CCD video scope with illumination to the object

A CCD video scope is mounted in a camera head and has an image capture optical system defining an optical axis, and a half mirror with a light source offset from the optical axis and facing the half mirror, which coaxially defracts illumination light in relation to the optical axis. The resultant optical image is incident on a CCD element also lying on the optical axis. Bundled fibers are mounted between the light source and the half mirror, and have a diameter of less than 250.mu. and a length of 10 times or more the diameter. The light source has a light focusing lens with an exit angle equal to or less than the maximum light incident angle of the optical fiber elements.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention is related to a CCD video scope with illumination to 
the object in which illumination light can be irradiated on the subject 
through the optical axis of the image capture optical system. 
2. Description of the Related Art 
FIG. 2 is a cross-sectional diagram indicating a conventional CCD video 
scope with illumination to the object. Half mirror 24, which causes the 
illumination light to be defracted coaxially in relation to optical axis X 
of image capture optical system 22, is arranged within camera head 23 
which incorporates photographic optical system 22 which causes the optical 
image to be incident on CCD element 21; and incandescent lamp 25 is 
arranged as the light source for illumination in a position displaced from 
optical axis X of said image capture optical system in order to face said 
half mirror. 
By doing this, the illumination light that is irradiated from the 
incandescent lamp is reflected by the half mirror; this illuminates the 
subject by being defracted coaxially in relation to optical axis X of the 
image capture optical system, and the optical image of the subject that is 
illuminated by this illumination light is captured by the CCD element 
through the image capture optical system. 
Nonetheless, because the light focusing efficiency is low, the light of the 
incandescent lamp cannot be efficiently utilized, a lamp that is brighter 
than necessary must be used in order to obtain sufficient illumination of 
the object, and there is the problem that there is a large energy loss. 
For this reason, a light focusing lens is used, but because the precision 
in manufacture is poor, the main light source cannot spot illuminate the 
half mirror. If a light diffusion plate is provided, part of the light can 
suitably spot illuminate the half mirror, but the light utilization 
efficiency is all the more decreased because of light diffusion. 
Furthermore, as indicated in FIG. 3, if instead of the incandescent lamp, 
the tip of bundled fibers 32 which are connected to an externally provided 
light source 31 are attached opposing the half mirror, the light output 
from the bundled fibers can irradiate illumination light on the half 
mirror with good precision because the directionality is good, but by 
connecting the bundled fibers, which are heavy and highly rigid, to a 
camera head, there is the problem that the ease of using the camera head 
is worsened. 
SUMMARY OF THE INVENTION 
Thus, the present invention takes up the technical issue of obtaining a 
bright light for illuminating objects with little energy loss by 
efficiently focusing the light of the light source incorporated in the 
camera head, and by illuminating the half mirror with good precision. 
In order to resolve these problems, the present invention involves a CCD 
video scope with illumination to the object in which a half mirror, which 
coaxially defracts the illumination light in relation to the optical axis 
(X) of the image capture optical system, is arranged within the camera 
head in which an image capture optical system is equipped to make the 
optical image incident on a CCD element, and light source for illumination 
is arranged in a position displaced from the optical axis (X) of the image 
capture optical system in order to face said half mirror; and is 
characterized by mounting between the aforementioned half mirror and the 
light source for illumination bundled fibers in which multiple optical 
fiber lines with a diameter of 250.mu. or less are bundled together, and 
the length of these fibers are selected at a length that is 10 times or 
more the diameter of the optical fiber elements, and by the aforementioned 
light source for illumination comprising a light emitting diode with light 
focusing lens or a filament lamp with light focusing lens, and by the exit 
angle of that illumination light being selected to be the maximum light 
incident angle or less of the optical fiber elements which compose the 
bundled fibers. 
According to the present invention, because the bundled fibers are mounted 
between the half mirror and the light source for illumination, and because 
these bundled fibers are formed by bundling optical fiber elements with a 
diameter of 250.mu. or less and have a length that is 10 times or more 
that diameter, incident light modes of the light lines mix and diffuse, 
and a light spot exits at a fixed exit angle corresponding to the quality 
of the optical fibers irrespective of the incident angle of the light. 
Moreover, because the exit angle of the illumination light of the 
aforementioned light source for illumination is selected to be the maximum 
light incident angle or less of the optical fiber elements that compose 
the bundled fibers, that light is efficiently focussed, and there is 
little energy loss.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In the Figure, 1 is the camera head which comprises image capture part 3A 
which incorporates aforementioned CCD element 2, and optical head 3B 
mounted attachably/detachably on said image capture part 3A; image capture 
optical system 4 which causes the optical image to be incident on CCD 
element 2 is incorporated into optical head 3B; half mirror 5 which 
coaxially deflects illumination light is arranged in relation to optical 
axis X of image capture optical system 4; and light source 6 for 
illumination is arranged in a position displaced from optical axis X of 
image capture optical system 4 so as to face half mirror 5. 
Image capture optical system 4 consists of a lens group that can enlarge 
the subject to the desired magnification, and if using multiple kinds of 
optical heads 3B, which have image capture optical systems 4 with 
differing magnifications, the magnification can be modified simply by 
replacing optical head 3B. 
Aforementioned light source 6 for illumination comprises a light emitting 
diode with light focusing lens or a filament lamp with light focusing lens 
with, for example, optical line directional characteristics of 60.degree. 
or less. Mounted between this light source 6 and half mirror 5 are bundled 
fibers 7, in which multiple optical fibers with diameters of 250.mu. or 
less, preferably 100.mu. or less, are bundled and selected for a length 
that is 10 times or more the diameter of the optical fiber elements, and 
the bundled fibers are housed within fitting 8 which is made of metal or 
plastic. 
For bundled fibers 7, so called conduit shaped fibers are used in which 
multiple optical fiber elements made of multi-component glass, plastic or 
quartz glass are bundled, and the entire body or both ends are affixed 
with adhesive or thermally fused together. 
In particular, in this example, 50.mu. diameter optical fiber elements made 
of multi-component glass are affixed with epoxy group adhesive, and are 
housed in fitting 8 with an internal diameter of 4 mm and a length of 6 
mm. In other words, in this example, the length of the optical fibers is 
around 100 times the diameter. 
Moreover, because the maximum incident angle of the optical fiber element 
is generally 20.degree.-60.degree., if, for example, bundled fibers 7 are 
configured with optical fiber elements having a maximum incident angle of 
60.degree., light source 6 for illumination is lit with a voltage of 1.8 V 
by adopting fibers which have directional characteristics of an angle that 
is the maximum light incident angle or less of the optical fiber elements 
(for example, 20.degree. in this embodiment). 
The above is the configuration of one example of the present invention, and 
next, an explanation will be given of its operation. 
First, when light source 6 for illumination is lit and the optical axis of 
image capture optical system 4 of camera body 1 faces the subject, the 
illumination light passes through bundled fibers 7, is reflected by half 
mirror 5, is coaxially defracted in relation to optical axis X of image 
capture optical system 4; and the illumination light is irradiated on the 
subject following said optical axis X, the optical image of the subject 
passes through half mirror 5 via optical axis X of image capture optical 
system 4, and is incident upon CCD element 2. 
At this time light source 6 for illumination consumes very little power 
because a light emitting diode with a light focusing lens is utilized. 
Moreover, because light source 6 for illumination is arranged within camera 
head 1, it is sufficient if an electrical cord (not indicated in the 
diagram) is connected to camera head 1. It is not necessary to connect 
bundled fibers for the purpose of introducing external illumination, and 
the ease of use is not worsened. 
Furthermore, because the directionality of the optical line of power source 
6 for illumination is selected to be 60.degree. or less, which is the 
maximum light incident angle or less of bundled fibers 7, and because 
optical fiber elements with a diameter of 250.mu. or less are bundled and 
selected with a length 10 times or more that of the diameter, light is 
incident from light source 6 for illumination onto the end surface of 
bundled fibers 7, the light modes within bundled fibers 7 mix and diffuse, 
and exit to half mirror 4 as a light spot with a fixed exit angle 
irrespective of the incident angle of the light. 
For this reason, the light incident within bundled fibers 7 is not 
diffused, and is efficiently utilized as the illumination light without 
waste; energy loss can be reduced; and object illumination of a sufficient 
brightness can be obtained by a small scale light source. 
In addition, a filament lamp with a light focusing lens may be substituted 
for the light emitting diode with focusing lens as light source 6 for 
illumination, and a prism may be used as half mirror 5. 
As described above, according to the present invention, because bundled 
fibers, by which a light spot exits at a fixed exit angle irrespective of 
the incident angle of the light, are mounted between the half mirror and 
the light source for illumination, and moreover because the exit angle of 
the illumination light from the light source for illumination is selected 
to be the maximum light incident angle or less of the optical fiber 
elements which compose the bundled fibers, there are the superior effects 
that that light is efficiently focused, there is little energy loss, and 
bright illumination light to the object can be obtained. 
Although some preferred embodiments of the invention have been described 
above by way of example only, it will be understood by those skilled in 
the field that modifications may be made to the disclosed embodiments 
without departing from the scope of the invention, which is defined by the 
appended claims.