U.S. patent number RE43,281 [Application Number 11/108,104] was granted by the patent office on 2012-03-27 for endoscope capable of being autoclaved.
Invention is credited to Susumu Aono, Yasuyuki Futatsugi, Masakazu Higuma, Jun Hiroya, Takahiro Kishi, Yasuhito Kura, Ichiro Nakamura, Takeaki Nakamura, Kazutaka Nakatsuchi, Hidetoshi Saito, Yutaka Tatsuno, Takao Yamaguchi, Yosuke Yoshimoto.
United States Patent |
RE43,281 |
Higuma , et al. |
March 27, 2012 |
Endoscope capable of being autoclaved
Abstract
An endoscope capable of being autoclaved in accordance with the
present invention includes an insertion unit, an internal endoscope
space, and contents. The insertion unit has a soft member, which is
made of a soft polymeric material, as at least part of a casing
thereof. The internal endoscope space includes the internal space
of the insertion unit that is formed at a first sealing level at
which the internal space is sealed in a watertight manner relative
to an outside. The contents include at least one hermetically
sealed unit composed of a plurality of airtight partition members
and formed at a second sealing level higher than the first sealing
level by joining the meeting portions of the airtight partition
members using an airtight joining material. All or part of the
airtight partition members is stowed in the internal endoscope
space. Even when high-pressure high-temperature steam permeates
through the soft member of the insertion unit which is made of a
polymeric material, and invades into the internal endoscope space
formed at the first sealing level, the high-pressure
high-temperature steam will be hindered from invading into the
hermetically sealed unit included in the contents and formed at the
second sealing level.
Inventors: |
Higuma; Masakazu (Hachioji,
JP), Futatsugi; Yasuyuki (Hachioji, JP),
Nakamura; Takeaki (Hino, JP), Yoshimoto; Yosuke
(Hachioji, JP), Kishi; Takahiro (Yokohama,
JP), Kura; Yasuhito (Hachioji, JP),
Tatsuno; Yutaka (Sagamihara, JP), Yamaguchi;
Takao (Hachioji, JP), Aono; Susumu (Hachioji,
JP), Nakamura; Ichiro (Kokubunji, JP),
Hiroya; Jun (Iruma, JP), Saito; Hidetoshi (Hanno,
JP), Nakatsuchi; Kazutaka (Hino, JP) |
Family
ID: |
27582246 |
Appl.
No.: |
11/108,104 |
Filed: |
April 15, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
09370659 |
Aug 6, 1999 |
6547721 |
Apr 15, 2003 |
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Foreign Application Priority Data
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Aug 7, 1998 [JP] |
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10-224822 |
Aug 7, 1998 [JP] |
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10-224923 |
Aug 27, 1998 [JP] |
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10-242036 |
Aug 28, 1998 [JP] |
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10-243649 |
Aug 28, 1998 [JP] |
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10-243650 |
Sep 1, 1998 [JP] |
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10-247459 |
Sep 8, 1998 [JP] |
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10-254263 |
Sep 9, 1998 [JP] |
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10-255743 |
Jul 22, 1999 [JP] |
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11-208128 |
Jul 22, 1999 [JP] |
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11-208129 |
Jul 22, 1999 [JP] |
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11-208131 |
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Current U.S.
Class: |
600/133; 600/169;
600/110; 600/109 |
Current CPC
Class: |
A61B
1/0011 (20130101); G02B 23/2476 (20130101); A61L
2/07 (20130101); G02B 23/2492 (20130101); A61B
1/121 (20130101); A61B 1/051 (20130101); A61B
1/00075 (20130101); A61B 1/00096 (20130101) |
Current International
Class: |
A61B
1/005 (20060101) |
Field of
Search: |
;600/133,103,110,129,130,169 ;348/65,294,340 |
References Cited
[Referenced By]
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0842633 |
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59129050 |
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6240413 |
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62-212614 |
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62212614 |
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63-315024 |
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63315024 |
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112802 |
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03-287218 |
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467445 |
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5269081 |
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6-209898 |
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6209898 |
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06-347707 |
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JP |
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7-51223 |
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JP |
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7512223 |
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JP |
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60107819 |
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JP |
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08-056895 |
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JP |
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08-202017 |
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JP |
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09-192093 |
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Jul 1997 |
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JP |
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9-265046 |
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Oct 1997 |
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JP |
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09-265046 |
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Oct 1997 |
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JP |
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9-265047 |
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Oct 1997 |
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JP |
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09-265047 |
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Oct 1997 |
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JP |
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9265046 |
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Oct 1997 |
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JP |
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9265047 |
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Oct 1997 |
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JP |
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Other References
European Search Report (in English) issued Nov. 29, 1999 in a
related application. cited by examiner.
|
Primary Examiner: Leubecker; John P
Claims
What is claimed is:
1. An endoscope capable of being autoclaved, comprising: an outer
casing of the endoscope made at least partially of a polymeric
material and having an interior; and a component housed in the
interior of the outer casing and constituted as a hermetically
sealed unit composed of a plurality of airtight partition members,
end parts of said plurality of airtight partition members being
hermetically joined to one another such as to at least partially
have said partition members overlap one another thereby to provide
an airtight space; wherein the outer casing is formed to provide a
first sealing level to hinder liquid from invading into the
interior thereof while permitting high-pressure, high-temperature
steam given off during autoclaving to invade into the interior
thereof; and the component is formed to provide a second sealing
level higher than the first sealing level of the outer casing, to
hinder the high-pressure, high-temperature steam penetrating
through the outer casing during autoclaving from invading into the
interior.Iadd., wherein said hermetically sealed unit includes at
least one of optical members and electronic parts or both said
optical members and said electronic parts as airtight partition
members, and wherein said hermetically sealed unit is a lens unit
having optical members as said airtight partition members, said
lens unit having a first and second end portions which are
hermetically locked as optical windows.Iaddend..
2. An endoscope capable of being autoclaved according to claim 1,
wherein said airtight partition members are members made of a
metal, ceramic, glass, or crystalline material.
3. An endoscope capable of being autoclaved according to claim 1,
wherein said hermetically sealed unit is composed of a plurality of
airtight partition members said airtight partition members are
hermetically joined to one another at one or more joints, said
joints are made of a metal, ceramic, glass, or crystalline
material.
4. An endoscope capable of being autoclaved according to claim 3,
wherein said airtight joining means is a joint formed by welding
carried out by one of fusion welding, pressure welding, brazing,
soldering or joining using molten glass.
5. An endoscope capable of being autoclaved according to claim 1,
wherein said hermetically sealed unit formed at said second sealing
level is pressure-resistant to resist a negative pressure or
pressurization to be attained or performed during autoclaving so as
not to be destroyed, and wherein said hermetically sealed unit is
sealed to such an extent that high-pressure high-temperature steam
given off during autoclaving will not invade into an interior of
said hermetically sealed unit.
.[.6. An endoscope capable of being autoclaved according to claim
1, wherein said hermetically sealed unit includes at least one of
optical members and electronic parts or both said optical members
and said electronic parts as airtight partition members..].
.[.7. An endoscope capable of being autoclaved according to claim
6, wherein said hermetically sealed unit is a lens unit having
optical members as said airtight partition members, said lens unit
having a first and second end portions which are hermetically
locked as optical windows..].
8. An endoscope capable of being autoclaved according to claim 7,
wherein a metal coating having a lowermost layer formed as a low
reflectance layer and an uppermost layer formed as a joining layer
formed on the outer circumferences of said optical members included
in said lens unit.
9. An endoscope capable of being autoclaved according to claim 8,
wherein said low reflectance layer has a two-layer structure
consisting of a lower layer made of chromium oxide and an upper
layer made of chromium.
10. An endoscope capable of being autoclaved according to claim 8,
wherein said outer circumferences of said optical members on which
said low reflectance layer is formed are polished so that an
average roughness (Ra) will fall within a range of 0.1 .mu.m to 1
.mu.m and the largest roughness (Pv) will fall within a range of 2
.mu.m to 5 .mu.m.
11. An endoscope capable of being autoclaved according to claim 7,
comprising an observing means having an optical fiber bundle as a
light introducing path, said optical fiber bundle has an input end
and an output end, and said lens unit is located at one of said
input end and output end of said optical fiber bundle.
12. An endoscope capable of being autoclaved according to claim 11,
wherein one of said optical members included in said lens unit is
coupled to one of said input end and output end of said optical
fiber bundle.
13. An endoscope capable of being autoclaved according to claim 11,
wherein said lens unit located at one of said input end and output
end of said optical fiber bundle is detachable.
14. An endoscope capable of being autoclaved according to claim 6,
wherein said hermetically sealed unit includes an observing means
having an optical member as said airtight partition member, said
optical member is hermetically locked as an optical window therein,
and said optical window is bared on an outer surface forming part
of said outer casing of said endoscope.
15. An endoscope capable of being autoclaved according to claim 14,
wherein said observing means is an imaging unit having a
solid-state imaging device as part of an image transmitting means,
said solid-state imaging device having an image input end, and an
objective unit having a first and second end portions which are
hermetically locked as optical windows, said objective unit is
located at said image input end of said solid-state imaging
device.
16. An endoscope capable of being autoclaved according to claim 15,
wherein one of said optical windows included in said objective unit
is placed in contact with a image input end of said solid-state
imaging device.
17. An endoscope capable of being autoclaved according to claim 16,
wherein said optical window and said image input end of said
solid-state imaging device are joined using a transparent
adhesive.
18. An endoscope capable of being autoclaved according to claim 15,
wherein said hermetically sealed unit is accommodated in said
objective unit, said objective unit forms an object image, said
object image is projected on said imaging surface of said
solid-state imaging device, said objective unit is located in front
of said imaging surface of said solid-state imaging device, and a
member opposed to a proximal outer surface of said solid-state
imaging device is sealed at said first sealing level.
19. An endoscope capable of being autoclaved according to claim 14,
comprising an insertion unit having a bendable part and a distal
rigid part, said bendable part being in gaseous communication with
said distal rigid part of said insertion unit, said hermetically
sealed unit is accommodated in said insertion unit and positioned
within said distal rigid part distal to said bendable part.
20. An endoscope capable of being autoclaved according to claim 6,
comprising an observing means having an optical fiber bundle as a
light introducing path, said optical fiber bundle has an input end
portion and an output end portion, said end portions of said
optical fiber bundle are infiltrated with an airtightness retaining
filler to make said optical fibers airtight, and wherein said end
portions of said optical fiber bundle are hermetically fixed to
said airtight partition members of said hermetically sealed
unit.
21. An endoscope capable of being autoclaved according to claim 6,
wherein one of the airtight partition members of the hermetically
sealed unit is a first optical member, the first optical member
engages with a frame member and has a distal surface, and wherein
when a second optical member is fixed to only the distal surface of
the first optical member, the second optical member is not engaged
with the frame member.
22. An endoscope capable of being autoclaved according to claim 1,
comprising an insertion unit having a bendable part and a distal
rigid part, and an operation unit, said bendable part of said
insertion unit is coupled to said operation unit, said bendable
part of said insertion unit is in gaseous communication with said
distal rigid part of said insertion unit, a first hermetically
sealed unit is included in said distal rigid part of said insertion
unit distal to said bendable part of said insertion unit, a second
hermetically sealed unit is located in said operation unit, and
said first and second hermetically sealed units are electrically
linked by a cable.
23. An endoscope capable of being autoclaved according to claim 1,
wherein one of said first and second sections being an insertion
unit whose outer casing is made at least partially of a polymeric
material.
24. An endoscope capable of being autoclaved according to claim 1,
wherein said first sealing level seals said internal spaces of said
first and second sections in a watertight manner relative to said
ambient space surrounding said outer casing.
25. An endoscope capable of being autoclaved according to claim 1,
wherein even when a high-pressure steam permeates through said
first sealing level and invades into said internal spaces of said
sections, said high-pressure high-temperature steam will be
hindered from invading into said hermetically sealing unit formed
at said second sealing level.
26. An endoscope capable of being autoclaved according to claim 23,
wherein the component is composed of a plurality of airtight
partition members which are hermetically joined to one another by
an airtight joining means.
27. An endoscope capable of being autoclaved according to claim 26,
wherein said airtight joining means comprises: locking parts
respectively provided on the plurality of airtight partition
members at positions to hermetically join the plurality of airtight
partition members to one another; a coating part formed by having a
metal or glass coating formed on at least one of the locking parts
provided on the plurality of airtight partition members; and
airtight joining part formed by heating the joined part of the
airtight partition members to fuse the coating part.
28. An endoscope capable of being autoclaved, comprising: an outer
casing means made at least partially of a polymeric material that
secures an internal space; a component housed in the internal space
of the outer casing means and constituted as a hermetically sealed
unit composed of a plurality of airtight partition members, end
parts of said plurality of airtight partition members being
hermetically joined to one another such as to at least partially
have said partition members overlap one another thereby to provide
an airtight space; a first sealing means, with which the outer
casing means is provided, to provide the outer casing means with
watertightness to hinder liquid from invading into the interior of
the outer casing means and to provide a first sealing level to
permit high-pressure, high-temperature steam given off during
autoclaving to invade into the internal space of the outer casing
means; and a second sealing means with which the component is
provided, to provide the component with a second sealing level
higher than the first sealing level provided by the first sealing
means, to hinder the high-pressure, high-temperature steam invading
through the outer casing means during autoclaving from invading
into the airtight partition members.Iadd., wherein said
hermetically sealed unit includes at least one of optical members
and electronic parts or both said optical members and said
electronic parts as airtight partition members, and wherein said
hermetically sealed unit is a lens unit having optical members as
said airtight partition members, said lens unit having a first and
second end portions which are hermetically locked as optical
windows.Iaddend..
.Iadd.29. An endoscope capable of being autoclaved, comprising: an
outer casing made at least partially of a polymeric material and
having an interior; a component housed in the interior of the outer
casing and constituted as a hermetically sealed unit composed of a
plurality of airtight partition members which are hermetically
joined to one another and at least partially overlapped; a frame
body which constitutes an end of the component; a first optical
member which is hermetically locked in the frame body and which
forms an optical path; and a second optical member which is
positioned, bonded and fixed to a distal surface of the first
optical member and which forms the optical path, wherein the outer
casing is formed to provide a first sealing level to hinder liquid
from invading into the interior thereof while permitting
high-pressure, high-temperature steam given off during autoclaving
to invade into the interior thereof; and the component is formed to
provide a second sealing level higher than the first sealing level
of the outer casing, to hinder the high-pressure, high-temperature
steam penetrating through the outer casing during autoclaving from
invading into the interior..Iaddend.
.Iadd.30. An endoscope according to claim 29, wherein the second
optical member has an outer configuration of a dimension that
leaves a predetermined gap between an outer circumference of the
second optical member and an inner circumference of the frame
body..Iaddend.
.Iadd.31. An endoscope according to claim 29, wherein the second
optical member is positioned, bonded and fixed to a distal surface
of the first optical member..Iaddend.
.Iadd.32. An endoscope comprising: an outer casing made at least
partially of a polymeric material and having an interior; a
component housed in the interior of the outer casing and
constituted as a hermetically sealed unit composed of a plurality
of airtight partition members which are hermetically joined to one
another and at least partially overlapped; a frame body defining an
airtight inner space, the frame body being capable of expanding
when subjected to autoclaving, while maintaining the airtightness
of the inner space; an optical window coupled to the frame body to
guide light into the inner space; a first optical member having a
first diameter and mounted within the airtight inner space and
disposed on an optical axis of incident light penetrating through
the optical window; a second optical member mounted within the
inner space without contacting any portion of the frame body in a
manner whereby expansion and contraction of the second optical
member does not affect the ability of the frame body to maintain
the airtightness of the inner space wherein the outer casing is
formed to provide a first sealing level to hinder liquid from
invading into the interior thereof while permitting high-pressure,
high-temperature steam given off during autoclaving to invade into
the interior thereof; and the component is formed to provide a
second sealing level higher than the first sealing level of the
outer casing, to hinder the high-pressure, high-temperature steam
penetrating through the outer casing during autoclaving from
invading into the interior..Iaddend.
.Iadd.33. An endoscope according to claim 32, in which the frame
body comprises a plurality of frame body sections that are arranged
following one another along the optical axis, the frame body
sections including a distal frame section, and a second frame
section..Iaddend.
.Iadd.34. An endoscope according to claim 33, further comprising an
isolating frame section disposed between and coupling the distal
frame section and the second frame section..Iaddend.
.Iadd.35. An endoscope according to claim 34, in which the frame
sections are made of the same material..Iaddend.
.Iadd.36. An endoscope according to claim 34, in which a material
of the distal frame section and the second frame section is
metal..Iaddend.
.Iadd.37. An endoscope according to claim 34, further comprising a
lens arrangement and a lens frame surrounding the lens arrangement
and disposed in the inner space..Iaddend.
.Iadd.38. An endoscope according to claim 37, in which the lens
arrangement and its lens frame is disposed adjacent the distal
frame section..Iaddend.
.Iadd.39. An endoscope according to claim 38, in which the lens
frame contacts a portion of the isolating frame and comprises a
section that is juxtaposed to a portion of the distal frame with an
airspace therebetween..Iaddend.
.Iadd.40. An endoscope according to claim 32, further comprising
adhesive material filling a portion of the inner space and disposed
in a region which partially contacts the first optical
member..Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an endoscope whose contents will
resist high-temperature high-pressure steam given off during
autoclaving so as not to be destroyed or deteriorated, and whose
insertion unit has a soft part.
2. Description of the Related Art
Endoscopes having an insertion unit thereof inserted into a body
cavity for observation of a deep region or for medical treatments
to be, if necessary, conducted using a treatment appliance have
been widely used in the field of medicine.
In the case of endoscopes for medical studies, disinfecting and
sterilizing a used endoscope is essential for preventing infectious
diseases. A sterilization gas such as an ethylene oxide (EOG) gas
or a disinfectant has been used to disinfect and sterilize a used
endoscope in the past.
However, sterilization gases are, as already known, quite toxic.
Sterilization work cannot help becoming imperfect because it must
be carried out safely. Moreover, adverse effects of a sterilization
gas on an environment are in question. Since it takes much time for
aeration intended to remove gas sticking on equipment after
sterilization, a sterilized endoscope cannot be used immediately
after sterilization. Moreover, there is a question of a high
running cost.
On the other hand, disinfectants are hard to manage. Besides, the
fact that a great expense is needed to dispose of a disinfectant
must be taken into consideration.
Autoclaving has become a mainstream of disinfection and
sterilization of endoscopic equipment these days. This is because
autoclaving does not require time-consuming work, makes it possible
to use equipment immediately after autoclaving, and costs a little
for running.
Typical conditions for autoclaving are stipulated as the ANSI/AAMI
ST37-1992 acknowledged by the American National Standards Institute
and issued by the Association for the Advancement of Medical
Instrumentation. The conditions define that pre-vacuum type
autoclaving should be performed at 132.degree. C. for four minutes
and that gravity type autoclaving should be performed at
132.degree. C. for ten minutes. Degrees of temperature at which
autoclaving is actually performed range from 115.degree. C. to
140.degree. C. in general.
A typical process of pre-vacuum type autoclaving includes a
pre-vacuum step, a sterilization step, and a drying step. At the
pre-vacuum step, a sterilization chamber in which medical equipment
to be sterilized is stowed is decompressed to exhibit a negative
pressure. At the sterilization step, high-pressure high-temperature
steam is injected into the sterilization chamber for sterilization.
At the drying step, the sterilization chamber is decompressed again
in order to dry a sterilized endoscope.
The pre-vacuum step is a step intended to facilitate infiltration
of steam into the minute spaces in medical equipment which is
performed at the sterilization step. The sterilization chamber is
decompressed, whereby high-pressure high-temperature steam
penetrates the whole of the stowed medical equipment. The pressure
in the sterilization chamber to be attained at the pre-vacuum step
and drying step is calculated as "an atmospheric pressure -0.07 MPa
or so." The pre-vacuum step is included in a process of gaseous
sterilization using an ethylene oxide gas. The pressure to be
attained at the sterilization step is often set to a value
calculated as "the atmospheric pressure +0.2 MPa or so."
In general, endoscopes have a soft insertion unit or are of a
bendable type having a bendable part. In this case, an armor tube
made of a soft polymeric material such as a rubber or elastomer is
used as a casing member for the soft insertion unit or bendable
part. Moreover, since the endoscopes must be immersed in a fluid
agent, the endoscopes are entirely watertight.
When a watertight endoscope is autoclaved, a soft armor tube may
dilate to break at the decompression step such as the pre-vacuum
step. Otherwise, a joint of parts may not fail to resist a
difference in pressure between the interior and exterior of the
endoscope any longer, and may eventually be broken.
For preventing the above incident, Japanese Unexamined Utility
Model Publication No. 1-12802 has disclosed an interior-exterior
communication device for airtight endoscopes.
According to the utility model, when a process of gaseous
sterilization including a pre-vacuum step is adopted, an
airtightness release cap is attached to the interior-exterior
communication device, which is located on the outer wall of an
endoscope, at each decompression step. This is intended to allow
the internal space of the endoscope (or in other words, the
interior of the endoscope) to communicate with the exterior of the
endoscope for preventing a burst of a bendable armor tube of a
bendable part.
Moreover, Japanese Unexamined Patent Publication No. 63-315024
describes an endoscope structured so that a communication path
formed in part of the outer wall of the endoscope is blocked using
a waterproof cap. The endoscope is sterilized using a gas with the
waterproof cap removed. It is thus prevented that an armor tube of
a bendable part or the like bursts at a decompression step.
However, as far as autoclaving is concerned, the interior and
exterior of an endoscope are allowed to communicate with each
other, and high-pressure high-temperature steam is actively invaded
into the interior. This poses a problem in that various contents of
the endoscope including an observing means and internal structural
members thereof deteriorate shortly because of the steam.
In efforts to cope with the problem, Japanese Examined Patent
Publication No. 4-67445 has disclosed an internal pressure
adjustment device for airtight endoscopes. The internal pressure
adjustment device has a non-return valve mechanism located on a
housing of an endoscope. The non-return valve mechanism permits
passage of gas from the interior of the endoscope to the exterior
thereof but prevents invasion of gas from the exterior of the
endoscope into the interior thereof. Even when autoclaving is
performed, it is prevented that high-pressure high-temperature
steam actively invades into the interior of the endoscope.
However, an endoscope may include members made of a polymeric
material such as a plastic or rubber. In this case, when the
endoscope is autoclaved, high-pressure high-temperature steam
permeates through the polymeric members and invades into the
interior of the endoscope. In other words, unless all members
constituting an endoscope are made of a raw material such as a
metal, ceramic (in a broad sense, including a glass), or
crystalline material, and assembled without a gap, high-pressure
high-temperature steam will invade into the interior of the
endoscope during autoclaving.
The Japanese Examined Patent Publication No. 4-67445 has disclosed
an endoscope having a non-return valve mechanism. If the endoscope
is an endoscope with a bending ability whose insertion unit has a
bendable part, the bendable part is sheathed with an armor tube
made of a polymeric material such as a soft rubber or elastomer.
High-pressure high-temperature steam permeates through the armor
tube and gradually invades into the interior of the endoscope.
Moreover, in the endoscope with a bending ability, a rubber-sealing
member made of a polymeric material such as an O ring is used as a
sealing member for sealing an axis of rotation of a bending lever
used to bend the bendable part. High-pressure high-temperature
steam used for autoclaving permeates through the rubber-sealing
member and gradually invades into the interior of the
endoscope.
Furthermore, even when an insertion unit of an endoscope does not
have the bending ability, if the whole insertion unit is soft, a
polymeric material is used to make the armor tube of the insertion
unit. During autoclaving, high-pressure high-temperature steam
permeates through the armor tube and gradually invades into the
interior of the endoscope.
Endoscopes referred to as airtight endoscopes include endoscopes
having a bending ability and endoscopes each of which insertion
unit is soft. In these endoscopes, high-pressure high-temperature
steam given off during autoclaving, as mentioned above, permeates
through a member made of a polymeric material and gradually invades
into the interior of the endoscope.
The phenomenon that steam invades into the interior of an endoscope
takes place during autoclaving irrespective of whether the
autoclaving is of a pre-vacuum type or gravity type.
When steam invades into the interior of an endoscope, there arises
a fear that various contents of the endoscope including an
observing means and internal structural members thereof may
deteriorate, though gradually.
An electronic endoscope will be taken for instance. Steam invading
into the interior of the endoscope may condense on the surface of a
lens included in an objective unit incorporated in an imaging unit
or the internal surface of a cover glass of the objective unit.
Moreover, electronic parts including a solid-state imaging device
may malfunction. In either case, there arises a possibility that
invading steam impairs the quality of a view.
Moreover, when steam invading into the interior of an endoscope
reaches an observation optical system, the steam may condense on
the surface of a lens included in the observation optical system or
the internal surface of a cover glass of the observation optical
system to narrow a field of view. This is not limited to the
electronic endoscope, but the same applies to a fiberscope.
Furthermore, a multi-component glass that can be machined readily
is a lens glass widely used as the foregoing lens or cover glass.
The multi-component glass deteriorates when exposed to
high-pressure high-temperature steam given off during autoclaving.
When steam invades into the interior of an endoscope, the glass
itself may deteriorate or a coating formed on the surface of the
lens or an adhesive applied to the surface thereof may deteriorate.
This may impair the quality of a view.
Japanese Unexamined Patent Publication No. 62-212614 describes an
endoscope in which at least part of an optical system is structured
hermetically in order to prevent invasion of steam into the optical
system. However, the endoscope has optical members including a lens
and cover glass bonded to a frame using an adhesive. When
autoclaving is performed under the conditions stipulated by the
American National Standards Institute and others, steam invades
into the optical system through the adhesive. In short, the
structure cannot hinder invasion of high-pressure high-temperature
steam in practice.
Under the foregoing conditions for autoclaving, high-pressure
high-temperature steam permeates through a layer of a hardened
adhesive whose major component is a polymeric material, such as, a
generally adopted epoxy adhesive or silicone adhesive.
Moreover, the strength of a joint secured with the above adhesive
is not so high as that of a joint secured by performing welding.
When parts made of different materials, for example, a metal and
glass are joined using an adhesive, the coefficient of thermal
expansion differs between the parts. When the parts change due to
heat during autoclaving, the joint of the parts is stressed.
Consequently, the adhesive may peel off.
In consideration of the foregoing drawbacks, a rigid endoscope
having a rigid insertion unit has, as described in Japanese
Unexamined Patent Publication No. 9-265046, a cover glass
hermetically locked in a sleeve, which is one of parts constituting
a housing of the endoscope, without a gap by performing soldering.
A housing structure serving as the housing of the endoscope is thus
sealed hermetically.
However, in the case of an endoscope whose insertion unit has a
bendable part or whose insertion unit is at least partly soft, a
member made of a polymeric material is used as at least part of a
housing of the endoscope. Even if only the distal part of the
insertion unit has members thereof joined hermetically, the whole
of the housing of the endoscope cannot be sealed fully
hermetically.
In other words, the endoscope whose housing can be sealed
hermetically as described in the Japanese Unexamined Patent
Publication No. 9-265047 is limited to rigid endoscopes not having
the bending ability and making it possible to make an insertion
unit thereof using a metal or ceramic.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an endoscope
capable of producing a high-quality view and resisting
high-pressure high-temperature steam. Specifically, during
autoclaving, high-pressure high-temperature steam may permeate
through an armor tube made of a polymeric material and used to
outline at least part of an insertion unit, and invade into the
interior of the endoscope. Nevertheless, it can be prevented that
the invading steam fogs an optical system to adversely affect
observation or that electronic parts or the like deteriorate.
Another object of the present invention is to provide an endoscope
that will not offer a field of view narrowed due to a degraded
optical system or fogging. Specifically, it can be prevented that
high-pressure high-temperature steam invades into an optical system
in the endoscope during autoclaving.
Still another object of the present invention is to provide an
endoscope capable of being autoclaved. Specifically, it is
prevented that incident light reflects from a coating covering the
outer circumference of an optical member to cause flare.
Briefly, an endoscope capable of being autoclaved in accordance
with the present invention includes an insertion unit, an internal
endoscope space, and contents. The insertion unit has a soft
member, which is made of a soft polymeric material, as at least
part of a casing thereof. The internal endoscope space includes the
internal space of the insertion unit which is formed at a first
sealing level at which the internal space keeps watertight relative
to an exterior. The contents are formed with a plurality of
airtight partition members all or part of which is stowed in the
internal endoscope space. The contents include at least one
hermetically sealed unit made by joining the airtight partition
members using an airtight joining means, and thus formed at a
second sealing level higher than the first sealing level.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 to FIG. 10 relate to a first embodiment of the present
invention;
FIG. 1 is an explanatory diagram concerning the configuration of an
electronic endoscope;
FIG. 2 is a cross sectional view for explaining the structure of a
non-return valve cap;
FIG. 3 is a longitudinal sectional view for explaining the
structure of the distal part of the electronic endoscope and its
neighborhood;
FIG. 4 is a longitudinal sectional view for explaining the
structure of an imaging unit;
FIG. 5A is an explanatory diagram concerning a metal coating formed
on a distal cover glass;
FIG. 5B is an explanatory diagram concerning a metal coating formed
on a back-end cover glass;
FIG. 6 is an explanatory diagram concerning the distal cover glass
covered with the metal coating having a low reflectance layer;
FIG. 7 is an explanatory diagram concerning a metal coating formed
on the outer surface of an isolating frame;
FIG. 8A is a sectional view showing a proximal cover glass
hermetically united with the isolating frame;
FIG. 8B is an enlarged view for explaining the airtight joint;
FIG. 9 is an explanatory diagram concerning a procedure of
assembling lenses to produce an objective unit included in an
imaging unit;
FIG. 10 is an explanatory diagram concerning a hermetically sealed
objective unit;
FIG. 11 is an explanatory diagram concerning a procedure of
assembling lenses to produce an objective unit included in an
imaging unit;
FIG. 12 is an explanatory diagram concerning notches of an
engagement portion of a frame;
FIG. 13 is an explanatory diagram concerning an imaging unit having
another structure;
FIG. 14 is a sectional view for explaining a beam narrowing mask
created on the proximal surface of the distal cover glass;
FIG. 15 is a perspective view of the distal cover glass for
explaining the beam narrowing mask created on the proximal surface
of the distal cover glass;
FIG. 16 and FIG. 17 relate to a second embodiment of the present
invention;
FIG. 16 is a longitudinal sectional view for explaining the
structure of the distal part of an electronic endoscope and its
neighborhood;
FIG. 17 is a longitudinal sectional view for explaining the
structure of an imaging unit;
FIG. 18 shows the electronic endoscope having a device frame and
HIC frame linked by a relay cable;
FIG. 19 is an explanatory diagram for detailing the device frame,
HIC frame, and relay cable;
FIG. 20 shows an electronic endoscope having a device frame and
substrate frame linked by a relay cable;
FIG. 21 is a longitudinal sectional view for explaining the
structure of a light guide connector;
FIG. 22 is a sectional view for explaining the structure of a
switch unit;
FIG. 23 to FIG. 25 relate to a third embodiment of the present
invention;
FIG. 23 is an explanatory diagram concerning the configuration of
an endoscope;
FIG. 24 is a longitudinal sectional view for explaining the
structure of the distal part of the endoscope and its
neighborhood;
FIG. 25 is a longitudinal sectional view for explaining the
structure of an eyepiece unit of the endoscope;
FIG. 26 is an explanatory diagram concerning another joined state
of an objective frame and image guide fiber frame;
FIG. 27 is a longitudinal sectional view for explaining another
structure of the distal part of an endoscope and its
neighborhood;
FIG. 28 is an explanatory diagram concerning an image output end of
an image guide fiber bundle to which a mask deposition cover glass
is fixed;
FIG. 29 is a perspective view for explaining the mask deposition
cover glass; and
FIG. 30 is an explanatory diagram concerning a connector unit
coupled to a light source apparatus.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1 to FIG. 10, a first embodiment of the present
invention will be described below.
As shown in FIG. 1, an electronic endoscope 1 of this embodiment
consists of different sections, mainly of an insertion unit 2, an
operation unit 3, and a universal cord 4. The insertion unit 2 has
a solid-state imaging device, for example, a charge-coupled device
(CCD) incorporated in the distal part thereof. The operation unit 3
is coupled to the proximal end of the insertion unit 2, and held by
an observer to be manipulated in various manners. The universal
cord 4 extends from the operation unit 3. A connector unit 5 is
attached to the other end of the universal cord 4. The connector
unit 5 is connected to a light source apparatus that is not shown
and a camera control unit (hereinafter abbreviated to a CCU) that
is not shown.
A light guide connector 6 is connected to the light source
apparatus, and a camera connector 7 is connected to the CCU.
Moreover, the internal spaces of the insertion unit 2, operation
unit 3, universal cord 4, and connector unit 5 communicate with one
another. In other words, the internal spaces constitute one
internal endoscope space (or simply an internal space) inside a
housing of the endoscope.
The insertion unit 2 consists of a distal part 8, a bendable part 9
that can be bent freely, and a flexible tube 10 having
flexibility.
The operation unit 3 has a bending lever 11, a treatment appliance
insertion port 12, and a plurality of switches 13. The bending
lever 11 is used to control the movements of the bendable part 9.
The treatment appliance insertion port 12 is a port through which a
treatment appliance such as forceps is inserted. The switches 13
are used to freeze or release an image. The bending lever 11 can be
rotated freely and mounted together with an O ring, which is not
shown, in order to attain watertightness.
The camera connector 7 has a vent 14 through which the internal
space is ventilated with outside air. A waterproof cap 15 can be
attached or detached to or from the camera connector 7. The
waterproof cap 15 is attached to the camera connector 7, whereby
the internal space of the endoscope 1 is set to a sealing level
(referred to a first sealing level) at which it is sealed in a
watertight manner. When the waterproof cap 15 is detached, the
interior and exterior of the endoscope 1 with respect to the
endoscope housing or the internal space and exterior thereof
communicate with each other.
The waterproof cap 15 is attached to the camera connector 7 in
order to clean the used endoscope 1 or immerse it in a fluid agent.
The waterproof cap 15 seals the internal space of the endoscope 1
in a watertight manner for fear that a fluid may invade into the
internal space thereof during cleaning under running water or
immersion in a fluid agent. A non-return (oneway) valve cap 20
having the capability of a non-return valve can also be attached or
detached to or from the camera connector 7. The non-return valve
cap 20 permits passage of gas from the internal space of an
endoscope to the exterior thereof but hinders passage of gas from
the exterior of the endoscope to the interior thereof.
As shown in FIG. 2, the non-return valve cap 20 consists of a
non-return valve cap body 22, a valve body 24, a spring 25, an
attachment portion 26, and a sealing member 27. The non-return
valve cap body 22 has a valve seat 21 and is made of, for example,
a metal. The valve body 24 has a rubber sealing member 23 united
therewith and is made of, for example, a metal. The spring 25
constrains the valve body 24 to move towards the valve seat 21. The
attachment portion 26 is attached to the camera connector 7 and
made of, for example, a metal. When the attachment portion 26 is
attached to the camera connector 7, the sealing member 27 made of,
for example, a rubber sustains the watertightness attained between
the inner circumference of the attachment portion 26 and the outer
circumference of the camera connector 7.
For autoclaving the endoscope 1, the non-return valve cap 20 rather
than the waterproof cap 15 is attached to the camera connector 7.
By attaching the non-return valve cap 20, high-pressure
high-temperature steam given off during autoclaving is hindered
from invading through the vent 14.
A constraining force exerted by the spring 25 is set to a magnitude
of force causing the sealing member 23 to meet closely the valve
seat 21 under the condition that: the valve body 24 is constrained
to move towards the valve seat 21 in a normal state in which the
non-return valve cap 20 is attached to the camera connector 7.
Moreover, the magnitude of force allows the valve body 24 to be
released from constraint causing it to move towards the valve seat
21 at a decompression step included in a process of
autoclaving.
As long as the internal pressure of the internal space of the
endoscope 1 does not exceed an atmospheric pressure, or in other
words, in a normal use situation, the internal space of the
endoscope 1 is retained at the first sealing level by attaching the
non-return valve cap 20. At this time, the first sealing level is
attained relative to outside air. For cleaning the endoscope 1 or
immersing it in a fluid agent, the non-return valve cap 20 rather
than the waterproof cap 15 may be attached.
As shown in FIG. 3, an imaging unit 17 serving as an observing
means and image transmitting means and a light guide fiber bundle
18 over which illumination light is transmitted are incorporated in
a distal body 16 outlining the distal part 8 of the endoscope 1. An
illumination lens 19 is placed on the distal surface of the light
guide fiber bundle 18, and bonded and fixed to the distal body 16
using an adhesive.
A distal cover member 31 is mounted on the outer circumference of
the distal body 16. A first bending piece 32a is located at the
foremost position among a plurality of bending pieces 32
constituting the bendable part 9. The first bending piece 32a is
coupled to the proximal end of the distal cover member 31 by a
rivet 33 so that the first bending piece 32a can pivot freely. The
plurality of bending pieces 32 is concatenated to the proximal end
of the first bending piece 32a by the rivets 33 so that they can
pivot freely. The outer circumferences of the bending pieces 32 are
sheathed with a metallic meshed tube 34 and an armor tube 35. The
armor tube 35 is made of a polymeric material such as a rubber or
elastomer having flexibility, for example, a fluorine-contained
rubber.
A range 28 covered by the imaging unit 17 corresponds to the length
of a distal rigid part and falls within a distal rigid length
distal to the rivet 33 located at the foremost position, that is, a
range 29.
As shown in FIG. 4, a distal cover glass 36 forming an optical
window of an observing means is included as part of the casing of
the insertion unit 2 (in this embodiment, part of the distal
surface) and placed at the tip of the imaging unit 17.
The distal cover glass 36 is made of sapphire that is highly
strong, resistive to high-pressure high-temperature steam, and made
into an airtight partition member, or a glass resistive to
high-pressure high-temperature steam. Metal coating that is one
kind of surface finishing is performed on the outer circumference
of the distal cover glass 36. The distal cover glass 36 is
hermetically locked inside the inner circumference of a metallic
distal frame 37 without a gap using an airtight joining means. The
metallic distal frame 37 is an airtight partition member resistive
to high-temperature steam. The airtight joining means enables
highly strong joining but does not deteriorate even when exposed to
steam. Depending on how to design an optical system, a lens may be
used as the optical window instead of the cover glass. The distal
frame 37 is made of a stainless steel or covar.
A plate layer is formed on the internal circumference of the distal
frame 37 by performing, for example, electroplating. The plate
layer is composed of, for example, a lower layer of a nickel plate
layer and an upper layer of a gold plate layer.
A lens frame 39 accommodating a group of objectives 38 is mounted
at the proximal end of the distal cover glass 36. The group of
objectives 38 includes a plurality of optical lenses and forms an
image of an object. The lens frame 39 is bonded and fixed to the
distal part of an isolating frame 41 serving as an airtight
partition member resistive to high-pressure high-temperature steam
and made of an insulating material such as ceramic. The isolating
frame 41 is made of one of ceramics exhibiting a high coefficient
of thermal conductivity and being strong to thermal shock.
Moreover, an aperture stop plate 42 is bonded and fixed to the
internal circumference of the proximal part of the isolating frame
41.
A CCD 43 is a solid-state imaging device on which an object image
formed by the group of objectives 38 is projected. The CCD 43 is
positioned using a reticle or the like, and bonded and fixed to a
proximal cover glass 44 made of sapphire or a glass resistive to
high-pressure high-temperature steam. The proximal cover glass 44
is a kind of optical window opposed to the proximal surface of the
group of objectives 38. In the present embodiment, a CCD cover
glass 45 is placed on the front surface of an imaging chip of the
CCD 43. A lens included in a group of lenses 46 is positioned, and
bonded and fixed to the distal surface of the proximal cover glass
44.
The outer circumference and chamfers of the proximal cover glass 44
have undergone the same surface finishing as the distal cover glass
36. The proximal cover glass 44 is hermetically locked in a frame
body 47 formed with a metallic member, which is an airtight
partition member resistive to high-pressure high-temperature steam,
using an airtight joining means that will be described later. There
is a gap between the outer circumference of the group of lenses 46
and the inner circumference of the frame body 47. The gap is
intended to prevent the frame body 47 from stressing the joined
surfaces of the lenses when the frame body 47 and group of lenses
46 exhibiting different coefficients of thermal expansion thermally
expand due to heating occurring during autoclaving.
The distal part of the frame body 47 and the proximal part of the
isolating frame 41 are hermetically joined using an airtight
joining means. The frame body 47 is, like the distal frame 37, made
of stainless steel or covar. The frame body 47 has the same plate
layer as the distal frame 37 formed on the inner circumference
thereof.
Moreover, when a gap between each pair of the distal cover glass 36
and distal frame 37, the distal frame 37 and isolating frame 41,
and the isolating frame 41 and frame body 47 is closest to nil, the
engagements of the pairs are accomplished reliably.
Moreover, there is a gap of a proper dimension between the proximal
cover glass 44 and frame body 47.
The CCD 43 is electrically coupled to a cable 49 via substrates 48.
Electronic parts including ICs and capacitors are mounted on the
substrates 48. These electronic parts are sealed and locked using a
sealing member such as an adhesive 50 having an insulation
property.
The CCD 43 and others are enclosed in a first shielding frame 51
made of a metal. The first shielding frame 51 is mounted unitedly
on the outer circumference of the frame body 47 by performing
bonding or welding. Moreover, a second shielding frame 52 made of a
metal is attached to the proximal part of the first shielding frame
51 by performing bonding or welding.
A space created by the first shielding frame 51, CCD 43, and
proximal cover glass 44 is filled with a filler 53. The filler 53
is an adhesive, sealant, or a potting material that is less
permeable to steam.
Moreover, an adhesive 54 is injected to the surroundings of the
portion of the cable 49 lying in the second shielding frame 52. The
outer circumference of the second shielding frame 52 is sheathed
with thermo-contractile tubes 55 and 56 made of, for example, a
fluorocarbon resin less permeable to steam.
When members are bonded to each other using an adhesive that is not
shown, the adhesive may readily or hardly peel off during
autoclaving depending on the material made into the members.
When an optical member is bonded and fixed to a metallic frame,
since the coefficient of thermal expansion differs greatly between
the metal and optical member, an adhesive may peel off. This is
because the joint of the optical member and metallic frame is
greatly stressed due to a difference in the coefficient of thermal
expansion when a high temperature is attained during
autoclaving.
By contrast, when identical members, for example, metallic members
are bonded and fixed using an adhesive, since the joint of the
members hardly undergoes a stress stemming from a difference in the
coefficient of thermal expansion, the adhesive will not peel off.
Moreover, a portion filled with an adhesive hardly undergoes a
stress stemming from a difference in coefficient of thermal
expansion. The adhesive therefore rarely peels off or cracks.
In the present embodiment, consideration is taken into the
foregoing facts. When members constituting a portion susceptible to
invasion of steam must be secured using an adhesive, members having
the same coefficient of thermal expansion or members whose
coefficients of thermal expansion are similar (having a small
difference) are bonded and fixed to each other using an adhesive.
If the members to be joined do not have the same or similar
coefficient of thermal expansion, an adhesive is used for a filling
within the members near the joints. Consequently, an adhesive
applied to such joints hardly peels off. Even joining using an
adhesive can therefore suppress permeation of steam.
Next, metal coating and airtight joining will be described with
reference to FIG. 5A to FIG. 8.
Metal coating is performed as surface finishing in order to form a
first metal coating 61 over the lateral surface 36a of the distal
cover glass 36 shown in FIG. 5A and the lateral surface 44a and
chamfers 44b of the proximal cover glass 44 shown in FIG. 5B.
The first metal coating 61 is composed of a chromium layer 62, a
nickel layer 63, and a gold layer 64. The chromium layer 62 is a
lowermost layer formed as a metallized layer. The nickel layer 63
is the second layer or an intermediate layer. The gold layer 64 is
an uppermost layer and serves as a joint layer. The layers are
produced by performing deposition, spattering, or plating in a
vacuum.
Furthermore, as shown in FIG. 6, the lowermost layer of the distal
cover glass 36 may be a chromium oxide (Cr.sub.2O.sub.3) layer 65
that is a low reflectance layer. Rays reaching the chromium oxide
layer 65 that is the low reflectance layer formed on the outer
circumference of the cover glass 36 will hardly be reflected.
Consequently, occurrence of flare or the like can be prevented, and
the optical characteristic of the endoscope improves.
When the chromium oxide layer 65 is formed, the nickel layer 63 and
gold layer 64 are, as illustrated, overlaid the chromium oxide
layer 65. Thus, the first metal coating 61 is realized. Otherwise,
the chromium layer 62, nickel layer 63, and gold layer 64 may be
overlaid a chromium oxide layer 134, thus realizing the first metal
coating 61. Moreover, the lowermost layer of the proximal cover
glass 44 may be the chromium oxide layer 65 that is the low
reflectance layer. Even in this case, the same operation and
advantage as those mentioned above can be exerted.
For putting emphasis on a low reflectance, the lateral surfaces 36a
and 44a of the cover glasses 36 and 44 may be polished to such an
extent that the average roughness (Ra) thereof will be any of 0.1
to 1 .mu.m and the highest roughness (PV) thereof will be any of 2
to 5 .mu.m. The surfaces are then finished as mentioned above.
If the lateral surfaces 36a and 44a were finished like a mirror,
not only light would be reflected from the surfaces but also a
degree of closeness at which the layers of the coating are meeting
would be lowered. If the roughness of a surface were too high, it
would become hard to remove foreign matters adhering to the
surface. The degree of closeness at which the layers of the coating
are meeting would therefore be lowered.
By the way, as shown in FIG. 7, a second metal coating 66 is formed
on the outer surface 41a of the isolating frame 41 engaging with
the distal frame 37 and the outer surface 41b of the isolating
frame 41 engaging with the frame body 47.
The second metal coating 66 on the outer surfaces 41a and 41b are
composed of a nickel layer 67 that is a lower layer of a metallized
layer and a gold layer 68 serving as an uppermost layer. The layers
are formed by performing deposition or spattering in a vacuum or by
performing plating.
The outer surfaces 41a and 41b an inner surfaces are not to be
finished using a conductive material. The distal frame 37 to be
attached in contact with the outer surface 41a and the frame body
47 to be attached in contact with the outer surface 41b are
therefore electrically isolated from each other.
Referring to FIG. 8, a description will be made of airtight joining
of the frame body 47 and proximal cover glass 44.
As shown in FIG. 8A, the depth of a recess 47a in the frame body 47
in which the proximal cover glass 44 is locked is set to a value
smaller than the thickness of the proximal cover glass 44. In other
words, one surface of the proximal cover glass 44 juts beyond the
end surface of the frame body 47 in which the recess 47a is
bored.
As shown in FIG. 8B, the lateral surface 44a of the proximal cover
glass 44 and the inner circumference of the recess 47a are joined
hermetically by injecting a brazing filler metal or solder into a
gap between them and the edges thereof. At this time, a fillet 71
having a substantially triangular section is formed on the end
surface of the frame body 47 beyond which the proximal cover glass
44 juts, and on the chamfer 44b of the proximal cover glass 44
located at a corner of the recess 47a. The fillet 71 is a lump of
the brazing filler metal or solder. When the sections of the
fillets 71 have a desired shape, the brazing filler metal or solder
has been injected unintermittently into the gap between the lateral
surface 44a of the proximal cover glass 44 and the inner
circumference of the recess 47a. Thus, hermetically joining is
completed. In the present embodiment, it can be visually checked
whether the fillets 71 have been shaped precisely.
When flax is used for soldering or brazing, the frame body 47 and
cover glass 44 must be cleaned while being joined in order to
prevent corrosion of a metal.
The soldered or brazed portions do not touch a living body. Any
solder or brazing filler metal can therefore be selected for use.
However, preferably, an alloy of gold and tin or a gold alloy is
used as a solder or brazing filler metal. The uppermost layer of
the plating formed on the frame body 47 and that of the metal
coating formed on the cover glass 44 are gold layers. The plating
and metal coating closely meet the alloy of gold and tin or the
gold alloy.
Referring to FIG. 9 and FIG. 10, a procedure of assembling the
component of the imaging unit 17 will be described below.
Referring to FIG. 9, a procedure of assembling the components of an
objective unit included in the imaging unit 17 will be described
briefly.
The CCD 43 is bonded and fixed to the proximal end of the proximal
cover glass 44, which is hermetically locked in the frame body 47,
using a transparent adhesive 72 in such a manner that no air layer
will be present. At this time, the center axis of the CCD 43 is
aligned with that of the proximal cover glass 44. The isolating
frame 41 and the frame body 47 in which the proximal cover glass 44
is locked are then joined hermetically. Thereafter, the lens frame
39 having the group of objectives 38 is inserted into the isolating
frame 41. The lens frame 39 is slid along the optical axis of the
group of objectives. The group of objectives 38 is focused on the
CCD 43. When the group of objectives 38 has come into focus, the
lens frame 39 is fixed to the isolating frame 41 using an adhesive.
Thereafter, the distal frame 37 in which the distal cover glass 36
is hermetically locked and the isolating frame 41 are joined
hermetically. This results in a hermetically sealed objective unit
40 shown in FIG. 10 having the whole group of objectives 38
hermetically sealed. Reference numeral 73 denotes an airtight joint
realized with a solder or brazing filler metal.
Referring to FIG. 10, a description will be made of the structure
of the hermetically sealed objective unit 40 in accordance with the
present embodiment.
To begin with, the distal cover glass 36 having a metal coating
formed on the lateral surface 36a thereof is locked in a recess 37a
of the distal frame 37 that is plated. In this state, laser light
is irradiated in the direction of arrow A to the whole outer
circumference of the distal frame 37 in which the distal cover
glass 36 is locked.
The gold layer 64 coated over the lateral surface 36a of the distal
cover glass 36 and the gold layer coated over the distal frame 37
are fused with the heat of the laser light. The fused gold layers
are then cooled and bonded mutually. Consequently, the outer
circumference of the distal cover glass 36 and the inner
circumference of the distal frame 37 are joined with no gap between
them. In short, the distal cover glass 36 and distal frame 37 are
joined hermetically.
A laser for irradiating laser light is preferably a YAG laser whose
power is low and can be finely adjusted. Moreover, when a laser for
producing laser light of a pulsating wave is used, an extent by
which adjoining pulses overlap is set to 80% or higher. Thus,
joining can be achieved with airtightness ensured.
Thereafter, the CCD 43 on which the substrates 48 and cable 49 are
mounted is positioned on the proximal cover glass 44 and, bonded
and fixed thereto. The group of lenses 46 is positioned on the
proximal cover glass 44, and bonded and fixed thereto. The image
input end of the CCD 43 serving as an image transmitting means and
the proximal cover glass 44 are fixed to each other using a
transparent adhesive.
At this time, an air layer must not be present in the layer of the
adhesive. Moreover, as the transparent adhesive, an adhesive to be
hardened with ultraviolet rays is used in order to reliably fix the
CCD and proximal cover glass each other with the optical axes
thereof aligned with each other. The portions to which the adhesive
is applied lie outside the airtight region. An adhesive having the
feature that it will resist high-pressure high-temperature steam
given off during autoclaving so as not to be peeled off or
decolorized must be selected for use. Consequently, a phenomenon
causing poor image quality is prevented from occurring while
involving the CCD 43 and proximal cover glass 44.
In the foregoing present embodiment, the CCD cover glass 45 is
bonded to the front surface of the imaging chip included in the CCD
43. The imaging surface of the imaging chip, which is not shown,
included in the CCD 43 and the CCD cover glass 45 are closely fixed
to each other or hermetically sealed so that an air layer
permitting invasion of steam will not be present. The front surface
of the CCD cover glass 45 works substantially as the image input
end of the CCD 43. However, when the CCD cover glass 45 is not
included, the image input end of the imaging chip included in the
CCD 43 is closely bonded directly to the proximal cover glass
44.
Thereafter, the frame body 47 is engaged with the isolating frame
41 to which the aperture stop plate 42 is bonded and fixed. Laser
light is irradiated in the direction of arrow B to the whole outer
circumference of the frame body 47. The gold layer 68b coated over
the isolating frame 41 and the gold layer coated over the frame
body 47 are fused due to the heat of the laser light. The gold
layers are then cooled and bonded mutually. Thus, the outer
circumference of the isolating frame 41 and the inner circumference
of the frame body 47 are hermetically joined without a gap between
them.
Thereafter, the lenses constituting the group of objectives 38 are
assembled and fixed to the lens frame 39 using an adhesive.
Thereafter, the lens frame 39 is inserted into the isolating frame
41. The position in the axial direction of the lens frame 39 is
adjusted in order to bring the group of objectives 38 into focus.
The lens frame 39 is then bonded and fixed to the isolating frame
41.
Thereafter, the distal frame 37 in which the distal cover glass 36
is locked is engaged with the isolating frame 41 so that it will
cover the lens frame 39. Laser light is then irradiated in the
direction of arrow C to the whole outer circumference of the distal
frame 37. The gold layer 68 coated over the isolating frame 41 and
the gold layer coated over the distal frame 37 are fused due to the
heat of the laser light. The gold layers are then cooled and bonded
mutually. Consequently, the outer circumference of the isolating
frame 41 and the inner circumference of the distal frame 37 are
joined hermetically without a gap between them.
A laser used for joining is a YAG laser whose power is low and can
be finely adjusted. When components are joined using the laser, the
temperature of the joint will be 1000.degree. C. or higher.
However, the heat will not adversely affect the portion of the
aperture stop plate 42 to which an adhesive is applied, a joint of
the CCD 43, lens frame 39, and isolating frame 41 realized with an
adhesive, and the group of objectives 38. This is because laser
light is irradiated locally and instantaneously.
The distal cover glass 36 and distal frame 37, the distal frame 37
and isolating frame 41, and the isolating frame 41 and frame body
47 are joined hermetically by fusing the gold layers coated over
the members preliminarily using laser light. Moreover, the frame
body 47 and proximal cover glass 44 are joined hermetically without
a gap between them using a solder or brazing filler metal. This
results in the hermetically sealed objective unit 40 that is a
hermetically sealed unit sealed at a degree of sealing (hereinafter
referred to as a second sealing level) at which steam will not
invade into the unit during autoclaving. The hermetically sealed
objective unit 40 is part of the imaging unit 18 that is one of the
contents of the endoscope.
The hermetically sealed objective unit 40 is realized by unitedly
joining airtight partition members using an airtight joining means.
Herein, the airtight partition members are characteristic of
offering a vacuum, and used to realize the distal cover glass 36,
distal frame 37, isolating frame 41, frame body 47, and proximal
cover glass 44. The airtight joining means enables joining without
a gap between joined members. The hermetically sealed objective
unit 40 is therefore so pressure-resistant and strong as to resist
decompression and pressurization performed during autoclaving as
well as a temperature change and not to destroy. Even if steam
permeates through the armor tube made of a polymeric material and
invades into the internal space during autoclaving, it can be
prevented that the steam invades into the hermetically sealed
objective unit 40 that is sealed at the second sealing level.
Moreover, the CCD 43 and the proximal cover glass 44 are closely
joined using a transparent adhesive in such a manner that no air
layer is present. By the way, the CCD 43 is located at the back end
of the hermetically sealed objective unit 40, and the proximal
cover glass 44 serves as an optical window and lies at the back end
thereof. Along an optical path from the distal cover glass 36,
which serves as an optical window bared on the distal surface of
the endoscope 1, to the image input end of the CCD 43, there is no
portion into which steam given off during autoclaving may invade.
The steam may then condense into water. Owing to this structure,
even if the solid-state imaging device is not sealed hermetically
together with the objectives, nothing will hinder observation. The
imaging unit can therefore be designed compactly.
The electronic parts including the solid-state imaging device are
somewhat resistive to steam unlike optical members on which
condensation or any other obstacle to observation occurs due to
even little invading steam.
Moreover, according to the present embodiment, the first shielding
frame 51 shielding the CCD 43 is mounted on the frame body 47 using
an adhesive or by performing welding. The second shielding frame 52
is mounted on the first shielding frame 51 using an adhesive or by
performing welding. The space created by the first shielding frame
51, CCD 43, and proximal cover glass 44 is filled with the filler
53 such as an adhesive, a sealant, or a potting material that are
less permeable to steam. Moreover, the adhesive 54 is injected to
the surroundings of the portion of the cable 49 lying inside the
second shielding frame 52. Although the surroundings of the CCD 43
are not structured fully hermetically, at least the CCD 43 and
other electronic parts are sealed at a sealing level at which they
will resist steam so as not to be destroyed. Owing to the
structure, the whole imaging unit 17 can resist autoclaving without
the necessity of using a hermetic connector employed in the second
embodiment. Besides, the imaging unit 17 can be designed
compactly.
By the way, an illumination optical system is not sealed
hermetically. This is because even if moisture condenses little on
an illumination lens, insufficient illumination or any other
functionally serious drawback will not come to light. Sealing of
the illumination optical system may be of a level to be attained by
securing components using an adhesive as adopted in the present
embodiment.
By adopting the structure shown in FIG. 11, the center axis of the
CCD 43 can be readily aligned with that of the group of objectives
38.
According to the present embodiment, as illustrated, the center
axis of the CCD cover glass 45 is aligned with that of the CCD 43
in advance. The CCD cover glass 45 is closely fixed to the CCD 43
by applying the transparent adhesive 72 without creating an air
layer.
The proximal cover glass 44 is locked hermetically in the
engagement portion 47b of the frame body 47, which is formed at the
end thereof, rather than in the end portion of the frame body
47.
The CCD cover glass 45 is inserted into the engagement portion 47b
of the frame body 47. The proximal cover glass 44 and CCD cover
glass 45 are then closely fixed to each other by applying the
transparent adhesive 72 without creating an air layer.
At this time, the center axis of the group of objectives 38 is
aligned with that of the frame body 47. Owing to the structure, the
center axis of the CCD 43 can be aligned readily with that of the
group of objectives 38.
As shown in FIG. 12, notches 47c are formed in the engagement
portion 47b of the frame body 47. When the CCD cover glass 45 is
closely fixed to the proximal cover glass 44 using the adhesive 72,
the excess adhesive 72 flows out of the notches 47c. Consequently,
an air layer composed of babbles or the like will not be left
between the CCD cover glass 45 and proximal cover glass 44.
In the structure of the present embodiment, the group of objectives
38 located in front of the image input end of the CCD 43 is placed
in the hermetically sealed space. Water droplets will therefore not
be produced to cloud the group of objectives 38.
Moreover, the CCD 43, CCD cover glass 45, and proximal cover glass
44 are closely fixed to one another using the transparent adhesive
72. Moisture will therefore not condense into water droplets over
these members.
Furthermore, when the group of objectives 38 is realized with a
non-focus optical system, an imaging unit 17A having the structure
shown in FIG. 13 should be employed.
Specifically, as illustrated, the CCD cover glass 45 is closely
fixed to the image input end of the CCD 43 by applying the
transparent adhesive 72 without creating an air layer. The CCD
cover glass 45 is closely fixed to the proximal end surface of the
proximal cover glass 44, which is hermetically locked in the lens
frame 39, by applying the transparent adhesive 72 without creating
an air layer.
The lens frame 39 is made of a metal or ceramic. The distal cover
glass 36 made of sapphire and having the outer circumference
thereof covered with the first metal coating 61 is hermetically
locked in the distal part of the lens frame 39. The group of
objectives 38 and spacer rings 74 are placed in the space
hermetically sealed by the lens frame 39, distal cover glass 36,
and proximal cover glass 44.
In the present embodiment, the group of objectives 38 is located at
a position, at which it is focused on the CCD 43, by means of the
spacer rings 74. This obviates the necessity of bringing the group
of objectives into focus during assembling. Consequently, it
becomes unnecessary to hermetically join units with the CCD
included in one of the units by performing soldering or brazing.
Assembling efficiency therefore improves. The other operations and
advantages are identical to those exerted by the aforesaid
embodiment.
Raw materials to be made into the airtight partition members
constituting the hermetically sealed objective unit 40 and
hermetically sealing it, such as, a metal, a ceramic, a glass, and
sapphire are highly heat-resistant and pressure-resistant to resist
decompression or pressurization performed during autoclaving and
not to be destroyed. Moreover, the raw materials themselves are
characteristic of offering a vacuum (when the volume of a space in
a specimen is any of 0.1 to 0.4 cm.sup.3, a syntype leakage
detected by a helium leakage detector stipulated in the JIS Z2331
is 1.times.10.sup.-9 Pam.sup.3/s or less). Besides, the raw
materials can be joined hermetically.
The raw materials that can be joined hermetically are
heat-resistant raw materials that are resistive to a temperature
rise occurring when the raw materials are joined using an airtight
joining means described below.
By contrast, polymeric materials including general resins and
rubbers cannot clear the conditions for airtight partition members.
The raw materials to be made into the airtight partition members
are therefore limited to raw materials whose main components are a
metal, a ceramic, a glass, or a crystalline material. Any
preferable raw material is selected from among these raw
materials.
As for the metal, various raw materials can be used. For example,
stainless steel or covar can be used.
Moreover, in the present embodiment, ceramic and glass are
distinguished from each other as if they were different raw
materials. However, ceramic is a generic name of non-metallic
inorganic materials produced through steps of molding and baking
and others. Therefore a broad sense, glasses are included in
ceramics. Many ceramics meet the conditions for airtight partition
members. When a metal cannot be adopted as a material of airtight
partition members for the insulation-related and optical reasons,
another ceramics is adopted.
However, some ceramics are less characteristic of offering a
vacuum, are likely to crack due to heating performed for airtight
joining, or may deteriorate terribly due to steam. A ceramic must
therefore be selected after profound thought.
Preferably, a fine ceramic having an insulation property and being
susceptible to a vacuum, such as, aluminum nitride, sialon,
alumina, silicon oxide, or silicon carbide should be used to
produce insulating members.
Moreover, many multi-component glasses used to produce optical
members in general are deteriorated with steam. An optical member
used as an airtight partition member, that is, an optical window
should be made of a crystalline material that is transparent or has
the property of transmitting light, or a multi-component glass that
is resistive to high-pressure high-temperature steam. Sapphire is a
monocrystal of Al.sub.2O.sub.3 and classified into transparent
crystalline materials. Sapphire is therefore a typical optical
material capable of clearing the conditions for airtight partition
members. Another transparent crystalline material is quartz.
In the present embodiment, a means for fusing a gold plate by
utilizing heat stemming from irradiation of laser light is adopted
as an airtight joining means. Otherwise, soldering, brazing, or
brazing and soldering may be adopted as an airtight joining means.
The present invention is not limited to these methods.
Alternatively, various kinds of welding may be adopted as a joining
means.
Various kinds of welding include fusion welding represented by
laser welding or electron-beam welding, pressure welding
represented by resistance welding, and brazing or soldering. When
any of these methods is adopted as a joining means, airtight
joining can be achieved. For example, laser welding may be adopted
to join two metallic parts serving as airtight partition members.
The two metallic parts are fused and united. The joint of the two
metallic parts consists of the airtight partition members alone.
Reliable airtightness can be ensured.
When brazing and soldering is adopted, the joint of airtight
partition members is infiltrated with a metal. Airtightness can
therefore be ensured. Brazing filler metals include a gold alloy, a
silver alloy, a nickel alloy, a copper alloy, and other various
alloys. However, the gold alloy, nickel alloy, or any other alloys
that hardly corrode should be selected in consideration of the
resistivity to corrosion. Moreover, solders include, aside from a
generally adopted alloy of lead and tin, a silver alloy, a copper
alloy, and an alloy of gold and tin. Solders that hardly corrode,
such as, the highly corrosion-resistant alloy of gold and tin
should be selected.
Moreover, aside from metal welding, joining using a molten glass is
also a joining means enabling airtight joining. This joining means
can be adopted naturally. The molten glasses to be injected to a
gap between members to be joined hermetically include a low fusion
point powdered glass. A molten glass is heated and fused, and then
injected into a joint of airtight partition members in order to
attain airtightness.
The low fusion point powered glass falls into a type to be shaped
like a plate glass and a crystallized type. Ceramics other than
glasses are baked to become jointing materials enabling airtight
joining. As a joining means for realizing a joint whose major
component is a metal, ceramic, glass, or crystalline material, any
ceramic can be adopted. The ceramic works as an airtight joining
means.
When any of the aforesaid airtight joining means is used to join
members, the temperature of a joint of the members often rises
considerably. For example, when soldering that is a typical metal
welding method is adopted, the temperature rises to 200.degree. C.
to 400.degree. C. In the case of brazing, the temperature rises to
700.degree. C. to 1000.degree. C. Furthermore, in the case of laser
welding, the temperature rises to the fusion temperature of a
metal. Specifically, when stainless steel is used, the temperature
rises to about 1400.degree. C. In the case of a low fusion point
glass generally adopted as a molten glass for airtight joining, the
fusion point thereof is 300.degree. C. to 600.degree. C.
Operations to be exerted by the endoscope having the foregoing
structures will be described below.
After the endoscope is used, even if the endoscope can be
autoclaved, the endoscope is cleaned without fail. For the
cleaning, at least the waterproof cap 15 is attached in order to
prevent invasion of a fluid during cleaning under running water or
immersion in a fluid agent. The whole housing of the endoscope is
thus sealed in a watertight manner at the first sealing level.
Consequently, it is prevented that a fluid invades into the
interior of the endoscope during cleaning of the endoscope, and
that the internal members of the endoscope deteriorate.
Thereafter, when cleaning is completed, the waterproof cap 15 is
detached and the non-return valve cap 20 is attached. The endoscope
1 is then sterilized using a pre-vacuum type autoclave.
At the pre-vacuum step, the internal space of the endoscope 1 is
deaerated externally through the non-return valve cap 20. This
causes a difference in pressure between the interior and exterior
of the hermetically sealed objective unit 40 that is hermetically
sealed at the second sealing level. However, it will not take place
that the armor tube 35 of the bendable part 9 serving as an
integral part of the endoscope housing dilates to burst. Moreover,
the hermetically sealed objective unit 40 is composed of airtight
partition members or realized by hermetically joining the airtight
partition members. It will therefore not take place that the
hermetically sealed objective unit 40 is destroyed due to the
pressure difference.
At the subsequent sterilization step, the non-return valve cap 20
is attached. High-pressure high-temperature steam will therefore
not actively invade into the internal endoscope space. However,
high-pressure high-temperature steam permeates through the armor
tube 35 and others, which are made of a polymeric material and
constitute the endoscope housing, and invades gradually into the
internal endoscope space. However, the hermetically sealed
objective unit 40 is composed of airtight partition members or
realized by hermetically joining the airtight partition members.
Steam will therefore not invade into the hermetically sealed
objective unit 40. Moreover, the endoscope 1 is heated up to any of
temperatures ranging from 115 to 140.degree. C. However, it will
not take place that the hermetically sealed objective unit 40 is
destroyed due to the temperature change.
The drying step succeeds the sterilization step. The same pressure
difference as that occurring at the pre-vacuum step occurs between
the interior and exterior of the hermetically sealed objective unit
40. At this time, it will not take place that the hermetically
sealed objective unit 40 is destroyed due to the pressure
difference, temperature change, or any other adverse effect.
Furthermore, steam will not invade into the hermetically sealed
objective unit 40.
After autoclaving is completed, the pressure in the internal
endoscope space becomes lower than the atmospheric pressure. The
armor tube 35 of the bendable part 9 therefore sticks to the
internal structure.
If the bendable part were bent in this state, the armor tube 35
would be damaged. However, before the endoscope is put to use, the
camera connector 7 must be attached to the CCU. In other words, the
non-return valve cap 20 is detached from the camera connector 7
without fail. Therefore, atmospheric air flows into the internal
space through the vent 14 of the camera connector 7. This
eliminates the pressure difference between the interior and
exterior of the hermetically sealed objective unit 40 and that
between the internal endoscope space and the exterior.
Consequently, the armor tube 35 is unsticked from the internal
structure. The armor tube 35 will therefore not be damaged during
bending.
The present embodiment is concerned with an endoscope for medical
studies to be autoclaved. The structure in accordance with the
present invention may be adapted to an endoscope to be sterilized
with steam, an endoscope to be immersed in a fluid agent for a long
time, an endoscope having a possibility that steam may invade into
the interior thereof, and an endoscope to be used in a highly humid
environment, for example, an endoscope for industrial use.
Moreover, the present embodiment is concerned with an endoscope
whose insertion unit 2 has the bendable part 9. Alternatively, the
structure in accordance with the present invention may be adapted
to an endoscope having a rigid insertion unit part of which is
formed as the bendable part 9, or an endoscope whose insertion unit
is made soft and has no bendable part.
The present embodiment provides the advantages described below.
Even when a bendable endoscope having a housing member thereof made
of a polymeric material is autoclaved, an armor tube sheathing a
bendable part will not burst.
Even when the endoscope is autoclaved, steam will not permeate
through airtight partition members outlining a hermetically sealed
objective unit or joints at which the airtight partition members
are hermetically joined, and will therefore not invade into the
interior of the endoscope. Consequently, it is prevented that the
quality of a view is impaired due to condensation on a lens.
Even when the endoscope is autoclaved, neither the airtight
partition members outlining the hermetically sealed objective unit
nor joints at which the airtight partition members are hermetically
joined will be destroyed. It will therefore not take place that
steam invades into the interior due to destruction. Needless to
say, it will not take place that the quality of a view is impaired
due to condensation on a lens.
When the endoscope is autoclaved, steam is prevented from actively
invading into the internal endoscope space owing to a non-return
valve cap. Deterioration of the internal members of the endoscope
will therefore be alleviated. Moreover, after autoclaving is
completed, before the endoscope is used, the non-return valve cap
is detached from a camera connector. It will therefore not take
place that the endoscope is put to use with the pressure in the
internal space thereof left lower than the outside air pressure.
This eliminates the possibility that the armor tube of a bendable
part is flawed when used while being stuck to the internal
structure.
The hermetically sealed objective unit is placed in close contact
with the image input end of a solid-state imaging device. It will
not take place that a field of view is narrowed due to autoclaving.
Moreover, an imaging unit can be designed compactly. The rigid part
of the imaging unit can be placed within a distal rigid length
covering the bendable part of the bendable endoscope. Besides, the
distal rigid length can be shortened.
The imaging unit has the objective unit hermetically sealed. The
portion enclosing the solid-state imaging device is sealed using a
joining means, for example an adhesive. Thus when the endoscope is
autoclaved, the solid-state imaging device will not be destroyed
and the quality of a view will not be impaired. Moreover, the
imaging unit can be designed compactly. Despite the bendable
endoscope, the rigid part of the imaging unit is resistive to
autoclaving and can therefore be placed within the distal rigid
length covering the bendable part. Moreover, it is prevented that
the distal rigid length extends.
Airtightness described in relation to the present invention shall
be referred to a state in which a syntype leakage (the volume of
the internal space of a specimen falls within the range of 0.1 to
0.4 cm.sup.3) detected by a helium leakage detector stipulated in
the JIS Z2331 is 1.times.10.sup.-9m.sup.3/s or less.
When the syntype leakage exceeds 1.times.10.sup.-9m.sup.3/s, steam
may invade during autoclaving. Otherwise, when autoclaving is
repeated, steam may accumulate to condense on a lens or cloud it.
Consequently, the lens, a coating covering the surface of the lens,
or an adhesive may deteriorate to cause a drawback such as the
impaired quality of a view.
Table 1 lists different syntype leakages and whether or not steam
invades in association with different joining methods.
An airtight structure realized by performing welding, or in short,
the airtight structure of the hermetically sealed objective unit 40
described in relation to the above embodiment is apparently
different from a watertight structure realized using a typical O
ring or adhesive in terms of the syntype leakage.
TABLE-US-00001 TABLE 1 Syntype leakage Joining method (Pa
m.sup.3/s) Invasion of steam Welding 0.6 .times. 10.sup.-10 to 1
.times. 10.sup.-9 Not observed Sealing with O ring 1 .times.
10.sup.-9 to 1 .times. 10.sup.-8 Observed (fluorine-contained
rubber) Sealing with O ring 5 .times. 10.sup.-8 to 5 .times.
10.sup.-7 Observed (silicon rubber) Fixation with epoxy 5 .times.
10.sup.-10 to 1 .times. 10.sup.-7 Observed resin adhesive
The data indicating whether steam invades after autoclaving
demonstrates that compared with when welding including brazing and
welding, and fusion welding is adopted, when an adhesive or sealer
made from a polymeric material is adopted, steam invades through an
adhesive-applied portion or sealer member. This becomes more
obvious after autoclaving is repeated.
Furthermore, as shown in FIG. 14 and FIG. 15, the chromium oxide
(Cr.sub.2O.sub.3) plate layer 65 may be formed not only on the
outer circumference of the distal cover glass 36 but also on a
doughnut-shaped portion of the proximal end surface thereof. The
plate layer 65 is the low reflectance layer of the first metal
coating 61 formed on the distal cover glass 36. In this case, the
chromium oxide plate layer 65 on the doughnut-shaped portion can
function as a mask for narrowing a beam.
Thus, the low reflectance layer intended to prevent flare is thus
assigned to the role of the mask for narrowing a beam. This
obviates the necessity of separately preparing a mask member for
narrowing a beam, thus contributing to a reduction in the number of
parts. Eventually, the cost of the endoscope can be minimized.
Referring to FIG. 16 and FIG. 17, the second embodiment of the
present invention will be described below.
The overall configuration of the present embodiment is
substantially identical to that of the first embodiment shown in
FIG. 1. The same reference numerals will be assigned to identical
components and only the description of the components different
from those of the first embodiment will be described below.
As shown in FIG. 16, the distal part 8 of the insertion unit 2 of
the endoscope 1 in accordance with the present embodiment consists
mainly of the metallic distal body 16, a distal cover 81, an
imaging unit 17B, and a light guide unit 82. The imaging unit 17B
is inserted into through holes bored in the distal body 16 and
distal cover 81 and locked therein, and serves as an observing
means and image transmitting means. The light guide unit 82 serves
as an illuminating means.
The distal cover 81 fills the role of an insulator, and is made of
a plastic that has an insulation property, and is heat-resistant
and waterproof, such as, polyphenylene sulphite, polyphenyl
sulfone, polyether ether ketone, or a ceramic.
The first bending piece 32a is located at the foremost end of the
plurality of bending pieces constituting the bendable part 9, and
fixed at the proximal end of the distal body 16. The bending pieces
32 are concatenated using the rivets 33 so that they can pivot
freely. The distal part of the armor tube 35 is fixed to the outer
circumference of the distal body 16 in a watertight manner. The
armor tube 35 is made from a soft polymeric material such as a
fluorine-contained rubber, and sheathing the outer circumferences
of the bending pieces 32 constituting the bendable part 9.
As shown in FIG. 17, the imaging unit 17B in accordance with the
present embodiment consists mainly of a group of objectives 83, the
CCD 43, a substrate 84, the lens frame 39, a CCD frame 85, a
hermetic connector 90, an airtightness retaining pipe 87, and a CCD
cable 88. The group of objectives 83 forms an object image. The CCD
43 has the formed object image projected thereon. Capacitors, ICs,
and other electronic parts for processing an electric signal
produced by the CCD 43 are mounted on the substrate 84. The lens
frame 39 made of a metal serves as an airtight partition member for
holding the group of objectives 38. The CCD frame 85 made of a
metal serves as an airtight partition member for holding the CCD
43, and is engaged with the proximal part of the lens frame 39. The
hermetic connector 90 is attached to the proximal end of the CCD
frame 85. The airtightness retaining pipe 87 made of a metal serves
as an airtight partition member, and is placed over the lens frame
39 and CCD frame 85 and engaged with them. The CCD cable 88 is
coupled to the hermetic connector 90.
The hermetic connector 90 has metallic contact pins 92 passed
through holes bored in a metallic connector body 91 serving as an
airtight partition member. An insulating and airtight sealing
member 93 made from a molten glass and serving as one of airtight
joining means is poured into the through holes. The contact pins 92
are thus isolated from the connector body 91. Since the through
holes are filled with the molten glass, there is no gap between
each contact pin 92 and the wall of a through hole. Thus, the
contact pins 92 are hermetically locked in the connector body
91.
As shown in FIG. 16, the hermetic connector 90 and CCD cable 88 are
sheathed with a thermo-contractile tube 86. The interior of the
thermo-contractile tube 86 is filled with a filler 89 that is an
epoxy adhesive, ceramic adhesive, or silicon adhesive. Joints of
the contact pins 92 and the signal lines contained in the CCD cable
88, that is, the portions thereof which are joined using a solder
or the like and having a metal thereof bared are covered by the
filler 89. The joints are thus prevented from corroding due to
steam. A range 98 corresponding to the length of the distal rigid
part of the imaging unit 17 B falls within a distal rigid length
indicated as a range 99 distal to the rivet 33 located at the
foremost end of the bending part 9.
As shown in FIG. 17, a first lens 101 lies at the foremost end of
the group of objectives 83, and serves as an optical window forming
the distal end surface of the endoscope 1. The first lens 101 is
made of sapphire or a glass resistive to high-pressure
high-temperature steam. Metal coating described in relation to the
first embodiment is performed on the lateral surface and chamfer of
the first lens 101. The first lens 101 is hermetically locked in
the metallic lens frame 39 by performing laser welding that is an
airtight joining means described in relation to the first
embodiment.
The CCD frame 85 and hermetic connector 90 are hermetically joined
by performing welding. For the welding, laser light is irradiated
in the direction of arrow D to the whole circumference of a
junction at which the CCD frame 85 meets the hermetic connector 90.
The CCD frame 85 and hermetic connector 90 are thus fused and
united with each other.
Furthermore, before the CCD frame 85 and hermetic connector 90 are
joined, the lens frame 39 having the group of objectives 83 locked
therein is engaged with the CCD frame 85. The lens frame 39 is
moved in the axial directions in order to bring the group of
objectives 83 into focus. When the group of objectives 83 comes
into focus, the lens frame 39 is fixed to the CCD frame 85 using an
adhesive.
Thereafter, the airtightness retaining pipe 87 is placed over the
lens frame 39 and CCD frame 85. In this state, laser light is
irradiated in the direction of arrow E to the whole circumference
of the airtightness retaining pipe 87. Thus, the meeting portions
of the airtightness retaining pipe 87 and CCD frame 85 are welded,
and the airtightness retaining pipe 87 and CCD frame 85 are joined
hermetically. Laser light is then irradiated in the direction of
arrow F to the whole circumference of the airtightness retaining
pipe 87. Thus, the meeting portions of the airtightness retaining
pipe 87 and lens frame 89 are welded, and the airtightness
retaining pipe 87 and lens frame 89 are hermetically joined. This
results in a hermetically sealed imaging unit body 100 that is
sealed at the same second sealing level as the hermetically sealed
objective unit 40 in the first embodiment.
A laser employed is, similarly to that in the first embodiment, a
YAG laser whose power is low and can be finely adjusted. Moreover,
when laser light of a pulsating wave is irradiated, a degree by
which adjoining pulses overlap is set to 80% or higher.
Consequently, reliable airtightness can be ensured.
The light guide unit 82 shown in FIG. 16 consists of the light
guide fiber bundle 18, a first light guide fiber frame 111, the
illumination lens 19, an illumination cover member 112, an
illumination lens frame 113, and a light guide fiber casing tube
114. The light guide fiber bundle 18 is formed as an optical fiber
bundle made by bundling fibers or a plurality of optical fibers
each composed of a core and cladding. The first light guide fiber
frame 111 made of a metal serves as an airtight partition member
having the light guide fiber bundle 18 incorporated therein. The
illumination lens 19 is located on the distal surface of the light
guide fiber bundle 18, and spreads an angle of illumination. The
illumination cover member 112 made of sapphire serves as an
airtight partition member located on the distal surface of the
illumination lens 19. The illumination lens frame 113 made of a
metal serves as an airtight partition member having the
illumination cover member 112 and others incorporated therein. The
light guide fiber casing tube 114 has one end thereof located at
the proximal end of the illumination lens frame 113, and encases
the light guide fiber bundle 18.
A molten glass that is one of airtight joining means is infiltrated
into the distal part of the light guide fiber bundle 18 inserted in
the first light guide fiber frame 111, whereby the fibers of the
light guide fiber bundle 18 are joined hermetically. In other
words, a molten glass (not shown) is infiltrated unintermittently
into the fibers constituting the light guide fiber bundle 18. The
molten glass should be a paste-type low fusion point powered glass
in which an organic binder is mixed. The fusion point of the low
fusion point powered glass is lower than that of a fiber. The low
fusion point powered glass will not be re-fused due to heat of
illumination light. The fusion temperature of the low fusion point
powered glass falls within the range of 300 to 600.degree. C.
Moreover, the low fusion point powered glass can be handled easily
during assembling.
Before the paste-type low fusion point powered glass is used to
join the fibers of the fiber bundle, first, the fiber bundle
infiltrated with the low fusion point powered glass is inserted
into the first light guide fiber frame 111. The portion of the
fiber bundle infiltrated with the powered glass is heated at any of
temperatures ranging from 300 to 600.degree. C., whereby the
organic binder is dispersed. When the low fusion point powered
glass is fused, the portion infiltrated with the low fusion point
powered glass is then cooled.
Thus, the molten glass is hermetically infiltrated into the fibers.
Moreover, the outer circumference of the end portion of the light
guide fiber bundle 18 having the molten glass infiltrated into the
fibers thereof and the inner circumference of the light guide fiber
frame 111 are joined hermetically owing to the molten glass.
The molten glass fills the role of an airtightness retaining filler
to be infiltrated into the fibers, and the role of an airtight
joining means for hermetically joining the light guide fiber bundle
18 and first light guide fiber frame 111.
The same metal coating as that employed in the first embodiment is
performed on the outer circumference of the illumination cover
member 112. The illumination cover member 112 and illumination lens
frame 113 are hermetically joined by the same airtight joining
means as that employed in the first embodiment.
The structure of the light guide unit 82 will be described more
particularly.
To begin with, the illumination lens 19 is put in the illumination
lens frame 113 hermetically united with the illumination cover
member 112. Thereafter, the light guide fiber frame 111
hermetically united with the end of the light guide fiber bundle 18
owing to the molten glass is put in the illumination lens frame
113. Laser welding is then performed in order to hermetically join
the illumination lens frame 113 and light guide fiber frame
111.
Consequently, the portion enclosed with the illumination cover
member 112, illumination lens frame 113, first light guide fiber
frame 111, and end of the light guide fiber bundle 18 is
hermetically sealed in the same manner as the hermetically sealed
imaging unit body 100.
Owing to the foregoing structure, steam is prevented from
permeating through the light guide fiber casing tube 114 and
invading into the illumination lens 19 through the fibers and the
gap between the light guide fiber bundle 18 and first light guide
fiber frame 111.
Owing to the foregoing structure, the illumination lens 19 is
placed in the fully hermetically sealed space. An airtight
partition member need not be used as the illumination lens 19, but
a generally employed multi-component glass that can be machined
quite readily can be adopted.
Furthermore, the illumination lens 19 may be made of sapphire or
any other optical material resistive to high-pressure
high-temperature steam. The illumination lens 19 and first light
guide fiber frame 111 may then be hermetically joined directly.
According to this structure, the illumination cover member 112 can
be excluded. In either structure, moisture will not condense on the
inner surface of the illumination lens 19. Eventually, insufficient
illumination will not arise.
In the endoscope of the present embodiment, as another example, as
shown in FIG. 18, a device frame 120 accommodating the group of
objectives 83 and CCD 43 may be included in the distal rigid part.
An HIC frame 122 accommodating a hybrid integrated circuit
(hereinafter, an HIC) 121 may be placed in the flexible tube 10
located behind the bendable part 9. In this case, a connector 123
locked in the device frame 120 and a distal connector 124 locked in
the HIC frame 122 are electrically linked by a plurality of signal
cables 126 contained in a relay cable 125 lying through the
bendable part 9.
As shown in FIG. 19, a distal cover glass 127 made of sapphire is,
like the one in the aforesaid embodiment, hermetically locked in
the distal part of the device frame 120. The connector 123 is
hermetically locked in the proximal part thereof by performing
metal welding such as fusion welding, brazing or pressure welding.
Thus, the lens unit 83 and CCD 43 are placed in the hermetically
sealed internal space of the device frame 120.
Connection pins 128 like the aforesaid ones are hermetically
implanted in the connector 123 using a molten glass. The distal
ends of the connection pins 128 are electrically connected to the
CCD 43, while the proximal ends thereof are electrically coupled to
the signal cables 126 contained in the relay cable 125.
By the way, the distal connector 124 and proximal connector 129 are
locked in the distal part of the HIC frame 122 and the proximal
part thereof respectively. The outer circumferences of the
connectors 124 and 129 and the inner circumference of the HIC frame
122 are hermetically joined by performing metal welding such as
fusion welding, brazing and welding, or pressure welding. Thus, the
HIC 121 is placed in the hermetically sealed internal space of the
HIC frame 122.
The bar-like connection pins 128 are hermetically implanted in the
connectors 124 and 129 using a molten glass in the same manner as
that mentioned above. The signal cables 126 bared at the proximal
end of the relay cable 125 are electrically spliced to the distal
ends of the connection pins 128 implanted in the distal connector
124. The proximal ends of the connection pins 128 are electrically
coupled to one surface of the HIC 121.
Moreover, the distal ends of the connection pins 128 implanted in
the proximal connector 129 are electrically coupled to the other
end surface of the HIC 121. The signal lines contained in the CCD
cable 88 extending to the connector unit 5 are spliced to the
proximal ends of the connection pins 128.
As mentioned above, the HIC 121 is not placed in the distal rigid
part but placed in the flexible tube 10. This leads to the
shortened distal rigid part.
Moreover, the CCD 43 placed in the distal rigid part is
electrically connected to the HIC 121 placed in the flexible tube
over the relay cable. The ratio at which the contents of the distal
rigid part and those of the bendable part occupy the internal
spaces of the distal rigid part and bendable part can be set to the
same values as those set for a conventional endoscope.
For example, as shown in FIG. 20, the device frame 120 placed in an
airtight space and a substrate frame 134 having a substrate 131 and
hermetic connector 132 placed in a metallic sleeve 133 are
separated from each other, and electrically linked by the relay
cable 125. The airtight space is defined by the lens frame 39
accommodating the group of objectives 38, the distal frame 37
having the distal cover glass 36 locked therein, the isolating
frame 41 having the proximal cover glass 44 locked therein, and the
airtightness retaining pipe 87 hermetically united with the
isolating frame 41 and distal frame 37. At this time, the relay
cable 125 is sheathed with a soft tube 135 that is pleated to be
bendable and foiled with, for example, stainless steel or aluminum.
The distal part of the soft tube 135 is overlaid the proximal part
of a metallic connection frame 136 joining the isolating frame 41.
The proximal part of the soft tube 135 is overlaid the distal part
of the sleeve 133. Thus, the soft tube 135 and the connection frame
136 and sleeve 133 are hermetically joined by performing metal
welding or the like.
Consequently, the signal cables 126 lying through the relay cable
125 and the contacts of the signal cables 126 and connection pins
92 will not be exposed to high-pressure high-temperature steam.
Now, the structure of the light guide connector 6 will be described
below.
As shown in FIG. 21, the light guide connector 6 consists of a
second light guide fiber frame 140, a rod lens 141, an incident end
cover member 142, an incident end frame 143, and a connector base
body 145. The second light guide fiber frame 140 made of a metal
serves as an airtight partition member into which the proximal part
of the light guide fiber bundle 18 is inserted. The rod lens 141 is
located on the proximal end surface of the light guide fiber bundle
18, and homogenizes incident light falling on the light guide fiber
bundle 18. The incident end cover member 142 made of sapphire
serves as an airtight partition member located on the back end
surface of the rod lens 141. The incident end frame 143 made of a
metal serves as an airtight partition member accommodating the
incident end frame 143 and others. The connector base body 145 is
attached to the incident end frame 143 using a screw 144. The head
of the screw 144 is covered with a filler 146 that is an adhesive
for retaining watertightness.
The proximal part of the light guide fiber bundle 18 is, similarly
to the aforesaid distal part thereof, unintermittently infiltrated
with a molten glass. The outer circumference of the proximal part
of the light guide fiber bundle 18 and the second light guide fiber
frame 140 are joined hermetically by the molten glass.
Moreover, metal coating is, as mentioned above, performed on the
lateral surface of the incident end cover member 142. The incident
end cover member 142 and incident end frame 143 are hermetically
joined by an airtight joining means.
Furthermore, the second light guide fiber frame 140 and incident
end frame 143 are hermetically joined by performing laser
welding.
Consequently, the portion enclosed with the incident end cover
member 142, incident end frame 143, second light guide fiber frame
140, and end of the light guide fiber bundle 18 is hermetically
sealed in the same manner as the hermetically sealed imaging unit
body 100.
Consequently, the rod lens 141 lies in the hermetically sealed
interior of the light guide connector 6. Even when a single fiber
made of a multi-component glass or the like that is not resistive
to high-pressure high-temperature steam is employed, it is
unnecessary to concern about deterioration due to steam.
Moreover, the light guide fiber bundle 18 is sealed by the light
guide fiber casing tube 114 and light guide fiber frames 111 and
140 at the first sealing level or higher. Generally, a silicon tube
is adopted as the light guide fiber casing tube 114. However, in
the present embodiment, a fluorocarbon resin tube is employed
because it is less permeable to steam and more resistive to
high-pressure high-temperature steam than the silicon tube. At this
time, it must be checked whether the tube must be somewhat
soft.
Now, the structure of a switch unit 13 will be described below.
As shown in FIG. 22, the switch 13 consists of an electric switch
148, a presser pin 149, a switch cover 150, a presser member 152, a
nut 153, screws 154, an O ring 155, and a switch cable 157. The
electric switch 148 is an electronic part mounted in a package
member 147, and designed compactly. The presser pin 149 is pressed
in order to turn on or off the electric switch 148. The switch
cover 150 is molded with the presser pin 149 inserted therein, and
made of a rubber such as fluorine-contained rubber. The presser
member 152 fixes the switch cover 150 to an operation unit housing
151 in a watertight manner. The presser pin 149 is passed through
the presser member 152. The nut 153 is used to immobilize the
presser member 152. The screws 154 are used to fix the package
member 147 to the operation unit housing 147. The O ring 155 is
used to attain watertightness between the package member 147 and
housing 151. The switch cable 157 is spliced to a contact 156 of
the electric switch 148. Consequently, the electric switch 148 lies
in the space sealed at the first sealing level or higher using the
switch cover 150 and O ring 155.
The switch cover 150 used to realize the sealed space is formed to
be thick enough not to be burst or damaged even when the air in the
sealed space expands or contracts due to decompression or
pressurization performed during autoclaving.
The sealed space is pressure-resistant to resist decompression and
pressurization performed during autoclaving. Moreover, the sealed
space is much smaller than the internal space of the endoscope. An
amount of air that expands due to decompression performed during
autoclaving is therefore limited. As there exists a low possibility
that the armor tube outlining the bendable part may burst as
described in conjunction with the related art, there is also a low
possibility that the switching cover 150 may burst. From this
viewpoint, it is unnecessary to make the switch cover 150 too
thick.
Aside from the switch unit 13, some portions of the internal
endoscope space need not be sealed fully hermetically but must be
sealed at a certain sealing level and protected from invasion of
steam. These portions are, like the foregoing switch unit 13,
sealed at the first sealing level or higher, whereby invasion of
steam can be minimized successfully.
Moreover, a moisture absorptive member 158 may be placed in the
sealed space. The moisture absorptive member 158 absorbs invading
steam and will thus help prevent deterioration of electronic parts.
If the moisture absorptive member can be replaced with a new one,
it would be more advantageous.
The O ring 155 and other rubber sealing members are generally made
of a silicon rubber or fluorine-contained rubber. However, a
silicon rubber is quite permeable to steam. For this reason, the
employment of the aforesaid sealing member made of a
fluorine-contained rubber is preferred. For the same reason, a
partition for a space that must be shielded from invasion of steam
should be made of, for example, a fluorine-contained rubber rather
than a silicon rubber. Likewise, a joint that must be shielded from
invasion of steam should be realized using an epoxy adhesive or
ceramic adhesive rather than a silicon adhesive.
A portion that cannot be hermetically sealed using an airtight
partition member or airtight joining means for a dimensional or
structural reason is covered with a gas barrier type coating. This
will prove effective in hindering invasion of steam.
For example, the outer surface of the light guide fiber casing tube
114, the outer surface of the thermo-contractile tube of the
imaging unit 17, and the other outer surfaces of joints formed with
an adhesive may be covered with a gas barrier type coating. This
will exert the advantage that an internal part, for example, the
light guide fiber bundle 18 hardly deteriorates.
The coating methods of forming the gas barrier type coating include
resin coating such as Parylene resin coating, metallic thin-film
coating such as deposition-based coating or dip soldering-based
coating, ceramic coating such as coating using silica into which
silazane is converted, and crystal coating. For example, with the
light guide fiber casing tube 114, a method of forming a soft
coating must be adopted. According to this method, invasion of
steam can be hindered without an increase in size of contents to be
sealed. When the second sealing level can be attained according to
the metallic thin-film coating, ceramic coating, or crystal
coating, the method can be adopted for an observation optical
system including optical members.
Similarly to the first embodiment, even when the endoscope of the
present embodiment is autoclaved, the hermetically sealed imaging
unit body 100 will not be destroyed, and steam will not invade into
the interior of the hermetically sealed imaging unit body 100.
Moreover, according to the present embodiment, similarly to the
hermetically sealed imaging unit body 100, the emission end portion
and incidence end portion of the light guide unit 32, which are
hermetically sealed and infiltrated with an airtight joining means,
will not be destroyed. Moreover, steam will not invade into the
light guide unit 82.
Furthermore, a switch unit 13 is sealed at the first sealing level
or higher. Invasion of steam into the switch unit 13 is thus
minimized. High-pressure high-temperature steam having invaded into
the interior of the endoscope will not directly attack an electric
switch.
Little steam having invaded will be absorbed by a moisture
absorptive member 158. It will therefore be prevented that the
electric switch 148 or the like fails due to steam or humidity.
Moreover, high-pressure high-temperature steam will not directly
attack a light guide fiber bundle 18 owing to the effect of an
armor tube 35. Deterioration of a fiber glass can be prevented.
This leads to a lowered possibility that a fiber may be broken.
In the present embodiment, almost all the contents of the endoscope
that are susceptible to steam invading into the internal endoscope
space are sealed in an airtight or watertight manner. This leads to
a lowered possibility that the whole endoscope may fail.
The endoscope may be autoclaved without a non-return valve cap
attached but with a vent in the outer wall of the endoscope left
open in the same manner as it is sterilized as conventionally using
an ethylene oxide gas. In this case, high-pressure high-temperature
steam may invade actively into the interior of the endoscope.
Nevertheless, since almost all the contents of the endoscope that
are susceptible to steam, such as, an observing means, illuminating
means, and switch unit are sealed in an airtight or watertight
manner, the endoscope will not fail.
The present embodiment provides the advantages described below.
Even when a bendable endoscope having a housing member thereof made
of a polymeric material is autoclaved, the armor tube of a bendable
part will not burst and the functional parts incorporated in the
endoscope will not fail.
Even when the endoscope is autoclaved, steam will not permeate
through airtight partition members constituting a housing of a
hermetically sealed imaging unit body, and joints of the
hermetically joined airtight partition members. The steam will
therefore not invade into the hermetically sealed imaging unit
body. It is therefore prevented that electronic parts including a
CCD will fail and that the quality of a view will be impaired due
to condensation occurring on a lens.
Even when the endoscope is autoclaved, airtight partition members
constituting a housing of a hermetically sealed objective unit and
joints of the hermetically joined airtight partition members will
not be destroyed. It will therefore not take place that steam
invades into the interior of the hermetically sealed objective lens
unit because of destruction. Needless to say, it will not take
place that the electronic parts such as the CCD fail, and that the
quality of a view is impaired due to condensation on a lens.
Even when the endoscope is autoclaved, steam will not invade into
the hermetically sealed emission and incidence end portions of a
light guide fiber bundle. Consequently, insufficient illumination
stemming from condensation on a lens will not take place.
Even when the endoscope is autoclaved, high-pressure
high-temperature steam having invaded into the internal endoscope
space will not directly attack an electric switch. Moreover, little
steam having invaded into a switch unit is absorbed by a moisture
absorptive member. It will not take place that the electric switch
fails due to steam or humidity.
Even when the endoscope is autoclaved, high-pressure
high-temperature steam will not directly attack the light guide
fiber bundle. This leads to a lowered possibility that fiber
glasses may deteriorate to be broken.
During autoclaving, the internal endoscope space may be ventilated
with outside air without a non-return valve cap attached in order
to prevent burst of the armor tube of the bendable part. Even in
this situation, the observation optical system, illumination
optical system, switches, and other various contents of the
endoscope will not fail.
Referring to FIG. 23 to FIG. 25, the third embodiment of the
present invention will be described below.
The structure of the present embodiment is substantially identical
to that of the second embodiment. The same reference numerals will
be assigned to identical components and only the description of the
components different from those of the first and second embodiments
will be described below.
An endoscope 200 in accordance with the present embodiment is, as
shown in FIG. 23 and FIG. 24, a fiberscope employing fibers as an
observing means, that is, an image transmitting means.
An image guide fiber bundle 201 lies through the insertion unit 2.
The image guide fiber bundle 201 serving as an image transmission
means is formed as an optical fiber bundle made by bundling fibers,
that is, a plurality of optical fibers each having a core and
cladding. Objectives 202 are located at the distal end of the image
guide fiber bundle 201. An eyepiece unit 203 is located at the
other end thereof.
A connector unit 204 has a light guide connector 205 and a
ventilation base 206 through which outside air is circulated
through the internal space of the endoscope 200. A ventilation cap
207 is mated with the ventilation base 206, whereby the interior of
the endoscope 200 is ventilated with outside air.
Unlike the aforesaid embodiments, no imaging unit is incorporated
in the distal part 8. Instead, an image guide fiber bundle 201, an
image guide fiber frame 208, a group of objectives 202, an
objective cover member 209, an objective lens frame 210, and an
image guide fiber casing tube 211 are incorporated in the distal
part 8. The image guide fiber frame 208, which is made of a metal,
serves as an airtight partition member accommodating the image
guide fiber bundle 201. The group of objectives 202 is located at
the distal end of the image guide fiber bundle 201, and forms an
object image. The objective cover member 209, which is made of
sapphire serves as an airtight partition member located at the
distal end of the group of objectives 202. The objective lens frame
210 made of a metal, serves as an airtight partition member
accommodating the objective cover member and others. The image
guide fiber casing tube 211 encases the image guide fiber bundle
201.
The fibers constituting the image guide fiber bundle 201 must be
arranged in the same manner at the distal end and proximal end
thereof. For this reason, both end portions of the fibers are
immobilized while infiltrated with a glass that is melted with a
fluid agent such as, an acid-dissolved glass. Therefore
acid-dissolved glass fills the role of an airtightness retaining
filler to be infiltrated into both end portions of the fibers
constituting the image guide fiber bundle 201.
The distal part of the image guide fiber bundle 201 immobilized
with the acid-dissolved glass and the image guide fiber frame 208
are, as described in relation to the second embodiment,
hermetically joined using a molten glass. Moreover, a proximal lens
included in the group of objectives 202 is bonded and fixed to the
distal end of the image guide fiber bundle 201 using a transparent
adhesive.
A metal coating is formed on the lateral surface of the objective
cover member 209 and the inner circumference of the objective lens
frame 210. The objective cover member 209 and objective lens frame
210 are hermetically joined by, for example, performing
soldering.
A front lens included in the group of objectives 202 is locked in
the objective lens frame 210 and hermetically united with the
objective cover member 209. Thereafter, the image guide fiber
bundle 201 to which a proximal lens included in the group of
objectives 202 is fixed is inserted into the objective lens frame
210. The image guide fiber bundle 201 is then temporarily locked at
a position, at which the group of objectives 202 comes into focus,
by performing, for example, spot welding. Thereafter, the objective
frame 210 and image guide fiber frame 208 are hermetically joined
by performing laser welding.
Consequently, similarly to the hermetically sealed imaging unit
body 100 in the second embodiment, the portion enclosed with the
objective cover member 209, objective frame 210, image guide fiber
frame 208 and end of the image guide fiber bundle 201 is,
hermetically sealed.
Therefore, steam will not invade into the objective cover member
209 through gaps among the fibers and a gap between the image guide
fiber bundle 201 and image guide fiber frame 208.
Any method other than a joining method using a molten glass may be
adopted for joining the distal part of the image guide fiber bundle
201 immobilized with an acid-dissolved glass and the image guide
fiber frame 208. For example, a metal coating may be formed on the
outer circumference of the distal part of the image guide fiber
bundle 201 immobilized with the acid-dissolved glass. The distal
part of the image guide fiber bundle 201, which surface has been
finished, and the image guide fiber frame 208 may be joined
hermetically using a solder.
Moreover, the image guide fiber bundle 201 is not limited to a
flexible fiber bundle having both end portions of the fibers
immobilized with the acid-dissolved glass, and the intermediate
portion of the fibers separated from one another with the
acid-dissolved glass melted with a fluid agent. Each of the fibers
has a core and cladding. Alternatively, a conduit fiber serving as
one conduit over the whole length thereof and made by encapsulating
a plurality of core glasses in cladding glasses will do. In this
case, the cladding glass fills the role of an airtightness
retaining filler for covering each core glass of an optical
fiber.
In general, the flexible fiber bundle is made of a multi-component
glass. The conduit fiber is made of a quartz glass as well as the
multi-component glass.
As shown in FIG. 25, the eyepiece unit 203 consists of a group of
eyepieces 215 and an eyepiece mount 213. The eyepiece unit 203 can
be attached or detached to or from an endoscope body 214.
The group of eyepieces 215 is mounted in a hollow of a metallic
eyepiece frame 216 serving as an airtightness partition member. A
first eyepiece cover glass 217 and second eyepiece cover glass 218
are hermetically locked in the distal part and proximal part of the
eyepiece frame 216 using, for example, a solder. The outer
circumferences of the first and second eyepiece cover glasses 217
and 218, which are made of sapphire, and serving as airtight
partition members are covered with a metal coating.
In other words, an internal space in which the group of eyepieces
215 is placed is sealed hermetically with the eyepiece frame 216,
first eyepiece cover glass 217, and second eyepiece cover glass
218.
With the eyepiece unit 203 attached to the endoscope body 214, the
first eyepiece cover glass 217 serves as an optical window that is
included as part of a housing of the endoscope.
Furthermore, the proximal part of the image guide fiber bundle 201
lying through the endoscope body 214 has the same structure as the
distal part of the aforesaid image guide fiber bundle 201.
Moreover, a metal coating is formed on the lateral surface of the
cover glass 219. The cover glass 219 and fiber holding member 220
are hermetically joined by performing, for example, soldering. A
second image guide fiber frame 221 and the fiber holding member 220
are hermetically joined using, for example, a solder.
Consequently, since the end of the image guide fiber bundle 201 is
sealed hermetically, steam will not permeate through the end of the
image guide fiber bundle 201 and the inner surface of the cover
glass 219.
When the eyepiece unit 203 is not attached to the endoscope body
214, the cover glass 219 serves as an optical window that is part
of the outer surface of the endoscope 200.
Moreover, the group of eyepieces 215 that is hermetically sealed
can be freely attached or detached to or from the image output end
of the image guide fiber bundle 201. Alternatively, similarly to
the hermetically sealed objective unit 40 and the image input end
of the CCD 43 employed in the first embodiment, the group of
hermetically sealed eyepieces 215 may be closely bonded to the
image output end of the image guide fiber bundle 201 by applying a
transparent adhesive in such a manner that no air layer is present.
In this case, an eyepiece focusing mechanism should be included in
the hermetically sealed eyepiece unit 203 for the purpose of
adjustment of the diopter of the eyepieces.
Moreover similar to the light guide fiber bundle 18 in the second
embodiment, the image guide fiber bundle 201 is sealed at the first
sealing level or higher level with a casing tube and base.
Operations to be exerted by the endoscope 200 having the foregoing
structure will be described below.
When the ventilation cap 207 is mated with the ventilation base
206, the internal space of the endoscope 200 is ventilated with
outside air. For cleaning, the ventilation cap 207 is not mated
with the ventilation base 206 in order to attain watertightness.
For autoclaving, the endoscope 200 is put in an autoclave with the
ventilation cap 207 mated with the ventilation base 206. Thus, a
burst of the armor tube 37 outlining the bendable part 9 is
prevented.
At this time, a large amount of steam invades into the endoscope
body 214 through the ventilation unit. Nevertheless, steam will not
permeate through the distal end of the image guide fiber bundle 201
hermetically sealed in the endoscope body 214 and the group of
eyepieces 215 included in the eyepiece unit 203 that can be
attached or detached to or from the endoscope body 214. Therefore,
steam will not invade into the sealed spaces and produce water
droplets on optical members.
The present embodiment has the advantages described below.
When a bendable endoscope whose housing member is made of a
polymeric material is autoclaved, it will not take place that the
armor tube of a bendable part bursts and that a field of view is
narrowed.
When the endoscope is autoclaved, steam will not invade into the
hermetically sealed distal part of an image guide fiber bundle and
an eyepiece unit. Moreover, when water droplets are produced on the
surface of the cover glass of the eyepiece unit, the eyepiece unit
can be detached in order to wipe off the water droplets.
Consequently, a field of view provided by the eyepiece unit will
not be narrowed due to condensation occurring on a lens.
When the endoscope is autoclaved, the hermetically sealed distal
part of the image guide fiber bundle, airtight partition members
constituting the housing of the eyepiece unit, and joints of the
hermetically joined airtight partition members will not be
destroyed by not take place that due to destruction. Naturally, the
field of view will not be narrowed due to condensation on a
lens.
When the endoscope is autoclaved, high-pressure high-temperature
steam will not directly attack the image guide fiber bundle.
Consequently, fiber glasses will not deteriorate and break.
According to the present embodiment, instead of the ventilation
cap, 207 a cap member having the capability of a non-return valve
may be, similarly to the non-return valve cap 20 in the first
embodiment, mated with the ventilation base 206.
In this case, the cap member must be designed so that when it is
mated with the ventilation base 206, it will communicate with an
outside and works as a non-return valve. When this structure is
adopted, similar to the first embodiment, steam will not, actively
invade into the interior of the endoscope 200 during autoclaving
and will prevent the contents of the endoscope 200 from
deteriorating.
Moreover, according to the present embodiment, the objective frame
210 and image guide fiber frame 208 are hermetically joined by
performing laser welding. Alternatively, as shown in FIG. 26,
similarly to the airtightness retaining pipe 87 in the second
embodiment, an airtightness retaining member 225 made of a metal,
ceramic, or the like may be employed. The airtightness retaining
member 225, the objective frame 210, and image guide fiber frame
208 may be hermetically joined by performing laser welding or
soldering. In this case, the objective frame 210 and image guide
fiber frame 208 can be bonded more firmly to each other.
Consequently, it becomes easy to bring the group of objectives 202
into focus during assembling.
Moreover, when moisture condenses into water droplets on the
surface of the cover glass 219 during autoclaving, or when water
droplets are produced on the surface of the second cover glass 218,
the water droplets can be wiped off easily by removing the eyepiece
unit 203.
As shown in FIG. 27, a hermetically sealed objective unit 337 may
be firmly bonded to the distal end of an image guide fiber bundle
336, that is, the image input end thereof using a transparent
adhesive 329 in such a manner that no air layer is present. The
objective unit 337 consists of an objective frame 338, a distal
cover glass 339, a back-end cover glass 340, a group of objectives
341, and a spacer ring 342. The objective frame 338 is made of a
metal. The distal cover glass 339, which is made of sapphire, is
hermetically locked in the distal part of the objective frame 338
by performing brazing or the like. A metal coating is formed on the
outer circumference between the distal cover glass 339 as a joint
of the distal cover glass 339 and objective frame 338. The group of
objectives 341 is placed in a space hermetically sealed with the
objective frame 338, and cover glasses 339 and 340.
In the structure, the spacer ring 342 is used to position the group
of objectives 341 and to focus it on the image input end of the
image guide fiber bundle 336. Therefore, particularly during
assembling, focusing does not need to be performed.
The back-end cover glass 340 is not fixed to the proximal end of
the objective frame 338 but secured with an engagement portion 338a
left at the end of the objective frame 338. The distal part of a
base 343 of the image guide fiber bundle 336 is inserted and fixed
to the engagement portion 338 a formed at the end of the objective
frame 338. Owing to the structure, the center axis of the group of
objectives 341 is aligned with the center axis of the image guide
fiber bundle 336.
Furthermore, in the present embodiment, a hermetically sealed
illumination lens unit 358 is, as shown in FIG. 27, closely fixed
to the emission end of a light guide fiber bundle 357 using a
transparent adhesive 329 in such a manner that no air layer is
present. The illumination lens unit 358 consists of an illumination
frame 359, a distal illumination cover glass 360, a back-end
illumination cover glass 361, and an illumination lens 362. The
illumination frame 359 is made of a metal. The distal illumination
cover glass 360, which is made of sapphire, is hermetically locked
in the distal part of the illumination frame 359 by performing, for
example, brazing. A metal coating is formed on the outer
circumference of the distal illumination cover glass 360 as a joint
of the distal illumination cover glass 360 and the illumination
frame 359. The back-end illumination cover glass 361 made of
sapphire, is hermetically locked in the proximal part of the
illumination frame 359. The illumination lens 362 is placed in a
space hermetically sealed by the illumination frame 359 and cover
glasses 360 and 361.
The light guide fiber bundle 357 and the illumination lens unit 358
are locked in a mounting hole bored in a distal structure of an
insertion unit 2. At this time, the light guide fiber bundle 357 is
inserted through the back end of the hole, while the illumination
lens unit 358 is inserted through the front end thereof.
As shown in FIG. 28, a mask deposition cover glass 344 is fixed to
the image output end of the image guide fiber bundle 336 using a
transparent silicon adhesive 346 in such a manner that no air layer
is present. As shown in FIG. 29, a black deposition material 345
such as chromium oxide is deposited on the mask deposition cover
glass 344, thus forming a field mask. A portion of the mask
deposition cover glass 344 on which the deposition material 345 is
not deposited defines a range of a field of view seen by an
observer. The field mask has an up indicator 344a to help the
observer recognize an up direction.
FIG. 30 shows a connector unit 365 to be coupled to a light source
apparatus. A hermetically sealed illumination light incidence end
optical member unit 366 is closely fixed to the incidence end of
the light guide fiber bundle 357 using a transparent adhesive 329
in such a manner that no air layer is present.
The illumination light incidence end optical member unit 366
consists of a rod lens frame 367, two cover glasses 368, and a rod
lens 369. The rod lens frame 367 is made of a metal. The two cover
glasses 368 made of sapphire are hermetically locked in both the
end portions of the rod lens frame 267 by performing brazing or the
like. A metal coating is formed on the outer circumferences of the
cover glasses 368 as joints of the cover glasses 368 and the rod
lens frame 367. The rod lens 369 is placed in a space hermetically
sealed with the rod lens frame 367 and cover glasses 368. The rod
lens 369 is formed with a single fiber made of a multi-component
glass, and homogeneously disperses incident light emanating from a
light source.
In FIG. 27 and FIG. 30, reference numeral 327 denotes the joints at
which the lenses and frames are hermetically joined by performing
brazing, soldering, or metal welding such as laser welding.
Assuming that the endoscope having the foregoing structure is
autoclaved using high-pressure high-temperature steam, steam
invades into the interior of the endoscope through the O rings,
adhesives, resin parts, or the like. However, since the objective
unit 337 located at the image input end of the image guide fiber
bundle 336 is hermetically sealed, steam will not invade into the
hermetically sealed space. Consequently, water droplets will not be
produced on optical members including the group of objectives 341
to eventually cloud them.
Moreover, the light guide fiber bundle 336 and back-end cover glass
340 are closely fixed to each other using the transparent adhesive
329 in such a manner that no air layer is present. Moisture will
therefore not condense into water droplets between the light guide
fiber bundle 357 and back-end cover glass 361. Furthermore, the
mask deposition cover glass 344 is closely fixed to the image
output end of the image guide fiber bundle 336 using the
transparent adhesive 329 in such a manner that no air layer is
present. Moisture will not condense into water droplets between the
mask deposition cover glass and image guide fiber.
Furthermore, the illumination lens unit 358 located at the emission
end of the light guide bundle 357 is sealed hermetically. Water
droplets will therefore not be produced to cloud the optical
members including the illumination lens 362. Moreover, the light
guide fiber bundle 357 and back-end illumination cover glass 361
are closely fixed to each other using the transparent adhesive 329
in such a manner that no air layer is present. Moisture will
therefore not condense into water droplets between the light guide
fiber bundle 357 and back-end, illumination cover glass 361.
Furthermore, the illumination light incidence end lens unit 366
located at the incidence end of the light guide fiber bundle 357 is
hermetically sealed. Steam will therefore not invade into the
hermetically sealed space and water droplets will not be produced
on the optical members including the rod lens 369 to eventually
cloud the optical members. Moreover, the light guide fiber bundle
357 and cover glass 368 are closely fixed to each other using the
transparent adhesive 329 in such a manner that no air layer is
present. Consequently, moisture will not condense into water
droplets between the light guide fiber bundle 357 and cover glass
368.
The present embodiment is expected to provide the advantages
described below.
Even when an endoscope is autoclaved, it will not take place that
optical members included in an objective unit and an eyepiece unit
are clouded or a field of view is narrowed due to deterioration of
lens glasses. The objective unit and the eyepiece unit are
hermetically sealed and located at the image input end of an image
guide fiber bundle and the image output end thereof
respectively.
Moreover, even when the endoscope is autoclaved, there is no fear
that moisture may condense into water droplets between the end of
the image guide fiber bundle and an optical member. This is because
optical members are closely fixed to the image input end and image
output end of the image guide fiber bundle in such a manner that no
air layer is present.
Furthermore, even when the endoscope is autoclaved, the optical
members locked in the spaces hermetically sealed at the emission
end and incidence end of a light guide fiber bundle will not be
clouded, or lens glasses will not deteriorate. Consequently, it
will not take place that illumination light diminishes or light is
distributed in an inhomogeneous manner.
Moreover, even when the endoscope is autoclaved, moisture will not
condense into water droplets between the ends of the light guide
fiber bundle and the optical members. This is because the optical
members are closely fixed to the incidence end and emission end of
the light guide fiber bundle in such a manner that no air layer is
present. Consequently, it will not take place that illumination
light diminishes and light is distributed in an inhomogeneous
manner.
Furthermore, the image output end of the image guide fiber bundle
and a mask deposition cover glass are closely fixed to each other
in such a manner that no air layer is present. Interference fringes
stemming from reflection occurring between the image output end and
mask deposition cover glass will not be produced.
Furthermore, the mask deposition cover glass is bonded to the image
output end of the image guide fiber bundle using a silicon adhesive
that can be wiped off relatively easily. The mask deposition cover
glass can therefore be repaired readily.
According to the present invention, it is apparent that a wide
range of different embodiments can be constructed based on the
invention without a departure from the spirit and scope of the
invention. The present invention will be limited by the appended
claims but not be restricted by any specific embodiments.
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