JP2013161611A - Ring-shaped lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ring-shaped lighting device capable of lighting at high efficiency irrespective of a distance to an irradiated object.SOLUTION: A ring-shaped lens part 2 includes a ring-shaped Fresnel lens in which triangular prisms 12 are formed in a shape of a plurality of concentric circles, and emitted light from a light emitter 10 is made incident from a base part 14 side of each of the triangular prisms 12 of this Fresnel lens 3 and is totally reflected at an inner face of a first lens face 15 on a farther side from a ring-shaped central axis O and is emitted from a second lens face 16 on a near side from the ring-shaped central axis O, and a light distribution angle is changed frontward in the ring-shaped central axis O direction. The Fresnel lenses 3 of a plurality of kinds having different concentric distances of each of the triangular prisms 12 are provided and are fitted to a case 9 removably in accordance with distances to an irradiated object.

Description

  The present invention relates to a lighting device in which a plurality of light emitters such as light emitting diodes (LEDs) are arranged side by side in a ring shape.

  An illumination device using a plurality of LEDs or the like as a light source as a light source is used in, for example, an image processing device. However, a plurality of LEDs are annularly arranged around an optical axis of an imaging camera, and an imaging target is arranged. A device that performs illumination from the surroundings is known (for example, Patent Document 1).

  An illumination device is also known in which a wiring board on which an LED is mounted is inclined in order to obtain light distribution characteristics in the annular central axis direction with respect to light emitted from LEDs arranged in an annular shape (for example, Patent Document 2).

  However, in Patent Document 2, structural restrictions are large because the wiring board on which the LED is mounted needs to be inclined. In addition, since the inclination angle of the wiring board is fixed, it is necessary to replace the entire lighting device when changing the light distribution characteristics of the LED. Furthermore, it takes much man-hours to form an inclined wiring board, resulting in high costs.

  For this reason, an annular wiring board comprising a plurality of LEDs mounted in an annular shape and front and back surfaces being parallel to each other and an annular Fresnel lens arranged in front of the LED on the emission side are formed, and an annular center is formed. An annular illumination device that illuminates an object to be illuminated positioned forward in the axial direction is also known (for example, Patent Document 3).

JP 2004-127922 A JP 2003-303511 A JP 2002-008410 A

  However, Patent Document 3 condenses light emitted from the LED at a single point with a Fresnel lens, and uses refraction of a general Fresnel lens. Depending on the angle of the peak of the triangular prism of the Fresnel lens, it is difficult to sufficiently focus the object to be illuminated due to its refraction, and it may be impossible to obtain the illumination necessary for image processing. In addition, since the focal length of the Fresnel lens is shifted depending on the distance to the object to be illuminated, it is also necessary to replace the entire illumination device.

  An object of the present invention is to provide an annular illumination device capable of highly efficient illumination regardless of the distance from an object to be illuminated.

  In order to achieve the above object, an annular illumination device according to the present invention includes an annular wiring board on which a plurality of light emitters are attached in an annular shape, and an annular lens portion disposed in front of the light emitter on the emission side. An annular illuminating device for illuminating an object to be illuminated positioned forward in the annular central axis direction, wherein the annular lens portion is a triangular prism. Has a plurality of concentric annular Fresnel lenses, and the light emitted from the light emitter is incident from the base side of each triangular prism of the Fresnel lens, and is the first on the side far from the annular central axis. The total light is reflected from the inner surface of the lens surface, emitted from the second lens surface closer to the annular central axis, and the light distribution angle is changed forward in the direction of the annular central axis. Are different from each other Multiple types of Fresnel lenses are provided that, depending on the distance between object to be illuminated, removably attached to the case.

  According to this configuration, the light emitted from the light emitter is totally reflected by the inner surface of the Fresnel lens, and the light distribution angle is changed forward in the direction of the annular central axis. Even when the distance to the body is short, sufficient light collection is possible. In addition, since a plurality of types of Fresnel lenses having different concentric intervals between the triangular prisms are detachably attached to the case according to the distance from the object to be illuminated, the illumination light can be selected by appropriately selecting the Fresnel lens. It is possible to accurately match the distance of the object to be illuminated. Thereby, an annular illuminating device capable of high-efficiency illumination regardless of the distance to the object to be illuminated is obtained.

  In the present invention, the Fresnel lens has an inclination angle at which the first lens surface of each triangular prism is less than 50 ° with respect to the annular central axis so that the emitted light from the light emitter is totally reflected. It is preferable that it is formed to have. In this case, total reflection of the emitted light from the light emitter on the inner surface of the first lens surface of each triangular prism of the Fresnel lens can be obtained more easily.

  In the present invention, the lens unit further includes a plurality of condensing lenses arranged in an annular shape so as to face the light emitters between the light emitters and the Fresnel lens, and each condenser lens emits each light. The light distribution angle may be changed such that light emitted from the body is incident on the base side of each triangular prism of the Fresnel lens in a direction of 20 ° or less with respect to the annular central axis. By using the condensing lens in this way, the emitted light can be smoothly incident on the base side in a direction approaching the direction parallel to the annular central axis, and on the inner surface of the first lens surface of each triangular prism. Total reflection can be facilitated.

  According to the present invention, the light emitted from the light emitter is totally reflected by the inner surface of the Fresnel lens, and the light distribution angle is changed forward in the direction of the annular central axis. Even when the distance to the body is short, sufficient light collection is possible. In addition, multiple types of Fresnel lenses with different concentric intervals between the triangular prisms are detachably attached to the case according to the distance to the illuminated body, so the Fresnel lenses can be adjusted according to the distance to the illuminated body. You can choose.

It is a disassembled perspective view of the annular illuminating device concerning one Embodiment of this invention. It is a longitudinal cross-sectional view of the same annular illuminating device. It is a top view of the annular illumination device. (A) is a bottom view showing the configuration of the Fresnel lens of the annular illumination device, and (B) is a longitudinal sectional view thereof. (A), (B) is the longitudinal cross-sectional view which expanded a part of the same annular illuminating device.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an exploded perspective view of an annular illumination device according to an embodiment of the present invention. This annular illumination device is arranged in an annular wiring board 1 in which a plurality of light emitters 10 made of LEDs are annularly mounted, and on the front side (upper side in FIG. 1) of the wiring board 1 on the emission side of the light emitter 10. A device body 7 having a lens portion 2 and an annular heat conductive sheet 6 having electrical insulation and high thermal conductivity, and a device having a bottomed double cylindrical shape between the outer wall 21 and the inner wall 22 A heat conductive case 9 for housing the main body 7 is provided.

  The wiring board 1 is formed of flat plates whose front and back surfaces are parallel to each other, and the light emitters 10 are surface-mounted LEDs arranged in a ring, for example. The lens unit 2 is annularly disposed between a plurality of light-emitting bodies 10 and the Fresnel lens 3 so as to face each light-emitting body 10 and between the plurality of light-emitting bodies 10 and the Fresnel lens 3. And a plurality of condensing lenses 5. Each condenser lens 5 is supported by an annular support 17.

  A plurality of wiring board fixtures 23 are attached to the annular wiring board 1 along the circumferential direction. The wiring board fixture 23 has, for example, a U-shape sandwiching the inner and outer peripheral surfaces of the wiring board 1, and the heat conductive sheet 6 is provided between the rear surface of the wiring board 1 and the U-shaped base. And a support 17 for the condenser lens 5 is attached to the front surface of the light emitter 1 mounted on the wiring board 1 by claws provided at both ends of the U-shape.

  As shown in FIG. 2, which is a longitudinal sectional view, the wiring board 1, the condensing lens 5 and the heat conduction sheet 6 before and after the wiring board 1 are fixed by the wiring board fixture 23, and have electrical insulation and high thermal conductivity. The heat conductive sheet 6 is brought into contact with the front surface of the bottom wall 9 a of the case 9 and attached between the outer wall 21 and the inner wall 22 of the case 9. Here, high thermal conductivity means having a thermal conductivity of 5 W / (m · K) or more at room temperature (25 ° C.), and corresponds to silicon, iron, aluminum, and the like. As shown in FIG. 1, a plurality of concave portions 31 and 32 along the outer peripheral surface of the annular Fresnel lens 3 and the heat conductive sheet 6, and a plurality of support members 17 and the wiring board 1 of the condenser lens 5 along the outer peripheral surface. A plurality of recesses 35, 36 are formed along the inner peripheral surface of the recesses 33, 34, and the inner peripheral surface is provided with a protrusion 37 protruding inward of the outer wall 21 of the case 9. This recess is configured to be fitted into a protrusion 38 protruding outward from the inner wall 22.

  The case 9 is provided with a plurality of screw holes 24 penetrating the bottom wall 9a, and the recesses 31 to 36 of the Fresnel lens 3, the condensing lens support 17, the wiring board 1 and the heat conductive sheet 6 are provided in the case 6 In the state where the protrusions 37 and 38 are fitted, the screw holes provided in the bottom portion (not shown) of the wiring board fixture 23 are matched with the screw holes 24, so that the rear surface side of the bottom wall 9 a of the case 9 is aligned. By screwing the screw body 25, the condenser lens support body 17, the wiring board 1 and the heat conductive sheet 6 are attached to the bottom wall 9 a at the rear part of the case 9. On the other hand, a plurality of through holes 26 are provided along the circumferential direction in the vicinity of the inner peripheral surface of the annular Fresnel lens 3, and the plurality of through holes 26 are provided on the front end surface 22 a of the inner wall 22 of the case 9. A plurality of screw bodies 27 are screwed in from the front side of the case 9 so as to match the screw holes 28, and the Fresnel lens 3 is attached to the front opening side of the case 9. The front opening of the case 9 is covered with a cover C (FIG. 2) formed of a material having excellent permeability such as a transparent resin, and can prevent entry of foreign matters such as dust and moisture from the front.

  Since the wiring board 1 is in contact with the front surface of the bottom wall 9a of the case 9 via the heat conductive sheet 6, the heat conductive sheet 6 transfers heat from the light emitter (LED) 10 and internal electronic components to the case 9 side. Since it plays a role of radiating and cooling the inside of the lighting device, the wiring board 1 is hardly affected by heat, and thermal damage can be avoided as much as possible. The heat conductive sheet 6 also has a function of holding the wiring board 1. The heat conductive sheet 6 is preferably formed of a silicon sheet that is excellent in electrical insulation and thermal conductivity and imparted with tackiness.

  The case 9 in FIG. 1 is made of a material having excellent thermal conductivity, for example, aluminum. As shown in FIG. 3, a plurality of heat radiating fins 19 are formed on the rear surface of the bottom wall. Heat generated by the body (LED) 10 and internal electronic components is efficiently radiated through the heat conductive sheet 6 to prevent performance degradation due to temperature rise. An electric wire 18 fixed to the back end portion of the wiring board 1 is drawn out from an extraction hole 30 of the case 9 to the outside. In addition, a plurality of mounting screw portions 40 in which female threads are formed by tapping are formed on the back surface of the case 9, and the lighting device is attached to another device (not shown) using this.

  As shown in FIG. 4A, the annular Fresnel lens 3 has a plurality of concentric circular prisms 12 spaced apart in the radial direction X, and is shown in the longitudinal sectional view of FIG. As described above, the light distribution angle of the emitted light from the light emitter 10 is changed forward in the direction of the annular central axis O.

  As shown in FIG. 4B, the Fresnel lens 3 causes the light emitted from the light emitter 10 to enter from the base 14 side of each triangular prism 12 shown in the enlarged view of the B portion, and is on the side far from the annular central axis O. The light is totally reflected by the inner surface of the first lens surface 15 and emitted from the second lens surface 16 on the side closer to the annular central axis O, and the light distribution angle is changed forward in the direction of the annular central axis O.

  In this case, as shown in FIG. 5A, the condenser lens 6 causes the light emitted from the light emitter 10 mounted on the wiring board 1 to be totally reflected by the inner surface of the first lens surface 15. The emitted light is made incident on the base 14 side of the triangular prism 12 in a direction in which the angle θ1 with respect to the direction Y parallel to the annular central axis O is 20 ° or less. In the base portion 14, the light emitted from the condenser lens 6 is slightly refracted so as to approach the direction Y due to the difference in refractive index, and enters the base portion 14. At the same time, the first lens surface 15 of each triangular prism 12 is formed to have an inclination angle θ of less than 50 ° with respect to the direction Y parallel to the annular central axis O. That is, as shown in FIG. 5B, the peaks of the triangular prisms 12 each having a saw-like cross section along the radial direction X are formed to have an acute angle θ0.

  In a Fresnel lens, a sawtooth triangular crest is usually formed at an acute angle gradually from the center of the concentric circle toward the periphery of the concentric circle. For example, unlike the present invention, when the first lens surface is inclined at a large distance with respect to the direction Y, for example, an angle of 50 ° or more, that is, when a triangular prism peak such as the concentric circle center side is formed, Light emitted from the light emitter is refracted, not totally reflected, on the inner surface of the first lens surface. Therefore, the Fresnel lens 3 in FIG. 5B has an annular shape with the central side removed, and each triangular prism 12 is located on the concentric peripheral side where the inclination angle θ of the first lens surface 15 is small. A mountain having a sharp angle θ0 is used. At this time, since the inclination angle of the second lens surface 16 is also small, the light totally reflected by the first lens surface 15 is emitted in a direction substantially perpendicular to the second lens surface 16. The range of the inclination angle θ with respect to the Y direction of the first lens surface 15 is preferably in the range of 25 ° to 49 °, for example.

  For this reason, light distribution to the front vicinity of the illuminating device is achieved by total reflection of the inner surface of the first lens surface 15 within the above-described range of the inclination angle θ with respect to the Y direction, as compared with a conventional lens using the Fresnel lens. Even when the angle increases and the distance to the object to be illuminated is short, sufficient light collection is possible. In addition, unlike the conventional use of refraction, reflection does not occur simultaneously with refraction, and the light efficiency in the Fresnel lens 3 is suppressed by total reflection. Moreover, it is also preferable that each triangular prism 12 of the Fresnel lens 3 does not have a focal point that focuses light at one point. In this case, the illumination light by total reflection from the triangular prisms 12 concentrically spaced from each other in the radial direction X of the Fresnel lens 3 overlap with each other, so that uniform illumination is obtained.

  Further, as shown in FIG. 5A, each condensing lens 5 has a triangular prism of the Fresnel lens 3 in the direction in which the angle θ1 is 20 ° or less as described above. The light distribution angle is changed so as to be incident on the base 14 side of the twelve. That is, the condensing lens 5 is refracted at the emission angle θ3 with respect to the incident angle θ2 of light (θ2> θ3). Accordingly, the emitted light can be smoothly incident on the base 14 side in a direction approaching the direction Y parallel to the annular central axis O, and is easily totally reflected by the inner surface of the first lens surface 15 of each triangular prism 12. Become.

  In this way, this apparatus totally reflects the light emitted from the light emitter 10 on the inner surface of the first lens surface 15 of each triangular prism 12 of the Fresnel lens 3 to change the light distribution angle forward in the direction of the annular central axis O. Therefore, compared with a conventional lens utilizing the refraction of a Fresnel lens, the light distribution angle can be greatly changed, and sufficient condensing can be performed even when the distance to the illuminated body is short.

  The direction of the illumination light from the Fresnel lens 3 changes depending on the width of the concentric circle interval of the triangular prism 12. That is, when the interval between the concentric circles of the Fresnel lens 3 is narrow and the number of peaks of the triangular prism 12 is large in the radial direction X, the inclination angle θ of each triangular prism 12 with respect to the Y direction of the first lens surface 15 is within the above range. At this time, the angle of total reflection at the inner surface of the first lens surface 15 is incident on the inner surface at a small angle and is emitted at a small angle. Reach farther forward in the O direction. Accordingly, a plurality of types of Fresnel lenses 3 having different concentric intervals between the triangular prisms 12 are prepared, and can be detachably attached to the case 9 according to the distance from the object to be illuminated. Irrespective of the distance to the body, highly efficient lighting is possible.

  In this way, in the present apparatus, a plurality of types of Fresnel lenses 3 having different concentric intervals between the triangular prisms 12 are detachably attached to the case 9 according to the distance from the object to be illuminated. By selecting, the illumination light can be accurately matched to the object to be illuminated according to the distance between the present apparatus and the object to be illuminated.

  Thus, in the present invention, the light emitted from the light emitter 10 is totally reflected by the inner surface of the Fresnel lens 3 and the light distribution angle is changed forward in the direction of the annular central axis O. As compared with the above, sufficient condensing is possible even when the distance to the illuminated body is short. In addition, since a plurality of types of Fresnel lenses 3 having different concentric intervals between the triangular prisms 12 are detachably attached to the case 9 in accordance with the distance from the object to be illuminated, the Fresnel lens 3 is appropriately selected. The illumination light can be accurately adjusted to the distance of the object to be illuminated. Thereby, an annular illuminating device capable of high-efficiency illumination regardless of the distance to the object to be illuminated is obtained.

  In this embodiment, the condenser lens 5 is provided, but may be omitted if necessary. Moreover, although the light emitter 10 is a surface-mount type LED, it may be a bullet-type LED.

  In this embodiment, the apparatus main body 7 is formed in an annular shape, but includes a shape in which a part of the annular ring is cut out, and other shapes such as a rectangular shape including a rectangle.

  As described above, the preferred embodiments have been described with reference to the drawings. However, those skilled in the art will readily understand various changes and modifications within the obvious scope by looking at the present specification. Accordingly, such changes and modifications are to be construed as within the scope of the invention as defined by the appended claims.

1: Wiring board 2: Lens part 3: Fresnel lens 5: Condensing lens 7: Device main body 9: Case 10: Light emitter (LED)
12: Triangular prism 14: Base 15: First lens surface 16: Second lens surface O: Ring center axis Y: Direction parallel to ring center axis

Claims (3)

An annular wiring board in which a plurality of light emitters are annularly attached, an apparatus main body having an annular lens portion disposed in front of the light emitter, and a case for housing the apparatus main body, An annular illumination device that illuminates an object to be illuminated located in front of the annular central axis direction,
The annular lens portion has an annular Fresnel lens in which triangular prisms are formed in a plurality of concentric circles, and light emitted from the light emitter is incident from the base side of each triangular prism of the Fresnel lens. The total light is reflected by the inner surface of the first lens surface on the side far from the annular central axis and emitted from the second lens surface on the side closer to the annular central axis, and the light distribution angle is changed forward in the direction of the annular central axis. And
A plurality of types of Fresnel lenses having different concentric intervals between the triangular prisms are provided, and are detachably attached to the case according to the distance to the object to be illuminated.
Annular lighting device. In claim 1,
The Fresnel lens is formed so that the first lens surface of each triangular prism has an inclination angle of less than 50 ° with respect to the annular central axis so that light emitted from the light emitter is totally reflected. An annular lighting device. In claim 2,
The lens unit further includes a plurality of condensing lenses arranged in an annular shape so as to face the light emitters between the light emitters and the Fresnel lens. An annular illumination device that changes a light distribution angle so that incident light is incident on a base side of each triangular prism of the Fresnel lens in a direction that is 20 ° or less with respect to the annular central axis.

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