JP2015002025A - Illumination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED illumination device of narrow angle light distribution or a middle angle light distribution in which a beam angle of emission light from a lens is sufficiently small, and also light extraction efficiency is high.SOLUTION: An illumination device at least includes an LED light source and a lens. The lens has a rotor shape with an optical axis being a center, and includes an incident surface, an emission surface and a reflection side surface. The incident surface is one recess provided so as to become a shape symmetrical with respect to the optical axis of the lens, and it comprises an upper incident surface facing the LED light source and a side incident surface surrounding the periphery of it. The upper incident surface is a convex lens, and when a maximum diameter of a light emitting surface of the LED light source is defined as X and a maximum diameter of the upper incident surface is defined as Y, 0.8≤X/Y≤1.2 is established.

Description

  The present invention relates to a lighting device using LEDs as light emitting elements.

A light-emitting diode (hereinafter referred to as “LED”) is expected to be a new light source because it has a higher efficiency and a longer life than conventional illumination light sources such as fluorescent lamps and incandescent lamps. In order to obtain an arbitrary light distribution characteristic according to the application of the lighting device, it is considered to combine such an LED light source and a lens for light distribution control.
For example, Patent Document 1 describes using a hybrid lens that combines a convex incident surface and a total reflection surface as a method of increasing luminance by changing the light distribution characteristics of an LED element from a wide angle to a narrow angle. The hybrid lens has an optical path for emitting the lens incident light from the LED element arranged at the center as substantially parallel light to the lens central axis (optical axis) by total reflection by the reflecting surface, and refraction by the convex incident surface. A light source unit with a narrow-angle light distribution is realized that has two types of optical paths, which are light beams that are condensed and emitted as substantially parallel light with respect to the optical axis. It is described that. As a specific example, a lens-equipped light-emitting unit that emits light from a plurality of light-colored LED elements in a mixed color is described (paragraphs [0004], [FIG. 1] to [FIG. 16]).

JP 2007-59073 A

  According to the study of the present inventor, even when a lighting device with a narrow-angle light distribution is designed using the hybrid lens disclosed in Patent Document 1, radiation of the emitted light collected through the lens is emitted. In some cases, the angle (beam angle) did not become sufficiently small. In particular, when a plurality of LEDs are mounted on the lighting device or the effective light emitting area of the LED light source is increased by expanding the light emitting surface of the one-core (one grain) LED light source, the tendency is likely to occur. In addition, it has been found that there is a tendency that the beam angle of the emitted light cannot be made sufficiently small even when the device is downsized due to the demand for improvement in design and thinness of the device which is an advantage of LED lighting. .

Further, according to the study by the present inventors, when the area of the convex incident surface of the lens is designed to be excessively small in order to reduce the beam angle of the emitted light, the light is emitted directly above the exit surface of the lens. It has been found that the effective light extraction efficiency may decrease due to a relative decrease in the amount of light.
The present invention has been made in view of the above problems, and even if the effective light emitting area of the LED light source is increased or the illumination device is thinned and miniaturized, the light emitted from the lens is obtained. It is an object of the present invention to provide a narrow-angle light distribution or medium-angle light distribution LED illumination device having a sufficiently small beam angle and high light extraction efficiency.

The gist of the present invention for solving the above problems is as follows.
[1] An illuminating device including at least an LED light source and a lens, wherein the lens has a rotating body shape around its optical axis, and includes an incident surface, an output surface, and a reflective side surface, and the incident surface Is a concave portion provided so as to have a symmetrical shape with respect to the optical axis of the lens, and includes an upper incident surface facing the LED light source and a side incident surface surrounding the upper incident surface. The incident surface is a convex lens, and when the maximum diameter of the light emitting surface of the LED light source is X and the maximum diameter of the upper incident surface is Y, 0.8 ≦ X / Y ≦ 1.2. A lighting device.
[2] The illumination device according to [1], wherein a shape of the side incident surface in a cross section when the lens is cut along a plane including the optical axis is a shape having a curved surface.
[3] The illumination device according to [1] or [2], wherein the LED light source is a one-core LED light source.
[4] The illumination device according to any one of [1] to [3], wherein the maximum diameter X of the light emitting surface of the LED light source is 300 μm or more and 10 mm or less.
[5] The illumination device according to any one of [1] to [4], wherein a diameter of the convex lens constituting the upper incident surface is not less than 300 μm and not more than 12 mm.

  According to the present invention, by setting the above X / Y within a specific range, the effective light emitting area of the LED light source can be expanded, or even when the lighting device is thinned and miniaturized, It is possible to provide a LED illumination device with narrow-angle light distribution or medium-angle light distribution that has a sufficiently small beam angle of light emitted from a lens and high light extraction efficiency.

It is sectional drawing which shows the relationship between the LED light source and lens of the illuminating device which concerns on embodiment of this invention. It is a side view of the lens which comprises the illuminating device which concerns on embodiment of this invention. It is a front view of the lens which comprises the illuminating device which concerns on embodiment of this invention. It is a perspective view of the lens which comprises the illuminating device which concerns on embodiment of this invention. It is a figure for demonstrating the conditions of the simulation of this invention. It is a figure for demonstrating the beam angle of this invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The following description of the constituent features of the invention is an example (representative example) of an embodiment of the present invention, and the present invention is not intended to be limited only to these forms as long as the gist of the invention is not exceeded. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

<Overall configuration of lighting device>
FIG. 1 is a cross-sectional view showing the relationship between the LED light source 20 and the lens 30 when the illumination device 10 according to the embodiment of the present invention is cut along a plane including the optical axis. The illumination device 10 includes at least an LED light source 20 and a lens 30. As will be described later, the lens 30 has a rotating body shape centered on the optical axis, and has a structure including an incident surface 31, an output surface 32, and a reflective side surface 33. Further, the shape of the incident surface 31 of the lens 30 is provided so as to be symmetrical with respect to the optical axis of the lens 30 and forms one concave portion. The incident surface 31 of the lens 30 includes an upper incident surface 31a that faces the LED light source 20 and a side incident surface 31b that surrounds the upper incident surface 31a. The upper incident surface 31a forms a convex lens.

As will be described later, in the illumination device 10 of the present invention, the ratio of the maximum diameter X of the light emitting surface of the LED light source 20 to the maximum diameter Y of the upper incident surface 31a (convex lens surface) of the lens 30 is within a predetermined range. Thus, even when the effective light emitting area of the LED light source 20 is expanded or the illumination device 10 is thinned and miniaturized, the emission angle of the light emitted from the lens 30 ( Beam angle) can be made sufficiently small, and a sufficient amount of light emitted toward the position directly above the exit surface 32 of the lens 30 can be ensured (light extraction efficiency can be increased).

<LED light source 20>
(Configuration of LED light source 20)
As the LED light source 20, for example, an LED light emitting module can be used by mounting an LED chip on a module substrate. In this case, it is preferable to use a one-core (one grain) type module in which LED chips are centrally arranged at the center of the module substrate. By adopting such a one-core LED light source, the entire LED lighting device can be a point light source. In addition, by adopting such a one-core LED light source, multi-shadows can be effectively eliminated or alleviated, and a uniform and stable illumination effect with little light unevenness can be realized.

As the module substrate for mounting the LED chip, for example, a metal base substrate formed of a metal material such as aluminum having good thermal conductivity or an insulating material is preferably used.
As the LED light source 20, for example, one having a chip-on-board structure in which one or a plurality of near-ultraviolet or purple LED chips are directly mounted on a wiring provided on the mounting surface of the module substrate can be used. Alternatively, it may be configured by being potted by a translucent resin in which a blue phosphor, a green phosphor, and a red phosphor that are excited by a purple LED chip to emit light are mixed. As the LED chip, not only a near-ultraviolet or purple LED chip but also various LED chips such as a blue LED chip can be used, and various phosphors can be selected depending on the LED chip to be used. The semiconductor substrate used for the LED chip is preferably a material having a lattice constant or a coefficient of thermal expansion that is the same as or close to that of the semiconductor material constituting the light emitting layer. For example, a nitride semiconductor is used for the light emitting layer, It is preferable to use a nitride semiconductor, silicon carbide, or sapphire for the substrate. In particular, when the semiconductor material constituting the light emitting layer is a Ga-containing nitride semiconductor, the GaN substrate has almost the same lattice constant and thermal expansion coefficient. This is particularly preferable from the viewpoint of durability and durability. When an LED chip using such a substrate is applied, even if a large current is applied to the LED chip, thermal degradation due to heat generation is small, and long-life LED illumination with a large luminous flux can be realized.

As materials constituting these LED chips, known materials can be appropriately selected according to the purpose and application of the LED lighting device, and the LED chips can be manufactured by a known method.
The LED light source 20 can adopt a package structure instead of using the chip-on-board structure, and can be applied to various forms. The LED light source 20 can also be provided with a plurality of LED chips dispersed on a semiconductor substrate.

(About the maximum diameter X of the light emitting surface of the LED light source)
In the present invention, the maximum diameter X of the light emitting surface of the LED light source means the maximum diameter X of the light emitting surface when the LED light source of the present invention is regarded as a single light source. That is, for example, in the case of an LED light source that is a one-core (one grain) type LED light-emitting module, the maximum distance X is the maximum distance X from the end to end of the light-emitting surface of the one-core LED light source. . Further, when a plurality of LED light emitting modules are simply provided on a semiconductor substrate, the distance from the outer end to the end of the light emitting surface of the LED light emitting module that is located farthest is the maximum diameter X.

  X is usually 300 μm to 10 mm, preferably 500 μm or more, more preferably 1 mm or more, and further preferably 3 mm or more. X is preferably 9 mm or less, more preferably 8 mm or less, and even more preferably 7 mm or less.

<Lens 30>
(Configuration of lens 30)
FIG. 1 is a cross-sectional view showing an outline of a lighting device 10 according to an embodiment of the present invention. FIG. 1 shows a cross-sectional view when a lens 30 is cut along a plane including an optical axis. 2 to 4 are a side view, a front view, and a perspective view of a lens constituting the illumination device according to the embodiment of the present invention.

The lens 30 has a rotating body shape centered on the optical axis, and has a structure including an incident surface 31, an output surface 32, and a reflective side surface 33. The above-mentioned rotator shape means that the entire lens is a substantially symmetric rotator shape, and even if a member is added or processed and deformed so as not to affect the light collecting function, the present invention It shall be included in the shape of the rotating body.
The shape of the incident surface 31 of the lens 30 is provided so as to be symmetrical with respect to the optical axis of the lens 30 and forms one concave portion 34 (see FIGS. 1 and 4). The incident surface 31 of the lens 30 includes an upper incident surface 31a that faces the LED light source 20 and a side incident surface 31b that surrounds the upper incident surface 31a. The upper incident surface 31a forms a convex lens.

In the embodiment of the present invention, the light emitted from the LED light source 20 is refracted by the upper incident surface 31a of the lens 30 having a convex shape, and is condensed as substantially parallel light with respect to the optical axis. The light is emitted from the emission surface 32 to the outside. Further, a part of the light incident from the upper incident surface 31a or the side incident surface 31b of the lens 30 is totally reflected by the reflecting side surface 33 inside the lens 30, and is converted into substantially parallel light with respect to the optical axis. The light is emitted from the light emission surface 32 to the outside.
Note that a small part of the light incident on the lens 30 may leak from a portion other than the emission surface 32 (for example, the reflective side surface 33 or the flange portion 35).

  In the present invention, the shape of the side incident surface 31b of the lens 30 is preferably a shape having a curved surface in a cross section when the lens 30 is cut by a plane including the optical axis, that is, in the cross sectional view of FIG. . Further, the shape of the side incident surface 31b is more preferably a part of a spherical shape, and particularly preferably a part of a hemispherical shape. By making the side incident surface 31b into the above-mentioned shape, the radiation angle (beam angle) of the emitted light from the lens 30 can be made sufficiently small, and the light is emitted directly above the emitting surface 32 of the lens 30. The design margin of the maximum diameter (convex lens diameter) of the upper incident surface 31a to ensure a sufficient amount of light (to increase light extraction efficiency) can be widened, and the yield when mass-producing lenses and the like is improved. be able to. Further, by forming the side incident surface 31b as described above, it is possible to realize a uniform and stable illumination effect with little light unevenness.

  The material of the lens 30 is not particularly limited as long as the object of the present invention can be achieved, but plastic can be suitably used. Specifically, thermoplastics such as acrylic, cyclic polyolefin, and polycarbonate, photocurable plastics, UV curable plastics, and the like can be used. Among these, from the viewpoint of reducing production costs, thermoplastic plastics such as acrylic, cyclic polyolefin, and polycarbonate that can be produced by injection molding can be suitably used, and among these, polycarbonate is particularly preferred.

(About the maximum diameter Y of the upper incident surface)
In the present invention, the maximum diameter Y of the upper incident surface is a part of the lens 30 that is opposed to the light emitting surface when the LED light source of the present invention is regarded as a single light source, and constitutes a convex lens. This means the maximum diameter Y of the upper incident surface 31a.
Y is usually 300 μm to 12 mm, preferably 500 μm or more, more preferably 1 mm or more, and further preferably 3 mm or more. X is preferably 10 mm or less, more preferably 8 mm or less, and 7 mm.
More preferably, it is as follows.

(About the ratio (X / Y) between the maximum diameter X of the light emitting surface of the LED light source and the maximum diameter Y of the upper incident surface)
In the present invention, X / Y is preferably 0.8 to 1.2, more preferably 0.85 or more, and 0.90 or more, as shown in the simulation results described later. Is more preferable. X / Y is more preferably 1.15 or less, and further preferably 1.10 or less. By controlling X / Y within a specific range in this way, the radiation angle (beam angle) of the light emitted from the lens 30 can be made sufficiently small, and the light is emitted directly above the exit surface 32 of the lens 30. It is possible to secure a sufficient amount of light (to increase the light extraction efficiency).

<Simulation>
In an illuminating device including an LED light source and a lens, the emission angle of the emitted light (beam angle) and the amount of light emitted directly above the exit surface of the lens, the light emitted from the original LED light source In order to analyze the ratio to light quantity (transmittance), TracePro ver. Manufactured by Lambda Research. The simulation was calculated using 7.2.7. FIG. 5 shows a diagram for explaining the simulation conditions, and FIG. 6 shows a diagram for explaining the beam angle of the present invention. FIG. 6 shows the angular distribution of the light emitted from the illumination device, and the horizontal axis shows the emission angle (unit: [Degrees] to [degree]) when the front direction of the lens is 0 degree. The vertical axis shows the radiant intensity (radiant flux per unit azimuth, unit [W / sr]) at each emission angle when the total radiant flux emitted from the LED light source is 1 W. The simulation was performed with the wavelength of light set at 550 nm.

(conditions)
The LED light source was regarded as a cylindrical object having a diameter of 5 mm, and light was uniformly emitted from the entire disk surface in a Lambertian manner. The calculation was made assuming that the radiant flux of the emitted light is 1 W and 500,000 light beams are emitted. In addition, about the material which comprises an LED light source, and the parameter regarding the surface, it calculated as what shows a behavior equivalent to air optically without performing calculation definition.

The size of the lens was calculated by assuming that the height was 11.44 mm (in the optical axis direction) and the maximum diameter was 20 mm (in the direction perpendicular to the optical axis), and that the material constituting the lens was polycarbonate (the polycarbonate was refracted with respect to 546 nm light). The rate n was calculated as 1.591).
The shape of the concave portion of the lens was such that the diameter was 7.5 mm and the side incident surface was a hemispherical surface of R3.75 mm. In this case, the LED light source was arranged so that the center of the light emitting surface of the LED light source coincided with the center of the hemisphere. Further, regarding the shape of the concave portion of the lens, the diameter of the upper incident surface (diameter of the convex lens) was adjusted in the range of 1 mm to 6.4 mm, and the calculation was performed. The calculation was performed assuming that the upper incident surface (convex surface of the convex lens) has a curvature of R7 mm (see FIG. 5).

(Evaluation)
In order to calculate the ratio (transmittance) of the beam angle and the amount of light emitted toward directly above the exit surface of the lens to the amount of light emitted from the original LED light source and evaluate the result, the diameter A disc-shaped light receiver with a diameter of 20 mm was installed at a position 0.06 mm directly above the exit surface of the lens, and the radiant flux and light exit angle of the light that passed therethrough were compared. Specifically, the transmittance of the lens is calculated from the radiant flux that has passed through the light receiver, and the angle at which the intensity is halved from the highest value of the radiant intensity of the emission angle distribution (full angle with respect to the normal) is calculated. Recorded as beam angle (see FIG. 6).

(Analysis result)
Table 1 shows the results of calculating the beam angle and transmittance with respect to X / Y.
In Table 1, the case where the beam angle was less than 23 was judged as ◎, the case where it was 23 or more and less than 27 was judged as ○, and the case where it was 27 or more was judged as Δ. Moreover, the case where the transmittance | permeability was 87 or more was evaluated as (double-circle), the case below 82 or less than 87 as (circle), and the case below 82 was evaluated as (triangle | delta).

In the LED lighting device of the present invention, it is required that the beam angle is small and the transmittance (light extraction efficiency) is large. As described above, X / Y is in the range of 0.8 to 1.2. In this case, neither the beam angle nor the transmittance has Δ, and both are ◎, or either is で and one is ○, and it has been found that both characteristics can be compatible.
The above-mentioned excellent effect is achieved by controlling the value of X / Y within the above range, and the amount of light incident on the side incident surface is appropriately set with respect to the light directly incident on the upper incident surface. This ensures that the beam angle can be narrowed, and that the amount of light directly incident on the upper incident surface is also adequately secured to increase the transmittance (light extraction efficiency). It is done.

  Thus, in the case of realizing a narrow-angle light distribution or medium-angle light distribution LED illumination device with a sufficiently small beam angle and high light extraction efficiency, the value of X / Y is within the scope of the present invention. It is effective to do.

DESCRIPTION OF SYMBOLS 10 Illuminating device 20 LED light source 30 Lens 31 Incident surface 31a Upper incident surface 31b Side incident surface 32 Outgoing surface 33 Reflective side surface 34 Concave part 35 Collar part

Claims (5)

An illumination device comprising at least an LED light source and a lens,
The lens has a rotating body shape centered on the optical axis, and includes an entrance surface, an exit surface, and a reflective side surface.
The incident surface is a concave portion provided so as to have a symmetrical shape with respect to the optical axis of the lens, and includes an upper incident surface facing the LED light source and a side incident surface surrounding the periphery. ,
The upper incident surface is a convex lens;
When the maximum diameter of the light emitting surface of the LED light source is X and the maximum diameter of the upper incident surface is Y,
0.8 ≦ X / Y ≦ 1.2
A lighting device characterized by the above.   The lighting device according to claim 1, wherein a shape of the side incident surface in a cross section when the lens is cut by a plane including the optical axis is a shape having a curved surface.   The lighting device according to claim 1, wherein the LED light source is a one-core LED light source.   The maximum diameter X of the light emission surface of the said LED light source is 300 micrometers or more and 10 mm or less, The illuminating device as described in any one of Claim 1 to 3 characterized by the above-mentioned.   5. The illumination device according to claim 1, wherein a diameter of the convex lens constituting the upper incident surface is 300 μm or more and 12 mm or less.