Illumination – Light fiber – rod – or pipe
Reexamination Certificate
2000-08-28
2002-10-08
O'Shea, Sandra (Department: 2875)
Illumination
Light fiber, rod, or pipe
C362S558000, C362S572000, C385S901000
Reexamination Certificate
active
06461031
ABSTRACT:
DETAILED DESCRIPTION OF THE INVENTION
1. Technical field
The present invention relates to a spot light fiber which can leak light which has been inserted at an incident end from an output end and its vicinity, and can be used as a light emitting body of an illuminating apparatus of a spot light fiber type, and a spot light fiber type illuminating apparatus using this spot light fiber.
2. Background
As known to the art, a light fiber can transmit the light inserted at the incident end to the output end with only a small amount of light leaking from the external peripheral face of its core, and can emit the light with relatively high brightness at the output end. By using such characteristics, the optical fiber can be used as a light emitting body of a light fiber type illuminating apparatus.
An illuminating apparatus of such a spot light fiber type is disclosed in Japanese Utility Model Laid-Open Publication No.
56-161704
, Japanese Patent Laid-Open Publication No. 1-169802 or the like. But in an ordinary light fiber, the light is emitted from the output end in an approximately parallel light beam, so that efficient extension cannot be provided in the illumination light and the illumination spot area cannot be made large.
A light fiber is known which can leak light from the part other than an output end, i.e., the external peripheral face of the core so that the light can be used as the illumination light. For example, in Japanese Patent Laid-Open Publication No. 4-70604, Japanese Patent Laid-Open Publication No. 1-58482, Japanese Patent Laid-Open Publication No. 6-21940 or the like is disclosed a light fiber having a light diffusive-reflective film adhered along the axial direction of the core on the external peripheral face of the core.
Such a light diffusive-reflective film, normally containing light transmissive resin and light diffusive-reflective particles, substantially does not allow the light to transmit therethrough. Rather, the light is reflected. Namely, in such a conventional light fiber as described above, a portion of light which reaches the interface between the light diffusive reflective film and the core is reflected by the light diffusive-reflective film so that the light leaks out of the core from the external peripheral face on the side opposite to the external peripheral face where the light diffusive-reflective film is positioned. As described above, in addition to the output end of the core of the light fiber, the external peripheral face also functions as a light emitting face. The light inserted into the incident end does not leak out of the core through the light diffusive-reflective film.
When the light diffusive-reflective film is used as described above, the light can be released along the axial direction of the core, and the light fiber can be used in place of a linear light source such as fluorescent tube or the like. However, the light fiber with a light diffusive-reflective film attached to it is not suitable for spot illumination.
Since the light diffusive-reflective film is normally not light transmissive, the size of the light leaking part is restricted, because the vicinity of output end of a core which becomes a light leaking part is covered by the light diffusive-reflective film itself when the light diffusive-reflective film is positioned as it is near the output end of the core. As the result, it becomes difficult to make the illuminated area (i.e., spot area) large.
SUMMARY OF THE INVENTION
The present invention provides a spot light fiber which can make the area which is irradiated by the light from the output end and the vicinity of the output end of the spot light fiber large. In another embodiment of the present invention, a spot light fiber type illuminating apparatus which can make the spot area large by efficiently using such a spot light fiber is provided.
The present invention provides a spot light fiber which comprises a core which can transmit the light inserted at an incident end toward an output end and output the light from the output end, and a light leaking means positioned along the peripheral direction on the external peripheral face near the output end of the core; characterized in that the light leaking means is formed by using a light diffusive-transmissive film. Preferably, the light leaking means circumscribes the core in a location adjacent the output end.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1
is a perspective view showing one embodiment of a spot light fiber of this invention. A spot light fiber
100
of this invention has a light leaking means
103
positioned along the peripheral direction on the external peripheral face near the output end
102
of the core
101
. In the present specification, the peripheral direction is referred to as a direction normal to the axis of the core.
By using a light diffusive-transmissive light leaking film which allows the light to be diffused and transmitted as the light leaking means of the light fiber, the light leaking brightness from the outer peripheral face near the output end is efficiently improved. Accordingly, the leaked light from the light diffusive-transmissive light leaking film and the emitted light from the output end can be efficiently irradiated toward the illuminated area, thereby the efficient illumination angle (for example, an angle by which brightness more than 1,500 luxes can be obtained) is expanded, and the spot area is efficiently enlarged.
FIG. 2
is a perspective view of one embodiment of a light diffusive-transmissive light leaking film to be used for forming a light leaking means of a spot light fiber of this invention. In the drawing, reference numeral A shows the peripheral direction of the core.
A suitable light diffusive-transmissive light leaking film
200
to be used by this invention has:
(i) a light transmissive base part
201
having two approximately parallel major faces; and
(ii) a plurality of light transmissive convex parts
202
formed and erected integrally with the base part on one major face of the base part, each convex part having approximately the same height, with a top face
203
having an adhesive property and the refractive index being 1.1 or more.
The light leaking means of this invention can be formed by using the light diffusive-transmissive light leaking film. Specifically, this is accomplished by adhering the top face
203
of the convex part
202
of the light diffusive-transmissive light leaking film
200
on the external peripheral face of the core. The film and the core are positioned so that a void
204
can be retained between the core external peripheral face and the base part of the light diffusive-transmissive light leaking film, and between the convex part and the convex part of the light diffusive-transmissive light leaking film.
When the light diffusive-transmissive light leaking film
200
is adhered on the external peripheral face of the core, the light diffusive-transmissive light leaking film is oriented so that the direction A on
FIG. 2
becomes normal to the axis of the core. That is, the convex part
202
of the light diffusive-transmissive light leaking film
200
runs perpendicular to the direction of the fiber.
Since such a light leaking means leaks the light by using the light scattering function by the concave-convex shape of the light diffusive-transmissive light leaking film, the diffusing reflection particles are not required to be contained in the light diffusive-transmissive light leaking film. The light transmissive rate of the film itself can be improved as high as possible. Thus, the brightness of the light to be illuminated through the light diffusive-transmissive light leaking film can be improved efficiently.
The refractive index of the convex part is normally 1.1 or more. The part of the light which reaches the output end and is not irradiated from the external peripheral face, in case that the light diffusive-transmissive light leaking film would not be provided, transmits through the light diffusive-transmissive light leaking film to leak out of the core. Na
3M Innovative Properties Company
Buckingham Stephen W.
DelGizzi Ronald E.
O'Shea Sandra
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