JPWO2012144325A1 - LED lighting device and LED lighting device lens - Google Patents

Abstract

Although the light distribution angle can be kept narrow, the lens for the LED illumination device capable of suppressing the occurrence of yellow ring in the emitted light or the image of the LED chip being reflected, and further suppressing unevenness in illuminance, and An LED lighting device using the same is provided. The exit surface 5 of the lens 1 includes an inner region 5a in which a lens array LA in which a plurality of microlenses MS are arranged and an outer region 5b formed of a flat surface, and satisfies the following expression. 3 ≦ φ2 / φ1 ≦ 5 (1) 0.6 ≦ φ3 / φ2 ≦ 0.9 (2) 1.0 (mm) ≦ R ≦ 2.0 (mm) (3) where φ1: the diameter of the LED light source (Mm) φ2: Diameter of exit surface (mm) φ3: Diameter of inner region (mm) R: Radius of curvature of microlens (mm)

Description

  The present invention relates to an LED lighting device and a lens for the LED lighting device.

  In recent years, LED lighting devices equipped with LEDs have attracted attention. By the way, there is a downlight that irradiates a down beam as a kind of lighting device. However, as a specification of the downlight, a light distribution angle must be narrowed within, for example, 30 degrees, so a plurality of LEDs are used as a light source. In some cases, what kind of lens is used becomes a problem. Here, FIG. 15 of Patent Document 1 discloses a vehicle headlamp that is not an illumination device but can illuminate a narrow range by combining an LED chip and a microlens array. Therefore, it is conceivable to apply such a configuration to a lighting device.

JP 2008-305802 A JP 2007-5218 A

  However, according to the examination results of the present inventors, when a plurality of LED chips are used as the light source in the lighting device in order to obtain stronger emitted light, there is one problem by combining this with a microlens array. I found it to happen. More specifically, if the radius of curvature of the microlens constituting the lens array is increased and the interval between the microlens arrays is increased, that is, if the area per microlens array is increased, the light distribution angle can be easily kept narrow. Although it is suitable for illumination for downlights, there is a problem that yellow ring occurs in the emitted light, and an image of the LED chip is reflected, and uneven illuminance is likely to occur. On the other hand, Patent Document 2 discloses a technique for performing a light diffusion process on the entrance surface of a lens in order to alleviate color unevenness. However, a yellow ring or an image of an LED chip is maintained with a narrow light distribution angle. No means for solving problems such as reflection are described.

  The present invention has been made in view of such problems of the prior art, and in spite of the fact that the light distribution angle can be kept narrow, a yellow ring is generated in the emitted light or an image of the LED chip is reflected. It is an object of the present invention to provide a lens for an LED lighting device that can suppress the unevenness of illumination and further suppress uneven illuminance and an LED lighting device using the same.

The LED illumination device according to claim 1 is provided with a plurality of LED light sources, an incident surface on which light emitted from the LED light sources is incident, and light incident from the incident surfaces. A lens having a reflecting surface for reflecting and an emitting surface for emitting the emitted light to the outside, the emitting surface of the lens having an inner region where a lens array in which a plurality of microlenses are arranged is formed, and a flat surface It consists of the outer area | region which consists of a surface, and it is characterized by satisfy | filling the following formula | equation.
3 ≦ φ2 / φ1 ≦ 5 (1)
0.6 ≦ φ3 / φ2 ≦ 0.9 (2)
1.0 (mm) ≦ R ≦ 2.0 (mm) (3)
However,
φ1: Diameter of the LED light source (mm)
φ2: Diameter of the exit surface (mm)
φ3: Diameter of the inner region (mm)
R: radius of curvature of the microlens (mm)

  According to the results of the study by the present inventor, if the radius of curvature R of the microlens is large and the optical axis interval between the plurality of microlenses is wide, the light distribution angle can be kept narrow, but unevenness occurs in the periphery, and the yellow ring Further, it has been found that there is a problem that images of a plurality of LEDs are reflected. Therefore, by first satisfying the formulas (1) and (2), when a plurality of LED light sources are used, the light distribution angle is suppressed to be small. It is possible to suppress the occurrence or the reflection of the image of the LED chip, and to further suppress the illuminance unevenness. In addition, high efficiency can be maintained without significantly reducing light utilization efficiency.

The LED lighting device according to claim 2 is characterized in that, in the invention according to claim 1, the following expression is satisfied.
1.0 ≦ R / D ≦ 2.1 (4)
However,
D: Distance between optical axes of adjacent microlenses (mm)

  The LED illumination device according to claim 3 is the invention according to claim 1 or 2, wherein the adjacent microlenses are connected by a curved surface having a radius r (mm).

  According to the research of the present inventor, it has been found that if the intersection (boundary) of the optical surfaces of the adjacent microlenses is an edge, light scattering occurs and a loss of emitted light occurs. From this knowledge, it has been found that by connecting adjacent microlenses with curved surfaces having a radius r (mm), scattering and the like can be suppressed, and a decrease in illuminance and a decrease in light utilization efficiency can be suppressed.

The LED lighting device according to claim 4 is characterized in that, in the invention according to claim 3, the following expression is satisfied.
R / 20 (mm) ≦ r ≦ R / 10 (mm) (5)

  If the value falls below the lower limit of the expression (5), the crossing portion is close to the edge, so that the suppression effect such as scattering may be reduced. On the other hand, if the value exceeds the upper limit of the expression (5), the optical surface of the microlens becomes small, and there is a possibility that light rays emitted along the desired light distribution characteristics may be reduced. Therefore, it is preferable to satisfy the range of the formula (5). In addition, the strength of the lens itself can be increased by suppressing the edge between the microlenses.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the outer shape of the microlens is a honeycomb shape. When the optical axes of the microlenses are brought close to each other, the optical surfaces of the microlenses overlap with each other, so that the outer shape of the microlens becomes a honeycomb shape. In other words, by making the outer shape of the microlens into a honeycomb shape, the optical axis interval of the microlens can be reduced.

  The LED illumination device according to claim 6 is characterized in that, in the invention according to any one of claims 1 to 5, the light distribution angle of the emitted light emitted from the lens is 30 degrees or less. Thereby, the LED illuminating device suitable for the illumination for downlights can be provided. In particular, when the lens of the present invention is used, the yellow ring and the LEDs of a plurality of LEDs can be used even in a narrow light distribution angle of 30 degrees or less, which is likely to cause a problem of yellow ring and reflection of images of the LEDs. Since there is no reflection of an image, the effect of the present invention is particularly remarkable.

  The LED illumination device lens according to claim 7 is used for the LED illumination device according to any one of claims 1 to 6.

  The LED (Light Emitting Diode) illumination device according to the present invention includes an LED light source and a lens.

  Various LED light sources can be used, but white LEDs are preferably used.

  As the white LED, a combination of a blue LED chip and a phosphor such as a YAG phosphor that emits yellow light by blue light emitted from the blue LED chip is preferably used, but a blue LED chip, a green LED chip, and a red LED are used. It may be a white LED that forms white light in combination with a chip. As white LED, what was described, for example in Unexamined-Japanese-Patent No. 2008-231218 can be used, However, It is not restricted to this.

  Specifically, the white LED light source in the present invention includes an LED chip and a phosphor layer formed on the LED chip so as to cover the LED chip. The LED chip emits light having a first predetermined wavelength. In the present embodiment, the LED chip emits blue light. However, the wavelength of the LED chip of the present invention and the wavelength of the emitted light from the phosphor are not limited, and the wavelength of the emitted light from the LED chip and the wavelength of the emitted light from the phosphor are in a complementary color relationship and the synthesized light is white. Any combination that provides light can be used.

  In addition, as such an LED chip, a well-known blue LED chip can be used. As the blue LED chip, any existing one including InxGa1-xN can be used. The emission peak wavelength of the blue LED chip is preferably 440 to 480 nm. In addition, as a form of the LED chip, the LED chip is mounted on the substrate and directly radiated upward or sideward, or the blue LED chip is mounted on a transparent substrate such as a sapphire substrate, and bumps are formed on the surface thereof. Any form of LED chip, such as a so-called flip chip connection type, in which it is formed and turned over and connected to an electrode on a substrate, can be applied.

  The phosphor layer has a phosphor that converts light having a first predetermined wavelength emitted from the LED chip into a second predetermined wavelength. In an embodiment described later, blue light emitted from the LED chip is converted into yellow light.

  The phosphor used for such a phosphor layer uses an oxide or a compound that easily becomes an oxide at a high temperature as a raw material of Y, Gd, Ce, Sm, Al, La and Ga, and converts them into a stoichiometric amount. The raw material is obtained by thoroughly mixing in a theoretical ratio. Alternatively, a coprecipitated oxide obtained by calcining a solution obtained by coprecipitation of oxalic acid with a solution obtained by dissolving a rare earth element of Y, Gd, Ce, and Sm in an acid at a stoichiometric ratio, and aluminum oxide and gallium oxide. Mix to obtain a mixed raw material. An appropriate amount of fluoride such as ammonium fluoride is mixed with this as a flux and pressed to obtain a molded body. The compact can be packed in a crucible and fired in air at a temperature range of 1350 to 1450 ° C. for 2 to 5 hours to obtain a sintered body having the phosphor emission characteristics.

  Further, each of the plurality of LED chips may be arranged symmetrically with respect to the optical axis of the lens, or may be arranged asymmetrically. Here, when the LED light source is configured by using a plurality of LED chips as shown in FIG. 1A, the diameter of the smallest circle C1 circumscribing the LED chip CP, and as shown in FIG. The larger one of the diameters of the yellow phosphor YEL when the yellow phosphor YEL is circular is defined as the diameter φ1 of the LED light source. When the yellow phosphor YEL has a polygonal shape, the diameter of the smallest circumscribed circle is the diameter φ1 of the LED light source.

  The LED light source is preferably a high-power LED light source. Here, the high-power LED light source can be constituted by an LED having an output of 0.5 watts or more.

The lens is disposed on the light emission side of the LED light source, the incident surface on which the emitted light from the LED light source is incident, the reflective surface that reflects the light incident from the incident surface, and the emitted light from the LED light source to the outside It has an exit surface that emits light. Further, the incident surface of the lens and the LED light source are not in contact with each other.
The space between the lens incident surface and the LED light source is preferably filled with air.

  The incident surface of the lens is preferably a lens surface having a positive refractive power, but may be a flat surface. The lens shape of the entrance surface of the lens is a convex shape. Furthermore, the shape of the incident surface may be an aspherical shape.

  The exit surface of the lens is composed of an inner region where a lens array in which a plurality of microlenses are arranged and an outer region consisting of a flat surface. The reflecting surface of the lens is preferably disposed between the entrance surface and the exit surface, and has a shape that reflects the light incident from the entrance surface and emits it from the exit surface, for example, using total reflection. A reflective film or the like may be formed on the reflective surface.

  The lens is supported by the leg and may have a recess. The concave portion preferably has an incident surface and a side incident surface, which are preferably smooth surfaces, but may be subjected to light diffusion treatment. Here, the incident surface is formed to face the LED light source with respect to the optical axis direction of the lens, and the side surface incident surface is formed to face the LED light source with respect to the direction perpendicular to the optical axis of the lens. ing. Further, it is preferable that the incident surface and the side incident surface are not in contact with the LED light source. Moreover, it is preferable that the LED light source is enclosed by the recessed part, and, thereby, the light radiate | emitted from the LED light source can be efficiently taken out with a lens. Further, by providing the lens with a concave portion, it is possible to make it easier to attach the lens to the wiring board.

  The lens may have a shape for positioning on the wiring board. As a shape for positioning, the shape which provided the recessed part in the lens as mentioned above, and the shape which provided the convex part are mentioned. By providing the lens with such a shape for positioning on the wiring board, it is possible to more easily attach the lens to the wiring board. In addition, by providing the lens with a shape for positioning on the wiring board, it is possible to visually determine the mounting direction of the lens on the wiring board, so that the mounting workability can be improved.

  A surface that partially reflects part of the light incident on the lens and guides the light to the front end side of the lens may be formed on a part of the surface of the concave portion of the lens. By providing such a surface on a part of the surface that forms the concave portion of the lens, that is, by providing the surface in the vicinity of the LED light source, it is possible to increase the extraction efficiency of the light emitted from the LED light source.

  The lens is preferably made of plastic. For example, polycarbonate or acrylic can be used as the plastic constituting the lens. By using polycarbonate or acrylic, it can be manufactured by injection molding, and the manufacturing cost can be greatly reduced.

As the LED illumination device, a reflector may be disposed between the LED light source and the lens.
Here, the reflector reflects light emitted from the LED light source, and the reflector preferably has a reflecting surface.

  When the intensity of the light emitted from the LED lighting device is measured, the angle with respect to the optical axis that is half the light intensity on the optical axis of the lens is called a half-value half-angle, and twice that angle. Is called full width at half maximum. In this specification, the light distribution angle means a full width at half maximum.

  As lighting fixtures equipped with LED lighting devices, it is suitable for indoor and outdoor use, especially for downlights, but for other uses, general lighting fixtures (laser pointers, indicators, etc.), residential use Lighting fixtures, office lighting fixtures, store / exhibit lighting fixtures, street lamp lighting fixtures, guide lamp fixtures and signaling devices, advertising towers, lighting poles, underwater lighting lights, strobe lights, spotlights, flashlights , Electronic bulletin boards (sign boards), dimmers, automatic flashers, backlights for displays, moving picture devices, illuminated switches, optical sensors, medical lights, in-vehicle lights, and the like.

  According to the present invention, despite the fact that the light distribution angle can be kept narrow, it is possible to suppress the occurrence of yellow ring in the emitted light or the image of the LED chip being reflected, and further to suppress illuminance unevenness, It is possible to provide a lens for a bright LED lighting device that can maintain high light utilization efficiency and an LED lighting device using the same.

It is a figure which shows the diameter of a LED light source, (a) is an example in case a LED light source is comprised using a some LED chip, (b) is an example in case the yellow fluorescent substance YEL is circular. It is the figure which looked at the LED lighting apparatus concerning this Embodiment from the output surface side. It is the figure which cut | disconnected the structure of FIG. 2 by the III-III line | wire, and looked at the arrow direction. It is sectional drawing which expands and shows a micro lens. It is an enlarged view which shows the processing state of the metal mold | die which shape | molds the lens concerning another embodiment. It is sectional drawing of the lens shape | molded with the metal mold | die of FIG. It is an enlarged view which shows the processing state of the metal mold | die which shape | molds the lens concerning another embodiment. It is sectional drawing of the lens shape | molded by the metal mold | die of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the dimension ratio of drawing is exaggerated on account of description, and may differ from an actual ratio.

  FIG. 2 is a view of the LED illumination device according to the present embodiment as viewed from the exit surface side. FIG. 3 is a view of the configuration of FIG. 2 taken along line III-III and viewed in the direction of the arrow. FIG. 4 is an enlarged cross-sectional view of the microlens. The LED lighting device according to the present embodiment includes a lens 1 and an LED light source 2.

  As shown in FIG. 3, the circuit board CB includes a substrate main body BS made of aluminum, an insulating layer IL stacked on the substrate main body BS, and a wiring pattern HP made of a conductor such as Cu formed on the insulating layer IL. It is roughly composed of A plurality of LED chips CP are connected in parallel to the wiring pattern HP.

  Further, the LED chip CP is completely covered with a plate-shaped molded phosphor-containing transparent resin body YEL (phosphor-containing transparent resin), and all the light emitted from the LED chip CP is phosphor-containing transparent. It is configured to pass through the resin body YEL. With this configuration, for example, a blue light emitting diode is used as the LED chip CP, and a yellow phosphor is used as the phosphor contained in the phosphor-containing transparent resin, whereby white light can be emitted. The plurality of LED chips CP are arranged as shown in FIG. 1A, for example, and constitute the LED light source 2 as described above. The diameter of the LED light source 2 is φ1 (mm).

The lens 1 uses polycarbonate or acrylic as plastic. Further, the lens 1 is disposed on the light emission side of the LED light source 2 and has an incident surface 3 on which emitted light from the LED light source 2 is incident and a parabolic surface that reflects part of the light incident from the incident surface. Reflection surface 8 and an emission surface 5 for emitting emitted light to the outside. The emission surface 5 includes a circular inner region 5a in which a lens array LA in which a plurality of microlenses MS are arranged is formed, and an annular outer region 5b having a flat surface. The diameter of the inner region is φ3 (mm), and the diameter of the emission surface 5 is φ2 (mm). At this time, the following expression is satisfied.
3 ≦ φ2 / φ1 ≦ 5 (1)
0.6 ≦ φ3 / φ2 ≦ 0.9 (2)

  As shown in FIG. 2, the adjacent microlenses MS are in contact with each other, and the outer shape thereof is a hexagonal shape.

FIG. 4 is an enlarged view showing a cross section of the lens array. The microlenses MS have the same radius of curvature R (mm). The distance between the optical axes of adjacent microlenses MS is D (mm). At this time, the following expression is satisfied.
1.0 (mm) ≦ R ≦ 2.0 (mm) (3)
1 ・ 0 ≦ R / D ≦ 2.1 (4)

  Further, as shown in FIG. 3, the lens 1 has a leg portion 7 having a recess 6 therein, and the recess 6 has an entrance surface 3 and a side entrance surface 4. Here, the incident surface 3, the side surface incident surface 4, and the LED light source 2 are not in contact with each other, and the periphery of the LED light source 2 is surrounded by the side surface incident surface 4.

In the present embodiment, the light emitted from the LED light source 2 is incident from the side incident surface 4 or the incident surface 3. Further, the light incident from the incident surface 3 is refracted and collected by the convex incident surface 3 and travels toward the output surface 5, and the light incident from the side surface incident surface 4 is reflected by the reflecting surface 8. Heading to the exit surface 5. After that, a part of the light is appropriately scattered by the lens array LA in the inner region 5a of the convex emission surface 5 and emitted to the outside, thereby suppressing the yellow ring and clearly displaying the image of the LED chip. In addition, illuminance unevenness is further suppressed. On the other hand, the remaining light passes through the outer region 5b, is controlled to have a light distribution angle as narrow as within 30 degrees, and is emitted to the outside of the lens 1.
Further, according to the examination results of the present inventors, the LED illumination device of φ2 / φ1 = 4, φ3 / φ2 = 0.8, R = 1.3 (mm), R / D = 2.0 (mm) It was also confirmed that the above-described effects can be obtained while the light distribution angle is 25 degrees and high efficiency of about 80% can be secured.

  FIG. 5 is an enlarged view showing a processing state of a mold for molding a lens according to another embodiment. In FIG. 5, the tool GT has a polished surface TP formed of a part of a spherical surface with a radius R that is rotationally symmetric with respect to the rotation axis X on the lower surface. While the tool GT is rotated about the rotation axis X, the polishing surface TP is brought close to the mold material M, and one molding surface RP that is a spherical surface having a radius R is formed. Thereafter, the tool T is moved in the direction intersecting the rotation axis X by a pitch D together with a drive source (not shown), and the adjacent forming surface RP is similarly processed and formed. At this time, the boundary portion BD is stroked on the polishing surface TP so that the boundary portion BD of the molding surface RP becomes a curved surface having a radius r (moved in an arc shape as indicated by an arrow in the plane of FIG. 5). Then, the tool GT and a drive source (not shown) are moved. By repeating the above, a plurality of molding surfaces RP can be molded.

FIG. 6 is an enlarged cross-sectional view of a lens molded by the mold thus formed.
By performing injection molding using such a mold, as shown in FIG. 6, the microlens MS is transferred and formed by the molding surface RP of the mold, and the curved connecting surface is formed between the microlenses MS by the boundary portion BD. CT is transferred and formed. When the radius of the microlens MS is R (mm) and the radius of the coupling surface CT is r (mm), it is desirable to satisfy the equation (5). Further, when the distance between the optical axes of adjacent microlenses MS is D (mm) and the height from the coupling surface CT of the microlens MS to the surface apex is H (mm), it is desirable to satisfy the equation (6).
R / 20 (mm) ≦ r ≦ R / 10 (mm) (5)
R−√ (R ² − (D / 2) ² ) <H <R (6)

  According to the present embodiment, adjacent microlenses MS are connected to each other by a curved connecting surface CT having a radius r (mm), so that when such a lens is used for an LED illumination device, scattering of emitted light and the like are performed. It is possible to suppress illuminance and light utilization efficiency. Further, by eliminating the edge between the microlenses MS, the stress concentration can be relaxed and the strength of the lens itself can be increased. According to the examination results of the present inventors, it has been found that the strength is improved by about 6% with respect to a lens having an edge between the microlenses MS.

  FIG. 7 is an enlarged view showing a processed state of a mold for molding a lens according to still another embodiment. Here, while rotating the tool GT shown in FIG. 5, the tool GT approaches the mold material M perpendicularly, is processed by a predetermined amount, is separated, and is further moved at a constant pitch in a direction perpendicular to the rotation axis. Then, the molding surface RP arranged in a honeycomb shape is formed by making it approach perpendicularly again with respect to the material M of the mold again, similarly processing a predetermined amount, and then separating it. In such a state, the space between the adjacent molding surfaces RP remains as an edge. Thereafter, as shown in FIG. 7, while rotating the mold material M, the cutting tool BT is moved closer to the predetermined amount and further moved in the radial direction to cut the edge between the molding surfaces RP, and the flat boundary. The surface BD can be formed.

FIG. 8 is an enlarged cross-sectional view of a lens molded by the mold thus formed.
By performing injection molding using such a mold, as shown in FIG. 8, the microlens MS is transferred and formed by the molding surface RP of the mold, and the planar connecting surface is formed between the microlenses MS by the boundary surface BD. CT is transferred and formed. Thereby, scattering of emitted light and the like can be suppressed.

  The present invention has been described above with reference to the embodiments. However, the present invention is not limited to the embodiments described in the present specification, and it is described in the present specification that other embodiments are included. It will be apparent to those skilled in the art from the embodiments, examples, and technical ideas.

DESCRIPTION OF SYMBOLS 1 Lens 2 LED light source 3 Incident surface 4 Side surface incident surface 5 Output surface 6 Concave part 7 Leg part 8 Reflecting surface

Claims (7)

A plurality of LED light sources;
An incident surface that is disposed on the light emission side of the LED light source and receives light emitted from the LED light source, a reflective surface that reflects light incident from the incident surface, and an emission surface that emits the emitted light to the outside Having a lens with
The LED illumination device is characterized in that an exit surface of the lens includes an inner region in which a lens array in which a plurality of microlenses are arranged and an outer region composed of a flat surface, and satisfies the following expression.
3 ≦ φ2 / φ1 ≦ 5 (1)
0.6 ≦ φ3 / φ2 ≦ 0.9 (2)
1.0 (mm) ≦ R ≦ 2.0 (mm) (3)
However,
φ1: Diameter of the LED light source (mm)
φ2: Diameter of the exit surface (mm)
φ3: Diameter of the inner region (mm)
R: radius of curvature of the microlens (mm) The LED illumination device according to claim 1, wherein the following expression is satisfied.
1.0 ≦ R / D ≦ 2.1 (4)
However,
D: Distance between optical axes of adjacent microlenses (mm)   The LED illumination device according to claim 1, wherein the adjacent microlenses are connected by a curved surface having a radius r (mm). The LED illumination device according to claim 3, wherein the following expression is satisfied.
R / 20 (mm) ≦ r ≦ R / 10 (mm) (5)   The LED illumination device according to claim 1, wherein an outer shape of the microlens is a honeycomb shape.   The LED illumination device according to any one of claims 1 to 5, wherein a light distribution angle of outgoing light emitted from the lens is 30 degrees or less.   A lens for an LED illumination device, which is used in the LED illumination device according to claim 1.

Images