Surgery – Endoscope – Having imaging and illumination means
Reexamination Certificate
2001-07-20
2002-11-19
Mulcahy, John (Department: 3739)
Surgery
Endoscope
Having imaging and illumination means
C600S181000
Reexamination Certificate
active
06482150
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a video endoscope system used in medical applications to obtain images of a surface of a subject illuminated by visible light and images of the subject through autofluorescence resulting from excitation light and specifically relates to an optical system for the light source device that generates illuminating light and excitation light to supply them into the video endoscope. The present disclosure relates to subject matter contained in Japanese Patent Application No. 2000-227328 (filed on Jul. 27, 2000), which is expressly incorporated herein by reference in its entirety.
2. Description of the Related Art
In recent years, a method has been proposed for observing the autofluorescence of a subject (specifically, body cavity wall) with a video endoscope systems. In a body cavity wall irradiated by light of a specific wavelength (generally ultraviolet light), the tissues are excited to emit fluorescence. The intensity of the fluorescence generated by healthy tissue is stronger than that generated from unhealthy tissue, such as cancerous tissue. This causes an intensity distribution of autofluorescence in the body cavity when the cavity includes unhealthy tissue. capturing images of autofluorescence from the body cavity wall with the solid state image sensing device (CCD) of the video endoscope makes it possible to observe special images of the body cavity wall that differ from images of the body cavity wall obtained by normal illumination with visible light.
As such video endoscope systems that allow the fluorescence observation, a video endoscope system of the so-called RGB frame sequential system is used, which has an RGB rotating shutter for separating white light (visible light) emitted from a light source into red, green, and blue light components, an illumination optical system for transmitting in sequence the red, green and blue light to the proximal end of the video endoscope and an ultraviolet source for supplying ultraviolet light to excite the body cavity wall into the above-mentioned illumination optical system.
FIG. 7
shows an optical configuration in the light source device
60
of such a video endoscope system.
FIG. 8
is a front view of an RGB rotating shutter
603
and a UV rotating shutter
609
in the light source device
60
.
As shown in
FIG. 7
, the light source device
60
is composed of a white light source
601
, an infrared cut-off filter
602
, the RGB rotating shutter
603
, a UV reflection filter
604
, a light aperture diaphragm
605
, a condenser lens
606
, an ultraviolet light source
607
, a UV transmission filter
608
, the UV rotating shutter
609
, and a mirror
610
.
The RGB rotating shutter
603
is, as shown in FIG.
7
and
FIG. 8A
, a disc coaxially mounted on a drive shaft of a motor
603
a
, on which are formed three fan-shaped window, respectively fitted with red, green and blue filters
603
b
-
603
d
. These filters
603
b
-
603
d
are band pass filters, respectively transmitting red, green and blue light and arranged side by side at predetermined intervals on the same circle coaxial with outer edge of the disc. These filters
603
b
-
603
d
are arranged to occupy almost a semicircular area within this circle.
As shown in FIG.
7
and
FIG. 8
, UV rotating shutter
609
is a disk coaxially mounted on a drive shaft of a motor
609
a
, on which are formed a fan-shaped opening whose apex coincides with the center of the disc. The central angle of the opening
609
b
is slightly less than 180 degrees.
As shown in
FIG. 7
, the collimated beam of white light emitted from the white light source
601
is deprived of its wavelength components in the infrared region by the infrared cut-off filter
602
, transmitted through one of the red, green or blue filters
603
b
-
603
d
provided on the RGB rotating shutter
603
and the UV reflection filter
604
, and subsequently adjusted to have a proper amount of light by the light aperture diaphragm
605
, and focused onto a proximal end face
70
a
of a light guide
70
of the video endoscope by the condenser lens
606
.
The collimated light beam consisting of wavelengths in the ultraviolet region emitted from the ultraviolet light source
607
in a direction parallel to the collimated beam of white light is filtered by the UV transmission filter
608
to be a collimated beam having wavelengths only in the ultraviolet region, then transmitted through the opening
609
b
formed on the UV rotating shutter
609
, then sequentially reflected by the mirror
610
and the UV reflection filter
604
to shift to trace the same optical path as the above-emitted collimated beam of white light, subsequently adjusted to have a proper amount of light by the light aperture diaphragm
605
, and focused onto the proximal end face
70
a
of the light guide
70
by the condenser lens
606
.
The RGB rotating shutter
603
and the UV rotating shutter
609
are rotated by the motors
603
a
and
609
a
, respectively, whose speeds and rotation phases are controlled, so that a beam consisting of a blue component (blue light), a beam consisting of a green component (green light), a beam consisting of a red component (red light), and a beam having wavelengths in the ultraviolet region (ultraviolet light) are incident onto the proximal end face of the light guide
70
, in turn.
FIG. 9
gives a schematic representation of these respective beams incident on the condenser lens
606
. In
FIG. 9
, an interval designated by two broken lines indicates a period in which the rotating shutter
603
and the rotating shutter
609
round in synchronism with each other, with periods corresponding to protruding portions of the lines in the graph indicating periods in which the collimated beam of white light enters one of RGB filters
603
b
-
603
d
or a period in which a collimated light beam consisting of the wavelengths in the ultraviolet region streams into the opening
609
b
, respectively. A symbol “x” appearing on each line indicates a blank period in which no beam enters the condenser lens
606
.
As shown in
FIG. 9
, while the rotating filter
603
and the rotating shutter
609
round, blue light, green light, red light, and ultraviolet light are sequentially onto the condenser lens
606
. Here, since the fan-shaped opening
609
b
formed on the UV rotating shutter
609
has a larger center angle than the center angles of each of the three fan-shaped windows formed on RGB rotating shutter
603
, the period when ultraviolet light is incident on the condenser lens
606
is longer than any one of periods for blue light, green light and red light.
Light of each color that enters the light guide
70
from the proximal end face
70
a
thereof is transmitted through this light guide
70
to its distal end face to illuminate or irradiate the body cavity wall through a light distribution lens fitted onto the distal end of the video endoscope (not shown in the figure). Images of the body cavity wall illuminated sequentially by the blue light, the green light, and the red light which are formed by an objective optical system (not shown in the figure), and an image of autofluorescence of the body cavity wall that is excited by the ultraviolet light which is formed by the objective optical system (not shown in the figure) are sequentially picked up by the CCD installed in the video endoscope, converted into electronic signals, and sent to an image signal processing circuit within an endoscope processor (not shown in the figure).
In the optical system of the above-mentioned light equipment
60
, the two light sources
601
,
607
are arranged side by side so that a collimated beam of white light and a collimated beam consisting of wavelengths in the ultraviolet region are parallel to each other. These two collimated light beams are guided to a common optical path through the mirror
610
and the UV reflection filter
604
. Thus, these two beams share light aperture diaphragm
605
and condenser lens
606
.
However, a configuration in which two collimated l
Asahi Kogaku Kogyo Kabushiki Kaisha
Mulcahy John
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