be in a direction substantially parallel to the reflection sheet 5 when viewed from the central axis 3 </ b> C of the rod lens 3.

FIG. 12 is a diagram for explaining an optical path of light emitted after being reflected once inside the rod lens 3.
The light emitted from the light emitting point 503 is incident on the rod lens 3 at the incident point 501 and refracted, reflected at the reflecting point 504, refracted at the emitting point 502 and emitted, and hits the light 4F at the irradiation point 505. Suppose.
The incident angle 518 and the reflection angle 519 at the reflection point 504 and the incident angle 513 at the exit point 502 are equal to the refraction angle 512 at the incident point 501.
The refraction angle 514 at the exit point 502 is equal to the incident angle 511 at the entrance point 501.

The incident angle 511 at the incident point 501 is θ _i , and the refraction angle 512 at the incident point 501 determined by Snell's law is θ _t . An angle 516 formed by the direction of the incident point 501 viewed from the central axis 3C of the rod lens 3 and the plane 522 parallel to the reflecting sheet 5 is θ ₁ ′, and the emission point 502 viewed from the central axis 3C of the rod lens 3 When an angle 515 formed by the direction and the plane 522 parallel to the reflection sheet 5 is θ ₂ ′, 4θ _t + θ ₁ ′ + θ ₂ ′ = 180 °. A radiation angle 517 formed by the direction in which light is emitted from the light emitting point 503 and the optical axis L parallel to the reflection sheet 5 is equal to θ _i + θ ₁ ′. Further, the irradiation angle 520 formed by the direction in which the light hitting the irradiation point 505 comes and the direction parallel to the reflection sheet 5 is equal to θ _i + θ ₂ ′.

  The rod is located at a position (tangent line 506) in which the inner surface (side closer to the rod lens 3) of the flange 4F is parallel to the reflecting sheet 5 and perpendicular to the reflecting sheet 5 when viewed from the central axis 3C of the rod lens 3. When the lens 3 is in contact with the cylindrical surface 3A, the distance 521 between the irradiation point 505 and the tangent 506 can be expressed by the following equation (12).

x = φ / 2 · cos (θ ₂ ′) + φ / 2 · [1-sin (θ ₂ ′)] / tan (θ _i + θ ₂ ′) (12)
However, x represents the distance 521 between the irradiation point 505 and the tangent 506.

FIG. 13 is a diagram for explaining how the position of the irradiation point 505 changes when the position of the incident point 501 is changed without changing the radiation angle 517 in FIG. 12.
As shown in this figure, the position of the irradiation point 505 varies depending on the position of the incident point 501. There is an angle 516 where the distance 521 is maximum.

FIG. 14 is a diagram illustrating an example of the relationship between the radiation angle 517 and the distance 521.
The horizontal axis θ ₀ ′ indicates the radiation angle 517. The vertical axis x _MAX / φ represents the quotient obtained by dividing the maximum value of the distance 521 by the diameter φ of the rod lens 3. n is the refractive index of the rod lens 3.
As shown in this figure, the maximum value of the distance 521 varies depending on the refractive index n of the rod lens 3, but in any case, the maximum value of the distance 521 increases as the radiation angle 517 increases. Accordingly, the maximum value of the distance 521 is obtained for the maximum value of the radiation angle 517 determined by the light distribution characteristic of the LED 1 (light is not emitted in a larger angle direction or the angle is negligibly weak), and 庇 4F is obtained. If the length is longer than that, it is possible to prevent light reflected once inside the rod lens 3 from being emitted to the outside of the LED lighting device 10 regardless of the position of the LED 1.
Note that the maximum value of the radiation angle 517 may be the same value as θ ₀ described in the first embodiment, but the light is weakened by the amount of reflection once inside the rod lens 3. The value may be smaller than θ ₀ described in 1.
For example, when the refractive index n of the rod lens 3 is 1.49 and the maximum value of the radiation angle 517 is 75 °, the maximum value of the distance 521 is about half of the diameter φ of the rod lens 3. Therefore, the distance between the tip of the flange 4F and the tangent 506 may be set equal to the radius φ / 2 of the rod lens 3.

  Further, as described above, the distance 521 changes when the position of the incident point 501 changes even if the radiation angle 517 is the same. Therefore, depending on the position of the light emitting point 503 of the LED 1, the length of the ridge 4F may be set shorter than that.

FIG. 15 is a diagram illustrating an example of the relationship between the radiation angle 517 at which the distance 521 is constant and the position of the incident point 501.
The horizontal axis θ ₀ ′ indicates the radiation angle 517. The vertical axis θ ₁ ′ represents an angle 516 formed by the direction of the incident point 501 viewed from the central axis 3C of the rod lens 3 and the plane 522 parallel to the reflection sheet 5. n is the refractive index of the rod lens 3.
The curve shows the relationship between the emission angle 517 and the angle 516 of the LED 1 where the distance 521 is equal to the radius φ / 2 of the rod lens 3. Since the distance 521 increases as the radiation angle 517 increases, the distance 521 is smaller than the radius φ / 2 of the rod lens 3 in the region on the left side of this curve, and the distance 521 is the radius φ / of the rod lens 3 in the region on the right side. Greater than 2.
For example, when the refractive index n of the rod lens 3 is 1.49 and the maximum value of the radiation angle 517 of the LED 1 is 80 °, the combination of the radiation angle 517 that falls within the hatched range 551 and the position of the incident point 501 If the light emission point 503 of the LED 1 is at a position where the corresponding light does not enter the rod lens 3, the maximum value of the distance 521 is shorter than the radius φ / 2 of the rod lens 3.

FIG. 16 is a diagram for explaining a condition that the position of the light emitting point 503 of the LED 1 should satisfy.
A region 534 sandwiched between the envelope 542 and the straight line 543 is a region corresponding to the range 551 in FIG. If the light emitting point 503 exists in the region 534, the irradiation point 505 may be ahead of the tip of the ridge 4F, and light may be emitted directly to the outside of the LED lighting device 10.
Therefore, the light emitting point 503 of the LED 1 needs to be outside the region 534.

In this figure, the region 532 described in the first embodiment is also shown. Similarly to the region 534, the region 532 is a region in which light may be emitted directly to the outside of the LED lighting device 10 when the light emitting point 503 of the LED 1 exists in the region 532.
Therefore, the LED 1 is disposed at a position where the light emitting point 503 does not enter either the region 532 or the region 534 as indicated by a two-dot chain line, for example.

The LED lighting device 10 in this embodiment includes a reflector 4 having an opening corresponding to the LED 1.
The reflector 4 has an inclined surface 4 </ b> C and an inner cylindrical surface 4 </ b> E following the cylindrical surface 3 </ b> A of the rod lens 3 on the reflective material (reflective sheet 5) side from the opening toward the rod lens 3 side.
An intersection line (ridge line) between the inclined surface 4C and the inner cylindrical surface 4E that switches from the inclined surface 4C to the inner cylindrical surface 4E is on the surface H or on the optical axis L side of the LED 1 from the surface H.

  Thereby, the direct light emitted from the illumination device at a shallow angle can be shielded.

The reflector 4 includes a flange 4F on the opposite side of the reflector (reflective sheet 5) with the rod lens 3 therebetween.
The tip of the flange 4F opposite to the LED 1 is located at a position where the cylindrical surface 3A of the rod lens 3 intersects the surface H, or further on the opposite side of the LED 1 from that position.

  Thereby, the direct light radiate | emitted from the illuminating device in a substantially front direction can be shielded.

Embodiment 3 FIG.
The third embodiment will be described with reference to FIGS.
In addition, about the part which is common in Embodiment 1 and Embodiment 2, the same code | symbol is attached | subjected and description is abbreviate | omitted.
The structure of LED lighting device 10 in this embodiment (the shape of reflector 4) is the same as that described in the second embodiment.
In this embodiment, an optimum value of the distance D between the central axis 3C of the rod lens 3 and the surface of the reflection sheet 5 will be described.

Through experiments, the light extraction efficiency of the LED lighting device 10 was measured. In the LED illumination device 10 used in the experiment, the width d of the light emitting surface 1A of the LED 1 is 4.3 mm, and the distance W (see FIG. 2) between the opposing LEDs 1 is 128 mm. A ridge line formed by the inclined surface 4C and the inner cylindrical surface 4E is located in a direction parallel to the reflection sheet 5 when viewed from the central axis 3C of the rod lens 3. The tip of the flange 4F is located at a radius φ / 2 of the rod lens 3 from a tangent 506 with the cylindrical surface 3A of the rod lens 3. The refractive index n of the rod lens 3 is 1.49. The distance t from the light emitting surface 1A of the LED 1 to the rod lens 3 is 1 mm.
Four types of rod lenses 3 having a diameter φ of 14 mm, 16 mm, 18 mm, and 20 mm were prepared. Experiments were conducted with respect to four cases of the eccentric amount Δ of the rod lens 3 with respect to the LED 1 of 3.5 mm, 4.5 mm, 5.5 mm, and 6.5 mm. The distance D (see FIG. 2) between the central axis 3C of the rod lens 3 and the surface of the reflection sheet 5 was changed, and the total luminous flux emitted from the LED illumination device 10 was measured to obtain the light extraction efficiency. .

FIG. 17 is a graph showing the relationship between the eccentricity Δ and distance D and the light extraction efficiency.
The horizontal axis indicates the distance D between the central axis 3C of the rod lens 3 and the surface of the reflection sheet 5. The vertical axis represents the optical system efficiency (light extraction efficiency) of the LED illumination device 10. The diameter φ of the rod lens 3 is 20 mm.

FIG. 18 is a graph showing the relationship between the diameter φ and the distance D and the light extraction efficiency.
The horizontal axis indicates the distance D between the central axis 3C of the rod lens 3 and the surface of the reflection sheet 5. The vertical axis represents the optical system efficiency (light extraction efficiency) of the LED illumination device 10. The eccentric amount Δ of the rod lens 3 with respect to the LED 1 is 3.5 mm.

  From this experimental result, the light extraction efficiency is maximized as the light extraction efficiency varies depending on the distance D, the distance D at which the light extraction efficiency is maximum exists, and the eccentricity Δ increases. It can be seen that the distance D also increases. It can also be seen that the distance D at which the light extraction efficiency is maximized decreases as the diameter φ increases. That is, the light extraction efficiency varies depending on the distance D, the eccentricity Δ, and the diameter φ.

Of the light rays that are diffusely reflected upon hitting the reflection sheet 5, the light rays that are reflected near the center in the short-side direction X are emitted through the opening 10 </ b> A to the outside rather than the light rays that are reflected near the rod lens 3. There is a high probability. Therefore, among the light rays radiated from the LED 1 and refracted by the rod lens 3, if there are many light rays that travel toward the center in the lateral direction X of the reflection sheet 5 and are diffusely reflected, a high light extraction efficiency can be obtained. it can.
For example, as can be seen from the comparison between the solid line and the broken line in FIG. 3, when the eccentricity Δ increases, more of the light refracted by the rod lens 3 is more than the rod lens 3 of the reflection sheet 5. Proceed toward the area close to. For this reason, if the distance D is increased, the tendency that the light extraction efficiency increases can be explained.
When the diameter φ of the rod lens 3 is increased, the focal length of the rod lens 3 is increased and the refractive power is weakened. For this reason, more of the light rays refracted by the rod lens 3 travel toward a region farther from the rod lens 3 of the reflection sheet 5, that is, a region near the opposite rod lens 3 in FIG. 2. For this reason, the tendency that the light extraction efficiency increases if the distance D is reduced can be explained.

Therefore, a parameter α represented by the following equation (13) is defined as a simple index for obtaining high light extraction efficiency.
α = (D × φ) / (Δ × W) (13)
Where D is the distance between the central axis 3C of the rod lens 3 and the surface of the reflection sheet 5, φ is the diameter of the rod lens 3, Δ is the amount of eccentricity of the rod lens 3 with respect to the LED 1, and W is between the opposing LEDs 1. Indicates the interval.

FIG. 19 is a graph showing the relationship between the parameter α and the light extraction efficiency.
The horizontal axis indicates the parameter α described above. The vertical axis represents the optical system efficiency (light extraction efficiency) of the LED illumination device 10. The diameter φ of the rod lens 3 is 20 mm. In this figure, the horizontal axis in FIG. 17 is replaced with the parameter α.

FIG. 20 is a graph showing the relationship between the parameter α and the light extraction efficiency.
The horizontal axis indicates the parameter α described above. The vertical axis represents the optical system efficiency (light extraction efficiency) of the LED illumination device 10. The eccentric amount Δ of the rod lens 3 with respect to the LED 1 is 3.5 mm. In this figure, the horizontal axis in FIG. 18 is replaced with the parameter α.

19 and 20, it can be seen that a high light extraction efficiency can be obtained when the parameter α is in the range indicated by the following equation (14).
0.35 <α <0.7 (14)

  As described above, by setting the parameter α defined as a simple index within the recommended range, high light extraction efficiency can be obtained.

  FIG. 21 is a diagram for explaining the relationship between the reflection point 562 in the reflection sheet 5 and the light extraction efficiency.

Assuming that the width in the short direction X of the opening 10A is ω and the distance between the opening 10A and the reflection sheet 5 is h, the light reflected at a certain reflection point 562 on the reflection sheet 5 is emitted from the opening 10A to the LED. The condition for direct emission to the outside of the illumination device 10 is expressed by the following equation (15).
− (Ω / 2−χ) / h ≦ tan θ ≦ (ω / 2 + χ) / h (15)
Here, χ is the distance from the center plane 561 that bisects the opening 10A in the short direction X on the reflection sheet 5 to the reflection point 562. θ is an angle formed by the direction of light reflected at the reflection point 562 and a plane perpendicular to the lateral direction X.

  That is, as the reflection point 562 is closer to the central axis of the reflection sheet 5 (the smaller the absolute value of χ is), light that is directly emitted from the opening 10A to the outside of the LED lighting device 10 among the light reflected by the reflection point 562. Will increase. Further, the smaller the distance h between the opening 10A and the reflection sheet 5, the more light that is directly emitted from the opening 10A to the outside of the LED lighting device 10 out of the light reflected at the reflection point 562.

Assuming that the reflective sheet 5 is a perfectly diffusing reflective surface, the intensity of light reflected in the θ direction is proportional to the cosine cos θ. Therefore, of the light reflected at the reflection point, the ratio of the light directly emitted from the opening 10A to the outside of the LED lighting device 10 is {(ω / 2 + χ) ² / √ [h ² + (ω / 2 + χ) ² ]. + (Ω / 2−χ) ² / √ [h ² + (ω / 2−χ) ² ]} / 2.
When this is averaged over a range where χ is −ω / 2 or more and ω / 2 or less, [√ (h ² + ω ² ) −h] / ω is obtained.

  Therefore, the smaller the distance h (distance D), the higher the light extraction efficiency. However, as described above, if the distance D is too small, the light emitted from the rod lens 3 is reflected by the reflection sheet 5 at a position close to the rod lens 3 (that is, the absolute value of χ increases). In some cases, the light extraction efficiency is lowered.

FIG. 22 is a cross-sectional side view showing another example of the structure of the LED lighting device 10.
In this example, the reflector 4 has an inclined surface 4 </ b> H at a portion between the rod lens 3 and the reflection sheet 5. The inclined surface 4H diffuses and reflects light. The inclined surface 4H has a normal line that is close to the center of the opening 10A. As a result, the light emitted from the rod lens 3 in a direction perpendicular to the reflecting sheet 5 is diffusely reflected on the inclined surface 4H, and a lot of the light is emitted from the opening 10A to the outside of the LED illumination device 10. Exit. The inclined surface 4H may be a flat surface or a curved surface that is curved like a cylindrical surface.

FIG. 23 is a side view sectional view showing still another example of the structure of the LED lighting device 10.
In this example, the reflection sheet 5 has a curved surface shape that is curved toward the inside at a position close to the rod lens 3. The curved portion of the reflection sheet 5 plays the same role as the inclined surface 4H in the above-described example. The reflective sheet 5 may have a shape in which a plurality of planes are combined.

FIG. 24 is a side cross-sectional view showing still another example of the structure of the LED lighting device 10.
In this example, the reflector 4 has a curved inclined surface 4H curved inward. The reflection sheet 5 has a curved surface shape that swells near the center. Thereby, since the light diffusely reflected near the center of the reflection sheet 5 has a short distance between the reflection point and the opening 10A, a lot of the light is emitted from the opening 10A to the outside of the LED illumination device 10. To do.

The LED illuminating device 10 in this embodiment is symmetrical with the pair of the LED 1 and the eccentric rod lens 3 and is arranged so that the LEDs 1 face each other. Prepare another set.
The distance between the facing LEDs 1 is W, the distance between the surface H and the reflective material (reflective sheet 5) is D, and the amount of eccentricity Δ of the rod lens 3 and the diameter φ of the rod lens 3 The parameter α defined as = (D × φ) / (Δ × W) is in the range of 0.35 <α <0.7.

  Thereby, high light extraction efficiency can be obtained.

  As described above, the configuration described in each embodiment is an example, and the configuration described in different embodiments may be combined, or the configuration of an unimportant part may be replaced with another configuration.

The illuminating device (LED illuminating device 10) demonstrated above has a light source part (board | substrate 2), a refractive part (rod lens 3), and a diffuse reflection part (reflective sheet 5).
The light source unit (2) has a plurality of light sources (LEDs 1) arranged side by side in a predetermined arrangement direction (longitudinal direction Y).
Each of the plurality of light sources (1) emits light toward a predetermined range centered on a predetermined radiation direction substantially perpendicular to the arrangement direction.
The refraction part (3) is substantially cylindrical, refracts and transmits the light emitted from the light source part (2), and is disposed substantially parallel to the arrangement direction (longitudinal direction Y).
The diffuse reflection part (5) is substantially planar, diffusely reflects the light refracted and transmitted by the refraction part (3), and is arranged substantially parallel to the arrangement direction and the radiation direction. The distance between the part (5) and the central axis (3C) of the refraction part (3) is shorter than the distance between the diffuse reflection part (5) and the plurality of light sources (1).

  As a result, the refracting unit refracts the light emitted from the light source unit toward the diffuse reflection unit, so that the light diffused and reflected by the diffuse reflection unit is emitted to the outside of the illumination device, and good indirect illumination is performed. Obtainable.

The said illuminating device (10) satisfy | fills the following formula | equation.
Δ ≧ d / 2 + 0.09φ−0.56t + 0.1
However, Δ is the distance between the diffuse reflection part (5) and the central axis (3C) of the refraction part (3) from the distance between the diffuse reflection part (5) and the plurality of light sources (1). Is the difference (eccentricity), d is the width of the light emitting surface of each of the light sources (1), φ is the diameter of the cross section perpendicular to the central axis (3C) of the refracting part (3), t represents a distance between a plane passing through the plurality of light sources (1) and perpendicular to the radiation direction and the refracting portion (3).

  This prevents light emitted from the light source unit in a direction away from the diffuse reflection unit from being refracted by the refracting unit and directly emitted to the outside of the LED lighting device 10. it can.

The illumination device (10) further includes a second light source part (2) and a second refracting part (3).
The second light source part (2) and the second refraction part (3) are different from the refraction part (3) and the second refraction part (3) with respect to the light source part (2) and the refraction part (3). Are disposed substantially opposite to each other with the refracting portion (3) inward.
A said 2nd light source part (2) is located in the said radial direction with respect to the said light source part (2), and several 2nd light source (1) arrange | positioned along with the said arrangement | positioning direction (longitudinal direction Y). Have
Each of the plurality of second light sources (1) emits light toward a predetermined range centering on a direction substantially opposite to the radiation direction.
The second refracting part (3) has a substantially cylindrical shape, refracts and transmits the light emitted from the second light source part (2), and is arranged substantially parallel to the arrangement direction (longitudinal direction Y). The distance between the central axis (3C) of the second refraction part (3) and the diffuse reflection part (5) is such that the plurality of second light sources (1) and the diffuse reflection part (5) Shorter than the distance between.

  As a result, the second refracting unit refracts the light emitted from the second light source unit toward the diffuse reflection unit, so that the light diffusely reflected by the diffuse reflection unit is emitted to the outside of the illumination device. Good indirect illumination can be obtained. Since only one diffuse reflection portion is required for the two light source portions, a lighting device with good design can be manufactured at low cost.

  In the illumination device (10), the light source unit (2) and the refraction unit (3), the second light source unit (2), and the second refraction unit (3) are arranged in plane symmetry. Yes.

  Thereby, the brightness of the diffuse reflection part is averaged regardless of the distance from the light source part.

The said illuminating device (10) satisfy | fills the following formula | equation.
0.35 <D ₁ · φ ₁ / (Δ ₁ · W) <0.7
0.35 <D ₂ · φ ₂ / (Δ ₂ · W) <0.7
However, D ₁ is the refractive distance (D), D ₂ is the diffuse reflection portion (5) and the second between the diffuse reflection portion (5) and the central axis of the refracting portion (3) (3C) part (3) central axis (3C) the distance between the (D), phi ₁ is the central axis (3C) section perpendicular diameters with respect to the refracting portion (3), phi ₂ is the second The diameter of the cross section perpendicular to the central axis (3C) of the refracting portion (3), Δ ₁ is the distance D ₁ from the distance between the diffuse reflection portion (5) and the plurality of light sources (1). the subtracted difference (eccentricity amount delta), delta ₂ is a difference obtained by subtracting the distance D ₂ from the distance between the diffuse reflection portion (5) and the second plurality of light sources (1) (eccentricity Δ) and W represent distances between the plurality of light sources (1) and the plurality of second light sources (1).

  Thereby, the light extraction efficiency of the lighting device can be increased.

The said illuminating device (10) has an inner side light-shielding part (inclined surface 4C) further.
The inner light-shielding portion (4C) is disposed between a plane that passes through the plurality of light sources (1) and is perpendicular to the radiation direction and the refracting portion (3), and the plurality of light sources (1) emit radiation. Of the reflected light, the light is refracted at a position closer to the diffuse reflection part (5) than a plane (522) passing through the central axis (3C) of the refractive part (3) and parallel to the diffuse reflection part (5). The light radiated in the direction incident on the part (3) is blocked.

  This prevents light emitted from the light source unit in a direction approaching the diffuse reflection unit from being refracted by the refracting unit and directly emitted to the outside of the LED lighting device 10. it can.

  The inner light shielding part (4C) reflects the shielded light.

  Thereby, the light extraction efficiency of the illuminating device can be increased by effectively using the light blocked by the inner light shielding portion.

The said illuminating device (10) further has an outer side light-shielding part (inside of the eaves 4F).
The outer light-shielding portion (4F) has a substantially planar shape, is substantially parallel to the diffuse reflection portion (5), and faces the diffuse reflection portion (5) with the refraction portion (3) in between. It is arranged at a position and blocks light emitted from the refraction part (3) in a direction substantially perpendicular to the diffuse reflection part (5).

  Thereby, it is possible to prevent the light emitted from the light source part from being reflected once inside the refracting part and directly emitted outside the illumination device.

  The front end of the outer light-shielding part (4F) has the diffuse reflection part (5) with respect to the surface of the refraction part (3) located in the radial direction when viewed from the central axis (3C) of the refraction part (3). It is located in a direction substantially perpendicular to the direction.

  Thereby, it is possible to efficiently prevent the light emitted from the light source unit and reflected once inside the refracting unit from being directly emitted outside the illumination device.

  The outer light shielding part (4F) reflects the shielded light.

  Thereby, the light extraction efficiency of the lighting device can be increased by effectively using the light blocked by the outer light shielding portion.

  1 LED, 1A emitting surface, 2 substrate, 3 rod lens, 3A cylindrical surface, 3B end surface, 3C central axis, 4 reflector, 4A opening, 4B, 4C, 4H inclined surface, 4D, 4E inner cylindrical surface, 4F 庇, 4G Annular part, 5 reflective sheet, 6 case, 6A bottom face, 6B end face, 7 housing, 7B end face, 10 LED lighting device, 10A opening, 501 incident point, 502 outgoing point, 503 luminous point, 504, 562 reflective point, 505 Irradiation point, 506 Tangent line, 511, 513, 518 Incident angle, 512, 514 Refraction angle, 515, 516 angle, 517 Radiation angle, 519 Reflection angle, 520 Irradiation angle, 521 Distance, 522 Plane, 531, 532, 533 534 region, 541, 542 envelope, 543 straight line, 551 range, 561 center plane.

Claims (10)

A light source unit, a refraction unit, and a diffuse reflection unit;
The light source unit has a plurality of light sources arranged side by side in a predetermined arrangement direction,
Each of the plurality of light sources emits light toward a predetermined range centered on a predetermined radiation direction substantially perpendicular to the arrangement direction,
The refraction part is substantially cylindrical, refracts and transmits light emitted from the light source part, and is arranged substantially parallel to the arrangement direction.
The diffuse reflection portion is substantially planar, diffusely reflects the light refracted and transmitted by the refracting portion, and is arranged substantially parallel to the arrangement direction and the radiation direction. An illumination device, wherein a distance from a central axis is shorter than a distance between the diffuse reflector and the plurality of light sources. The lighting device according to claim 1, wherein:
Δ ≧ d / 2 + 0.09φ−0.56t + 0.1
However, (DELTA) is the difference which deducted the distance between the center axis | shaft of the said diffuse reflection part and the said refractive part from the distance between the said diffuse reflection part and said several light source, d is the light emission surface of each of the said several light source , Φ is the diameter of the cross section perpendicular to the central axis of the refracting portion, and t is the distance between the plane passing through the plurality of light sources and perpendicular to the radiation direction, and the refracting portion. The lighting device further includes a second light source unit and a second refracting unit,
The second light source part and the second refracting part are disposed substantially opposite to the light source part and the refracting part with the refracting part and the second refracting part inside.
The second light source unit has a plurality of second light sources located in the radial direction with respect to the light source unit and arranged side by side in the arrangement direction,
Each of the plurality of second light sources emits light toward a predetermined range centered on a direction substantially opposite to the radiation direction,
The second refracting portion has a substantially cylindrical shape, refracts and transmits the light emitted by the second light source portion, and is arranged substantially parallel to the arrangement direction. The central axis of the second refracting portion 3. The lighting device according to claim 1, wherein a distance between the light source and the diffuse reflection unit is shorter than a distance between the plurality of second light sources and the diffuse reflection unit.   The lighting device according to claim 3, wherein the light source unit and the refraction unit, and the second light source unit and the second refraction unit are arranged in plane symmetry. The lighting device according to claim 3 or 4, wherein at least one of the following expressions is satisfied.
0.35 <D ₁ · φ ₁ / (Δ ₁ · W) <0.7
0.35 <D ₂ · φ ₂ / (Δ ₂ · W) <0.7
However, D ₁ is the distance between the center axis of the diffuse reflection portion and the refraction portion, a distance between the center axis of D ₂ is the diffuse reflection portion and the second refractive section, phi ₁ is the refractive The diameter of the cross section perpendicular to the central axis of the part, φ ₂ is the diameter of the cross section perpendicular to the central axis of the second refracting part, and Δ ₁ is the difference between the diffuse reflection part and the plurality of light sources. distance from the difference obtained by subtracting the distance D ₁ of the between, delta ₂ is a difference obtained by subtracting the distance D ₂ from the distance between the diffuse reflection portion and the second plurality of light sources, W is a plurality of light sources It represents the distance between the plurality of second light sources. The lighting device further includes an inner light shielding portion,
The inner light-shielding part is disposed between a plane passing through the plurality of light sources and perpendicular to the radiation direction and the refracting part, and has a central axis of the refracting part out of the light emitted by the plurality of light sources. The light radiated in the direction incident on the refracting portion at a position closer to the diffusing reflective portion than a plane parallel to the diffusing reflective portion is blocked. The lighting device described in 1.   The lighting device according to claim 6, wherein the inner light shielding portion reflects the blocked light. The illumination device further includes an outer light shielding portion,
The outer light-shielding part is substantially planar, is substantially parallel to the diffuse reflection part, and is disposed at a position facing the diffuse reflection part with the refractive part in between, and the diffuse reflection from the refractive part. The lighting device according to claim 1, wherein light emitted in a direction substantially perpendicular to the portion is blocked.   The front end of the outer light-shielding part is located in a direction substantially perpendicular to the diffuse reflection part with respect to the surface of the refraction part located in the radial direction when viewed from the central axis of the refraction part. The lighting device according to claim 8.   The lighting device according to claim 8 or 9, wherein the outer light shielding portion reflects the blocked light.

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