JP3981263B2 - Electronic endoscope - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic endoscope using a solid-state imaging device that captures an image obtained by forming a subject image with an objective optical system.
[0002]
[Prior art]
In the case of a medical endoscope, it is indispensable to surely sterilize the used endoscope in order to prevent infection. In the case of disinfecting or sterilizing with a cleaning liquid, there is a drawback that the disinfection work is complicated and the waste liquid treatment of the cleaning liquid requires a large amount of cost.
[0003]
Therefore, recently, high-pressure and high-temperature steam sterilization (autoclave or the like) without complicated work is becoming mainstream in endoscope devices, particularly rigid endoscopes.
[0004]
Especially in electronic endoscopes, if a slight amount of moisture such as moisture enters the tip, the objective optical system may be fogged from the inside, or an electronic component that processes a signal from a solid-state image sensor or solid-state image sensor. There is a risk that the mounted substrate or the like may be corroded or short-circuited, and an endoscopic image obtained in such a state will have a significantly deteriorated image quality.
[0005]
Therefore, various means have been proposed for preventing moisture from entering the imaging unit including the objective optical system, the solid-state imaging device, and the substrate, and preventing deterioration of the constituent members. However, there have been few proposals that take into account the repair and replacement of the imaging unit.
[0006]
[Problems to be solved by the invention]
For example, Japanese Patent Application Laid-Open No. 59-129050 makes it possible to prevent the intrusion of moisture by adopting a structure in which a tip body and a frame to which a solid image-control element is fixed are hermetically bonded and fixed with a sealant or the like. Yes. In order to improve the resistance in this way, the structure tends to be such that the imaging unit is directly assembled to the main body with an adhesive or solder.
[0007]
However, in this structure, since not eject the imaging unit from the main body, it is impossible to repair or replace, in some cases using the imaging unit a new even when performing no repair problem in imaging unit repairs There is a problem that the repair cost is increased.
[0008]
Further, for example, in Japanese Patent Laid-Open No. 2000-201884, a CCD frame having a CCD attached thereto is airtightly connected and fixed to a lens frame to which an objective optical system is attached. Cover the outer peripheral surface of the frame with a metal frame that is hermetically connected at the tip, and fix the rear end of the metal frame airtight with solder on the outer peripheral surface of the metal ring that is crimped and fixed by crimping the protective tube of the imaging cable. It has a structure.
[0009]
In this structure, since the lens frame and the CCD frame, and the CCD frame and the metal frame are joined by soldering, a considerable temperature is applied to the lens and the CCD during joining, resulting in distortion and deterioration. In particular, since the CCD is vulnerable to heat, it is necessary to perform solder bonding as far as possible from the lens and the CCD.
[0010]
The present invention has been made in view of the above circumstances, and even when performing high-pressure high-temperature steam sterilization or the like, the imaging unit can be held in an airtight space, and the imaging unit can be easily repaired or replaced. An object of the present invention is to provide an electronic endoscope that can reduce the influence of heat on a solid-state imaging device and a lens.
[0011]
[Means for Solving the Problems]
The electronic endoscope of the present invention performs processing of an objective unit that forms a subject image, a solid-state imaging device positioned at the imaging position of the objective unit, and an electrical signal from the solid-state imaging device, and outputs the processed signal. An imaging unit comprising a substrate having an imaging cable covered with a flexible protective tube for transmission, and a mounting provided at the distal end of the insertion portion of the endoscope and mounting the imaging unit An endoscope apparatus having a hard tip portion main body with a hole formed therein, a tip portion optical component airtightly joined to a tip side of a mounting hole in which the objective unit is disposed, and the imaging unit, is a separate one end hermetically joined to the base end side of the solid-state imaging element and the substrate are disposed mounting hole and the other end is a metal frame which is hermetically joined to the imaging cable It is provided and configured.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0013]
First embodiment:
1 to 14 relate to a first embodiment of the present invention, FIG. 1 is a block diagram showing a configuration of an electronic endoscope, and FIG. 2 is a cross-sectional view showing a configuration of a distal end portion of the electronic endoscope in FIG. 3 is a diagram showing a configuration of a first modification of the tip optical component in FIG. 2, FIG. 4 is a diagram showing a configuration of a second modification of the tip optical component in FIG. 2, and FIG. FIG. 6 is a diagram showing a configuration of a fourth modification of the tip optical component in FIG. 2, and FIG. 7 is a diagram showing a configuration of the tip optical component in FIG. FIG. 8 is a second diagram showing the configuration of the fifth modification of the tip optical component in FIG. 2, and FIG. 9 is the diagram of the objective unit in FIG. FIG. 10 is a diagram showing a configuration of a second modification of the objective unit of FIG. 2, FIG. 11 is a diagram showing a configuration of a third modification of the objective unit of FIG. 12 is the same as FIG. FIG. 13 is a diagram showing a configuration of a fifth modification of the objective unit in FIG. 2, and FIG. 14 is a diagram showing a configuration of a sixth modification of the objective unit in FIG. FIG.
[0014]
As shown in FIG. 1, an electronic endoscope 1 used in the present embodiment includes an elongated insertion portion 2 and operations that are connected to the proximal side of the insertion portion 2 and held by an operator to perform various operations. And a universal cord 4 extending from the operation unit 3.
[0015]
A connector portion 5 is provided at the other end of the universal cord 4 and is connected to a light source device (not shown) and a CCU (camera control unit).
[0016]
A light guide connector 6 is connected to the light source device, and a camera connector 7 is connected to the CCU.
[0017]
The insertion portion 2 includes a flexible flexible tube 10 provided continuously with the operation portion 3, a bending portion 9 provided continuously with the distal end of the flexible tube, and a distal end of the bending portion 9. It is comprised from the provided front-end | tip part 8. FIG. The operation unit 3 includes a bending operation lever 11 and a treatment instrument insertion port 12 for inserting a treatment instrument such as forceps.
[0018]
As shown in FIG. 2, the tip 8 is inserted and fixed from the tip side of a metal tip part body 13, a tip cover 14, and a mounting hole 13 a provided on the tip side of the tip part body 13. The distal end optical component 15, the imaging unit 16 inserted and fixed from the rear end side of the mounting hole 13 b provided in the distal end body, and a flexible protective tube 18 that sends a signal from the imaging unit 16. An imaging cable 17 covered with a metal ring 19, and a metal ring 19 fixed to the end of the protective tube 18 on the imaging unit side, one end on the rear end surface of the tip body 13 and the other end on the outer surface of the metal ring 19. And a metal frame 20 fixed thereto.
[0019]
The distal end body 13 is made of metal, and mounting holes 13a, 13b, and 13c are formed so that the distal optical component 15 and the imaging unit 16 can be mounted. In addition, in order to make soldering and brazing easier, a metal coating such as gold plating or nickel plating may be applied to the fitting portion with the tip optical component 15 on the tip side.
[0020]
The tip cover 14 plays a role of insulation in addition to the protection of the tip portion 8, and the material is a plastic having insulation, heat resistance and water resistance.
[0021]
The tip optical component 15 is provided with a metal coating 21 such as gold plating or nickel plating on the outer peripheral surface thereof to enable soldering or brazing. The tip end body and the solder 22 are hermetically joined via the metal coat 21.
[0022]
The shape of the tip optical component 15 is not limited to flat glass but may be a lens having an uneven portion.
[0023]
The imaging unit 16 is fixed to an objective unit 23 that forms an image of a subject and a solid-state imaging device fixing frame 24 that is fitted and fixed to the objective unit 23 via a cover lens 25 and a glass lid 26. A solid-state image sensor 27 positioned at the image forming position, and a substrate 28 on which an electronic component for processing an electrical signal from the solid-state image sensor 27 and transmitting a signal to the imaging cable 17 is mounted. It is fixed with a screw or the like (not shown) so that it can be easily removed from the body 13.
[0024]
The solid-state imaging device 27 and the substrate 28 in the imaging unit 16 are covered with a shield frame 29 fitted to the solid-state imaging device fixing frame 24, and the inside is filled with an insulating sealant 30. The substrate 28 and the imaging cable 17 are fixed.
[0025]
In addition, by using a sealant having low moisture permeability for the sealant 30, a structure in which moisture cannot easily enter is obtained. Further, the heat shrinkable tube 31 covering the shield frame 29 and the front side of the metal ring 19 from the solid-state image sensor fixing frame 24 prevents the sealant 30 filled in the shield frame 29 from flowing out. together, there is also an effect of reducing the moisture penetration into such a solid-state imaging devices and electronic components.
[0026]
The objective unit 23 is arranged on the lens frame 23a from the front end side in the order of the lens 23b, the beam stop 23c, the flat glass 23d, the lens 23e, the spacing ring 23f, the filter 23g, the spacing ring 23h, and the lens 23i. And the lens 23i at the rear end is adhered 43 around the lens frame 23a with an adhesive.
[0027]
Since there are protrusions in the lens frame, the three members, the lens 23b, the light beam stop 23c, and the flat glass 23d, are arranged from the front end side to the five members of the lens 23e, the spacing ring 23f, the filter 23g, the spacing ring 23h, and the lens 23i. The member is inserted and assembled from the rear end side.
[0028]
The imaging cable 17 is for transmitting a signal from the substrate 28 in the imaging unit 16, and is inserted into the universal cable 4 from the operation unit 3 through the insertion unit 2, and the side of the connector unit 5. Is connected to the camera connector 7 provided in FIG.
[0029]
The imaging cable 17 has a structure in which a plurality of coaxial wires 17a having a core wire, an insulation coating, a shield wire, and an insulation coating are bundled from the center side. The bundled coaxial wires 17a are further provided with an insulation coating, an overall shield wire 17b, an insulation wire. It is composed of a coating.
[0030]
The protective tube 18 is for protecting the imaging cable 17 and has flexibility. A metal ring 19 is attached near the tip.
[0031]
The metal ring 19 is joined to the entire shield wire 17c of the image pickup cable 17 at the end of the image pickup unit by the airtight solder 32 over the entire circumference, and moisture from the gap between the metal ring 19 and the protective tube 18 is obtained. To prevent intrusion. Further, by caulking and fixing the metal ring 19 to the protective tube 18, the metal ring 19 bites into the soft protective tube 18 and the airtightness is further increased.
[0032]
The metal frame 20 has a taper-shaped rear narrow structure, with one end closing the mounting hole 13c on the rear end surface of the tip body 13 and the other end along the outer surface of the metal ring 19. The tip end body 13 and the metal ring 19 are joined over the entire circumference by airtight solders 33 and 34, respectively.
[0033]
Instead of providing the metal ring 19, the tip body 13 and the coupling shield 17c of the imaging cable 17 may be joined over the entire circumference with airtight solder.
[0034]
With the configuration described above, the imaging unit 16 is held in a space that is kept airtight by the distal end body 13, the distal end optical component 15, the metal frame 20, and the metal ring 19, and is connected to the members in the imaging unit 16. It is possible to prevent deterioration due to moisture intrusion.
[0035]
Further, when the imaging unit 16 is repaired or replaced, the imaging unit 16 can be easily taken out by removing the solders 33 and 34 of the metal frame 20 or breaking the metal frame 20.
[0036]
Further, since the place where the solder joint is performed is the outer peripheral surface of the metal ring 19 and the rear end surface of the tip body 13, it is a place that is thermally conductive away from the objective unit 22 and the solid-state image sensor 27. The influence on the lens and the solid-state image sensor is also reduced.
[0037]
Moreover, it is also possible for the front-end | tip part optical component 15 to take the structure shown in FIGS. This will be described below with reference to the drawings.
[0038]
3 is a lens having a step structure in which the outer diameter of the rear end side lower stage outer periphery 15b is smaller than the outer diameter of the front end side upper stage outer periphery 15a. The lens is hermetically joined to the mounting hole 13a of the tip body 13 by solder 22 through the metal coat 21 on the upper outer periphery 15a on the tip side. By applying the metal coat 21 only to the front end side upper stage outer periphery 15a, the area of the metal coat 21 as a flare generation source is reduced, and the rear end side lower stage side face 15b, the front end side upper stage bottom face 15c, and the rear end side lower stage bottom face 15d are provided. By applying a low-reflection coating 35 such as chromium oxide or ceramic, unnecessary light 36 is blocked and absorbed, and flare can be reduced.
[0039]
4 has a structure in which a rear end surface of the first optical component 37 is formed in a concave shape and a second optical component 38 having the same diameter as the inner diameter of the concave portion is fitted. A metal coat 21 is applied to the outer periphery of the first optical component 3, and the range thereof has a relationship of fitting length (A) ≧ metal coat length (B) with the second optical component 38. . The tip body 13 and the solder 22 are hermetically joined via the metal coat 21. In addition, a low reflection coating 35 is applied to the outer periphery of the second optical component 38, thereby preventing unnecessary light 36 and preventing flare. The first optical member 37 and the second optical member 38 may be fitted using a black adhesive to replace the low reflection coating.
[0040]
The tip optical component 15 shown in FIG. 5 has a structure in which the rear end surface of the tip optical component 15 is formed in a concave shape and the lens frame 23a of the objective unit 23 having the same outer diameter as the inner diameter of the recess is fitted. A metal coat 21 is applied to the outer periphery of the distal end optical component 15, and the range is such that the fitting length with the lens frame 23 a (A) ≧ the metal coat length (B). The tip body 13 and the solder 22 are hermetically joined via the metal coat 21. The unnecessary light 36 is blocked by the lens frame 23a, and flare can be prevented.
[0041]
The tip optical component 15 shown in FIG. 6 is a lens in which a metal coat 21 is applied only to the tip side chamfer 15e. The tip body 13 and the solder 22 are hermetically joined via the metal coat 21. For this reason, the area of the metal coat 21 which is the generation source of flare is also narrow, and the flare hardly occurs. Further, a low-reflection coating 35 is applied to the side surface, whereby unnecessary light 36 is absorbed and flare can be reduced.
[0042]
The tip optical component 15 shown in FIGS. 7 and 8 has a tapered outer peripheral surface and is provided with a metal coat 21. The tip body 13 and the solder 22 are hermetically joined via the metal coat 21. The angle of the tapered portion 39 is appropriately set so as to escape flare predicted by the objective optical system. As a result, unnecessary light 36 is released and flare can be reduced.
[0043]
In addition, according to the shape of the tip end optical component 15, the tip end body 13 is similarly tapered. Further, the beam stop 40 is fixed to the rear end surface of the front end optical component 15.
[0044]
Further, the objective unit 23 can be configured as shown in FIGS. This will be described below with reference to the drawings.
[0045]
9, the lens 23b and a flat glass 23d having substantially the same outer diameter as the lens 23b are bonded and bonded to each other, and the bonded lens is inserted into the lens frame 23a and bonded around the entire periphery 43. ing. As a result, the entire path until the moisture reaches the spherical surface 41 is blocked with the sealant, so that the intrusion of moisture is reduced and the lens is less likely to be clouded.
[0046]
The flat end of the objective unit 23 shown in FIG. 10 is smaller than the lens 23b and the lens 23b, and a flat glass 23d having a light aperture 44 formed by vapor deposition is formed on the front surface. Reinforcing adhesion 45 is applied to the entire circumference from the back surface of the flat glass 23d to the outer peripheral surface of the flat glass 23d, and the adhered lens is inserted into the lens frame 23a and adhered to the entire circumference 43. As a result, the entire path until the moisture reaches the spherical surface 41 is blocked with the sealant, so that the intrusion of moisture is reduced and the lens is less likely to be clouded.
[0047]
The front end of the objective unit 23 shown in FIG. 11 has a lens 23b having a concave surface on the rear end side, a beam stop 23c formed so as to have substantially the same diameter as the inner diameter of the concave surface of the lens 23b, and a flat glass 23d. 23b is fitted / bonded and bonded 42, and a reinforcing bond 45 is applied to the entire periphery from the back surface of the lens 23b to the outer peripheral surface of the flat glass 23d. The bonded lens is inserted into the lens frame 23a and bonded to the entire periphery. 43. As a result, the entire path until the moisture reaches the spherical surface 41 is blocked with the sealant, so that the intrusion of moisture is reduced and the lens is less likely to be clouded.
[0048]
The front end of the objective unit 23 shown in FIG. 12 is formed in two steps on the rear end side, and in the same manner as the lens 23b in which the metacoat 21 is applied to the outer peripheral surface of the stepped portion 46, and the front end side is formed in two steps. A light diaphragm 23c is sandwiched between flat glass 23d having a metacoat 21 on the outer peripheral surface of the stepped portion 46, and is hermetically joined by solder 47 through the metal coat 21, and the joined lens is inserted into the lens frame 23a. The entire circumference is bonded 41.
[0049]
In addition, the outer periphery and level | step-difference part of the lens 23b and the flat glass 23d are substantially the same diameter. As a result, the space surrounded by the lens 23b and the flat glass 23d becomes airtight, so that the lens is not clouded by the intrusion of moisture.
[0050]
The tip of the objective unit 23 shown in FIG. 13 has a lens 23b having a metal coat 21 applied to the rear end side plane portion, an outer diameter smaller than the lens 23b, a metal coat 21 applied to the outer peripheral surface, and vapor deposition on the front surface. The flat glass 23d on which the beam stop 44 is formed is hermetically joined by the solder 47 through the metal coat 21 with both cores aligned, and the joined lens is inserted into the lens frame 23a, Bonding 47 is applied. As a result, the space surrounded by the lens 23b and the flat glass 23d becomes airtight, so that the lens is not clouded by the intrusion of moisture.
[0051]
The front end of the objective unit 23 shown in FIG. 14 is formed with a small-diameter portion 48 on the front side, a large-diameter portion 49 on the rear side, and a tapered portion 50 having a tapered shape therebetween. A portion of the lens frame 23 a is caulked along the tapered portion 50, and this portion is hermetically joined by solder 47. As a result, moisture does not enter from the tip of the objective unit, and the lens is less likely to fog up. Further, since the metal coating 21 is applied to the taper portion 50, it is advantageous against flare caused by incident light from outside the field of view.
[0052]
Second embodiment:
FIG. 15 is a cross-sectional view showing the configuration of the distal end portion of the electronic endoscope according to the second embodiment of the present invention.
[0053]
Since the second embodiment is almost the same as the first embodiment, only different points will be described, and the same components are denoted by the same reference numerals and description thereof will be omitted.
[0054]
The second embodiment shown in FIG. 15 is different from the first embodiment in the structure of the imaging unit 16 and the metal frame 20.
[0055]
That is, in the present embodiment, as shown in FIG. 15, the imaging unit 16 includes an objective unit 23 that forms an image of a subject, and a solid image-control element fixing frame 24 that is fitted and fixed to the objective unit. A solid-state image sensor 27 fixed through the cover lens 25 and the prism 51 and positioned at the image forming position of the objective unit 23, processing of electrical signals from the solid-state image sensor 27 and transmitting a signal to the imaging cable 17. And a board 28 on which electronic components for mounting are mounted, and are fixed with screws or the like (not shown) so that they can be easily removed from the tip body 13.
[0056]
The metal frame 20 supplements the space behind the prism 51 in the imaging unit 16 by enlarging a part of the metal frame 20. Generally, when sealing in an airtight manner, bonding is performed so that moisture does not enter the sealed space. However, the smaller the imaging unit space, the smaller the total moisture amount, and the moisture content in the imaging unit 16 is reduced. This is advantageous against deterioration due to penetration and lens fogging of the objective unit 23. The metal frame 20 is formed with a thin portion 20a so as to go around the metal frame, and this portion can be easily broken.
[0057]
Thus, even in an imaging unit such as an imaging unit with a prism that is difficult to take an airtight structure by the imaging unit itself, the tip body, the tip optical component, the metal frame, the metal ring, and the imaging cable were kept airtight. It is held in the space, and it becomes possible to prevent deterioration of the member due to the intrusion of moisture into the imaging unit. Other effects are the same as those of the first embodiment.
[0058]
As described above, according to each of the above embodiments, the imaging unit is held in an airtight space, and deterioration and lens fogging due to moisture intrusion can be prevented without particularly improving the imaging unit itself to an airtight structure. The imaging unit can be easily repaired and replaced, and the effects of heat on the solid-state imaging device and lens can be reduced.
[0059]
【The invention's effect】
As described above, according to the present invention, even when performing high-pressure high-temperature steam sterilization or the like, the imaging unit can be held in an airtight space, and the imaging unit can be easily repaired or replaced. The effect of heat on the lens can be reduced.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a configuration of an electronic endoscope according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a configuration of a distal end portion of the electronic endoscope shown in FIG. FIG. 4 is a diagram showing a configuration of a first modification of the tip optical component of FIG. 2. FIG. 4 is a diagram showing a configuration of a second modification of the tip optical component of FIG. FIG. 6 is a diagram showing the configuration of a fourth modification of the tip optical component in FIG. 2; FIG. 7 is a fifth modification of the tip optical component in FIG. FIG. 8 is a second diagram showing the configuration of the fifth modification of the tip optical component in FIG. 2. FIG. 9 is the configuration of the first modification of the objective unit in FIG. FIG. 10 is a diagram showing a configuration of a second modification of the objective unit shown in FIG. 2. FIG. 11 is a diagram showing a configuration of a third modification of the objective unit shown in FIG. 4th of the objective unit FIG. 13 is a diagram showing a configuration of a fifth modification of the objective unit shown in FIG. 2. FIG. 14 is a diagram showing a configuration of a sixth modification of the objective unit shown in FIG. Sectional view showing the structure of the distal end portion of an electronic endoscope according to a second embodiment of the present invention
DESCRIPTION OF SYMBOLS 1 ... Electronic endoscope 2 ... Insertion part 3 ... Operation part 4 ... Universal cord 5 ... Connector part 6 ... Light guide connector 7 ... Camera connector 8 ... Tip part 9 ... Bending part 10 ... Challenge tube 11 ... Bending operation lever DESCRIPTION OF SYMBOLS 12 ... Treatment tool insertion port 13 ... Tip part main body 13a ... Mounting hole 13b ... Mounting hole 13c ... Mounting hole 13e ... Tapered mounting hole 14 ... Tip cover 15 ... Tip part optical component 15a ... Tip side upper stage outer periphery 15b ... Rear end Lower end outer perimeter 15c ... Top end upper step bottom surface 15d ... Rear end lower step bottom surface 15e ... Tip side chamfer 16 ... Imaging unit 17 ... Imaging cable 17a ... Coaxial wire 17b ... General shield wire 18 ... Protective tube 19 ... Metal ring 20 ... Metal frame 20a ... Thin part 21 ... Metal coat 22 ... Solder 23 ... Objective unit 23a ... Lens frame 23b ... Lens 23c ... Light aperture 23d ... Parallel glass 23e ... Ren 23f ... Spacing ring 23g ... Filter 23h ... Spacing ring 23i ... Lens 24 ... Solid-state image sensor fixing frame 25 ... Cover lens 26 ... Glass lid 27 ... Solid-state image sensor 28 ... Substrate 29 ... Shield frame 30 ... Sealant 31 ... Heat shrinkable tube 32 ... solder 33 ... solder 34 ... solder 35 ... low reflection coating 36 ... unnecessary light 37 ... first optical component 38 ... second optical component 39 ... tapered portion 40 ... beam stop 41 ... spherical surface 42 ... bonding adhesion 43 ... All-around adhesion 44 ... Light aperture 45 by vapor deposition ... Reinforcement adhesion 46 ... Stepped part 47 ... Solder 48 ... Small diameter part 40 ... Large diameter part 50 ... Tapered part 51 ... Prism

Claims (5)

An objective unit that forms an image of a subject, a solid-state imaging device positioned at the imaging position of the objective unit, and processing of electrical signals from the solid-state imaging device, and transmitting the processed signals, has a flexible protection An imaging unit comprising a substrate with an imaging cable covered with a tube, and a rigid tip provided at the tip of the insertion portion of the endoscope and having a mounting hole for mounting the imaging unit In an endoscope apparatus having a main body,
A tip optical component airtightly joined to the tip side of the mounting hole in which the objective unit is disposed;
A separately from the image pickup unit, one end of which is hermetically joined to the base end side of the solid-state imaging device and the mounting hole in which the substrate is disposed, the other end of which is joined hermetically to said imaging cable A metal frame,
An electronic endoscope characterized by comprising: 2. The metal frame according to claim 1, wherein one end of the metal frame is hermetically joined to a proximal end side of a mounting hole formed in the distal end portion main body, and the other end is hermetically joined to a metal ring fixed to the protective tube. An electronic endoscope according to 1. The metal frame has a taper-shaped rear narrow structure, and a large-diameter portion on the distal end side is airtightly joined to a proximal end surface of the distal end body, and a small-diameter portion on the proximal end side is airtightly adhered to the outer peripheral surface of the metal ring. The electronic endoscope according to claim 2, wherein the electronic endoscope is joined to the electronic endoscope. The electronic endoscope according to claim 1, wherein the metal frame is provided with a thin portion at a part thereof. The electronic endoscope according to claim 2, wherein the metal ring is airtightly joined to a general shield wire constituting the imaging cable with the protective tube interposed therebetween.

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