JP2003004641A - Illumination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable illumination with an even and high illuminance by efficiently collecting light emitted from an annular light source to a body to be illuminated on an axis. SOLUTION: LEDs 1b are set outwards annularly, and a reflecting mirror 2 having a reflecting plane 2a of a concave surface is set to surround the LEDs 1b. A section of the reflecting plane 2a including the axis C and the LEDs 1b is a part of an ellipse A which has the LEDs 1b as one focal point F and an irradiation target point (irradiation face 3) as the other focal point F'. The reflecting plane 2a is formed by rotating the curve about the axis C with the F' being fixed. The reflecting plane 2a comprises parts which cover an effective emission angle ±ω of each LED 1b and prevent the reflection light from being blocked by the annular light source 1. The light emitted from each LED 1b hits the reflecting plane 2a without being wasted and overlaps each other at the irradiation face 3, so that the high illuminance and the illuminance evenness are achieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination device suitable for an image device or the like for recognizing or inspecting an object to be inspected using a camera, and more specifically, a light source arranged in an annular shape and a reflecting surface suitable for the light source. And a lighting device provided with.

[0002]

2. Description of the Related Art In order to obtain a desired image with a camera, it is necessary to have optimum illumination suitable for the purpose. As one of such illuminations, an illumination device including a light source in which a plurality of LEDs are arranged in an annular shape is known. For example, in the illumination device disclosed in Japanese Patent Application Laid-Open No. 10-149705, a plurality of LEDs are arranged side by side in a ring shape so that a space is formed in the central portion, and each optical axis of the plurality of LEDs is a ring shape. They are arranged so as to be oriented in the axial direction and inclined at a predetermined angle. As a result, a plurality of lights are irradiated so as to overlap with each other from different directions on the object to be inspected placed at a predetermined position on or near the axis of the ring, so that irradiation with less unevenness as a whole can be performed. It is possible. Also,
In addition to this, there are illumination devices described in Japanese Patent Application Laid-Open No. 10-112121 and Japanese Patent No. 3118503.

[0003]

One of the greatest demands for such an illuminating device is to obtain a high illuminance on the object to be inspected. In the conventional lighting device described above,
It is possible to perform illumination with less unevenness, but on the other hand, the illumination range is considerably wide. In the case of the illumination for the inspection device, there are cases where it is desired to illuminate a wide range of the object to be inspected at the same time, but there are also cases where it is desired to focus on a narrow range and illuminate the area. In such a case, the above-mentioned conventional lighting device has a problem in that the illuminance is not necessarily high and the illuminance is insufficient because a large amount of light falls outside the desired range. Of course, if the number of LEDs is increased in the above-mentioned technique, the illuminance can be increased accordingly. However, as a matter of course, the cost increases accordingly. Especially when trying to use a white LED to obtain a uniform white light, the cost of the white LED currently accounts for a large proportion, so LE
The method of increasing the number of D is not a good idea.

In order to obtain a higher illuminance while limiting the number of LEDs used, it is necessary to irradiate the object to be irradiated with light emitted from the LEDs as little as possible. The present invention has been made to solve such problems, and its main purpose is to provide an LED.
An object of the present invention is to provide a lighting device capable of intensively irradiating an object with light of high illuminance at a relatively low cost by effectively utilizing the emitted light from the.

[0005]

Means for Solving the Problems and Effects The lighting device according to the present invention made to solve the above problems comprises: a) an annular shape with a predetermined axis as a center and a light emitting direction with respect to the axis. An annular light source composed of a light emitting source arranged so as to face outward; and b) a reflecting mirror surrounding the annular light source and having a reflecting surface facing the annular light source. In one half cross section divided by the axis among the cross sections including the axis and the light emission source, an aspherical curve having the light emission source as one focal point, the curve being centered on the axis It is a concave curved surface formed in a space by rotating, and is characterized in that light emitted from the annular light source and reflected by the reflecting surface is applied to the axis or the vicinity thereof.

In the illuminating device according to the present invention, a typical light source is a light emitting diode (LED), but in addition to this, for example, through an aperture opening provided at an appropriate position of a light shield that shields an annular fluorescent lamp. A light source that emits light to the outside or an annular fluorescent lamp itself may be used as the annular light source.

In the illuminating device according to the present invention, since each light emitting source forming the annular light source is arranged at one focal point of the reflecting surface, the light emitted from each light emitting source with a certain spread. Hits the reflecting surface and is converged or substantially collimated, and both travel toward or near the axis. And
On the irradiation surface placed substantially perpendicular to the axis, the reflected lights corresponding to the respective light emitting sources are overlapped with each other, thereby increasing the illuminance and enabling highly uniform illumination with less uneven illuminance.

The above-mentioned aspherical curve may be, for example, a part of an ellipse having the light emitting source as one focal point.
When the curve of the aspherical surface has two focal points as described above, the reflecting surface can be configured such that the other focal point of the aspherical curve in the half cross section is located on the axis. According to this configuration, the light emitted from the annular light source is concentrated on the focal point located on the axis, so that extremely high illuminance can be obtained near the focal point.

Further, at the positions shifted before and after the focal point on the axis, the reflected lights corresponding to the light emitting sources do not completely overlap with each other, and the light hardly reaches the vicinity of the axis. Circular illumination can be provided.

The aspherical curve may be a parabola whose focal point is a light emitting source. With such a configuration, since the reflected light from the reflecting surface becomes almost parallel light and travels toward the irradiation surface, it is suitable for uniformly illuminating a wider area rather than intensively illuminating a very narrow area. Is. Further, by disposing a diffusion plate between the irradiation surface and the reflection surface and introducing the diffused light that has passed through the diffusion plate to the irradiation surface, the uniformity of illuminance can be further enhanced.

The positional relationship between the light emitting source and the reflecting mirror may be determined so that almost all light within an effective light distribution angle including the optical axis of the light emitting source strikes the reflecting surface. preferable. According to this configuration, almost all the light emitted from the light emitting source is reflected by the reflecting mirror without waste and travels toward the irradiation surface, so that the illuminance on the irradiation surface can be further increased. Further, since the light emitted from any of the light emitting sources is reflected in the same manner, the uniformity of illuminance on the irradiation surface is improved.

In the illuminating device according to the present invention, the reflecting mirror has an opening around the axis including the axis, and the irradiation site can be observed from the opposite side of the reflecting surface through the opening. Can be According to such a configuration, the irradiation site on the irradiation surface can be observed from a direction substantially perpendicular to the irradiation surface, which is suitable for applications such as a microscope and an inspection device.

As an aspect of the present invention, the annular light source is
A light emitting diode as the light emitting source and a tubular body surrounding the shaft may be included, and a plurality of the light emitting diodes may be arranged side by side in the circumferential direction of the outer periphery of the tubular body. Further, in such a configuration, the cylindrical body is
It is preferable to use a structure in which the member is divided into a plurality of cut surfaces that extend in the same direction as the axis. According to this configuration, in the state before combining the members divided into a plurality, the inner peripheral side of the cylindrical body is completely open toward the outside, so that the leads of the light emitting diode protruding to the inner peripheral side of the cylindrical body, Alternatively, the work of soldering the lead and the electric wire can be easily performed, and the workability in manufacturing is improved.

Further, it is convenient that the cylindrical body is attached to the reflecting mirror. Here, the cylindrical body may be directly attached to the reflecting mirror with screws or an adhesive agent, but may be indirectly attached by inserting another member. According to this configuration, the light emitting diode attached to the cylindrical body is positioned and angled so that the light emitting diode is located at one focal point of the reflecting surface and the optical axis of the light emitting diode forms a predetermined angle with the reflecting surface. It can be done easily and accurately. Therefore, it is advantageous for increasing the illuminance on the target irradiation surface and accurately setting the illumination range.

Further, the plurality of light emitting diodes may include those having different emission wavelengths.
According to this configuration, light having various colors can be obtained on the irradiation surface by selectively turning on the light emitting sources having different wavelengths.

In the above-mentioned various embodiments, the target points on the light-emitting source and the irradiation surface do not necessarily have to be exactly on the respective focal points, and even if they are slightly deviated from them, it is sufficient to achieve the object of the present invention. It is possible. Therefore, the "focal point" used above and in the claims includes not only the geometrical focal point but also the vicinity thereof. The "cutting surface" that divides the tubular body may not be strictly in the same direction as the axis but may be slightly inclined.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION [First Embodiment] First, the principle configuration of an illumination device according to the present invention and its operation will be described. FIG. 1 is a sectional view of a lighting device according to a first exemplary embodiment of the present invention, taken along a plane including an axis C and a light source. The axis C is a rotational symmetry axis of the reflecting surface 2a described later. Note that, in FIG. 1, only representative optical paths are shown in order to avoid complication of the drawing, but it is natural that light other than those shown in the drawings may pass through many optical paths.

The annular light source 1 comprises a plurality of LEDs 1b, which are light emitting sources, arranged on a substrate 1a having a substantially cylindrical shape centered on an axis C with a predetermined interval in the circumferential direction. The reflecting surface 2a of the reflecting mirror 2 is provided so as to surround the annular light source 1, and the cross section of the reflecting surface 2a is a part of ellipses (second-order aspherical curves) A and A'shown by dotted lines in FIG. Are configured.
This ellipse A, A'has two focal points, LED1
b (strictly speaking, the light emitting body of the LED 1b) is placed at one focus (first focus) F, and the irradiation target point of the irradiation surface 3 arranged on the axis C is set at the other focus (second focus F ′). Put.

That is, the major axis S, which is the line connecting the two focal points F and F'of the ellipse A (or A '), forms an angle θ with respect to the axis C.
A part of the curved surface which is inclined by 1 and which is formed by fixing the second focus F ′ and rotating the ellipse A once around the axis C is the reflecting surface 2a in the three-dimensional space.
It should be noted that even if these arrangements are slightly displaced, there is often no problem in practical use, and rather, it is also possible to use a method of intentionally defocusing in order to expand the irradiation range somewhat.

The light emitted from the LED 1b has a light distribution that spreads in a solid angle around the optical axis P. The wider the light distribution, the greater the optical aberration of the LED. Only light included in a certain range of solid angle is used as effective light. In FIG. 1, the half value of the effective emission angle, which is the range of this effective light, is represented by ω. From LED1b,
Most of the light is emitted within the effective emission angle range ± ω centered on the optical axis P. In the present embodiment, the optical axis P of each LED 1b is inclined from the major axis S of the ellipse A as shown in FIG. The reflecting surface 2a of the reflecting mirror 2 is provided at a position that surely covers the effective emission angle range ± ω emitted from each LED 1b. Therefore, the LED 1b does not directly face the reflecting surface 2a of the reflecting mirror 2. Of course, the irradiation surface 3 is not directly faced. With this arrangement, the LED1
All the light emitted from b within the effective emission angle range ± ω is reflected by the reflecting mirror 2 and focused on the irradiation surface 3 without being blocked by the LED 1b or the substrate 1a.

A specific method for determining the arrangement of the LED 1b and the reflecting surface 2a in the cross section shown in FIG. 1 will be described below. Figure 3
FIG. 4 is a partially enlarged cross-sectional view of an LED 1b and a reflecting surface 2a. In FIG. 3, the angle at which the optical axis P of the LED 1b is inclined from the short axis of the ellipse A (the axis perpendicular to the long axis S) is α
I am trying. First, it is necessary to determine the ellipse A. There are innumerable ellipses A having two focal points F and F ′, and the size of the ellipse to be selected is appropriately selected in consideration of the size of the reflecting mirror 2 and the position of the irradiation surface 3. decide.

Next, the inclination angle α of the LED 1b and the position of the reflecting surface 2a of the reflecting mirror 2 are determined as follows. First, L
Of the light emitted from ED1b within the effective emission angle range ± ω,
After the light having the outermost angle distant from the optical axis P by an angle −ω is reflected by the ellipse A, the inclination angle α and one boundary 2b of the reflecting surface 2a are determined so as not to be blocked by the LED 1b or the substrate 1a. The other boundary 2c of the reflecting surface 2a is the reflection position on the ellipse A of the light (optical axis + ω) at the other outermost angle in the effective emission angle range. Of course, the boundaries 2b and 2c are the minimum limit positions of the reflecting surface 2a, and may extend to the outside of the reflecting surface 2a, and the extending portions do not have to be along the ellipse A.

FIG. 2 is a diagram showing a state in which the light reflected by the reflecting surface 2a is projected on the horizontal plane in FIG. 1 in the configuration of this embodiment. For convenience of explanation, the optical path and the illumination state by only one LED 1b are shown. I am drawing. Light is emitted from the LED 1b with a predetermined spread in the horizontal direction (in-plane direction of FIG. 2). Light emitted in a direction coinciding with the optical axis P in this plane (that is, light that spreads around the optical axis P in FIG. 1) is reflected by the reflecting surface 2a and is focused on the second focal point F ′. On the other hand, the light that spreads and propagates in the plane of FIG. 2 is reflected by the reflecting surface 2a, and then the second focus F ′ in the horizontal direction.
To focus on each point on the horizontal plane including the second focal point F ′. Therefore, the illumination state in the vicinity of the second focus F ′ emitted by a certain LED 1b by the reflecting surface 2a has a linear shape having a predetermined length including the second focus F ′. However, this is L
This is a story under the ideal condition that the ED 1b can be regarded as a point light source. Due to the deviation from the ideal condition, the light is not actually completely focused on one point, so that the irradiation surface 3 As shown by B in FIG. 2, the irradiation range of is an elliptical shape that spreads on a substantially horizontal plane centered on the second focal point F ′.

In the present embodiment, the plurality of LEDs 1b are arranged in a ring shape to form the ring-shaped light source 1, but the interval between the LEDs 1b adjacent in the circumferential direction is the effective emission angle range ± ω of both.
Are arranged so as to overlap each other on the reflection surface 2a. Therefore, in the horizontal plane including the second focal point F ′, the individual LEDs 1
The oblong illuminations of b overlap each other, and the overall illumination state is substantially circular as shown by D in FIG. Naturally, the pitch of the array of LEDs 1b (individual LED1
The closer the (b arrangement interval) is, the closer the illuminations are overlapped with each other, thereby eliminating the unevenness of the illuminance on the irradiation surface 3 and increasing the illuminance.

As described above, according to the first embodiment, by tilting the optical axis P of each LED 1b constituting the annular light source 1 with respect to the minor axis of the ellipse A by a predetermined angle, each LED
All the light emitted from 1b within the effective emission angle range including the optical axis P can be guided to the reflecting mirror 2 and reflected by the reflecting surface 2a. The concave section of the reflecting surface 2a of the reflecting mirror 2 is an aspherical surface (ellipse A in this embodiment), the LED 1b is placed in the vicinity of the first focus F of the ellipse, and the irradiation surface 3 is the other (second). By setting in the vicinity of the focal point F ′, all of the reflected light can be focused on the irradiation surface 3, and illumination with high illuminance without unevenness in illuminance can be obtained.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIG. The basic configuration is similar to that of the first embodiment, but in the second embodiment, the cross section of the reflecting surface 2a of the reflecting mirror 2 uses parabolas E and E'instead of an ellipse. . LE constituting the annular light source 1
D1b is placed in the vicinity of the focal point F of the reflecting surface 2a having a parabolic cross section, and the effective emission angle range ± ω is the same as in the case of an ellipse.
When all the light inside is incident on the reflection surface 2a, the axis C and the LED
The reflected lights are all parallel in the plane including 1b. Further, as in the case of FIG. 2, the reflection is a concave curved surface in the horizontal plane, and after the reflection, it is slightly focused. Therefore, on the irradiation surface 3, unlike the first embodiment, the irradiation area is wide in a plane. In addition, the LEDs 1b arranged in the circumferential direction
Since most of the light emitted from the and reflected by the reflecting surface 2a overlaps, it is suitable for illumination in a wider range with less uneven illuminance.

In order to reduce the unevenness of the illuminance on the irradiation surface 3 to obtain highly uniform illumination, as shown in FIG. 4, the diffusion plate 4 is inserted at an appropriate position before the irradiation surface 3,
Light may be diffused at random to increase light overlap. The improvement of the uneven illuminance by the diffusion plate 4 can be applied to the first embodiment.

[0028]

[First Embodiment] An embodiment (hereinafter referred to as a "first embodiment") of an illuminating device embodying the above-described principle configuration will be described below with reference to FIGS. Figure 1 is the first
FIG. 6 is a cross-sectional view in a plane including the axis C of the lighting device according to the embodiment of FIG. The lighting device according to the first example basically embodies the configuration of the first embodiment.

A cylindrical bobbin 10 made of a thermoplastic resin such as polyacetal resin or polycarbonate resin.
The LED mounting holes (corresponding to the substrate 1a in FIGS. 1 to 4) are drilled at angular intervals of 30 ° about the axis C, and the LEDs 11 (see FIGS. L at 4
The body (corresponding to ED1b) is inserted and fixed using an adhesive or the like. Each LED 1 is provided on the inner circumference of the bobbin 10.
Each LED 11 is connected by an electric wire 12 soldered to the lead of which one lead protrudes. The bobbin 10 itself may be formed of a printed board (for example, a flexible board having flexibility), and pads for soldering the leads of the LEDs 11 and pattern wirings for connecting the pads may be formed. Good. In this configuration, if the leads of the LED 11 are soldered to the pad, the fixing of the LED 11 and mutual electrical wiring can be performed at the same time.

The reflecting mirror 14 (corresponding to the reflecting mirror 2 in FIGS. 1 to 4) is a concave curved surface having the above-described shape, that is, a curve obtained by cutting out a part of the ellipse A in the cross section of FIG. It has a base body 14a which is processed by injection molding or the like from a polyacetal resin or a polycarbonate resin into a predetermined shape and has a concave curved surface formed by rotating it to the center (on the upper side in FIG. 5). The reflective surface 14b (see FIG. 1) is made of a material having specularity such as aluminum on the curved surface.
(Corresponding to the reflecting surface 2a in FIG. 4) is vapor-deposited. Such a method is cost-effective, especially when a large quantity of uniform quality is manufactured. Of course, the reflective surface 14b may be functionally provided with specularity by another method such as plating the base 14a with a metal such as aluminum or attaching a metal tape, and further, a metal having specularity. You may use what pressed the plate in the concave curved surface shape.

The reflecting mirror 14 has a circular opening 14c in the inner peripheral portion around the axis C. Further, the surface opposite to the reflecting surface 14b (the lower surface in FIG. 5) is a substantially flat surface, but a groove 14d that linearly connects the central opening 14c and the outer edge portion is formed. The groove 14d is used as a passage for taking out the electric wire 13 connected to the lead of the LED 11.
A step 14e is formed at the upper edge of the inner periphery of the reflecting mirror 14 facing the opening 14c in the circumferential direction about the axis C, and the lower end of the bobbin 10 is just fitted into the step 14e. ing.

The casing in which the bobbin 10 and the reflecting mirror 14 are housed is a first casing 15 and a second casing 16.
It consists of and. The first casing 15 has a disk portion 15a having a circular opening having a diameter slightly smaller than that of the bobbin 10 at the center, and a cylindrical portion 15b standing around the circular opening.
And have integrally. The second casing 16 has a cylindrical portion 16a having the same diameter as the outer edge portion of the first casing 15, and an annular extending piece portion 1 extending toward the inner peripheral side on one end face side of the cylindrical portion 16a.
6b and 6b are integrated.

The reflecting mirror 14 in which the bobbin 10 is fitted as described above is seated on the disk portion 15a of the first casing 15 and fixed by screws. At this time, the wire 13 is in the groove 1
4d and the disc portion 15a are inserted into a passage and taken out. On the upper part of the bobbin 10 and the reflecting mirror 14, a transparent plate 17 made of glass, acrylic or the like having a circular opening at the center is placed, and the second casing 1 is placed on the transparent plate 17.
The base body 14 of the reflecting mirror 14 is mounted by screwing so as to cover 6
Fix to a. The transparent plate 17 includes the LED 11 and the reflecting surface 14b.
It is not functionally essential as a lighting device because it is intended to protect it from dirt and mechanical damage.

As described above, the illuminating device of this embodiment has a doughnut-shaped body having a substantially cylindrical shape centered on the axis C and extending vertically, and supplies a predetermined current to the electric wire 13 drawn to the outside. Then, each LED 11 emits light, and the light is emitted from the inside to the outside through the transparent plate 17 on one surface thereof. In this example, since the reflecting surface 14b of the reflecting mirror 14 has an elliptical cross section, the light radiated to the outside is focused on the irradiation surface at a predetermined distance above the lighting device, and a relatively narrow range is illuminated with a high illuminance. You can evenly illuminate. If the irradiation surface is not aligned with the second focal point F ′ and is moved back and forth along the axis C, almost no light is incident on the vicinity of the axis C, and an annular irradiation area is formed so as to surround the light. . Therefore, the illumination in such a state may be used depending on the application.

Furthermore, when the reflecting surface 14b of the reflecting mirror 14 has a parabolic cross section as described above, it is possible to illuminate a relatively wide range on the irradiation surface. Further, as a matter of course, the size of the irradiation range on the irradiation surface can be changed by appropriately adjusting the distance between the irradiation surface and the illumination device. Further, if necessary, a diffuser plate may be inserted between the illumination device and the irradiation surface to introduce diffused light to the irradiation surface.

Further, in the above illuminating device, since the opening is provided around the axis C, the illuminating surface can be seen vertically from the side opposite to the illuminating surface with the illuminating device in between. Therefore, it is very convenient, for example, when the object to be inspected on the irradiation surface is brightly illuminated while being photographed by a CCD camera or visually observed through a magnifying lens or the like.

[Second Embodiment] Next, an illuminating device according to a second embodiment of the present invention will be described with reference to FIGS. Figure 7
Is a cross-sectional view of the illumination device according to the second embodiment in a plane including the axis C, and FIG. 8 is a perspective view of a bobbin member that is a component of the illumination device according to the present embodiment. The same or corresponding parts as those of the first embodiment are designated by the same reference numerals, and the description thereof will be omitted unless particularly necessary. The illumination device of the second embodiment basically embodies the configuration of the second embodiment, but any other modification may be a concrete device. It goes without saying that you can do it.

As shown in FIG. 8, a bobbin member 100, which is an integrally molded product of polyacetal resin, polycarbonate resin, or the like, has a substantially cylindrical body having an end face wall portion having a central opening (a portion corresponding to 100b) at one end face. Has a shape that is cut in two in a plane including the axis C, and the two bobbin members 100 are attached (or simply brought into close contact) at a position corresponding to the cut surface, so that a substantially cylindrical bobbin 10 is obtained. To be formed. This bobbin member 1
LED mounting holes 100a at a predetermined angular interval in the circumferential direction of 00.
Are perforated, and each hole 100a has an LED1
The body 1 is inserted and fixed using an adhesive or the like. The leads of each LED 11 protruding to the inner circumference of the bobbin 10 are connected to each other by soldering, and the electric wire 13 connected to the end of the wiring is connected to the bobbin 10 and the reflecting mirror 14.
Is pulled out to the outside through the opening 14c. In this embodiment, since the bobbin 10 is composed of two bobbin members 100, the LED 11 is attached and the leads are soldered with the inner peripheral side of the bobbin member 100 wide open as shown in FIG. It can be performed. Therefore, workability during manufacturing is very good.

Further, in the lighting device of the second embodiment,
Unlike the first embodiment, there is no casing that covers the reflecting mirror 14, the base body 14a of the reflecting mirror 14 is exposed, and a substantially annular holding frame body (first holding member) for holding the transparent plate 17 thereon is used. (Corresponding to the second casing 16 of the first embodiment) 18 is only fixed with screws. Further, unlike the first embodiment, the reflecting mirror 14 may be formed in a bottomed shape without an opening for a CCD camera, and a small opening 14c for passing the electric wire 13 may be bored. Therefore, a cylindrical body for smoothing the inner peripheral side of the opening 14c (see FIG.
Since the cylindrical portion 15b) of the first casing is unnecessary, the cost can be reduced. In the second embodiment, the curved surface of the reflecting surface 14b of the reflecting mirror 14 has a parabolic shape, and the LED 11 is arranged at the focal point of the reflecting surface 14b. Therefore, the light emitted from the LED 11 while spreading is reflected by the reflecting surface 14 as shown in FIG.
At b, the light is made to be substantially parallel and the light moves toward the axis C.

Further, in the configuration of the second embodiment, the LED 11
Are only arranged in one row around the bobbin 10, but two rows, three rows, a plurality of rows, and LEDs 11 may be arranged. In this case, the LEDs 11 in the other rows are the reflective surface 1
Although not focused on 4b, lights that are directed in substantially the same direction as a whole overlap each other on the irradiation surface to increase the illuminance. Of course, the same method can be adopted in the configuration of the first embodiment.

In the above first and second embodiments,
For general lighting, LEDs that emit white light may be used, but of course, other red, green,
An LED that emits visible light of each color such as yellow or light having various wavelengths such as infrared light and near infrared light may be used. In addition, by arranging LEDs of three primary colors of red, green and blue lights in order in the circumferential direction and selectively turning on these LEDs, light is overlapped on the irradiation surface, and various colors of light of different colors are mixed. The illumination color may be obtained. In this case, white light can be obtained by turning on all the red, green, and blue LEDs.

Furthermore, in the above description, LE is used as the light emission source.
Although D was used, various other light sources can be used as the annular light source in the present invention. As an example,
It may be an aperture fluorescent tube in which a reflective film is applied between the glass tube and the fluorescent material of the annular fluorescent tube, and a part of the film is peeled off at appropriate intervals to provide a plurality of openings (apertures) in the circumferential direction. . Such a fluorescent lamp has a directional characteristic that it has a high intensity only within a predetermined angle (effective emission angle) about the optical axis, and emits only extremely low intensity light in the other directions. Therefore, by using such a light source in the lighting apparatus according to the present invention, the efficiency of the light source and the light-collecting efficiency according to the present invention are combined with each other to perform very efficient lighting.

It should be noted that the above-described embodiments and examples are merely examples of the present invention, and it is apparent that even if appropriate changes and modifications are made within the scope of the gist of the present invention, they are included in the claims of the present application. Is. Specifically, the materials forming each optical component and other members are not limited to those described above. Further, the shape and arrangement of each optical component can be appropriately changed within the range of conditions satisfying the gist of the present invention.

[Brief description of drawings]

FIG. 1 shows an illumination device according to a first embodiment of the present invention with an axis C
And a cross-sectional view taken along a plane including a light source.

FIG. 2 is an explanatory diagram of a state in which reflection by a reflecting surface is projected on a horizontal plane in FIG. 1 in the lighting device according to the first embodiment.

FIG. 3 is a partially enlarged sectional view of an LED and a reflecting surface with respect to FIG.

FIG. 4 is a sectional view of a lighting device according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view of a lighting device according to a first example embodying the first embodiment in a plane including an axis C.

FIG. 6 is a partial cross-sectional top view of the lighting device of FIG.

FIG. 7 is a cross-sectional view of a lighting device according to a second example embodying the second embodiment in a plane including an axis C.

8 is a perspective view of a bobbin member that is a component of the lighting device of FIG.

[Explanation of symbols]

1 ... Ring light source 1a ... substrate 1b, 11 ... LED 2, 14 ... Reflector 2a, 14b ... Reflective surface 3 ... Irradiation surface 4 ... Diffuser 10 ... Bobbin 100 ... Bobbin member 12, 13 ... Electric wire 14a ... Base 14c ... opening 14d ... groove 14e ... Step 15 ... First casing 15a ... Disc part 15b ... Cylindrical part 16 ... Second casing 16a ... Cylindrical part 16b ... Extending piece 17 ... Transparent plate 18 ... Holding frame

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ken Iwai             Kyoto Electric Co., Ltd. 19-1 16 Makishimacho, Uji City, Kyoto Prefecture             Ware corporation F term (reference) 2G051 BA02 BA20 BB11 EA12                 5F041 AA04 AA06 DA78 DA81 DA92                       EE23 FF11

Claims (8)

[Claims] 1. A ring-shaped light source comprising: a) a light-emitting source arranged annularly around a predetermined axis and in a state where the light-emitting direction is directed outward with respect to the axis; and b) the ring-shaped light source. A reflecting mirror surrounding and having a reflecting surface facing the annular light source, wherein the reflecting surface has one half cross section divided by the axis of the cross sections including the axis and the light emitting source. An aspherical curve having the light source as one focal point, which is a concave curved surface formed in space by rotating the curve about the axis, and which is emitted from the annular light source and reflected by the reflecting surface. The illuminating device is characterized in that the above-mentioned light is radiated on or near the axis. 2. The illumination device according to claim 1, wherein the reflecting surface is a point where the other focus of the aspherical curve in the half cross section is located on the axis. 3. The positional relationship between the light emitting source and the reflecting mirror is determined so that almost all light within an effective light distribution angle including the optical axis of the light emitting source strikes the reflecting surface. The lighting device according to claim 1. 4. The reflecting mirror has an opening around the axis including the axis, and an irradiation site can be observed from the opposite side of the reflecting surface through the opening. The lighting device according to any one of 3 above. 5. The annular light source includes a light emitting diode as the light emitting source, and a cylindrical body surrounding the shaft, and a plurality of the light emitting diodes are arranged side by side in a circumferential direction of an outer periphery of the cylindrical body. The lighting device according to any one of claims 1 to 4, wherein: 6. The lighting device according to claim 5, wherein the tubular body is formed of a plurality of members divided by a cut surface extending in the same direction as the axis. 7. The lighting device according to claim 5, wherein the cylindrical body is attached to the reflecting mirror. 8. The light emitting diode according to claim 5, wherein the plurality of light emitting diodes include light emitting wavelengths different from each other.
The lighting device according to any one of 1.