JP5810317B2 - Lighting device - Google Patents

Description

  The present invention relates to a downlight type illumination device including a light emitting element such as an LED (Light Emitting Diode) as a light source. The present invention particularly relates to a concentrating illumination device.

  In recent years, from the viewpoint of energy saving, lighting devices using semiconductor light emitting elements such as LEDs with high efficiency and long life as light sources have been developed. Particularly in recent years, downlights and spotlights using a wide light emitting area of LED light emitting modules have been proposed. For example, Patent Document 1 proposes a concentrating illumination device including an LED light emitting module having a planar light emitting unit and a Fresnel lens. The cross-sectional view of FIG. 14 shows the configuration of the lighting device 800 described in Patent Document 1.

The lighting device 800 includes a housing 801, a light emitting module 802 housed inside the housing 801, and a Fresnel lens 803 disposed on the optical path. The light emitting module 802 includes a plate-like substrate 8020, a light emitting element (LED) 8021 mounted on the substrate 8020, and a phosphor layer 8022 disposed in front of the light emitting element 8021. By supplying power to the lighting device 800, each light emitting element 8021 is turned on. Lights L ₁ and L ₂ emitted from the light emitting element 8021 pass through the Fresnel lens 803. Lights L ₁ and L ₂ are adjusted to parallel light by a Fresnel lens 803 and irradiated outside.

JP 2012-114022 A

However, in the conventional condensing type illumination device, it is necessary to secure an optical path having a predetermined length between the light source and the lens in order to condense at a constant light distribution angle. As a result, it has been difficult to simultaneously realize the thinning and narrow orientation of the lighting device.
For example, in the conventional illumination device 800 described in Patent Document 1, when the 1/2 beam angle, which is one of the indices for evaluating the orientation, is 45 °, the optical path from the light emitting part of the light source to the lens surface A length of 27 mm was required. On the other hand, when the optical path length was shortened to 10 mm, the 1/2 beam angle was 100 °, and further improvement was necessary to achieve both thinness and narrow orientation.

  The present invention has been made in view of the above problems, and an object thereof is to provide a lighting device that is thin and capable of realizing narrow orientation.

  In order to achieve the above object, an illumination device according to one embodiment of the present invention includes a plurality of light-emitting elements, a light guide plate that guides light emitted from the plurality of light-emitting elements in the plate, and a main part of the light guide plate. A light collecting cover that covers at least a part of the surface, wherein the light guide plate has a part of the back surface facing away from the main surface and the light guided into the plate of the light guide plate. A plurality of concave reflecting portions to be reflected to the light cover side, wherein each concave reflecting portion is located on the frustum portion and the frustum portion from the back surface of the light guide plate toward the main surface; A conical part having a slope with a smaller taper angle than the slope of the frustum part, and the light collecting cover is disposed in an optically opposed relationship with each of the concave reflecting parts and has a concave shape. A plurality of lens portions for condensing the reflected light of the reflecting portion in a direction perpendicular to the main surface of the light guide plate; And a lighting device to be.

Here, in another aspect of the present invention, the frustum portion may be a truncated cone portion, and the cone portion may be a conical portion.
In another aspect of the present invention, when the taper angle of the cone portion is θ ₁ and the taper angle of the frustum portion is θ ₂ , 48 ° ≦ θ ₁ ≦ 96 ° and θ ₁ <θ ₂ <180 ° It is also possible to adopt a configuration in which the above relationship is established.

  In another aspect of the present invention, it further includes a mounting substrate in which the plurality of light emitting elements are mounted on the surface of the substrate, each light emitting element forms an annular element array on the substrate, and the light guide plate includes: It is a disc shape having an annular portion arranged along the element row on the mounting substrate, and an inside of the annular portion continuously arranged with the annular portion inside the annular portion, and the concave reflecting portion is at least It can also be set as the structure which exists in the said ring inside.

In another aspect of the present invention, it further includes a reflective member interposed between the light guide plate and the mounting substrate, the reflective member having an opening at a position facing each of the light emitting elements, The light emitted from the light emitting element may be incident on the annular portion through the opening.
In another aspect of the present invention, the light guide plate may further include an annular outer peripheral portion arranged continuously to the annular portion outside the annular portion.

In another aspect of the present invention, a configuration may further include an annular diffusion cover disposed outside the light collecting cover so as to cover the annular outer peripheral portion of the light guide plate and subjected to light scattering treatment. it can.
In another aspect of the present invention, the condensing cover is disposed above the light guide plate, and each of the lens portions is formed on a surface facing away from at least the surface facing the light guide plate. You can also

In another aspect of the present invention, the light emitting element may be an LED.
In another aspect of the present invention, a configuration having a power supply unit for supplying power to the light emitting element may be employed.

The lighting device in one embodiment of the present invention includes a plurality of light-emitting elements, a light guide plate, and a light collection cover. The concave reflection part formed on the back surface of the light guide plate is configured by a combination of a frustum part and a cone part arranged on the frustum part. The taper angle of the frustum portion is larger than the taper angle of the cone portion.
In the lighting device according to one embodiment of the present invention, the optical path from the light-emitting element to the lens portion can be shortened with the above structure. Thereby, it is possible to reduce the thickness of the lighting device.

  In addition, if the concave reflecting portion as described above is used, light that is difficult to be reflected by the cone portion with a small taper angle or light that can be diffused when reflected by the cone portion is reflected by the frustum portion so that the concave reflecting portion It can enter into the lens part of the condensing cover located right above. On the other hand, since the height of the concave reflection part can be secured by providing the cone part on the frustum part, the amount of light reflected by the entire concave reflection part can be maintained. As a result, the amount of light collected by the lens unit located directly above the concave reflection unit increases. Therefore, the condensing characteristic is improved by exhibiting good reflection characteristics in the concave reflecting portion, and thus a narrowly oriented lighting device can be provided.

It is a partial cross section figure which shows the structure and installation example of the illuminating device 100 which concern on Embodiment 1. FIG. It is a perspective view which shows the external appearance structure and internal structure of the lighting fixture 1. FIG. 1 is a front view of a lighting fixture 1. FIG. 2 is an exploded view showing an internal configuration of the lighting fixture 1. FIG. FIG. 3 is a cross-sectional perspective view showing an internal configuration of the lighting fixture 1. 4 is a front view showing a configuration of a reflecting member 30. FIG. It is an expanded sectional view of the area | region A of FIG. It is an expanded sectional view of the area | region B of FIG. It is sectional drawing which shows the specific structure of the concave reflection part 403. (A) is a figure for demonstrating the subject assumed by the concave reflective part 403A with a comparatively small taper angle. (B) is a figure for demonstrating the subject assumed with the concave reflective part 403B with a comparatively large taper angle. It is sectional drawing for demonstrating the effect of the concave reflection part. It is a figure which shows the simulation result of the relationship between the light distribution angle and radiation intensity of an Example and each comparative example. 13 is a graph showing the intensity of a luminous flux (lm) between light distribution angles of ± 10 ° in Examples and Comparative Examples based on the simulation results of FIG. It is sectional drawing which shows the structure of the conventional illuminating device 800. FIG. It is sectional drawing which shows the structure of the illuminating device 900 which is an assumed illuminating device. (A) is sectional drawing of the whole illuminating device 900. FIG. (B) is an expanded sectional view of the area | region C of (a).

<Background to Invention>
In the illuminating device 800 shown in FIG. 14, for example, the light distribution angle (hereinafter referred to as “½ beam angle”) in an angle range in which the luminous intensity is ½ or more of the maximum luminous intensity in the illuminance distribution is within ± 45 °. When setting, if the diameter of the phosphor layer 8022 is 60 mm, the diameter of the Fresnel lens 803 is 162 mm. At this time, for example, 27 mm must be secured as an optical path (distance h ₁ ) between the light emitting element 8021 and the Fresnel lens 803. Accordingly, it is difficult to make the lighting device 800 thin. On the other hand, the structure of the illuminating device 900 shown, for example in sectional drawing of Fig.15 (a) can be assumed.

  The lighting device 900 includes a base 910, a mounting substrate 920 disposed on the base 910, a reflecting member 930 disposed on the mounting substrate 920, and a light guide plate 940 disposed on the reflecting member 930. Furthermore, the lighting device 900 includes a light collecting cover 950 disposed on the light guide plate 940 and a light-transmitting cover 960 that covers the periphery of the light collecting cover 950. The mounting substrate 920 has a plurality of light emitting elements (LEDs) 922 mounted on the surface of the substrate. As shown in FIG. 15B, which is an enlarged cross-sectional view of region C in FIG. 15A, the light guide plate 940 has a conical concave reflection formed by recessing the back surface facing the reflecting member 930 in the thickness direction. A plurality of portions 941 are provided. The light collection cover 950 includes a plurality of minute lens portions 951 at positions overlapping with the respective concave reflection portions 941.

In such an illuminating device 900, as shown in FIG. 15B, light L ₃ and L ₄ incident on the light guide plate 940 from the light emitting element 922 is reflected to the lens portion 951 side by the inclined surface of the concave reflecting portion 941. The lights L ₃ and L ₄ are condensed by the lens portion 951 directly above the concave reflecting portion 941 and become illumination light. In the lighting device 900, parallel light can be incident on the lens unit 951 from a short distance using the light guide plate 940 and the concave reflection unit 941. Accordingly, the distance h ₂ between the light emitting element 922 and the lens portion 951 can be made relatively short. Accordingly, the lighting device can be thinned. In addition, light diffusion can be prevented by bringing a minute lens portion 951 close to each concave reflection portion 941 and a good light collecting effect can be expected.

In the illumination apparatus 900, as in the light L _3, L _4, it is to increase the amount of light incident on the lens portion 951 just above the concave reflecting portion 941, is important in obtaining good focusing characteristics. Therefore, the concave reflection portion 941 is required to have good reflection characteristics. In this respect, the lighting device 900 has room for further improvement.
Therefore, in the present invention, in a configuration including a lens plate having a plurality of lens portions and a light guide plate having a plurality of concave reflection portions, the concave reflection portions further exhibit good reflection characteristics. As a result, a thin and narrowly oriented illumination device has been realized.

Hereinafter, a lighting device according to an embodiment of the present invention will be described with reference to the drawings.
<Embodiment>
(Lighting device 100)
As illustrated in the partial cross-sectional view of FIG. 1, the lighting device 100 includes a lighting fixture 1, a hooking member 3, and a power supply unit 4. The retaining member 3 is a leaf spring and is attached to the base 10 on the back side of the lighting fixture 1. The power supply unit 4 turns on the lighting fixture 1. The power supply unit 4 is electrically connected to the lighting fixture 1 through the wiring 23. The lighting device 100 is a buried downlight that is installed on a construction material such as a ceiling.

In the lighting device 100 shown in FIG. 1, the power supply unit 4 is placed on the back surface 2 b of the ceiling 2 through the through hole 2 a provided in the ceiling 2. The lighting fixture 1 is arrange | positioned so that the base 10 may be accommodated in the through-hole 2a. The latch member 3 is latched on the periphery of the through hole 2a. Thereby, the lighting device 100 is installed on the ceiling 2.
As shown in FIG. 2, the lighting fixture 1 includes a base 10, a light collecting cover 50, and a diffusion cover 60. A wiring 23 extends to the outside from the notch 16 provided in the base 10. A dotted line in FIG. 2 indicates each position of the mounting substrate 20 incorporated in the lighting fixture 1, the substrate 21 in the mounting substrate 20, and the light emitting element 22. As shown in FIG. 3, the luminaire 1 is covered with a diffusion cover 60 when viewed from the front, as shown in FIG. 3. As an example, the size of the lighting fixture 1 is an outer diameter of about 136 mm and a thickness of about 18 mm.
(Lighting fixture 1)
As illustrated in FIG. 4 of the exploded view, the lighting fixture 1 includes a base 10, a mounting substrate 20, a reflecting member 30, a light guide plate 40, a light collecting cover 50, and a diffusion cover 60. The lighting fixture 1 has a disc shape as a whole. The outer periphery of the base 10, the mounting substrate 20, the reflection member 30, the light guide plate 40, the light collection cover 50, and the diffusion cover 60 is formed in a circular shape.
[Base 10]
The base 10 is made of a material having excellent heat dissipation characteristics, for example, a metal material such as aluminum. The base 10 has a main body part 11 and a flange part 12. The flange portion 12 has a notch portion 16.

The main body 11 includes a disk-shaped inner bottom portion 13, a side wall portion 14 erected on the peripheral edge of the inner bottom portion 13, and an annular outer bottom portion disposed around the side wall portion 14 from the central side toward the peripheral side. 15.
The mounting substrate 20 and the reflecting member 30 are sequentially stacked on the inner bottom portion 13. An annular outer peripheral portion 43 of the light guide plate 40 is placed on the outer bottom portion 15.

The flange portion 12 is erected around the main body portion 11. The base 10 is joined to the side wall portion 62 of the diffusion cover 60 near the top of the flange portion 12 in the Z direction using an adhesive, a seal member, or the like.
[Mounting board 20]
The mounting substrate 20 includes an annular substrate 21, a plurality of light emitting elements 22, and wirings 23.

The substrate 21 has a structure in which, for example, an insulating layer made of a ceramic material or a heat conductive resin and a metal layer made of aluminum or the like are laminated. A wiring pattern (not shown) for electrically connecting the light emitting element 22 and the wiring 23 is formed on the surface of the substrate 21.
The light emitting element 22 is an LED as an example. The light emitting element 22 is mounted on the surface of the substrate 21 facing the reflecting member 30 so that the main emission direction is aligned with the vertical (Z) direction. On the substrate 21, the light emitting elements 22 form a circumferential element array at a predetermined interval. On the mounting board 20, as an example, a total of 18 light emitting elements 22 are face-up mounted on a wiring pattern using a COB (Chip on Board) technique.

The surface of the substrate 21 is a reflective surface having light reflectivity in order to efficiently reflect the emitted light of the light emitting element 22 toward the light guide plate 40 side.
The wiring 23 is used to supply power to the light emitting element 22 from the power supply unit 4 side. Both ends of the wiring 23 are electrically connected to the wiring pattern of the substrate 21 and the power supply unit 4.
[Reflection member 30]
The reflection member 30 is a plate-like member, and reflects the return light from the light guide plate 40 toward the light guide plate 40 side. The reflection member 30 is sandwiched between the mounting substrate 20 and the light guide plate 40. The reflection member 30 is configured using a material having high light reflection characteristics, for example, polybutylene terephthalate (PBT) resin, polycarbonate (PC) resin, nylon resin, foam resin, or the like. The reflective member 30 can be configured with high accuracy by injection molding the reflective member 30 with these resin materials. The reflection member 30 should just have a light reflection characteristic in the surface at least.

  A specific configuration of the reflecting member 30 is shown in a sectional view (FIG. 5) of the luminaire 1, a front view of the reflecting member 30 (FIG. 6), and an enlarged sectional view (FIG. 7) of the region A in FIG. 5. The reflecting member 30 includes an inner reflecting portion 31, a recessed portion 32, and an outer reflecting portion 33 from the center side toward the outside. The outer diameter of the reflecting member 30 substantially matches the inner diameter of the side wall portion 14 of the base 10. The inner reflection portion 31 faces the light guide plate 40 on the upper surface 310. Further, the outer reflecting portion 33 faces the light guide plate 40 on the upper surface 320.

As shown in FIG. 5, the inner reflecting portion 31 is provided at a position inside the mounting position of the light emitting element 22 of the mounting substrate 20. The outer reflecting portion 33 is provided at a position outside the mounting position of the light emitting element 22 on the mounting substrate 20. The inner reflection part 31 and the outer reflection part 33 reflect the return light from the light guide plate 40 to the light guide plate 40 side again.
As shown in FIG. 5 and FIG. 7, the recessed portion 32 is formed so that a region of the reflecting member 30 corresponding to the mounting position of each light emitting element 22 on the mounting substrate 20 is recessed toward the mounting substrate 20 along the thickness (Z) direction. Let me enter.

As shown in FIG. 7, a plurality of openings 34 penetrating in the thickness (Z) direction of the reflecting member 30 are present in the recessed portion 32 at regular intervals. The position of the opening 34 coincides with the position of each light emitting element 22 on the mounting substrate 20.
[Light guide plate 40]
The light guide plate 40 guides the light emitted from the light emitting element 22 in the plate. As shown in FIG. 4, the light guide plate 40 is interposed between the reflecting member 30 and the light collecting cover 50 (diffusion cover 60). Thereby, the light emitted from above the light guide plate 40 enters the light collection cover 50 and the diffusion cover 60. The light guide plate 40 is made of a material having excellent translucency, such as an acrylic resin, a polycarbonate resin, a polystyrene resin, or glass. As a specific configuration, the light guide plate 40 includes a ring interior 41, an annular portion 42, and an annular outer peripheral portion 43 from the center side toward the outside. As an example, the light guide plate 40 has an outer diameter of about 128 mm and a plate thickness of about 1.5 mm.

(I) Ring inside 41
The ring interior 41 has a disk shape, and guides the light of the light emitting element 22 that has entered the light guide plate 40 from the annular portion 42 to the inside of the mounting position of the light emitting element 22. The diameter of the ring interior 41 is about 80 mm. As shown in the enlarged sectional view of the region B in FIG. 5 (FIG. 8), there are a plurality of concave reflecting portions 403 on the back surface 401 of the inside 41 of the ring. The concave reflecting portion 403 is formed by recessing a part of the back surface 401 and reflects light guided in the light guide plate 40 toward the upper surface 402 side. The concave reflecting portion 403 has a frustum portion 4030 and a frustum portion 4031 located on the frustum portion 4030 from the back surface 401 side toward the upper surface 402. The center of gravity of each concave reflecting portion 403 is disposed so as to overlap the optical axis of the lower lens portion 502 and the upper lens portion 501 of the light collecting cover 50 positioned directly above the concave reflecting portion 403.

FIG. 9 shows a specific shape of the concave reflecting portion 403. The frustum portion 4030 is a truncated cone portion having a relatively large taper angle. Imaginary line P ₁ along the inclined surface of the frustum portion 4030, when assuming P _2, the taper angle between the inclined surface of the frustum portion 4030 that corresponds to the intersection angle of the imaginary line P _1, P ₂ (apex angle) theta ₂ Is 96 °, and the inclination angle between the inclined surface of the frustum portion 4030 and the back surface 401 is 42 °.
The cone part 4031 is a cone part whose taper angle is smaller than the slope of the frustum part 4030. The pyramid part 4031 has a bottom surface having the same diameter as the upper surface of the frustum part 4030. When imaginary lines P ₃ and P ₄ along the slope of the cone part 4031 are assumed, the taper angle (vertical angle) θ ₁ between the slopes of the cone part 4031 corresponding to the intersection angle of the virtual lines P ₃ and P _4. Is 60 °, and the inclination angle between the inclined surface of the cone portion 4031 and the back surface 401 is 60 °.

A large number of concave reflection portions 403 are formed in the ring interior 41 (here, a total of 491), and are formed concentrically from the center of the ring interior 41 toward the periphery. As an example, the pitch of the concave reflecting portions 403 along the diameter direction of the inside 41 of the ring is about 3 mm. The pitch of the concave reflecting portions 403 is preferably about 1.5 to 2.5 times the plate thickness of the light guide plate 40. As an example, the height of the concave reflecting portion 403 in the Z direction is not less than 0.4 mm and not more than 1.0 mm. The shape of the concave reflecting portion 403 can be designed based on the following conditions. As shown in FIG. 9, virtual lines P ₅ and P ₆ along the slope of the cone part 4031 are brought into contact with the back surface 401. On the back surface 401, the virtual radius of the cone part 4031 indicated by the virtual lines P ₅ and P ₆ is r _1, and the radius of the frustum part 4030 is r ₂ . Here, the shape of the concave reflecting portion 403 can be a shape in which r ₂ / r ₁ is in the range of 1.1 to 1.3. If the angle θ ₁ is decreased (or the angle θ ₂ is increased), the height h ₄ of the frustum portion 4030 relative to the height h ₃ of the cone portion 4031 from the back surface 401 can be increased within a certain range.

The apex angle θ ₁ of the cone portion 4031 is a value that takes into account at least the refractive index of the material of the light guide plate 40. As an example, when the light guide plate 40 is made of an acrylic material (refractive index n = 1.49), according to Snell's equation, the minimum incident angle of light that can be reflected by the concave reflector 403 is 42 °. Therefore, when the apex angle θ ₁ of the cone part 4031 is larger than 96 °, the reflected light reflected by the cone part 4031 may be regularly reflected by the upper surface 402 of the light guide plate 40. Further, when the apex angle θ ₁ is smaller than 48 °, the angle of the reflected light reflected by the cone part 4031 is symmetric with respect to the normal direction of the upper surface 402 of the light guide plate 40, and more than that, the apex angle θ _{Even if 1} is an acute angle, improvement in light collection efficiency cannot be expected. Therefore, when the light guide plate 40 is made of an acrylic material, the apex angle θ ₁ of the cone portion 4031 is preferably in the range of 48 ° ≦ θ ₁ ≦ 96 °. Accordingly, the apex angle θ ₂ of the frustum portion 4030 is preferably in the range of θ ₁ <θ ₂ <180 °.

  Increasing the size of the concave reflecting portion 403 increases the amount of light reflected by the concave reflecting portion 403 due to an increase in surface area. However, if the size of the concave reflecting portion 403 is too large, the 1/2 beam angle increases accordingly. The amount of diffused light also increases. In order to allow light to properly enter the lower lens unit 502 and the upper lens unit 501 directly above the concave reflection unit 403, the size of the concave reflection unit 403 does not exceed the diameter of the upper lens unit 501 positioned at least directly above. Should be.

  In addition, on the upper surface 402 of the ring interior 41 and the rear surface of the light collecting cover 50, a convex portion and a concave portion (not shown) that can be fitted to each other are provided in the same order. For example, in the vicinity of the center O of the light collecting cover 50, the convex portion and the concave portion are provided corresponding to three positions having different circumferential angles by about 120 ° from each other. Thereby, alignment with the light-guide plate 40 and the condensing cover 50 can be performed precisely.

(Ii) Annular portion 42
The annular portion 42 is a light incident portion that guides light emitted from the light emitting element 22 toward the light guide plate 40. As shown in FIG. 4, the annular portion 42 is disposed so as to overlap the recessed portion 32 of the reflecting member 30. Thereby, the annular portion 42 is formed so as to extend over the mounting position of each light emitting element 22 on the mounting substrate 20.
As a specific configuration, as shown in FIG. 7, the annular portion 42 includes an element facing portion 420, an inner inclined portion 421A, and an outer inclined portion 421B. The annular portion 42 has a substantially V-shaped cross section as a whole.

The element facing portion 420 is disposed close to the light emitting element 22. For example, the surface of the element facing portion 420 is a flat surface.
The inner inclined portion 421A and the outer inclined portion 421B have a cross-sectional shape in which the inclination angle gradually increases as the distance from the element facing portion 420 increases. The inner inclined portion 421A is continuous with the ring interior 41. The outer inclined portion 421B is continuous with the annular outer peripheral portion 43. The inner inclined portion 421A and the outer inclined portion 421B are inclined in directions opposite to each other with respect to the vertical (Z) direction. Accordingly, the inner inclined portion 421A and the outer inclined portion 421B efficiently guide incident light incident along the (Z) direction directly above the element facing portion 420 to the inner ring portion 41 and the annular outer peripheral portion 43 in the same order. Let

In the lighting fixture 1, the height in the Z direction of the inner inclined portion 421A is made higher than the height in the Z direction of the outer inclined portion 421B for design reasons. By aligning the heights in the Z direction of the inner inclined portion 421A and the outer inclined portion 421B, the lighting fixture 1 can be further reduced in thickness.
(Iii) Annular outer periphery 43
The annular outer peripheral portion 43 guides the light of the light emitting element 22 that has entered the light guide plate 40 from the annular portion 42 to the outside of the mounting position of the light emitting element 22.

As shown in FIG. 7, a plurality of concave reflecting portions 404 exist in the Z direction on the back surface 430 of the annular outer peripheral portion 43. The concave reflecting portion 404 is a conical concave portion having an apex angle of 42 °, and the height in the Z direction is the same as that of the concave reflecting portion 403.
[Condensing cover 50]
The condensing cover 50 condenses the emitted light from the light guide plate 40 and emits it forward. The light collecting cover 50 is disposed so as to cover at least a part of the light guide plate 40. As shown in FIG. 8, the light collecting cover 50 includes a base portion 500, an upper lens portion 501, and a lower lens portion 502.

  The base part 500 is a plate-like part having a main surface along the XY plane. In the light collecting cover 50, the base unit 500 is a member that arranges the upper lens unit 501 and the lower lens unit 502 at target positions. The back surface of the base unit 500 is disposed to face the main surface (upper surface 402) of the light guide plate 40, and the lower lens unit 502 is formed on the surface. An upper lens portion 501 is formed on the main surface of the base portion 500.

The upper lens portion 501 is a minute aspheric lens, and is formed to bulge upward (Z direction) from the upper surface of the base portion 500. Here, as shown in FIG. 8, the radius of the upper lens portion 501 from the arbitrary position A in the downward direction of the light collecting cover 50 along the optical axis of the upper lens portion 501 to the surface of the upper lens portion 501 is set to r ₃ , The height from an arbitrary position A to the top of the upper lens unit 501 is t ₁ . Further, the refractive index of the light guide plate 40 is n, and the angle between the height (Z) direction of the upper lens portion 501 and the radius r ₃ is θ ₃ . At this time, the shape of the upper lens portion 501 can be a shape that satisfies the following relational expression 1.

(Relational formula 1)
r ₃ = (n−1) × t ₁ / (n−cos θ ₃ )
The radius of the lower lens portion 502 from the arbitrary position B in the downward direction of the light collecting cover 50 along the optical axis of the lower lens portion 502 to the surface of the lower lens portion 502 is r ₄ , and the lower lens from the arbitrary position B is the height to the top of the parts 502 and t _2. Further, the refractive index of the light guide plate 40 is n, and the angle between the height (Z) direction of the lower lens portion 502 and the radius r ₄ is θ ₄ . At this time, the shape of the lower lens unit 502 can be a shape that satisfies the following relational expression 2.

(Relational expression 2)
r ₄ = (n−1) × t ₂ × cos θ ₄ / ((n × cos−1) × √n ² −sin ² θ ₄ )
As shown in FIG. 3, a large number (up to 491 in this case) of the upper lens portions 501 are densely formed concentrically from the central point O to the peripheral edge of the light collecting cover 50.
The lower lens portion 502 is a convex lens having a larger curvature than the upper lens portion 501, and is formed to bulge downward (in the reverse Z direction) with respect to the back surface of the base portion 500. The condensing cover 50 includes an upper lens portion 501 and a lower lens portion 502 so as to be disposed in an optically opposing relationship with each of the concave reflecting portions 403 of the light guide plate 40. Specifically, as illustrated in FIG. 8, the lower lens unit 502 is disposed at a position corresponding to the upper lens unit 501 with the base unit 500 interposed therebetween. The upper lens portion 501 and the lower lens portion 502 corresponding to each other in the Z direction are integrally formed with the base portion 500 by injection molding.

The light collecting cover 50 is configured using a material having excellent translucency, such as a silicone resin, an acrylic resin, a polycarbonate resin, or glass. In the luminaire 1, the light collection cover 50 is disposed so as to contact the light guide plate 40.
As an example, the plate thickness of the base portion 500 is 0.5 mm, and the total height of the upper lens portion 501 and the lower lens portion 502 along the Z direction is 2.5 mm.

According to the studies by the inventors, it is desirable that the light collecting cover 50 and the light guide plate 40 are disposed so as to contact each other, and the distance between the light collecting cover 50 and the light guide plate 40 is set to 0 mm. According to this configuration, by adjusting the lens shapes of the upper lens portion 501 and the lower lens portion 502, the ½ beam angle can be controlled within a range of 10 ° or less and 100 ° or more.
[Diffusion cover 60]
The diffusion cover 60 uses light emitted from the annular outer peripheral portion 43 of the light guide plate 40 as scattered light. The diffusion cover 60 is configured using a translucent material such as a silicone resin, an acrylic resin, a polycarbonate resin, or glass.

Specifically, as shown in FIGS. 3 and 4, the diffusion cover 60 has a main body 61 and a side wall 62.
The main body 61 has an annular shape, and is subjected to a light scattering process to efficiently scatter the light emitted from the light guide plate 40. As the light scattering process, for example, the surface of the main body 61 that faces the light guide plate 40 is subjected to a fine uneven process. The main body 61 is arranged so as to cover the annular outer peripheral portion 43 of the light guide plate 40. From the opening 63 present at the center of the main body 61, the upper lens portion 501 of the light collecting cover 50 is exposed to the outside. The diameter of the opening 63 is about 80 mm as an example.

The side wall 62 is disposed on the periphery of the main body 61. The side wall portion 62 is joined to the flange portion 12 of the base 10.
(Basic operation of lighting device 100)
When the lighting device 100 having the above configuration is turned on, power is supplied to each light emitting element 22 from the power supply unit 4 connected to the commercial power supply via the wiring 23. Thereby, each light emitting element 22 is driven. The emitted light generated by each light emitting element 22 enters the light guide plate 40 from the annular portion 42 through each opening 34 of the reflecting member 30. Incident light repeats regular reflection within the light guide plate 40 and is guided to both the ring inner portion 41 and the annular outer peripheral portion 43. The return light leaking downward from the light guide plate 40 is reflected by the upper surfaces 310 and 320 of the reflecting member 30 and is incident on the light guide plate 40 again.

  The light emitted from the light emitting element 22 guided to the ring interior 41 of the light guide plate 40 is reflected by the concave reflecting portion 403 in the direction directly above (Z) or in the vicinity thereof, and is positioned directly above each concave reflecting portion 403. The light is sequentially incident on the lower lens unit 502 and the upper lens unit 501. Incident light is collected by the lower lens unit 502 and the upper lens unit 501. The condensed light becomes narrow-oriented illumination light having an illuminance peak within a light distribution angle of about 5 ° on an irradiation surface at a distance of about 2000 mm.

On the other hand, the emitted light of the light emitting element 22 guided to the annular outer peripheral portion 43 of the light guide plate 40 is reflected in the thickness (Z) direction or the vicinity thereof by the concave reflection portion 404. Thereafter, the emitted light is incident on the upper diffusion cover 60. Incident light is diffused by the light scattering-processed main body 61 and emitted to the outside.
(Effects produced by lighting device 100)
In the lighting device 100, the following effects can be expected mainly.

[1] Effect by Frustum 4030 and Frustum 4031 FIG. 10A shows a cross section of a light guide plate 40A having a conical concave reflector 403A having a relatively small taper angle. In this case, when the light guided in the light guide plate 40A strikes the concave reflecting portion 403A from the side, the light L ₅ penetrating the concave reflecting portion 403A is generated because the incident angle to the concave reflecting portion 403A is small. sell. Similarly, since the incident angle on the concave reflecting portion 403A is small, light L ₆ that diffuses to the periphery from the concave reflecting portion 403A can be generated.

Next, FIG. 10B shows a cross section of a light guide plate 40B having a conical concave reflecting portion 403B having a relatively large taper angle. In FIG. 10B, 401B and 402B are the back and top surfaces of the light guide plate 40B in the same order. In this case, the height of the concave reflecting portion 403B in the thickness (Z) direction of the light guide plate 40B is reduced due to size restrictions of the upper lens portion 501 and the concave reflecting portion 403B. Therefore, the light guided through the light guide plate 40B is less likely to be reflected by the concave reflecting portion 403B, and light L ₇ that is not reflected by the concave reflecting portion 403B can be generated. Further, due to the large angle of incidence to the concave reflecting portion 403B, the incident angle is too large to the upper surface 402B of the light guide plate 40B, the light L ₈ serving as a return light by specular reflection may occur.

FIG. 11 shows the effects obtained by using the concave reflection portion 403 for these problems. The frustum portion 4030 has a relatively large taper angle. For this reason, when the light traveling as indicated by L ₅ and L ₆ shown in FIG. 10A is reflected by the frustum 4030, the light is directed upward or in the vicinity thereof as indicated by the lights L ₉ and L _{10 in} FIG. It can be reflected toward. Such lights L ₉ and L ₁₀ can be sequentially incident on the lower lens unit 502 and the upper lens unit 501 positioned immediately above the concave reflection unit 403.

Furthermore, the height of the concave reflecting portion 403 in the Z direction can be ensured by providing the conical portion 4031 on the frustum portion 4030. Therefore, the light traveling like L ₇ and L ₈ shown in FIG. 10B can be favorably reflected by the cone portion 4031. As shown in FIG. 11, such reflected light becomes light L ₁₁ and L ₁₂ that are directed directly upward or in the vicinity thereof. By using the cone part 4031, the amount of light reflected by the entire concave reflection part 403 can be maintained.

[2] The frustum portion 4030 and the cone portion 4031 effects concave reflecting portion 403 by continuous reflection, as light L ₁₃ shown in FIG. 11, the cone portion of the light is reflected once at the frustum portion 4030 4031 Can be reflected again. Thus, the light L ₁₃ continuously reflected by the frustum part 4030 and the cone part 4031 can be reflected in a direction close to the directly above (Z) direction, and the lower lens part 502 directly above the concave reflecting part 403. And the upper lens portion 501 can be efficiently incident. Thus the light L _13, can be utilized as an advantageous light for obtaining excellent focusing characteristics.

[3] Effect by setting the respective taper angles of the frustum portion 4030 and the cone portion 4031 In the light guide plate 40, the incident angle when the light reflected by the concave reflection portion 403 hits the upper surface 402 of the light guide plate 40 is at least a cone. The angle is equal to or less than half the taper angle of the body portion 4031 (30 ° or less when the taper angle θ ₁ of the cone portion 4031 is 60 °). In this way, by making the incident angle of light on the upper surface 402 sufficiently small, it is prevented that the light is regularly reflected on the upper surface 402 of the light guide plate 40 and becomes return light like the light L ₈ in FIG. 10B. it can. As described above, by appropriately setting the taper angles θ ₁ and θ ₂ of the frustum part 4030 and the cone part 4031, the lower lens part 502 and the upper lens part 501 positioned directly above the concave reflection part 403 are arranged. Thus, light can be easily incident.

By producing the above various effects, the illumination device 100 has a large amount of light that is sequentially collected by the lower lens unit 502 and the upper lens unit 501 directly above the concave reflection unit 403, and near a light distribution angle of 0 °. It is possible to realize a concentrated illumination distribution with a narrow orientation. Therefore, the illuminating device 100 which can expect the outstanding condensing characteristic can be provided.
The light distribution characteristic can be controlled by the size of the concave reflecting portion 403. For example, the thickness of the inner ring 41 of the light guide plate 40 is 1.5 mm, the thickness of the lens portion of the light collecting cover 50 is 2.5 mm, r ₂ / r ₁ in FIG. 9 is 1.2, and the taper angle θ ₁ is 60. When the taper angle θ ₂ is 96 °, r ₂ is 0.45 mm, t ₁ in the relational expression ₁ is 3.9 mm, and t ₂ in the relational expression ₂ is 80 mm, the 1/2 beam angle is about 20 °. Further, if the value of r ₂ is increased, the ½ beam angle can be increased in proportion to it.
[4] Effects on Thinning In the lighting device 100, similarly to the lighting device 900, the corresponding upper lens unit 501 and lower lens unit 502 are formed using the light guide plate 40 including the concave reflection unit 403 and the light collecting cover 50. In addition, parallel light can be incident from a short distance. Thereby, since the distance between the light emitting element 22 and the light collecting cover 50 along the Z direction can be relatively short, the lighting device 100 can be thinned.
(Performance confirmation)
In order to confirm the performance of the lighting device 100, a simulation calculation was performed on the relationship between the light distribution angle and the radiation intensity.

  An illuminating device 100 was used as an example, and an illuminating device having the same configuration as that of the example was used as a comparative example, except that the concave reflecting portion was formed of a single cone. The concave reflecting portion of the example has a structure including the frustum portion and the frustum portion shown in FIG. 9A, and the inclination angle of the frustum portion is 60 ° and the inclination angle of the frustum portion is 42 °. A plurality of comparative examples were prepared in which the concave reflecting portion of the comparative example was conical and the inclination angles were set to 44 °, 48 °, 52 °, 56 °, and 60 °, respectively. The diameter of the bottom surface of the concave reflecting portion of each comparative example and the diameter of the frustum portion of the concave reflecting portion of the example were set to be the same. In the example and each comparative example, the thickness of the light guide plate was 1.5 mm, and the height of each concave reflection portion was 0.7 mm. The position of the irradiated surface was set at a position at infinity.

FIG. 12 is a diagram illustrating a simulation result of the relationship between the light distribution angle and the radiation intensity in the example and each comparative example. FIG. 13 is a graph showing the intensity of the luminous flux (lm) between the light distribution angles of ± 10 ° in the examples and the comparative examples based on the simulation results of FIG.
Referring to FIG. 12, in the range of the light distribution angle of ± 5 ± 10 °, in the comparative example, the radiation intensity was highest when the inclination angle was 52 °. Further, in the comparative example, when the inclination angle is smaller than 52 °, the radiation intensity near the light distribution angle of 0 ° falls, and when the inclination angle is larger than 52 °, the radiation intensity tends to increase. As shown in FIGS. 12 and 13, when the light distribution angle is between ± 10 °, the light flux at the inclination angle of 52 ° is maximum in the comparative example.

On the other hand, in the Example, as shown in FIG. 13, it turned out that it has high radiant intensity with respect to all of each comparative example in the range whose light distribution angle is +/- 5 +/- 10 degree. From the results shown in FIGS. 12 and 13, it was confirmed that the example had better light collecting characteristics than the comparative examples. The reason why the result of this example was obtained is that the condensing characteristic exhibited by the condensing cover 50 was improved by configuring the concave reflecting portion 403 by a combination of the frustum portion 4030 and the conical portion 4031. Conceivable.
<Other matters>
The lighting device according to the present invention is not limited to a buried ceiling light. For example, a ceiling light installed on the surface of the construction material may be used. Moreover, it can be widely used for general lighting applications such as downlights and backlights.

In the present invention, the latch member 3 is not essential. The luminaire 1 may be fixed to the construction material using screws, rivets, adhesion, or the like.
In the lighting device 100, the power supply unit 4 and the lighting fixture 1 are configured separately, but the present invention is not limited to this structure. That is, the illuminating device of the present invention may be configured such that the luminaire 1 includes the power supply unit 4 therein.

The light emitting element according to the present invention may be, for example, an LD (laser diode) or an EL element (electric luminescence element). The light emitting device according to the present invention may be an SMD (Surface Mount Device) type.
Moreover, in the illuminating device which concerns on this invention, the cyclic | annular outer peripheral part and diffusion cover of a light-guide plate are not essential. Therefore, the annular outer peripheral portion of the light guide plate and the diffusion cover can be omitted.

In the above embodiment, the reflecting member 30 is configured as an integral type. However, in the present invention, adjacent openings 34 may communicate with each other. In this case, the reflecting member 30 can be composed of two members, an inner reflecting portion 31 and an outer reflecting portion 33.
In each of the above embodiments, the reflecting member 30 is exemplified as the plate-like member provided above the mounting substrate 20. However, in the present invention, the configuration of the plate member is not limited to the reflecting member. That is, the plate-like member can be configured not to have reflectivity.

  In each of the above embodiments, the luminaire 1 has a disk shape, but the luminaire 1 is not limited to this shape. For example, the mounting substrate 20 may be configured by arranging a plurality of light emitting elements on a long substrate body. In this case, the base 10, the reflection member 30, the light guide plate 40, the light collection cover 50, and the diffusion cover 60 are each configured to be long like the mounting substrate 20. Thereby, the lighting fixture 1 can also be made into long shape.

In the light guide plate 40, the concave reflection part 403 may be provided at least in accordance with the arrangement positions of the upper lens part 501 and the lower lens part 502.
In addition, the concave reflecting portion 404 is not an essential configuration and may not be provided. Furthermore, the concave reflecting portion 404 may have the same configuration as the concave reflecting portion 403.
In the light collection cover 50, the lower lens portion 502 may be omitted. That is, the lens part provided in the light collection cover 50 should just be formed on the surface facing the light guide plate 40 at the back. However, if the light collecting cover 50 and the light guide plate 40 are in close contact with each other, regular reflection of light may increase on the upper surface 402 of the light guide plate 40. Therefore, in order to prevent an increase in return light, it is preferable to provide the lower lens portion 502 on the light collecting cover 50.

The shapes of the frustum part 4030 and the frustum part 4031 in the concave reflecting part 403 are not limited to mathematically exact shapes. The shape may include an error variation during actual manufacturing. For example, at least one of the frustum portion 4030 and the cone portion 4031 may have a curved slope.
In the concave reflecting portion 403 shown in FIG. 9, the diameter of the top surface of the frustum portion 4030 and the diameter of the peripheral edge of the bottom surface of the cone portion 4031 are the same. However, the present invention is not limited to this. For example, the diameter of the upper surface of the frustum portion may be larger than the diameter of the bottom surface of the frustum portion 4031, and a step may exist between the frustum portion 4030 and the frustum portion 4031.

DESCRIPTION OF SYMBOLS 1 Lighting fixture 2 Ceiling 4 Power supply unit 10 Base 20 Mounting board 21 Board 22 Light emitting element 30 Reflective member 31 Inner reflection part 32 Recessed part 33 Outer reflection part 34 Opening 40, 40A, 40B, 940 Light guide plate 41 Inner light guide part 42 Annular Part 43 Outer light guide part 50 Condensing cover 60 Diffusion cover 100 Illuminating device 401, 401B Back surface 402, 402B Upper surface 403, 403A, 403B, 404 Concave reflection part 500 Base part 501 Upper lens part 502 Lower lens part 4030 Frustum part 4031 Cone

Claims (10)

A plurality of light emitting elements;
A light guide plate for guiding light emitted from the plurality of light emitting elements in the plate;
A light collecting cover that covers at least a part of the main surface of the light guide plate;
The plurality of light emitting elements are disposed to face a part of the back surface facing away from the main surface of the light guide plate,
The light guide plate has a plurality of concave reflecting portions that are recessed in the thickness direction in the other part of the back surface and reflect light guided into the light guide plate toward the light collection cover. And
Each recess portion formed by recessed in said plurality of concave reflecting portion, Te direction odor toward the main surface from the opening side, and a frustum portion having a frustum-shaped space shaped, positioned on the frustum portion And a cone portion having a cone- shaped space shape ,
The slope surrounding each of the recessed portions has a taper angle of the slope surrounding the cone portion smaller than the taper angle of the slope surrounding the frustum portion,
The condensing cover is disposed in an optically-opposed relationship with each concave reflecting portion, and a plurality of the condensing covers condense the reflected light of each concave reflecting portion in a direction perpendicular to the main surface of the light guide plate. An illumination device having a lens unit. The frustum portion is a truncated cone portion;
The lighting device according to claim 1, wherein the cone portion is a cone portion. The taper angle of the slope surrounding the cone part is θ ₁ ,
When the taper angle of the slope surrounding the frustum portion is θ ₂ ,
The lighting device according to claim 1, wherein a relationship of 48 ° ≦ θ ₁ ≦ 96 ° and θ ₁ <θ ₂ <180 ° is established. Further comprising a mounting substrate in which the plurality of light emitting elements are mounted on the surface of the substrate,
Each light emitting element forms an annular element array on the substrate;
The light guide plate has a disc shape having an annular portion arranged along the element row on the mounting substrate and an inside of the ring continuously arranged with the annular portion inside the annular portion,
The illuminating device according to any one of claims 1 to 3, wherein the concave reflecting portion is present at least inside the ring. A reflection member interposed between the light guide plate and the mounting substrate;
The reflecting member has an opening at a position facing each light emitting element,
The illumination device according to claim 4, wherein the light emitted from the light emitting element is incident on the annular portion through the opening. The illuminating device according to claim 4, wherein the light guide plate further includes an annular outer peripheral portion arranged continuously with the annular portion outside the annular portion. The lighting device according to claim 6, further comprising an annular diffusion cover disposed outside the light collection cover so as to cover the annular outer peripheral portion of the light guide plate and subjected to a light scattering process. The light collection cover is disposed above the light guide plate,
The illuminating device according to any one of claims 1 to 7, wherein each lens unit is formed on a surface facing away from at least a surface facing the light guide plate. The lighting device according to claim 1, wherein the light emitting element is an LED. The lighting device according to claim 1, further comprising a power supply unit for supplying power to the light emitting element.

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