JP2011249294A - Lighting device and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED lighting device downsized and capable of attaining a uniform illumination distribution.SOLUTION: The LED lighting device has a condensing lens 2 composed of a convex lens 2A thin at a central section and a transparent annular body 2B having a curvature larger than that of the convex lens 2A at an outer peripheral section.

Description

Detailed Description of the Invention

  The present invention relates to an illuminating device, and more particularly to an illuminating device with excellent energy efficiency that can obtain a substantially uniform illuminance within a required circle.

  In a lighting device using a semiconductor light emitting element as a light source, a part of the light emitted from the light source to the front surface diffuses, so that the illuminance in the irradiation field tends to be non-uniform. Many ideas have been made to make the illuminance uniform, which is disclosed as patent information.

  The illuminating device disclosed in Japanese Patent Publication No. 2006-243603 (Patent Document 1) includes a light emitting diode and a lens for controlling an irradiation angle, and a lens formed of a rotationally symmetric transparent member has four regions having different functions. Have. The four areas are a light incident area located in the central part on the light source side, a reflection area around it, a first light emitting area in the central part on the side far from the light source, and a second (inside) surrounding it. , A third (outside) light exit region. The light incident area is a concave curved surface, the third light exit area is a conical surface or a concave curved surface, and the other three are convex curved surfaces.

  Light incident from the light incident area in a direction close to the optical axis passes through the first light exit area and is converged and travels to the front. Part of the light incident in the direction away from the optical axis is reflected by the reflection area (mostly considered to be total reflection), emitted forward from the third light emission area, and slightly closer to the optical axis. The part directly reaches the second light exit area and is emitted forward.

  FIG. 5 shows a conventional lighting device described in Patent Document 1. The illumination device 80 includes a hemispherical LED element 82 and a lens (light condensing element) 81. The lens 81 is made of a transparent member having a rotationally symmetric shape with respect to the axis X. The lens 81 has a convex surface area A in the center, a curved surface area B on the peripheral side, a curved surface reflection area C, a concave curved surface incidence area D in the center, and a convex curved surface area E provided between the areas A and B. The LED element 82 is disposed to face the concave curved surface incident area D. The LED element 82 and the lens 81 have the same optical axis.

  Of the light that has entered the concave curved surface incident area D from the LED 82, the light that has reached the convex curved surface area A is emitted frontward. The light traveling toward the curved reflection area C is reflected by this area and emitted forward through the curved area B on the peripheral side. The refractive index of the lens 81 and the curvature of the curved surface area are so selected. A portion of light corresponding to the light in these two directions is emitted forward through a convex curved region E between regions A and B.

  In Japanese Patent No. 4377211 (Patent Document 2), light is emitted forward at a relatively large diffusion angle from the first portion close to the axis, and emitted at a relatively small diffusion angle from the second portion around it. There is described an illuminating lamp that uses a condensing lens designed to form a rectangular light distribution pattern on an irradiated surface.

  FIG. 6 shows a main part of the illumination device described in Patent Document 2. The illuminating device 90 is composed of a light emitting diode 92 and a lens 93, and their optical axes are matched. A transparent protective plate 94 is provided between the two. The lens 93 is a plano-convex lens and is divided into a first region 93A close to the optical axis and a peripheral second region 93B. The convex surface of the first region 93A has a relatively small curvature (average), and the second region 93B. The convex surface of has a larger curvature (average).

  The light incident on the lens 93 from the light emitting diode 92 is emitted at a relatively large angle with respect to the optical axis in the first region 93A close to the optical axis, while at a relatively small angle in the second region 93B far from the optical axis. Converged. As a result, as shown by the representative trajectories L1 and L2 in the figure, the light L1 from the first region 93A and the light L1 from the second region 93B are near the optical axis. It is said that the illuminance decrease at a position where the angle with respect to the optical axis is slightly larger is compensated, and the illuminance that is equalized over the wide range of angles is obtained.

  Japanese Patent Publication No. 2006-243603   Japanese Patent No. 4377211

Problems to be solved by the invention

  The lens described in Patent Document 1 has a large thickness in the optical axis direction, and further has a reflective region that protrudes laterally (in a direction away from the optical axis), and thus has a large weight.

  The lens described in Patent Document 2 is also heavy because it has a large thickness in the optical axis direction as a whole. The large weight of the lens makes the entire lighting device heavy, and even if there are no problems during use, the burden on the operator when carrying many for installation or replacement is great.

  In this structure, the distance from the entrance surface to the exit surface is particularly long in the first portion, so that the light absorption in the lens increases and the loss of light amount is not small.

  Furthermore, in both Patent Documents 1 and 2, since the lens provided on the front surface of the light emitting element is thick, heat dissipation through the lens is hindered, and when used for a long time, the light emitting element itself and the lens back surface (light source side) Increase in temperature. In particular, the illumination device of Patent Document 1 has a structure in which the light emitting element and the condenser lens are in close contact with each other, and therefore, the temperature rise at the light source side portion of the lens is large.

  An object of the present invention is to provide an illuminating device using a semiconductor light emitting element as a light source, in which the illuminance of the irradiated surface is made uniform using a lightweight lens.

  Another object of the present invention is to provide an illumination device that uses a semiconductor light-emitting element as a light source to obtain an efficient illumination device in which the illuminance of the irradiated surface is made uniform and the light absorption in the lens is small.

  A further object of the present invention is to obtain an illuminating device in which the illuminance of the irradiated surface is made uniform and the heat radiation through the lens is improved.

Means for solving the problem

  In order to achieve the above object, an illumination device of the present invention includes a substrate, a semiconductor light emitting element such as a light emitting diode provided on one surface thereof, and a transmissive optical element such as a lens provided coaxially facing the semiconductor light emitting element. In the illuminating device, the transmissive optical element includes a convex lens having a first circumference as an outer edge, and a second circumference having a diameter that is concentric with the first circumference and having a diameter larger than the outer circumference. The annular body is composed of a bottom surface facing the semiconductor light emitting device, a circular inner wall having a circular cross section concentric with the first circumference and having the same or a smaller diameter, and a side surface. The cross section including the axis of the annular body (passing through the center of the second circumference) has a first straight line corresponding to the inner wall and a second straight line corresponding to the bottom surface or an arc that is concave outward. One curve and a third straight line corresponding to the side or It consists of a triangle or a similar triangular figure mainly surrounded by a second curve such as a convex arc toward the surface, and the convex lens is provided at the light source side end of the inner wall of the annular body or at an intermediate portion close to the end, The bottom surface of the annular body is characterized by having an inclination from the outer edge toward the inner edge and away from the surface of the substrate.

  A typical example of a semiconductor light emitting device is a light emitting diode. The transmissive optical element is a convex lens and an annular convex lens (hereinafter referred to as an annular body) surrounding the convex lens.

  The annular body includes a bottom surface facing the substrate on which the semiconductor light emitting element is provided, a cylindrical inner wall having a circular cross section that is concentric with the first circumference and has the same diameter or a smaller diameter. The cross section including the axis passing through the center of the annular body may be a triangle surrounded by first, second, and third straight lines, or a straight line corresponding to the inner wall of the circular tube and an outer side corresponding to the bottom surface ( It may be a figure surrounded by a concave curve (first) and an outer convex curve (second) corresponding to the side surface. The outwardly convex curve corresponding to the side surface may be replaced with a straight line. The annular body corresponds to a rotating body formed by rotating such a cross section around an axis. In other words, it has a shape like a face with a hole in the bottom. You may have a plane part in a part of upper end (end far from a light source) of an annular body.

  When the convex lens is provided at the light source side end of the inner wall of the circular tube, the outer edge portion of the convex lens may penetrate into the inner side (the side closer to the center) of the bottom surface of the annular body. At this time, the diameter of the convex lens is larger than the diameter of the inner wall of the annular body.

  An annular body is an annular prism when the cross section including the axis is a triangle, and has a light converging effect, but has an effect of improving the brightness of the central portion of the irradiation field.

  The annular body can be made of glass, acrylic resin, polyethylene, polypropylene, polycarbonate, styrene resin, epoxy resin, or other transparent solid material. In principle, it is colorless, but it may be colored to adjust the hue. A part of the surface may be matted.

  When the light source has a plurality of light emitting elements on the substrate, an optical element may be individually provided on the front surface of the light emitting element. If necessary, optical elements having different shapes may be used for the plurality of light emitting elements. In an illuminating device in which a plurality of light emitting elements are arranged concentrically or radially on the substrate, an optical element having a stronger condensing function than the one near the center may be used as the light emitting element closer to the outside. The light emitting element and the optical element are not strictly coaxial, and the former may be slightly deviated from the latter optical axis.

The invention's effect

  According to the present invention, in an illuminating device using a semiconductor light emitting element such as a light emitting diode as a light source, the illuminance on the irradiated surface can be made uniform using a lightweight lens. Further, according to the present invention, in the illumination device using the semiconductor light emitting element as the light source, the illuminance on the irradiated surface can be made uniform without causing a decrease in illuminance due to light absorption in the lens. Furthermore, according to the present invention, it is possible to make the illuminance of the irradiated surface uniform without hindering heat dissipation through the lens, and to suppress an increase in temperature when used for a long time.

  The transmissive optical element used in the present invention does not require a particularly thick lens as the convex lens in the central portion, and uses a convex lens having a normal thickness. Therefore, unlike a conventional lighting device, the weight of the lighting device is increased. Therefore, the illuminance on the irradiated surface can be made uniform. Not only that, but also a decrease in illuminance due to light absorption in the thick lens can be avoided. Furthermore, since heat dissipation through the lens is not hindered, temperature rise when used for a long time can be suppressed, and a uniform illuminance distribution can be obtained.

  In the illuminating device of the present invention, since the bottom surface of the annular body has an inclination from the outer edge to the inner edge and away from the substrate surface, both the bottom of the annular body and the convex lens disposed near the axis are heated to a high temperature. Therefore, the temperature is less likely to rise than when the light source is in close contact with the light source.

  In the apparatus of the present invention, the convex lens disposed in the central portion is located at the bottom or intermediate portion of the cylindrical tube passing through the annular body, so that the light passing through the convex lens is reflected by the inner wall of the tube, preventing wide-angle scattering. The illuminance near the center of the irradiation field is improved. That is, the annular body serves as a hood for the convex lens.

BEST MODE FOR CARRYING OUT THE INVENTION

(Configuration of the first embodiment)
1 and 2 show a lighting device according to a first embodiment of the present invention. 1 is a plan view, and FIG. 2 is a cross-sectional view in a plane including the optical axis. The illumination device 10 includes a light emitting diode element 1 and a lens unit 2 that covers the light emitting diode element 1. The light emitting diode element 1 is mounted on the substrate 1b using the space 3. The lens unit 2 includes a convex lens unit 2A and an annular lens unit 2B. The convex lens portion 2A is formed of a spherical surface 2a on the light source side (back surface) and a spherical surface 2b on the side far from the light source (front surface). The annular lens portion 2B is an annular body that is mainly defined by a spherical surface 2e and a spherical inner surface 2d on the front side in the axial direction and a cylindrical inner surface 2c in the radial direction. A connecting portion 2g is provided on the outer periphery of the annular lens portion 2B.

(Operation of the first embodiment)
Of the light emitted from the light-emitting diode element 1, a portion close to the optical axis of the lens unit 2 enters the convex lens unit 2A from the spherical surface 2a, passes through the spherical surface 2b on the front surface, and proceeds to the front of the lens unit. Illuminate the vicinity. Most of the light traveling from the spherical surface 2b to a slightly larger angle with respect to the optical axis is reflected at least once by the cylindrical inner surface 2c, and reinforces the illumination near the center of the irradiated surface.

  Light exiting the light emitting diode element 1 and traveling in a direction away from the optical axis of the lens unit 2 enters the annular lens unit 2B from the spherical inner surface 2d, travels to the front of the annular lens unit via the front spherical surface 2e, and is irradiated. Mainly illuminate the area outside the surface. In addition, a part of the light is emitted through the flat portion 2f at the front end of the annular lens portion.

(Effect of the first embodiment)
Since the thickness of the convex lens near the optical axis is small, the entire condenser lens, and hence the entire illumination device, is lightened, and the illuminance reduction due to light absorption in the lens is extremely small. That is, it is possible to realize a light-weight LED lighting device that avoids light absorption in a thick lens (having a large axial length) as in a conventional lighting device, and that has a uniform illuminance on an irradiated surface. In addition, the heat dissipation through the lens is not hindered, as in the case of using a thick lens as a whole, so the temperature rise around the light emitting element when used for a long time is suppressed, and the illuminance on the irradiated surface is uniform. Can be realized.

(Second embodiment)
FIG. 3 shows a lighting device according to the second embodiment, and is a plan view from the lens side. The lighting device 20 is composed of nine and three LED lighting units 21 and 22 arranged along two circumferences. These lighting units have the same structure as the lighting device 10 shown in FIGS. The extension of the connecting portion 2g in FIG.

  FIG. 4 shows a cross section along the cutting line AA in FIG. Since the structure and operation (operation, effect) of the LED illumination units 21 and 22 are the same as those of the illumination device 10 of the first embodiment, description thereof is omitted.

The lighting device 20 according to the second embodiment includes an LED light emitting element having a power consumption of 1 W and a color temperature of 3400 ° K for the LED lighting unit 21, and an LED element having a power consumption of 1 W and a color temperature of 6500 ° K for the LED lighting unit 22. Produced using each. The dimensions of each lens part are as shown in Table 1.

  The top view which shows the illuminating device which is 1st embodiment of this invention.   Cross-sectional explanatory drawing   The top view of the illuminating device by 2nd embodiment   Cross-sectional explanatory drawing   Cross-sectional explanatory drawing showing a conventional lighting device (corresponding to Patent Document 1)   Cross-sectional explanatory drawing showing a conventional illumination device (corresponding to Patent Document 2)

DESCRIPTION OF SYMBOLS 1 Light emitting diode element 1b Board | substrate 2 Lens part 2A Convex lens part 2B Annular lens part 2a, 2b Spherical surface 2c Cylindrical inner surface 2d Spherical inner surface 2e Spherical surface 2f Flat part 2g Connection part 3 Space 4 Base 10 Lighting device 20 Lighting device 21, 22 LED lighting unit 80 Illuminator 81 Lens 82 LED Element A Convex Curved Area B Curved Area C Curved Reflection Area D Concave Curve Incidence Area E Convex Curved Area 90 Illuminator 92 Light Emitting Diode 92a Light Emitting Point 93 Lens 93A First Area 93B Second Area 94 Protection Plate

Claims (7)

In an illuminating device comprising a light source comprising a substrate and a semiconductor light emitting element such as a light emitting diode provided on one surface thereof, and a transmissive optical element such as a lens provided concentrically facing the semiconductor light emitting element,
The transmissive optical element includes a convex lens having a first circumference as an outer edge;
The outer circumference is a second circumference that is concentric with the first circumference and has a larger diameter, and comprises a transparent annular body surrounding the convex lens,
The annular body includes a bottom surface facing the semiconductor light emitting element, a circular inner wall having a circular cross section having a diameter that is concentric with, or close to, the first circumference, and a side surface;
The cross section including the axis of the annular body (passing through the center of the second circumference) has a first straight line corresponding to the inner wall and a second straight line corresponding to the bottom surface or an arc that is concave outward. Consisting of a triangle or similar triangle figure mainly surrounded by a first curve such as and a second straight line corresponding to the side surface or a second curve such as an outwardly convex arc;
The convex lens is provided at a light source side end of the inner wall of the annular body or an intermediate portion close to the end, and the bottom surface of the annular body has an inclination from the outer edge toward the inner edge and away from the surface of the substrate. A lighting device.   The lighting device according to claim 1, wherein the cross section is mainly surrounded by the first straight line, the first curved line, and the second curved line or the third straight line.   The lighting device according to claim 1, wherein the first curve is an arc.   The lighting device according to claim 1, wherein the semiconductor light emitting element is a light emitting diode.   The illuminating device according to claim 1, wherein a plurality of the light emitting elements are provided on a substrate, and the transmissive optical element is individually provided for each light emitting element.   The illumination device according to claim 5, wherein different transmissive optical elements are provided for one or more of the light emitting elements. A convex lens with the first circumference as the outer edge;
A transparent annular body that is concentric with the first circumference and has a second circumference with a larger diameter as an outer edge and surrounds the convex lens;
The annular body is composed of a bottom surface on which light is incident, a circular inner wall having a circular cross section, concentric with the first circumference and having the same diameter or a smaller diameter, and a side surface.
The cross section including the axis of the annular body (passing through the center of the second circumference) includes a first straight line corresponding to the inner wall and an arc concave outward toward the bottom. Consists of a pair of triangular figures similar to a triangle, consisting of a first curve and a second curve, such as an outwardly convex arc, corresponding to the side surface,
The bottom surface has a negative height relative to a plane whose inner edge includes the outer edge;
The optical element, wherein the convex lens is provided at an end near the bottom surface of the inner wall of the annular body or an intermediate portion near the end.

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