CA2094834A1

CA2094834A1 - Endoscope couplere with liquid interface

Info

Publication number: CA2094834A1
Application number: CA002094834A
Authority: CA
Inventors: Koichiro Hori
Original assignee: Individual
Current assignee: Linvatec Corp
Priority date: 1992-05-13
Filing date: 1993-04-26
Publication date: 1993-11-14
Also published as: EP0570161A1; JPH0627391A; AU3700793A; AU663935B2; US5347988A

Abstract

ABSTRACT
An improved endoscope assembly includes a quantity of optically transparent liquid filling the space between facing windows of adjoining mechanically and optically coupled components to eliminate fogging due to condensation and thereby provide improved image quality. One component includes a male connector with its window at its mating end. The other component has a recess defined therein for receiving the male connector. A stop member on the connector abuts the other component to define maximal insertion of the connector and establish a space between the windows for retaining the liquid. The space between the windows is sufficiently small to permit retention of the liquid in the recess by means of surface tension.

Description

2~9483~

BACKGROUND OF THE INVENTION
1 Technical Field 2 The present invention pertains to a method and apparatus for 3 mechanically and optically coupling an endoscope to a video camera, 4 or the like. In particular, the invention is directed to eliminating fogging of adjacent optical windows in two mechanically 6 and optically coupled devices.

7 Discussion of the Prior Art 8 Endoscopes have been successfully utilized in surgery for 9 viewing body cavities and organs to permit diagnoses and surgical procedures to be performed internally without requiring open 11 surgery or other invasive procedures. An endoscope is typically 12 inserted through a small incision portal providing access to a body 13 cavity. A lens at a distal end of the endoscope is positioned to 14 receive light reflected from a site to be observed, and images of that site can be viewed remotely in conducting histological 16 examinations and performing closed, or endoscopic, surgery. As 17 utilized herein, the term endoscope refers generically to viewing 18 devices for remotely observing otherwise inaccessible body cavities 19 with minimal trauma and intrusion, and includes, but is not limited to, arthroscopes, colonoscopes, bronchoscopes, hysteroscopes, 21 cystoscopes, sigmoidoscopes, laparoscopes and ureterscopes.

2~4834 1 Endoscopes are sometimes supplied with an eyepiece at a 2 proximal end thereof, and relay lenses in the endoscope typically 3 produce an image for direct viewing through the eyepiece. However, 4 adaption of video camera technology to endoscopy imaging has enabled the output image of an endoscope to be viewed on a video 6 monitor via a video camera electronically connected with the video 7 monitor and optically and mechanically coupled to the proximal end 8 of the endoscope. Indirect or video monitor viewing of endoscopic 9 images provides numerous benefits over direct viewing through an eyepiece, including: protection of viewer's vision when high 11 intensity illumination passing through the endoscope reflects off 12 bodily tissue at the site to be viewed; enhancement of an 13 operator's comfort and freedom of movement; increased utility and 14 efficiency of endoscopes; reduction in the time required to conduct endoscopic procedures; simultaneous viewing of endoscopic images by 16 more than one person; and recordation and real time transmission of 17 surgical procedures. When a video camera is utilized with an 18 endoscope, an endoscope coupler is required to mechanically and 19 optically couple the proximal end of the endoscope with the video camera, illustrative endoscope couplers being shown in U.S. Patent 21 Nos.: 4,569,333 (Bel et al); 4,611,888 (Prenovitz et al); 4,722,000 22 (Chatenever); 4,740,058 (Hori et al); 4,781,448 (Chatenever et al);
23 4,807,594 (Chatenever); 4,844,071 (Chen et al); 4,851,866 (Ciarlei 24 et al); 4,863,304 (Bauer et al); and 4,g69,450 (Chinnock et al).

2~9~83~

One recurring problem in endoscopç coupler design is poor 2 image quality resulting from moisture, condensation or residue from 3 dried moisture on transparent windows optically coupling various 4 components of the assembly. More particularly, it is conventional for a complete endoscope assembly to include an extended probe 6 referred as to the endoscope, an endoscope coupler and an image-7 forming device such as a video camera or optical eyepiece. The 8 optical path through each of these elements is typically terminated 9 by a window, flat or optically powered, and it is a recognized problem that moisture, condensation or residue tends to form on 11 these windows resulting in the degradation of the surgeon's view of 12 the surgical site. For example, the endoscope and coupler are 13 typically sterilized by immersion in bactericidal solutions such as 14 Cidex or Sporiciden and then rinsed with distilled water, usually leaving some residual moisture on the optical windows. If steps 16 are taken to dry the windows, a residue may still remain. Further, 17 moisture from surrounding air and surgical irrigation may condense 18 on the window surfaces. In any case, the moisture or residue 19 interferes with the surgeon's view of the surgical site.
There are numerous patents directed to methods and apparatus 21 for eliminating "fogging" in an endoscope assembly. For example in 22 the Chatenever '000 patent and in U.S. Patent No. 4,076,018 23 (Heckele), fogging due to condensation is eliminated by providing 24 resistive heating elements at various locations in the assembly.
The presence of the resistive heating elements adds undesired 26 complexity and cost. The Chatenever '594 patent discloses .. . .. . . . ... .. ... .

~. . . . . .. :;: .. . : :

209483~ ~
1 prevention of condensation by providing glass-to-glass contact 2 between the proximal endoscope window and the ad;acent distal 3 window of the coupler. Such glass-to-glass contact requires 4 relatively precise mechanical tolerances on the manufactured components and their assembly. The Bauer '304 patent discloses an 6 attempt to eliminate condensation by flowing air through 7 appropriate spaces in the endoscope assembly, thereby unduly 8 complicating the overall design and increasing the cost.
9 Similarly, in the Ciarlei et al '866 patent, a vent is disclosed for connection to a suction adapter employed to withdraw moisture, 11 again complicating the structure of the system and requiring the 12 surgeon to couple a source of suction to the vent whenever fogging 13 is detected. It is also common in various endoscopic procedures to 14 provide ample flow of irrigating liquid to flush debris from the surgical site. The application of suction to the instrument, as 16 suggested by Ciarlei et al, would tend to cause the assembly to be 17 filled with the irrigating liquid. The approach disclosed in the 18 Prenovitz et al '888 patent is to provide O-rings at the interfaces 19 between all components of the coupler, between the coupler and the endoscope, and between the coupler and the camera. The resulting 21 structure is relatively complex and difficult to implement.
22 Each of the above-described patents is directed to a technique 23 for avoiding fogging due to condensation. None of these patents 24 addresses the issue of preventing degradation of image quality due to residue of dried moisture on the optical windows. U.S. Patent 26 No. 4,805,598 (Ueda), on the other hand, suggests that a viscous . . . . . .. . . .. ...:. . .

. , , . : ~ . . . . . . . :. , , . ~.

2~948~
gel-like substance, free from moisture, can be utilized to fill the 2 space between adjacent associated lenses of endoscope system 3 components to prevent condensation of water on the lenses. The gel 4 may be provided at one or more locations in the optical system but it appears that the gel is applied only during manufacture; that 6 is, the gel is not applied during assembly of the components in the 7 surgical operating theater. Accordingly, it is quite likely that 8 condensation will form on the windows of adjacent components of the - 9 optical assembly.
Other patents having general relevance to the present 11 invention, although not directly addressing the problem of fogging, 12 are U.S. Patent No. 4,641,912 (Goldenberg) disclosing the use of a 13 water mass for coupling laser energy into an optical fiber 14 waveguide of an endoscope, and U.S. Patent No. 4,742,818 (Hughes et al) disclosing a seal located between components of the focusing 16 mechanism of an endoscope to prevent sterilizing liquid from 17 leaking between them during sterilization.
18 Until the present invention there has been no effective 19 technique for eliminating both condensation on optical windows and moisture and/or residue of such moisture in an endoscope assembly.

21 SUMMARY OF THE INVEN~ION
22 Accordingly, it is an object of the invention to provide a 23 method and apparatus for avoiding condensation, moisture and 24 moisture residue on optical windows of an endoscope assembly without incorporating the above-mentioned disadvantages.

,. . - . . . . , .: . . .. . . .

. . . .. , ., .~. .. . . .
- . ~ , .: ~..... . .. . :

2~9~3~

1 It is a further object of the present invention to provide an 2 endoscope system, and a method for its assembly in a surgical 3 operating theater, whereby condensation or fogging on optical 4 windows of the assembly is eliminated without unduly complicating the assembly steps performed by operating theater personnel or 6 complicating the structure of the overall assembly.
7 According to the invention an endoscope system comprises an 8 endoscope having a male connector and an endoscope coupler 9 connecting the endoscope to a video camera or other image forming device. The coupler includes a recess for receiving the male 11 connector in a relatively snug fit. A window at the end of the 12 connector is axially spaced a short distance from a wlndow in the 13 coupler recess in the assembled system. Prior to insertion of the 14 connector, a small quantity of optically transparent liquid, typically distilled water, is placed in the recess. Upon insertion 16 of the connector excess water is extruded out around the connector 3 17 from the recess, thereby eliminating air from the space between the 18 two windows and preventing any possibility of fogging while 19 simultaneous'y preventing drops of moisture or residue of dried moisture from interfering with the formation of a clear image. In 21 the preferred embodiment the dimensions of the male connector and 22 the recess are sufficiently small as to permit surface tension to 23 prevent water from subsequently leaking out of the recess, thereby 24 eliminating the need for seals or the like to maintain the liquid between the windows.

,.. . ~ :

. . .. ... . .

209~83~

1 Other objects and advantages of the present invention will 2 become apparent from the following description of the preferred 3 embodiment taken in con;unction with the accompanying drawings 4 wherein like parts each of the several figures are identified by the same reference characters.

6 BRIEF_DESCRIPTION OF THE DRAWINGS
7 Fig. 1 is an exploded side view of an endoscope assembly, 8 including an endoscope, a coupler and a camera, employing the 9 principles of the present invention:
Fig. 2 is a side view in longitudinal section of a connector 11 of the endoscope of Fig. 1 received in a recess defined in the 12 coupler of Fig. l; and 13 Fig. 3 is a partially diagrammatic side view in longitudinal 14 section illustrating the insertion of the connector of Fig. 2 into a liquid-containing recess in the coupler in accordance with the 16 principles of the present invention.

18 Referring to the drawings in greater detail, an endoscope 19 assembly according to the present invention is illustrated in Fig.
1 and includes an endoscope 10 having a conventional elongated 21 optical probe 12. Probe 12 may be flexible or not and, if 22 flexible, typically includes a first optical fiber or fiber bundle 23 for transmitting light to the interior of a patient's body cavity 24 and a second optical fiber or fiber bundle for conducting reflected ~, . . .. . . ..
-, , . , . .; ~, 2~4834 1 light from the body cavi~y to an imaging device. If probe 12 is 2 rigid it typically includes a fixed optical system. Where desired, 3 the elongated probe 12 may be inserted into a tubular bore defined 4 in a larger diameter elongated member having one or more further bores defined therein for surgical instrument and fluid conduits.
6 Endoscope 10 also includes a terminal member 14 permanently affixed to the proximal end of optical probe 12. Terminal member 14 8 optically and mechanically couples the elongated optical probe 12 9 to an endoscope coupler 16 serving to mechanically and optically couple terminal member 14 to a conventional video camera or other 11 imaging device indicated generally at 18. A proximally extending 12 male connector 20 is defined as part of terminal member 14 and is 13 adapted to be received in a recess 22 defined in the distal end of 14a hollow and generally cylindrical body 24 of coupler 16 (Figs. 2 15and 3). Male connector 20 and recess 22 are generally cylindrical 16 in cross-section.
17A window 26 is centrally disposed at the proximal end of 18 connector 20 and faces a similar window 28 centrally disposed in 19 the distally facing end of recess 22 in body 24. Light traversing the optical paths through endoscope 10 and coupler 12 must pass 21 through these windows which may be flat or contoured to serve as 22 lenses. In accordance with the present invention a quantity 30 of 23 transparent liquid, typically distilled water, is disposed between 24 windows 26 and 28 to completely fill the space therebetween and prevent any condensation or residue from forming on the windows.
26 Accordingly, windows 26, 28 are disposed in respective annular ... . . . ..
. . .,.. : . : ,, . ....:., . , ''' ~ ,' ~. '' '' ', ' ~' ,. `

1 recesses in connector 20 and the base of recess 22, and are sealed 2 in place by suitable adhesive or the like to prevent leakage of the 3 liquid into the interiors of connector 20 and coupler 16.
4 Terminal member 14 of endoscope 10 is releasably connected to coupler 16 in a generally conventional manner. In particular, a 6 plurality of locking balls 32 are carried in respective radial 7 bores 34 in the main body 24 of the coupler, and engage an annular 8 groove 36 formed about male connector 20. Groove 36 has an arcuate 9 cross-section with a radius of curvature slightly larger than the radius of balls 32. The locking balls 32 are held in groove 36 by 11 an interiorly facing cylindrical surface 38 of an annular plastic 12 insert 40. The insert has its outer surface secured to and movable 13 with a locking sleeve 42 retained coaxially about the coupler body 14 24 for axial movement relative to that body. Locking sleeve 42 is biased by a helical spring 44, also disposed about body 24, toward 16 the distal end of the coupler (i.e., the end receiving male 17 connector 20 of the endoscope). In order to remove male connector 18 20 from recess 22, locking sleeve 42 is moved axially along the 19 coupler body 24 (i.e., rightwardly in Fig. 2), displacing insert 40 axially and thereby allowing the locking balls 32 to be moved 21 radially outward in bores 34 so as to be removed from the annular 22 groove 36 of connector 20. This movement of the locking balls is 23 achieved by withdrawing connector 20 from recess 22, thereby 24 causing the moving arcuate surface of groove 36 to force the balls radially outward into bores 34 with a camming action and permitting 26 complete withdrawal of connector 20. Locking sleeve 42 is -209483~

1 similarly moved rightwardly when it is desired to insert connector 2 20 into recess 22. In such a case, a chamfered annular edge of the 3 connector initially forces the locking balls radially outward into 4 bores 34, the balls being maintained in their outward position by the cylindrical end section of the connector. Upon radial 6 alignment between the groove 36 and bores 34 (i.e., the maximal 7 insertion of the connector into the recess), the locking balls ar~
8 free to move inwardly and can be so urged by returning locking 9 sleeve and its attached insert 40 to their quiescent positions (i.e, to the left in Fig. 2) under the bias of spring 44.
11Spring 44 is urged against locking sleeve 42 by a focus ring 12 46 disposed about coupler body 24 and retained thereon by a 13threaded sleeve 48. A focusing pin 50, secured to focus ring 46, 14 extends radially through a circumferential slot 52 defined in body 1524 and into a helical slot 54 defined in an inner lens carrier 56 16 supporting a focusing lens 58. A dowel pin 60, secured to and 17 extending radially from body 24, is received in an axially 18extending slot 62 defined in lens carrier 56. Dowel pin 60 serves 19 to permit lens carrier 56 to move axially within body 24 while preventing the lens carrier from rotating. Accordingly, when the 21 focus ring 46 is rotated, focusing pin 50 exerts an axial force on 22 the walls of the helical slot 54, causing lens carrier 56 and 23 focusing lens 58 to move axially to adjust the endoscope system 24 focus.

- . . . .. . . .

- ~ .; , .. . . .

2~483~

1 Prior to assembling the components, a quantity 30 of optically 2 transparent liquid, typically distilled water, is disposed in 3 recess 20 as shown in Fig. 3. The quantity of water may be equal 4 to or less than the capacity of the recess. When the male connector 20 is inserted into the recess, any water exceeding the 6 volume of the space between connector 20 and recess 22 is extruded 7 out through the annular gap between these components. Accordingly, 8 no air can remain present in the space between the windows 26 and 9 28 when the assembly is complete, as shown in Fig. 2, and no condensation droplets of moisture or residue on either window can 11 interfere with accurate formation of the image.
12 The fit of connector 20 in recess 22 is required to provide 13 some axial space between windows 26 and 28 after the assembly is 14 completed. This axial space is typically in the range of a few thousandths of an inch to several tens of thousandths of an inch, 16 and preferably on the order of 0.010 inch. Connector 20 is 17 provided with an annular stop flange extending radially outward at 18 a location permitting it to abut an annular shoulder 66 surrounding 19 the distal end of the recess 22, thereby preventing windows 26, 28 from contacting one another. Alternatively, spacer members may be 21 provided in recess 22 to contact connector 20 and assure that 22 windows 26, 28 remain properly spaced from one another. Although 23 connector 20 has been illustrated and described as being formed on 24 terminal member 14 while recess 22 is formed in coupler 16, the opposite arrangement is also possible within the scope of the 26 present invention.

.. ..

` 2094834 1 The cross-sectional shapes of connector 20 and recess 22 are 2 desirably sufficiently closely matched to assure that water is 3 retained in the recess by surface tension while allowing ready 4 removal and insertion of the male connector. A circumferential S clearance or gap on the order of 0.002 inch is appropriate for this 6 purpose. In order to assure smooth insertion of connector 20 into 7 recess 22, terminal member 14, including connector 20, may be 8 molded of a plastic material such as that sold under the trademark 9 "Delrin", while coupler body 24 may be made of aluminum, or the like.
11 It will be appreciated that the present invention provides an 12 extremely simple yet highly reliable method and apparatus for 13 eliminating condensation between the optical components of an 14 endoscope assembly. The surgeon needs simply to pour a small quantity of distilled water into recess 22 before connecting the 16 endoscope to the coupler. The quantity of water must at least 17 equal the volume of the space remaining between windows 26, 28 18 after connection of the components, thereby preventing any 19 condensation from forming on the windows. Accordingly, residue from drying moisture is also eliminated. Preferably, the optical 21 characteristics of the endoscope assembly are such that light rays 22 passing through the water in the axial gap between windows 26, 28 23 are collimated, thereby simplifying the overall optical design of 24 the assembly and rendering the spacing of the windows less critical 209~83~

1 than would otherwise be the case. By comparison, it Ls not 2 possible to design a conventional endoscope to compensate for the 3 presence of uncertain amounts of disinfecting or rinsing fluids.
4 Assembly of the components in practicing the present invention can readily be accomplished utilizing design and manufacturing 6 techniques well understood by those of ordinary skill in the art.
7 The dimensional requirements for the system components are much 8 less critical than in the assembly disclosed in the Chatenever '594 9 patent, for example, which requires glass-to-glass contact between the windows of adjacent components of an endoscope assembly in 11 order to eliminate condensation. The principles of the invention 12 can be employed in joining other components of the endoscope 13 system, if needed, or components of other optical instruments.
14 According to the invention, the problem of condensation addressed extensively in the prior art is eliminated in a simple 16 and essentially cost-free fashion, thereby eliminating image 17 impairment due to residue from dried moisture or from varying 18 amounts of liquid on the windows.
19 Having described the preferred and alternative embodi~1ents of a new and improved endoscope system, it is believed that other 21 modifications, variations and changes will be suggested to persons 22 skilled in the art in view of the teachings set forth herein. It 23 is therefore to be understood that all such variations, 24 modifications and changes are believed to fall within the scope of the present invention as defined by the appended claims.

Claims

1. An endoscope assembly, comprising:
an elongated endoscope having a distal end and a proximal end with a first transparent window disposed in said proximal end;
a coupler having a distal end with a second transparent window disposed therein, and a proximal end adapted for connection to apparatus for forming a visible image; and joining means for connecting said endoscope to said coupler with a predetermined space between said first and second windows, the size of said space being selected to permit substantially unimpeded transmission of light therethrough when the space is filled with a transparent liquid.

2. An endoscope assembly as recited in claim 1 wherein said joining means includes a recess of predetermined depth formed in said distal end of said coupler, said second window being secured in fluid sealing relation at an innermost part of said recess, and a male connector formed on said proximal end of said endoscope and adapted for insertion into said recess, wherein said first window is secured in fluid sealing relation to said connector, and means for limiting the depth of insertion of said connector into said recess to establish said predetermined space between said first and second windows.

3. The endoscope assembly as recited in claim 2 wherein said means for limiting comprises stop means disposed on said connector for abutting a surface on said coupler.

4. The endoscope assembly as recited in claim 2 wherein said male connector and said recess have similar cross-sectional shapes and are closely sized with respect to one another such that said liquid is retained in said recess by surface tension.

5. An endoscope for use with an optical coupler, said coupler having a forward end and a transparent coupler window at the base of a recess formed in said forward end, and a rearward end adapted to be mechanically and optically coupled to a camera, said endoscope comprising:
an elongated probe having a distal end and a proximal end, said probe including a transparent endoscope window disposed at said proximal end, and means for positioning said endoscope window within the recess in the coupler in spaced relation to the coupler window: and means for cooperating with the recess in the coupler to retain a quantity of transparent liquid between said endoscope window and the coupler window.

6. The endoscope as recited in claim 5 wherein said means for cooperating comprises an elongated male connector formed on said proximal end of said endoscope for fitting closely within the recess in the coupler to retain said fluid in the recess by means of surface tension.

7. The endoscope as recited in claim 6 wherein said transparent endoscope window is mounted on a proximal end of said male connector.

8. The endoscope as recited in claim 7 further comprising stop means disposed on said male connector for abutting a surface of the coupler in order to limit insertion of said male connector into the recess and thereby control the spacing of said windows.

9. In an assembly comprising an endoscope and a coupler for optically coupling the endoscope to an image forming optical device, wherein the endoscope includes an elongated optical probe and a connector disposed at a proximal end of the probe, wherein one of the coupler and connector defines a recess for receiving a male member comprised by the other of the coupler and connector, and wherein a first optical window is disposed at a bottom surface of the recess and a second optical window is disposed at the received end of the male member, the improvement comprising:

cooperating spacing means on the male member and coupler defining a predetermined space between the optical windows when said male member is maximally inserted into said recess; and means for confining a quantity of optically transparent liquid in said recess to fill said predetermined space between the optical windows.

10. The improvement as recited in claim 9 wherein said cooperative spacing means comprises flange means surrounding the male member for abutting a surface surrounding the recess, the depth of the recess from said surface surrounding the recess being greater than the length of the male member as measured from said flange means.

11. The improvement as recited in claim 9 wherein the recess is formed in said coupler and the male member is comprised by the connector.

12. The improvement as recited in claim 9 wherein the male member and recess are correspondingly shaped and sized with respect to one another such that said quantity of liquid is retained between the optical windows by surface tension.

13. The improvement as recited in claim 12 wherein the male member and recess are cylindrical, the recess being sufficiently greater in diameter than the male member to permit ready insertion and withdrawal of the male member into and out of the recess, and to allow extrusion of any excess liquid from the recess between the windows upon insertion of the male member into the recess while assuring that the liquid is retained in the recess by surface tension.

14. The improvement as recited in claim 9 wherein the connector and coupler further comprise cooperating retainer means for releasably retaining the male member within the recess.

15. In combination:
an endoscope comprising a male connector and an elongated optical probe, said male connector having a first window at an exposed end thereof;
a coupler having a distal end with a recess defined therein for receiving said connector, said recess having a second window at its base;
means for maintaining a predetermined spacing between said windows when said connector is maximally inserted into said recess;
and a quantity of optically transparent liquid disposed between said windows and filling said predetermined spacing.

16. The combination as recited in claim 15 further comprising stop means disposed on said male connector for abutting said distal end of said coupler when said connector is maximally inserted in said recess, the depth of the recess being greater than the length of said connector in said recess, whereby said first and second windows are spaced from one another when said stop means abuts said distal end of said coupler.

17. The combination as recited in claim 15 wherein said connector and recess have corresponding cross-sectional shapes and are sized with respect to one another such that said liquid is retained in said recess by surface tension.

18. A method for assembling first and second components of an optical instrument, the first component including an extended male connector having a first optical window at its end, the second component having a body defining a recess for receiving the male connector, the recess having a second optical window at its base, the first and second components including cooperative spacing means defining a space having a predetermined volume between the windows when the male connector is maximally inserted into the recess, said method comprising the steps of:
disposing a volume of optically transparent liquid in the recess, said volume of liquid being greater than the predetermined volume of the space between the windows;

inserting the male connector into the recess to extrude all liquid in excess of the predetermined volume from said recess such that the recess remains filled with said liquid; and releasably joining the first and second components.