JP2579280Y2 - Lighting equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a lighting device for irradiating light emitted from a light source to a desired arbitrary portion through an optical fiber light guide, and in particular, to a high illuminance and uniform illumination device. The present invention relates to a device that can be used for illumination or the like in image processing requiring illumination.

[Prior Art] Conventionally, as shown in FIG.
The light L emitted from the optical fiber light guide 300 is condensed by the elliptical mirror 200, introduced into the optical fiber light guide 300 from the incident end face of the optical fiber light guide 300, and emitted from the output end face of the optical fiber light guide 300. Thus, a lighting device that irradiates a desired portion with light is known.

By the way, as shown in FIG. 2 (a), when the light L condensed by the elliptical mirror 200 is directly introduced into the optical fiber light guide 300 and illuminated, the illuminance near the center of the illuminating unit is compared with the surroundings. As a result, an uneven illuminance distribution is formed. FIG. 2B shows this state. For this reason, there is a drawback that it cannot be used for illumination for image processing which requires high illumination and uniform illumination. This is considered to be because most of the light L condensed by the elliptical mirror 200 does not perpendicularly enter the incident end face of the optical fiber light guide 300.

Therefore, the light L condensed by the elliptical mirror 200 has been conventionally used.
Various methods have been attempted to make as much as possible perpendicularly incident on the incident end face of the optical fiber light guide.

That is, as shown in FIG.
The concave lens 401 is disposed inside the focal point F of the elliptical mirror 200 as shown in FIG.
5, a convex lens 402 is disposed outside the focal point F of the elliptical mirror 200 as shown in FIG. 5, or a double lens 403 is disposed outside the focal point F of the elliptical mirror 200, as shown in FIG. By tilting the optical axis of the elliptical mirror 200 at a predetermined angle with respect to the optical axis of the optical fiber light guide 300,
There is known an optical fiber light guide 300 in which most of the light L is vertically incident on an incident end face of the optical fiber light guide 300.

[Problem to be Solved by the Invention] By the way, the light source 100 is not actually a point light source, but a filament or the like has a finite size. Therefore, the light L emitted from the light source is condensed by the elliptical mirror 200 with a spread called a beam waist, as shown in FIG. As a result, of the above-described conventional methods, the following problems occur in the method of interposing a lens.

That is, first, in order for all the light L condensed by the elliptical mirror 200 to enter the optical fiber light guide 300, the aperture of the lens needs to be larger than the diameter of the beam waist. When the diameter of the beam waist is larger than the aperture of the optical fiber light guide 300, the aperture of the lens must be set to be larger than the aperture of the optical fiber light guide 300 after all. Then, in the above-described method of interposing the concave lens 401, as shown in FIG. 8, a light ray such as a light ray AA ′ that is substantially parallel to the optical axis O and passes through the periphery of the concave lens 401 or a light ray C- Light such as C 'is diffused at the incident end face of the optical fiber light guide 300 instead of becoming vertically incident light. For this reason, if the aperture of the concave lens 401 is larger than the aperture of the optical fiber light guide 300, light at the peripheral portion of the lens will not be incident on the optical fiber light guide 300, and the light collection efficiency will be reduced, and high illuminance will not be obtained.

In the method of interposing the convex lens described above, when the convex lens 402 having a small curvature is interposed as shown in FIG. 9, light in the peripheral portion is collected in the same manner as when the concave lens is interposed. There is a problem of not being able to shine.
On the other hand, as shown in FIG. 10, a convex lens having a large curvature
In the case where the 412 is interposed, the light-collecting ability is improved, but there is a problem that the vertically incident light cannot be obtained, causing uneven illuminance.

Further, when the above-mentioned compound lens 403 is interposed, as shown in FIG. 11, the space occupied by the lens itself increases, so that the device becomes large, and in addition, the surface becomes larger than a single lens. However, there is a problem that the reflection loss at the point increases.

In the method of inclining the elliptical mirror 200 with respect to the optical axis, as shown in FIG. 12, only light reflected on a partial area S of the reflection surface of the elliptical mirror 200 becomes vertical incident light. It is disadvantageous from the viewpoint of obtaining illuminance.

The present invention has been made under the above-mentioned background,
It is an object of the present invention to provide an illumination device that can realize uniform and high-illumination illumination with a relatively simple configuration.

[Means for Solving the Problems] The present invention has solved the above-mentioned problems by adopting the following configuration.

The light emitted from the light source is condensed by an elliptical mirror, introduced into the optical fiber light guide from the incident end face of the optical fiber light guide, and the light is emitted from the output end face of the optical fiber light guide, thereby obtaining a desired light. In an illumination device configured to irradiate light to a part, light condensed by the elliptical mirror is passed through a hemispherical lens disposed close to an incident end face of the optical fiber light guide from an incident end face of the optical fiber light guide. A configuration characterized by being introduced into the optical fiber light guide.

[Operation] According to the above configuration, the light condensed by the elliptical mirror is introduced into the optical fiber light guide from the incident end face of the optical fiber light guide through the hemispherical lens. The collimating effect is obtained for most light incident near the part,
Many light condensed by the elliptical mirror can be perpendicularly incident on the incident end face of the optical fiber light guide. At the same time, the light incident on the periphery of the hemispherical lens is largely refracted and an effective light collecting action is obtained, so that most of the light can be introduced into the optical fiber light guide. Thereby, illumination with uniform and high illuminance can be performed.

FIG. 1 is a partial cross-sectional view showing a configuration of a lighting device according to an embodiment of the present invention. Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG.

In FIG. 1, reference numeral 1 denotes a light source, reference numeral 2 denotes an elliptical mirror, reference numeral 3 denotes an optical fiber light guide, and reference numeral 4 denotes a hemispherical lens.

The light source 1 is a halogen lamp, and emits light by passing a predetermined current through a built-in filament 11.

The elliptical mirror 2 has almost the same shape as one of the two parts obtained by dividing the elliptical surface by a plane passing through the center and perpendicular to the main axis, and has a reflection surface 21 formed on the inner surface thereof. Also,
The light source 1 is mounted on the elliptical mirror 2 such that the center of the filament 11 is located near one focal point f1 of the elliptical surface in a space surrounded by the reflecting surface 21. Therefore, the light R1 emitted from the focal point f1 is reflected by the reflecting surface 21 and collected so as to pass through the other focal point f2 of the elliptical surface including the reflecting surface 21.

The optical fiber light guide 3 is a bundle of a large number of optical fibers having a diameter of 30 to 70 μm. Although not shown, both ends are fixed with an adhesive and a terminal fitting to form a 6 mm diameter, and a covering material is formed over the entire length. It is coated.

The hemispherical lens 4 is made of a high refractive index glass material (refractive index nd = 1.6
Above) in a hemispherical shape with a diameter of 16 mm.

The hemispherical lens 4 has a reflection surface 21 of the elliptical mirror 2.
Are arranged so that the optical axis thereof coincides with the optical axis O on the main axis of the ellipsoid including, and is located outside the other focal point f2 of the ellipse. The spherical portion of the hemispherical lens 4 is defined as an incident surface 41 facing the focal point f2, and the flat portion is defined as an emitting surface 42.
The optical fiber light guide 3 is arranged so that the light emitting surface 42 contacts the incident end face 31 of the optical fiber light guide 3 and the optical axis of the optical fiber light guide 3 coincides with the optical axis O. ing.

Now, in the above configuration, the reflection surface 21 of the elliptical mirror 2
Consider reflected light at an arbitrary point A in FIG.

First, when the light R1 emitted from the focal point f1 is reflected at the point A, it is collected so as to pass through the other focal point f2 of the ellipse. After passing through the focal point f2, the hemispherical lens 4
The light enters the hemispherical lens 4 from a point C near the center of the entrance surface 41 of the optical fiber light guide 3 and is refracted to substantially vertical light from the point C ′ of the incident end face 31 of the optical fiber light guide 3. Introduced within.

On the other hand, since the filament 11 has a finite size,
Lights R2 and R3 are also emitted from positions before and after the focal point f1, respectively. After being reflected at point A, these lights R2 and R3 enter the hemispherical lens 4 from points B and D located at the peripheral portion away from the center of the hemispherical lens 4 without passing through the focal point f2. . In this case, these lights are largely refracted by the properties of the hemispherical lens 4 and almost all of them are introduced into the optical fiber light guide 3.

Therefore, according to this configuration, the focal point of the elliptical mirror 2
The light emitted from the vicinity of f1 is introduced into the optical fiber light guide 3 almost vertically, and at the same time, almost the most of the light emitted from before and after the focal point f1 is also introduced into the optical fiber light guide 3. The light emitted from the light emitting end of the light guide 3 is uniform and of high intensity.
Even when the filament 11 has a finite size, illumination with uniform and high illuminance can be performed.

FIG. 13 shows an illuminance distribution when illuminated by the illuminating device of the above-described embodiment and a conventional concave lens (radius of curvature on both surfaces).
9 is a graph showing the measurement results with the illuminance distribution when illuminated using an illumination device interposed at 9.5 mm). In FIG. 13, the vertical axis represents the illuminance of the site showing the maximum illuminance of 100%.
The illuminance of other parts is an illuminance distribution ratio expressed as a ratio (%) to the maximum illuminance, and the horizontal axis is the distance (unit: mm) from the center of the illumination spot. In this case, the photodetector (photodiode) was placed at a position 100 mm away from the emission end of the optical fiber light guide, and the illuminance at each position was measured by moving the photodetector using an XY moving stage. It was done. The dashed line in the drawing is the case of this embodiment, and the solid line is the case where a conventional concave lens is used.

As is clear from FIG. 13, the illuminance at the center is higher in the conventional example, but it is clear that the present embodiment is significantly superior in terms of uniformity. Moreover, when comparing the total light amount (expressed by the volume of a cone formed when the illuminance distribution is rotated around the central axis), (this embodiment): (conventional example) = 1.53: 1, It can be seen that the light from the light source 1 is more efficiently introduced into the optical fiber light guide 3 in this embodiment. It has been confirmed that this ratio is the same as the illuminance ratio when the total amount of light is actually measured by the illuminometer.

FIG. 14 is a collective diagram for collimating light emitted from the light-emitting end face to the light-emitting end face of the optical fiber light guide of the lighting apparatus of the present embodiment and the conventional lighting apparatus (with a concave lens interposed). 14 is a graph showing the results of performing the same measurements as in FIG. 13 with the optical lenses installed. In this case, the distance from the exit end face of the condenser lens to the photodetector is 200 mm. Other conditions are the same as those in FIG. In this case, the total light amount ratio is (this embodiment) :( conventional example) = 1.1: 1, which is almost the same. However, as is clear from FIG. Is remarkably excellent.

[Effects of the Invention] As described above in detail, in the present invention, the light condensed by the elliptical mirror is introduced into the optical fiber light guide through the hemispherical lens. This allows not only a large amount of light to be incident perpendicularly to the incident end face of the optical fiber light guide, but also allows light incident on the periphery of the hemispherical lens to be introduced into the optical fiber light guide without leakage. Accordingly, an illumination device capable of performing uniform and high illuminance illumination is obtained.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing the structure of a lighting device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of a conventional lighting device, and FIG.
Fig. 4 shows an example in which a concave lens is interposed, Fig. 4 shows an example in which a convex lens is interposed, Fig. 5 shows an example in which a compound lens is interposed, and Fig. 6 shows a tilted elliptical mirror. FIG. 7 is an explanatory diagram of a beam waist, FIG. 8 is an operational explanatory diagram of an example in which a concave lens is interposed, FIG. 9 is an operational explanatory diagram of an example in which a convex lens having a small curvature is interposed, 10 is an operation explanatory view of an example in which a convex lens having a large curvature is interposed, FIG. 11 is an operation explanatory view of an example in which a compound lens is interposed, and FIG. 12 is an operation explanatory view of an example in which an elliptical mirror is tilted. FIG. 13 and FIG. 14 are graphs showing the illuminance distribution of one embodiment. DESCRIPTION OF SYMBOLS 1 ... Light source, 2 ... Elliptical mirror, 3 ... Optical fiber light guide, 4 ... Hemispherical lens.

Claims (1)

(57) [Scope of request for utility model registration] 1. An optical fiber light guide, wherein light emitted from a light source is condensed by an elliptical mirror and introduced into the optical fiber light guide from an incident end face of an optical fiber light guide formed by bundling a plurality of optical fibers. An illumination device configured to irradiate a predetermined portion with light by emitting the light from an emission end face of the guide, wherein the light condensed by the elliptical mirror is arranged close to an incidence end face of the optical fiber light guide. An illumination device, wherein the light is introduced into the optical fiber light guide from an incident end face of the optical fiber light guide through a hemispherical lens.