JP2014160616A - Illumination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination device capable of reducing thickness, and capable of acquiring a light condensing characteristic more excellent than that of a conventional one.SOLUTION: An illumination device 100 comprises: a plurality of light emitting elements 22; a light guide plate 40; and a light condensing cover 50 for covering a part of a main surface 402 of the light guide plate 40. The light guide plate 40 has a plurality of concave-shaped reflection parts 403 for reflecting light guided into the plate. The light condensing cover 50 has a plurality of upper lens parts 501 and lower lens parts 502 arranged by maintaining an optically opposed relation with each of the concave-shaped reflection parts 403 individually. The upper lens part 501 comprises: a first lens region 5010 which includes an apex 5010a and in which a cross-sectional shape along an optical axis is regulated by a first relational expression; and a second lens region 5011 which includes a base part of the upper lens part 501 and in which a cross-sectional shape is regulated by a second relational expression different from the first relational expression. The cross-sectional shape along an optical axis of the second lens region 5011 is regulated by the second relational expression so that the position of the surface comes outside compared with the case in which it is regulated by the first relational expression.

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 condensing illumination device including an LED light emitting module having a planar light emitting unit and a Fresnel lens.

The cross-sectional view of FIG. 19 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 that are reflected on the light cover side, and the light collecting cover is disposed in an optically opposed relationship with each concave reflecting portion and reflects light from each concave reflecting portion. A plurality of lens portions that condense in a main emission direction perpendicular to the main surface of the light guide plate, and the lens portion includes a distance from a reference position on the optical axis to an arbitrary position on the lens surface, and the reference position. And an angle formed by a straight line passing through an arbitrary position on the lens surface and the optical axis. The aspherical lens whose surface shape is defined by the equation, a first lens region including a top portion of the lens portion, and a second lens region including a base portion of the lens portion and adjacent to the first lens region And the surface shape of the first lens region is defined by a first relational expression, and the surface shape of the second lens region is longer than that defined by the first relational expression. The lighting device is defined by the relational expression.

  In the illumination device according to another aspect of the present invention, the light collecting cover further includes a plate-like base portion in which the lens portions are arranged on a main surface, and the light collecting cover is a main portion of the base portion. 1.5 ≦ W / D ≦ 2.5, where the back surface opposite to the surface is opposed to the main surface of the light guide plate, the pitch of the lens portions is W, and the thickness of the light guide plate is D. It is also possible to adopt a configuration in which

In the illumination device according to another aspect of the present invention, the distance from the reference position A in the light guide plate to an arbitrary position on the surface of the first lens region is r ₁ , and the distance from the reference position A to the top is t. ₁ , where θ _{1 is} the angle between the straight line passing through the distance r ₁ and the optical axis of the lens unit, and n is the refractive index of the light guide plate, r ₁ = (n−1) ) × t ₁ / (n−cos θ ₁ ).

In the illumination device according to another aspect of the present invention, the distance from the reference position A in the light guide plate to an arbitrary position on the surface of the second lens region is r ₂ , and from the reference position A to the surface of the first lens region. T ₁ , the angle between the straight line passing through the distance r ₂ and the optical axis of the lens unit is θ ₂ , n is the refractive index of the light guide plate, k ₁ and k ₂ are positive constants, When the angle between the straight line passing through the boundary between the first lens region and the second lens region on the surface of the lens unit from the reference position A and the optical axis of the lens unit is θ _ch , the second relationship It is also possible to adopt a configuration in which r ₂ = (n−1) {t ₁ + k ₁ (θ ₂ −θ _ch ) ^k ₂ / (n−cos θ ₂ ) is established as an expression.

In the illumination device according to another aspect of the present invention, the light collection cover further includes a plurality of auxiliary lens portions arranged so as to face the main surface of the light guide plate, and each of the auxiliary lens portions is the It can also be set as the structure arrange | positioned so that a mutual optical axis may correspond with a lens part separately.
In the illumination device according to another aspect of the present invention, the distance from the reference position B in the light guide plate along the optical axis of the auxiliary lens unit to an arbitrary position on the surface of the auxiliary lens unit is r ₃ , and the reference position When the distance from B to the top of the auxiliary lens is t ₃ , the angle between the straight line passing through the distance r ₃ and the optical axis of the auxiliary lens part is θ ₃ , and n is the refractive index of the light collecting cover. As a third relational expression, r ₃ = (n−1) × t ₃ × cos θ ₃ / ((n × cos−1) × √n ² −sin ² θ ₃ ) may be established.

In the illumination device according to another aspect of the present invention, the concave reflecting portion may be conical.
The lighting device according to another aspect of the present invention further includes a mounting substrate in which the plurality of light emitting elements are mounted on a surface of the substrate, the plurality of light emitting elements forming an annular element array on the substrate, The light guide plate has a disc shape having an annular portion arranged annularly along the element row and an inside of the annular portion continuously arranged with the annular portion inside the annular portion, and the concave reflecting portion is It can also be set as the structure which exists in the said annular part at least.

In the illumination device according to another aspect of the present invention, the light-emitting element may be an LED.
The lighting device according to another aspect of the present invention may include a power supply unit for supplying power to the light emitting element.

In the lighting device according to one embodiment of the present invention, the light path from the light emitting element to the lens unit is shortened by using the light guide plate and the light collecting cover arranged to cover at least a part of the main surface of the light guide plate. Can be planned. By shortening the optical path, the lighting device can be made thinner.
Further, the lens portion provided in the light collecting cover has a distance from a reference position on the optical axis to an arbitrary position on the lens surface, and an angle formed by a straight line passing through the reference position and the arbitrary position on the lens surface and the optical axis. The surface shape is defined by the relational expression to be related. The lens portion includes a top portion of the lens portion and the surface shape is defined by the first relational expression, and includes a base portion of the lens portion and is adjacent to the first lens area, and the surface shape is the second relational expression. And a second lens region defined by Here, the second relational expression is a relational expression in which the distance becomes longer than that in the case where the surface shape of the second lens region is defined by the first relational expression.

According to the lens portion having such a shape, when light is incident on the light collecting cover from the light guide plate, the incident angle of light on the surface of the second lens region can be reduced. This reduces the light that is reflected back from the surface of the second lens region and the light that is reflected back and diffused from the surface of the second lens region, and efficiently emits light from the second lens region to the outside. it can.
Therefore, from the lens unit, the light emitted to the outside from the second lens region and the light emitted to the outside from the first lens region including the top of the lens unit are transmitted in the main emission direction perpendicular to the main surface of the light guide plate. It can be condensed and emitted. As a result, it is possible to provide an illuminating device that can obtain excellent narrow orientation light condensing characteristics.

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. FIG. 6 is a cross-sectional view showing specific configurations of an upper lens unit 501 and a lower lens unit 502. 5 is a graph showing surface shapes of a first lens region 5010 and a second lens region 5011 of the upper lens unit 501. 5 is a graph showing a surface shape of a lower lens unit 502. It is a figure which shows the subject in the condensing cover 50A periphery. It is a figure which shows the effect show | played by the condensing cover 50 periphery. It is a figure which shows the subject in the condensing cover 50B periphery. It is a figure which shows the effect show | played by the condensing cover 50 periphery. It is a graph which shows the simulation result of the illumination intensity distribution of an Example and a comparative example. It is the graph which expanded the curve within the orientation angle +/- 30 degree in FIG. It is the graph which compared the light beam of the range of +/- 10 degree and +/- 20 degree of an Example and a comparative example computed based on the simulation result. It is sectional drawing which shows the structure of the conventional illuminating device 800. FIG.

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 outer diameter of the light guide plate 40 is about 128 mm, and the plate thickness D ₃ (FIG. 9) is about 1.5 mm.

(I) Ring interior 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 main surface 402 side. The concave reflecting portion 403 is formed in a conical shape from the back surface 401 side toward the main surface 402. The taper angle (vertical angle) between the inclined surfaces of the concave reflector 403 is, for example, 60 °. 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.

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. 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.
If the size of the concave reflection portion 403 is increased, the amount of light reflected by the concave reflection portion 403 increases due to an increase in surface area. If the size of the concave reflecting portion 403 is too large, 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.

  The main surface 402 of the inside 41 of the ring and the back surface of the light collecting cover 50 are provided with convex portions and concave portions (not shown) that can be fitted to each other 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 where the circumferential angles are different from each other by about 120 °. Thereby, alignment with the light-guide plate 40 and the condensing cover 50 is performed.

(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) An annular outer peripheral portion 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 60 °, 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. The light collecting cover 50 is configured using a material having excellent translucency as a whole, for example, silicone resin, acrylic resin, polycarbonate resin, glass, or the like. Is done. In the luminaire 1, the light collection cover 50 is disposed so as to contact the light guide plate 40.

As shown in the enlarged sectional view of FIG. 9, the condensing cover 50 includes a base portion 500, an upper lens portion 501, and a lower lens portion 502.
(I) Base unit 500
The base part 500 is a plate-like part whose plane direction is the XY direction. An upper lens portion 501 is formed on the main surface of the base portion 500. A lower lens portion 502 is formed on the back surface of the base portion 500. The back surface of the base unit 500 is disposed to face the main surface 402 of the light guide plate 40.

It is desirable to make the plate thickness D ₁ of the base portion 500 as thin as possible. As an example, the base portion 500 has a plate thickness D ₁ of 0.5 mm and a lens pitch W of 3.05 mm. The height D ₂ from the top 5020a of the lower lens unit 502 to the top 5010a of the upper lens unit 501 is 2.5 mm.
(Ii) Upper lens unit 501
The upper lens portion 501 is a minute aspheric lens, and is formed upward (Z direction) from the upper surface of the base portion 500. The upper lens unit 501 has a surface expression according to a relational expression that relates a distance from a reference position on the optical axis to an arbitrary position on the lens surface, and an angle formed by a straight line passing through the reference position and the arbitrary position on the lens surface and the optical axis. The shape is defined. In the light condensing cover 50, the upper lens portion 501 is used as a lens portion that condenses the light emitted from the light guide plate 40. The upper lens unit 501 includes a first lens region 5010 and a second lens region 5011.

The first lens region 5010 is a region including the top portion 5010a of the upper lens portion 501. The first lens region 5010 has, for example, the following shape. As shown in FIG. 9, the distance from the reference position A in the light guide plate 40 along the optical axis of the upper lens portion 501 to an arbitrary position on the surface of the first lens region 5010 is r ₁ , and the distance from the reference position A to the upper lens portion 501 is the height to the top 5010a and t _1. Further, the angle between the straight line passing through the distance r ₁ and the optical axis of the first lens region 5010 is θ ₁ , and the refractive index of the light guide plate 40 is n. At this time, the cross-sectional shape of the first lens region 5010 along the optical axis is defined by the following relational expression 1 (Formula 1).

(Formula 1)
r ₁ = (n−1) × t ₁ / (n−cos θ ₁ )
The second lens region 5011 includes the base portion 5011 a of the upper lens portion 501, is continuous with the first lens region 5010, and has a more gentle surface shape than the first lens region 5010. The second lens region 5011 has, for example, the following shape. The distance from the reference position A in the light guide plate 40 along the optical axis of the upper lens portion 501 to an arbitrary position on the surface of the second lens region 5011 is r ₂ , and the reference is along the direction perpendicular to the main surface of the light guide plate 40. A height from the position A to the top 5010a of the upper lens portion 501 is defined as t ₁ . Further, the angle between the straight line passing through the distance r ₂ and the optical axis of the upper lens portion 501 is θ ₂ , n is the refractive index of the light guide plate 40, k ₁ and k ₂ are positive constants, and the upper lens portion from the reference position A An angle between a straight line (straight line along the distance r ₀ ) passing through the boundary between the first lens region 5010 and the second lens region 5011 on the surface of 501 and the optical axis of the upper lens unit 501 is θ _ch . At this time, the surface shape of the second lens region 5011 is defined by the following second relational expression (Formula 2).

(Formula 2)
r ₂ = (n−1) {t ₁ + k ₁ (θ ₂ −θ _ch ) ^k ₂ / (n−cos θ ₂ )
By defining the surface shape of the second lens region 5011 with the second relational expression (Formula 2), the second lens region 5011 is defined from the reference position A to the second lens region 5011 as compared with the case where the second lens region 5011 is defined with the first relational expression. The distance to an arbitrary position on the surface becomes longer. Here, as an example, the reference height of the second lens region 5011 where t ₂ > t ₁ is t _2, and k ₂ = 1, k ₁ = (t ₂ −t ₁ ) / (cos ⁻¹ (1 / n ) −θ _ch ).

FIG. 10 is a graph showing the surface shapes of the first lens region 5010 and the second lens region 5011, and shows a part of the surface shape of the upper lens portion 501 along the optical axis (vertical axis). The lens height on the vertical axis and the lens radius (r) on the horizontal axis are shown as relative values. The position of the boundary Q is a position where θ _ch = 25 °. Here, the surface of the second lens region 5011 (portion indicated by the solid line) is outside the surface of the second lens region 5011 (portion indicated by the dotted line V) when the surface shape is defined by the first relational expression. Located in.

As shown in FIG. 10, the height h ₃ of the first lens region 5010 of the upper lens portion 501 is changed by changing the angle of θ _ch and moving the position of the boundary Q in any direction along the vertical axis. And the height h ₄ of the second lens region 5011 can be adjusted. By reducing the angle of θ _ch , it is possible to reduce the proportion of light that is regularly reflected on the surface of the upper lens portion 501, but the radiation intensity at a light distribution angle of 0 ° is reduced, and the 1/2 beam angle is also reduced. growing. The appropriate angle of θ _ch is due to the thickness of the light guide plate 40 and the size of the concave reflecting portion 403. For example, when the thickness of the light guide plate 40 is 1.5 mm and the diameter of the concave reflecting portion 403 is φ0.9 mm, the light that is regularly reflected on the surface of the first lens region 5010 is increased by setting the angle of θ _ch to 20 ° or more. No longer exists. Further, by increasing the value of t ₂ shown in FIG. 9, it is possible to reduce the proportion of light that is regularly reflected on the surface of the upper lens portion 501, but the radiation intensity at a light distribution angle of 0 ° decreases. The 1/2 beam angle is also increased.

From the above, the value of θ _ch is effective in the range of 20 ° to 30 °, and θ _ch = 25 ° in this embodiment. Further, t ₂ is effective in the range of 1 <t ₂ / t ₁ <1.1. In this embodiment, t ₂ / t ₁ = 1.05 with respect to t ₁ = 3.9 mm.
(Iii) Lower lens unit 502
The lower lens unit 502 is a minute aspheric lens (convex lens), and has a larger curvature than the second lens region 5011 of the upper lens unit 501. The lower lens unit 502 is used as an auxiliary lens for reducing light that repeats regular reflection in the condensing cover 50 and improving condensing characteristics when the light emitted from the light guide plate 40 is collected by the upper lens unit 501. It is done. The lower lens portion 502 is formed on the back surface of the base portion 500 disposed to face the light guide plate 40.

The lower lens unit 502 has a shape that satisfies the following relational expression, for example. FIG. 11 is a graph showing the surface shape of the lower lens unit 502. The distance of the lower lens portion 502 from the reference position B in the lower direction of the light collecting cover 50 along the optical axis of the lower lens portion 502 to an arbitrary position on the surface of the lower lens portion 502 is r ₃ , and the lower lens portion from the reference position B 502 the distance to the top 5020a and t ₃ of. Further, the refractive index of the light guide plate 40 is n, and the angle between the optical axis (axis P) of the lower lens portion 502 and a straight line passing through the distance r ₃ is θ ₃ . At this time, in the lower lens unit 502, the following third relational expression (Expression 3) is established.

(Formula 3)
r ₃ = (n−1) × t ₃ × cos θ ₃ / ((n × cos−1) × √n ² −sin ² θ ₃ )
The height of the lower lens portion 502 (D ₂ − (h ₃ + h ₄ ) shown in FIG. 9) is (0.2) mm as an example. The t ₃ value of the lower lens unit 502 is t ₃ = 80 mm as an example. When the t ₃ value is small, the appropriate value of the t ₁ value is small and the lens pitch is small. As a result, the ratio of the light incident on the adjacent lens increases, so that a value as large as possible is desired as the t ₃ value.

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.
(Iv) Overall shape of the condensing cover 50 In the luminaire 1, the upper lens portion 501 and the lower lens portion 502 are disposed in an optically opposing relationship with each of the concave reflecting portions 403 of the light guide plate 40. The Further, in the light collecting cover 50, the upper lens portion 501 and the lower lens portion 502 sandwich the base portion 500 so that each optical axis overlaps with the axis P along the thickness (Z) direction of the light collecting cover 50. They are individually arranged at corresponding positions (FIG. 8).

When the light collecting cover 50 is manufactured, the base unit 500, the upper lens unit 501, and the lower lens unit 502 are integrally injection-molded. 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. As an example, the pitch of each upper lens unit 501 and the pitch of each lower lens unit 502 along the XY plane is 3.05 mm. Here, when the plate thickness of the light guide plate 40 is D ₃ as shown in FIG. 9 and the pitch of the adjacent upper lens portions 501 (the pitch of the lower lens portion 502) is W as shown in FIG. 8, the plate thickness D ₃ and The lens pitch W is set so that the relationship of 1.5 ≦ W / D ≦ 2.5 is established.
[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. Light incident on the lower lens unit 502 and the upper lens unit 501 from the vicinity of the center of the concave reflection unit 403 is emitted as parallel light. Light incident on the lower lens unit 502 and the upper lens unit 501 from a position away from the center of the concave reflecting unit 403 is collected in a direction slightly inclined with respect to the axis P. The light thus collected becomes narrowly oriented illumination light having an illuminance peak within a light distribution angle of ± 5 ° on the irradiated 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] Effects exhibited by the upper lens portion 501 FIG. 12 shows a state in which the light collecting cover 50A of the comparative example is used. The condensing cover 50A has an upper lens portion 501A having a single focal length. In FIG. 12, a back surface 401A and a main surface 402A are shown as the main surface of the light guide plate 40. The curvature of the upper lens portion 501A is the same as the curvature of the first lens region 5010. The height of the upper lens portion 501A in the Z direction is the same as the height (h ₃ + h ₄ ) of the upper lens portion 501.

When the condensing cover 50A is used, the light irradiated from the lens focal point C is refracted on the surface of the upper lens portion 501A and is emitted parallel to the optical axis like La. However, the light L ₃ irradiated from a position shifted from the lens focal point C and hits the surface of the upper lens portion 501A repeats regular reflection because the incident angle θ ₃ to the surface of the upper lens portion 501A is large, and the light guide plate In some cases, the return light is incident on 40A. Similarly, since the incident angle θ ₄ on the surface of the upper lens portion 501A is large, light L ₄ that diffuses from the upper lens portion 501A to the surroundings may be generated.

FIG. 13 shows the effects obtained by using the light collecting cover 50 for these problems. In the upper lens portion 501, the curvature of the second lens region 5011 is smaller than the curvature of the first lens region 5010. The surface of the second lens region 5011 is inclined more gently than the surface of the first lens region 5010. Therefore, when light traveling as indicated by L ₃ and L ₄ shown in FIG. 12 is incident on the second lens region 5011, the incident angle at the time of incidence can be suppressed to be small and regular reflection can be prevented. In FIG. 13, the light L ₅ and L ₆ traveling in the same direction as the light L ₃ and L ₄ are incident on the second lens region 5011 at incident angles θ ₅ and θ ₆ smaller than the incident angles θ ₃ and θ ₄ in FIG. Fig. 2 shows how each is incident. The lights L ₅ and L ₆ penetrate outside and are emitted directly upward or in the vicinity thereof. However, the light emitted from the lens focal point C is refracted on the surface of the upper lens portion 501A, and is emitted in a direction that extends slightly outward with respect to the optical axis, such as La.

Further, in the light collecting cover 50, the first lens region 5010 is positioned on the second lens region 5011, so that the light L ₇ incident on the upper lens unit 501 from the inside of the second lens region 5011 is sufficiently small in incident angle. Incident light can be incident at θ ₇ . The light L ₇ penetrates from the first lens region 5010 to the outside and is emitted in the direction directly above or in the vicinity thereof. As described above, the light emitted to the outside from the second lens region 5011 and the light emitted to the outside from the first lens region 5010 including the top 5010a of the upper lens portion 501 are mainly perpendicular to the main surface of the light guide plate 40. Light can be efficiently emitted by condensing light in the emission direction (Z direction). As a result, it is possible to provide the illuminating device 100 capable of obtaining excellent narrow orientation light collecting characteristics.

[2] Effect produced by the thickness of the light guide plate 40 FIG. 14 shows a state in which the light guide plate 40B and the light collecting cover 50B of the comparative example are used. The thickness D ₄ of the light guide plate 40B is thicker than the thickness D _{3 of the} light guide plate 40. The curvature of the upper lens portion 501B is the same as that of the upper lens portion 501A in FIG. The height of the upper lens portion 501B in the Z direction is the same as the height (h ₃ + h ₄ ) of the upper lens portion 501. In this case, the light L ₈ was regularly reflected by the surface of the upper lens portion 501B becomes return light, which may be incident from the light guide plate 40B oblique direction. At this time, since the optical path in the light guide plate 40B is relatively long, the light L may be reflected by the back surface 401B of the light guide plate 40B and incident on another upper lens portion 501B, resulting in diffused light.

FIG. 15 shows the effect produced by the thickness of the light guide plate 40 for this problem. In the illuminating device 100, the pitch W of the upper lens portion 501 (pitch of the lower lens portion 502) W with respect to the plate thickness D ₃ of the light guide plate 40 is set so as to satisfy 1.5 ≦ W / D ₃ ≦ 2.5. , it can be reduced and thickness D ₃ of the pitch (the pitch of the lower lens portion 502) W and the light guide plate 40 of the upper lens portion 501 in this range. Thereby, the optical path of the light guide plate 40 along the thickness (Z) direction vicinity can be shortened.

Here, as shown in FIG. 15, a light L ₉ that travels in the same direction as the light L ₈ and is regularly reflected by the surface of the upper lens portion 501 is assumed. When the light L ₉ enters the light guide plate 40B from an oblique direction as return light, if the light path in the light guide plate 40 is short, the light L ₉ is reflected by the back surface 401 of the light guide plate 40 and then again true. It becomes easy to enter the upper lens unit 501. As a result, the light L ₉ can be prevented from becoming diffused light, and the light L ₉ can be effectively used as irradiation light. According to experiments conducted by the inventors, it was confirmed that when the thickness D ₃ of the light guide plate 40 is reduced from 1.5 mm to 1.2 mm, the light extraction efficiency is improved by about 10%. Therefore, in manufacturing the extent possible, it is desirable to reduce the thickness D ₃ of the light guide plate 40.

When the diameter of the upper lens portion 501 is 2.7 mm or more, diffused light such as light L ₈ can be effectively prevented by setting the plate thickness D ₁ to 0.5 mm. Without considering challenges lens fabrication, it is possible to effectively prevent diffusion light enough thickness D ₁ is small. On the other hand, the diameter of the upper lens portion 501 may be 2.7 mm or less for the purpose of avoiding a decrease in transmittance when the incident angle of light with respect to the upper lens portion 501 is close to the total reflection angle.

By producing the above effects, the illumination device 100 can realize an illuminance distribution in which the illuminance is concentrated in the vicinity of a light distribution angle of 0 °. Therefore, the illuminating device 100 which can acquire the outstanding condensing characteristic can be provided.
[3] Effect Regarding Thinning of Lighting Device 100 In the conventional lighting device 800 shown in FIG. 19, for example, the orientation angle (hereinafter referred to as “1/2”) in an angular range in which the luminous intensity is ½ or more of the maximum luminous intensity in the illuminance distribution. When the angle of the phosphor layer 8022 is 60 mm, the diameter of the Fresnel lens 803 is 162 mm. At this time, 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 reduce the thickness of the lighting device 800.

On the other hand, in the lighting device 100, parallel light can be incident on the upper lens unit 501 and the lower lens unit 502 positioned in the directly above (Z) direction of each concave reflection unit 403 from a shorter distance than each concave reflection unit 403. . Therefore, as shown in FIG. 7, the optical path (distance h ₂ ) between the light emitting element 22 and the light collecting cover 50 in the thickness (Z) direction of the lighting fixture 1 can be made relatively short. Thereby, the thickness of the lighting fixture 1 can be suppressed to about 18 mm or less, and it is possible to aim at thickness reduction of the illuminating device 100 favorably.
<Performance confirmation>
In order to confirm the performance of the lighting device 100, a light distribution characteristic in the illuminance distribution was calculated by simulation.

The lighting device 100 was used as an example. As a comparative example, an illumination device having the same configuration as that of the example was used except that the upper lens portion having a single focal length was provided on the light collecting cover. In both the example and the comparative example, the thickness of the base portion of the light collecting cover is 0.5 mm, the height of the upper lens portion from the upper surface of the base portion is 1.8 mm, and the height of the lower lens portion from the back surface of the base portion Was 0.2 mm. In the embodiment, the switching angle θ _ch = 25 ° between the first lens region 5010 and the second lens region 5011 is set. The positions of the irradiation surfaces of the example and the comparative example were set to infinity.

  FIG. 16 is a graph showing a simulation result of the light distribution characteristics in the illuminance distributions of the example and the comparative example as a 180 ° orientation distribution in orthogonal coordinates. FIG. 17 is a graph obtained by enlarging the curve within the orientation angle ± 30 ° in FIG. The vertical axis | shaft of FIG. 16, FIG. 17 was made into the irradiation intensity | strength of logarithm display. FIG. 18 is a graph comparing light fluxes in the range of ± 10 ° and ± 20 ° between the example and the comparative example calculated based on the simulation result.

Referring to FIG. 16, in the comparative example, the irradiation intensity is rapidly increased and a peak is observed in the vicinity of the orientation angle ± 70 °. Further, when the result of FIG. 17 is seen, in the comparative example, a slight peak is observed in the irradiation intensity even in the vicinity of the orientation angle ± 10 °. The peak in the vicinity of the orientation angle ± 70 ° is presumed to be caused by L ₄ light that is regularly reflected on the lens surface as shown in FIG. Such a peak forms unnecessary ring light on the irradiated surface and causes a reduction in light collection characteristics.

  On the other hand, in the example, in the range of the orientation angle ± 30 ° to ± 90 ° shown in FIG. 16, no conspicuous peak as in the comparative example is seen, and the irradiation intensity increases with the increase in the absolute value of the orientation angle. It decreases continuously and smoothly. Further, as shown in FIG. 17, the irradiation intensity is higher than that of the comparative example in the range of the light distribution angle where the orientation angle is about ± 3 ° or more and ± 23 ° or less. No peak is seen. For this reason, in an Example, formation of ring light is suppressed rather than a comparative example.

In the results of FIG. 18, the example exhibits a higher luminous flux than the comparative example in both the ± 10 ° and ± 20 ° orientation angles. As a reason why such a result is obtained, in the embodiment, the upper lens portion 501 is configured by a combination of the first lens region 5010 and the second lens region 5011, so that the emitted light is efficiently radiated in the optical axis direction, It is presumed that the luminous flux increased within an orientation angle of ± 20 °.
<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 excessively adhered, regular reflection of light may increase on the main surface 402 of the light guide plate 40. Accordingly, it is preferable to provide the lower lens portion 502 in the light collecting cover 50 in order to prevent an increase in return light.

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 face 402, 402B Main surface 403, 403A, 403B, 404 Concave reflection part 500 Base part 501 Upper lens part 502 Lower lens part 5010 First lens Region 5010a Top portion of upper lens portion 5011 Second lens region 5011a Base portion 5020a Top portion of lower lens portion

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 light guide plate has a plurality of concave reflecting portions that have a part of the back surface facing away from the main surface and that reflect the light guided into the plate of the light guide plate toward the light collection cover side. ,
The condensing cover is disposed in an optically opposing relationship with each concave reflecting portion and collects the reflected light from each concave reflecting portion in a main emission direction perpendicular to the main surface of the light guide plate. A plurality of lens parts,
The lens unit has a relational expression that relates a distance from a reference position on the optical axis to an arbitrary position on the lens surface, and an angle formed between the reference position and a straight line passing through the arbitrary position on the lens surface and the optical axis, An aspherical lens whose surface shape is defined, and includes a first lens region including a top portion of the lens portion, and a second lens region including a base portion of the lens portion and adjacent to the first lens region,
The surface shape of the first lens region is defined by a first relational expression,
The illumination device characterized in that the surface shape of the second lens region is defined by a second relational expression in which the distance becomes longer than that defined by the first relational expression. The condensing cover further includes a plate-like base portion in which the lens portions are arranged on the main surface,
The condensing cover is disposed opposite to the main surface of the light guide plate on the back surface opposite to the main surface of the base portion,
The lighting device according to claim 2, wherein a relationship of 1.5 ≦ W / D ≦ 2.5 is established, where W is a pitch between the lens portions and D is a thickness of the light guide plate. The distance from the reference position A in the light guide plate to an arbitrary position on the surface of the first lens region is r ₁ , the distance from the reference position A to the top is t ₁ , and the straight line passing through the distance r ₁ and the lens When the angle between the optical axis of the portion is θ ₁ and n is the refractive index of the light guide plate, r ₁ = (n−1) × t ₁ / (n−cos θ ₁ ) as the first relational expression. The lighting device according to claim 1 or 2. The distance from the reference position A in the light guide plate to an arbitrary position on the surface of the second lens region is r ₂ , the maximum height from the reference position A to the surface of the first lens region is t1, and the distance r ₂ is The angle between the straight line passing through and the optical axis of the lens unit is θ ₂ , n is the refractive index of the light guide plate, k ₁ and k ₂ are positive constants, and the first position on the surface of the lens unit from the reference position A When the angle between the straight line passing through the boundary between the lens region and the second lens region and the optical axis of the lens unit is θ _ch , r ₂ = (n−1) {t ₁ + K ₁ (θ ₂ −θ _ch ) ^k ₂ / (n−cos θ ₂ )
The lighting device according to any one of claims 1 to 3. The light collecting cover further includes a plurality of auxiliary lens portions arranged to face the main surface of the light guide plate,
The illuminating device according to any one of claims 1 to 4, wherein the auxiliary lens units are arranged so that the optical axes of the auxiliary lens units individually match the lens units. The distance from the reference position B in the light guide plate along the optical axis of the auxiliary lens portion to an arbitrary position on the surface of the auxiliary lens portion is r ₃ , and the distance from the reference position B to the top of the auxiliary lens is t ₃ , where θ _{3 is} the angle between the straight line passing through the distance r ₃ and the optical axis of the auxiliary lens unit, and n is the refractive index of the light collecting cover, r ₃ = (n− The lighting device according to claim 5, wherein 1) × t ₃ × cos θ ₃ / ((n × cos−1) × √n ² −sin ² θ ₃ ) is established. The illuminating device according to claim 1, wherein the concave reflecting portion has a conical shape. Further comprising a mounting substrate in which the plurality of light emitting elements are mounted on the substrate surface,
The plurality of light emitting elements form an annular element array on the substrate,
The light guide plate has a disc shape having an annular portion arranged annularly along the element row and an inside of the ring continuously arranged with the annular portion inside the annular portion,
The illuminating device according to claim 1, wherein the concave reflection portion is present at least in the annular portion. 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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