JP3780177B2 - Electronic endoscope and method of assembling the electronic endoscope - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic endoscope having a built-in imaging unit at a distal end portion of an insertion portion and a method for assembling the electronic endoscope .
[0002]
[Prior art]
Endoscopes that can be used for observing deep parts of body cavities by inserting them into body cavities, etc., and performing treatments by using treatment tools as needed, have come to be widely used in the medical field. .
[0003]
In the case of a medical endoscope, it is indispensable to surely sterilize the used endoscope in order to prevent infection and the like. For this reason, conventionally, once used endoscopes are sterilized by gas sterilization using ethylene oxide gas or the like, or by a disinfectant solution.
[0004]
However, as is well known, sterilizing gases are extremely toxic. For this reason, the work has been complicated in order to ensure the safety of the sterilization work. In addition, after sterilization, it takes time for the aeration operation to remove the sterilization gas adhering to the device, and thus there is a problem that it cannot be used immediately after sterilization is completed. Furthermore, there is a problem that the running cost becomes high.
On the other hand, in the case of a disinfectant, the management of the disinfectant is complicated. In addition, there is a problem that the disposal of the disinfectant is very expensive.
[0005]
Therefore, recently, autoclave sterilization (high-pressure steam sterilization), which does not involve complicated work, has a low running cost, and can be used immediately after sterilization, is becoming the mainstream for sterilization of endoscope devices. is there.
[0006]
This autoclave sterilization is performed by infiltrating an object to be sterilized with high-temperature water vapor at about 120 ° C. to 135 ° C. under high pressure, and is a resin system mainly used in an optical system of a conventional endoscope. In the adhesive, water vapor entered and resistance was insufficient. For this reason, it is necessary to make the endoscope compatible with autoclave sterilization so that water vapor does not enter the optical system.
[0007]
In order to make the endoscope compatible with autoclave sterilization, the structure of the optical system and the optical member are joined in an airtight manner. For example, the endoscope apparatus disclosed in Japanese Patent Laid-Open No. 2000-70215 shows a technique in which an optical member is covered with a frame in which a cover glass provided integrally with a solid-state imaging element is airtightly bonded to a metal frame and the other is also airtightly bonded. ing.
[0008]
In addition, in the lens device disclosed in JP-A-8-234070, in order to prevent peeling due to a difference in thermal expansion of an optical member, an optical member having a low thermal expansion is fitted into a frame, and another optical member bonded is attached. A structure that does not fit into the frame is shown.
[0009]
[Problems to be solved by the invention]
However, in the endoscope apparatus disclosed in Japanese Patent Laid-Open No. 2000-70215, the cover glass and the optical member disposed inside the airtight side are bonded together. For this reason, when the cover glass and the metal frame are hermetically bonded by solder or the like, which is a means for heating and bonding the cover glass, the cover glass is assembled by being distorted convexly toward the solid-state image sensor side by heat. When the optical member inside the airtight side is bonded to the cover glass surface, the metal frame repeatedly undergoes thermal expansion and contraction during autoclave sterilization, so that the cover glass is also repeatedly deformed and peeling occurs on the bonded surface. Image defects may occur.
[0010]
Further, in the structure of the lens device disclosed in JP-A-8-234070, it is effective when fitting and bonding, but when performing hermetic bonding, the fitted and assembled optical member is compressed. When the metal frame thermally expands at high temperatures during autoclave sterilization, the diameter increases so that the compressed optical member returns to its original shape. In this case, generally, the thermal expansion coefficient of the metal is considerably larger than the thermal expansion coefficient of the optical member, so that the optical expansion of the optical member may cause separation at the surface bonding portion between the optical members, resulting in an image defect. It was.
[0011]
The present invention has been made in view of the above circumstances, and eliminates the problems due to the influence of high temperature during high-pressure steam sterilization, and includes an electronic endoscope and an electronic endoscope provided with an imaging unit having a structure with good assembly properties . The purpose is to provide an assembly method .
[0012]
[Means for Solving the Problems]
A first electronic endoscope according to the present invention includes an imaging element for imaging a subject, a first optical member that covers an imaging surface of the imaging element, an outer peripheral surface of the first optical member, and solder A metal frame member joined by brazing, brazing, or welding, a second optical member for causing light from a subject to enter the imaging surface, and the first optical member inside the metal frame member; A positioning member provided so as to abut, a through-hole provided in the positioning member and forming an optical path to the imaging surface, and the first optical member and the second optical member being separated by a predetermined distance And a lens arrangement concave portion for providing and arranging.
The second electronic endoscope of the present invention includes an imaging element for imaging a subject, a first optical member that covers an imaging surface of the imaging element, an outer peripheral surface of the first optical member, and solder A metal frame member joined by brazing, brazing or welding, a positioning member provided so as to abut on the first optical member inside the metal frame member, and provided on the positioning member to the imaging surface A lens arrangement recess having a through-hole that forms an optical path of the lens, and a lens arrangement recess of the positioning member, and through the positioning member, the predetermined distance is formed with respect to the first optical member. And a second optical member held by the metal frame member.
According to a third electronic endoscope of the present invention, an imaging device for imaging a subject, a first optical member that covers an imaging surface of the imaging device, an outer peripheral surface of the first optical member, and solder A metal frame member joined by brazing, brazing, or welding, a second optical member for causing light from a subject to enter the imaging surface, and the first optical member inside the metal frame member; A positioning member provided so as to abut, a lens arrangement recess for arranging the first optical member and the second optical member at a predetermined interval, and the imaging provided in the lens arrangement recess And a through hole that forms an optical path to the surface.
According to a fourth electronic endoscope of the present invention, in the first to third electronic endoscopes, the first optical member is distorted in a recessed state.
The electronic endoscope assembling method of the present invention includes a step of soldering the outer peripheral surface of the first optical member that covers the imaging surface of the image sensor and the inner peripheral surface of the metal frame member, and joining them by brazing or welding; Dropping the positioning member into the inner hole of the metal frame member so as to contact the first optical member; dropping the second optical member into the lens placement recess of the positioning member; and the positioning member and the And a step of adhering and fixing the metal frame member and adhering and fixing the second optical member and the positioning member.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
1 to 5 relate to an embodiment of the present invention, FIG. 1 is a diagram for explaining the configuration of an endoscope, and FIG. 2 is a cross-sectional view for explaining the configuration of an imaging unit built in the distal end portion of the endoscope. 3 is a diagram for explaining the relationship between the tip metal frame and the cover glass, FIG. 4 is a diagram for explaining the insulating frame, and FIG. 5 is a diagram for explaining the relationship between the image sensor frame and the cover glass.
[0015]
3A is a cross-sectional view showing a tip metal frame to which a cover glass is bonded, and FIG. 3B is an enlarged view of a portion A in FIG. 3A.
[0016]
As shown in FIG. 1, an electronic endoscope (hereinafter abbreviated as an endoscope) 1 of the present embodiment has an insertion portion 2 to be inserted into the body. The insertion portion 2 is provided with at least a distal end portion 3 incorporating an imaging unit, which will be described later, and a bending portion 4 configured to bend in the vertical direction, for example, by connecting a bending piece (not shown).
[0017]
An operation portion 5 is provided at the proximal end portion of the insertion portion 2. The operation portion 5 is provided with an angle lever 6 for remotely operating the bending portion 4.
[0018]
A light source connector 7 a that is detachably connected to a light source device (not shown) is provided at the end of the flexible cord 7 that extends from the operation unit 5. An electric cable 8 having an electric connector 8a detachably connected to a camera control unit (not shown) is connected from the side of the light source connector 7a.
[0019]
The light source connector 7 a is provided with a base 9 that communicates with the internal space of the endoscope 1. The endoscope 1 has a watertight structure, and an adapter (not shown) is assembled to the base 9 so that the internal space of the endoscope 1 communicates with the outside of the endoscope.
[0020]
In the case where the internal space of the endoscope 1 is communicated with the outside of the endoscope without using an adapter, the pressure in the internal space of the endoscope 1 is set to a predetermined pressure from the external pressure. A check valve structure that connects the inside and the outside when the height is increased.
[0021]
Here, the configuration of the imaging unit built in the distal end portion 3 will be specifically described with reference to FIGS. 2 to 5.
As shown in FIG. 2, the imaging unit 10 built in the distal end portion 3 includes an imaging optical system having a solid-state imaging device 11 and a plurality of optical lenses for forming an optical image on the imaging surface of the solid-state imaging device 11. .., 12 and an objective optical system in which a plurality of substantially pipe-shaped metal frame members, which will be described later, are joined in an airtight state. Therefore, the endoscope 1 is compatible with high-pressure steam sterilization.
[0022]
The exterior of the imaging unit 10 is connected to a front end metal frame 13 that is a metal frame member, an insulating frame 14 that is an insulating member, an imaging element frame 15 that is a metal frame member, a shield pipe 16, and a cable holder 17 in order from the front end side. The outer periphery of the image sensor frame 15, shield pipe 16 and cable holder 17 is covered with a heat shrinkable tube 18.
[0023]
A lens frame 19 in which a plurality of optical lenses 12,..., 12 constituting the objective optical system are arranged and fixed is disposed in the inner hole of the insulating frame 14. The outer circumference of the cable holder 17 is covered with an outer tube 30a that constitutes the exterior of the signal cable 30.
[0024]
As shown in FIG. 2 and FIGS. 3A and 3B, the tip metal frame 13 has a substantially convex cross-sectional shape, and the tip portion 3 is formed on the tip end side fitting surface 13a having a small inner hole. The front end side cover glass 21 exposed to the front end surface of the A is joined in an airtight state.
[0025]
On the outer peripheral surface 21a and the chamfered portion 21b of the front end side cover glass 21, for example, a metal film such as chromium, nickel, and gold is formed by a metallization process such as vacuum deposition, sputtering, or ion plating as shown by a broken line. Yes. Then, the front end side cover glass 21 provided with this metal coating is fitted and arranged at a predetermined position of the front end side fitting surface 13a and is joined to the front end metal frame 13 in an airtight state by the solder 40.
[0026]
An antireflection film is formed on the proximal side flat surface 21 c of the distal end side cover glass 21. Moreover, nickel plating etc. are given to the front end side fitting surface 13a and the chamfered part 13b of the said front end metal frame 13, and solder wettability is improved. Further, solder fillets 41a and 41b having a substantially triangular cross section are formed between the front end fitting surface 13a and the chamfered portion 13b and the outer peripheral surface 21a and the chamfered portion 21b of the front end side cover glass 21. The Further, an edge portion 13c is provided on the proximal end side of the distal end side fitting surface 13a, and the solder 40 flowing into the gap between the distal end side cover glass 21 and the distal end metal frame 13 passes through the distal end side fitting surface 13a and has a large diameter. It is configured to prevent the flow to the inner peripheral surface 13d side. The size of the chamfered portion 13b is set to be equal to or larger than the wire diameter of the solder.
[0027]
As shown in FIGS. 2 and 4, the cross-sectional shape of the insulating frame 14 is also substantially convex. The insulating frame 14 is formed of, for example, ceramics which is a member that can be electrically insulated and does not transmit water vapor.
[0028]
On both side end faces 14a and 14b of the insulating frame 14, a molybdenum-manganese alloy baking or a metal film made of an active metal such as a titanium alloy is formed.
[0029]
Further, a distal end side metal member 22 having a substantially cylindrical shape and having a central communication hole 22a is fitted and disposed at the distal end portion of the insulating frame 14, and a proximal end side metal member 23 having a pipe shape is disposed at the proximal end portion. The fitting is arranged. The respective metal members 22 and 23 are joined to the end faces 14 a and 14 b of the insulating frame 14 in an airtight state by solder 40. At this time, a solder fillet 42a is formed between the front end surface 14a of the insulating frame 14 and the communication hole inner peripheral surface 22b of the central communication hole 22a.
[0030]
The communication hole inner peripheral surface 22b of the tip end side metal member 22 and the base end side inner peripheral surface 23a of the base end portion side metal member 23 are subjected to nickel plating or the like. The outer peripheral surface 22c, the outer peripheral surface 23b of the base end side metal member 23, and the outer surface of the step portion 23c having a smaller outer diameter than the outer peripheral surface 23b are not plated. A boundary portion between the stepped portion 23c and the outer peripheral surface 23b substantially coincides with the base end surface 14b of the insulating frame 14.
[0031]
Further, in this embodiment, the base end portion of the base end portion 23 is assembled so as to protrude from the base end surface 14 b of the insulating frame 14. As a result, a solder fillet 42 b is formed between the base end surface 14 b of the insulating frame 14 and the base end side inner peripheral surface 23 a of the base end portion side metal member 23.
[0032]
That is, when the insulating frame 14 and the base end side metal member 23 are solder-bonded, the base end portion of the base end side metal member 23 is projected from the base end surface 14b of the insulating frame 14, so that the solder 40 is Even if it does not protrude to the outer peripheral surface 23b side and is rarely protruded, the outer surface and the outer peripheral surface 23b are not plated, so the outer surface and the outer peripheral surface 23b are not wetted by solder.
[0033]
Therefore, the positional relationship between the fitting portion and the solder portion of the distal end side metal member 22 and the insulating frame 14 and the proximal end side metal member 23 and the insulating frame 14 is such that the solder portion is positioned inside the airtight structure. The fitting portion is located outside the airtight structure.
[0034]
Thus, for example, when soldering is performed using a flux, even if the soldering is poor after soldering to the fitting portion between the insulating frame 14, the distal end side metal member 22 and the proximal end side metal member 23, the flux Even if the residue remains, the flux is prevented from entering the airtight structure, and the field of view is prevented from being disturbed by the flux. Note that it is not necessary to adopt this configuration when performing soldering or brazing in a vacuum heating furnace or hydrogen furnace that does not use flux.
[0035]
The distal end metal frame 13 is fitted on the distal end side metal member 22 of the insulating frame 14 configured as described above and is airtightly joined by welding. On the other hand, the imaging element frame 15 is fitted on the base end side metal member 23 and is airtightly joined by welding. The welding at this time is through welding with YAG leather, which is easy to manage with low output. The positional relationship between the distal end side metal member 22 and the distal end metal frame 13 is not influenced by the solid welding due to the focus adjustment of the lens system.
[0036]
On the other hand, the solid-state imaging device 11 is integrally fixed to the device cover glass 24 which is a first optical member disposed on the imaging surface side by adhesion.
As shown in FIGS. 2 and 5, the element cover glass 24 is joined to the image sensor frame 15, which is a metal frame member, in an airtight state by, for example, solder 40. For example, a metal film such as chromium, nickel, or gold is formed on the outer peripheral surface 24a and the chamfered portion 24b of the element cover glass 24, and an antireflection film is formed on the tip side flat surface 24c.
[0037]
Note that the solder wettability is improved by applying nickel plating or the like to the proximal end fitting surface 15a and the proximal end chamfered portion 15b of the imaging element frame 15. Therefore, solder fillets 43 a and 43 b are formed between the outer peripheral surface 24 a and the chamfered portion 24 b of the element cover glass 24 and the imaging element frame 15.
[0038]
In addition, the outer peripheral surface 15c of the step portion of the imaging element frame 15 is in a non-platable range so that the solder does not get wet. The stepped outer peripheral surface 15c is processed so as not to be plated by performing a mask after additional plating or plating after plating.
[0039]
Furthermore, the fitting part 15d by which the one end part of the shield pipe 16 is externally fitted and arrange | positioned adjacent to the step part outer peripheral surface 15c which is this plating impossible range is provided. The outer diameter of the fitting portion 15d is formed larger than the outer diameter of the stepped outer peripheral surface 15c.
[0040]
As a result, when the element cover glass 24 is soldered to the image pickup element frame 15, the image pickup element frame 15 is fitted to the outer periphery of the element cover glass 24 and the proximal end side of the image pickup element frame 15 due to thermal expansion during soldering. Even when the gap with the mating surface 15a becomes large and solder enters the gap, and the outer diameter of the outer peripheral surface 15c of the stepped portion of the image sensor frame 15 becomes large after cooling, the outer dimensions of the fitting portion 15d are almost the same. Since it does not change, the shield pipe 16 and the image sensor frame 15 can be reliably fitted.
[0041]
A lens arrangement recess 26a for positioning the proximal lens 25, which is the second optical member, communicates with the lens arrangement recess 26a in the inner hole of the imaging element frame 15 in which the element cover glass 24 is integrated by soldering. A lens centering member 26, which is a positioning member formed with the central through hole 26b, is disposed.
[0042]
After the lens centering member 26 is dropped into the inner hole of the image sensor frame 15, the proximal lens 25 is dropped into the lens placement recess 26 a of the lens centering member 26. As a result, the element cover glass 24 and the proximal lens 25 are arranged in a state having a predetermined gap without surface contact. Reference numeral 27 denotes a spacing member disposed on the distal end side of the lens centering member 26, and a diaphragm 28 is further disposed on the distal end side of the spacing member 27.
[0043]
Here, the assembly from the base end side lens 25 to the stop 28 will be described.
First, the element cover glass 24 and the image pickup element frame 15 are joined with the solder 40.
[0044]
Next, the lens centering member 26 and the base end side lens 25 are dropped into the inner hole of the imaging element frame 15 to which the element cover glass 24 is bonded, and are fixed by adhesion. At this time, the axial length of the fitting length of the lens arrangement recess of the lens centering member 26 is set to be shorter than the thickness that is the axial length of the proximal lens 25. For this reason, after dropping the base end side lens 25 into the lens arrangement recess 26a and before dropping the spacing member 27, the front end side surface of the base end side lens 25 can be easily wiped and cleaned.
[0045]
Next, the spacing member 27 is dropped, and is bonded and fixed to the lens centering member 26 and the image sensor frame 15, and the diaphragm 28 is bonded and fixed to the spacing member 27.
[0046]
The frame members are joined to each other in an airtight state by the soldering and welding, and the front end side cover glass 21 and the element cover glass 24 are joined to the front end metal frame 13 and the imaging element frame 15 in an airtight state, respectively. Airtightness is ensured at the portion, and the internal space sandwiched between the element cover glass 24 and the front end side cover glass 21 becomes an airtight space where high-pressure steam or the like does not enter.
[0047]
A substrate 31 is electrically connected to the solid-state image sensor 11. A signal line 32 passing through the signal cable 30 is electrically connected to the substrate 31. The cable holder 17 is assembled to the outside of the signal line 32, and the other end of the shield pipe 16 is fitted on the cable holder 17. The shield pipe 16 and the cable holder 17 and the shield pipe 16 and the imaging element frame 15 are joined in an airtight manner by welding.
[0048]
Note that the substrate 31 and the signal line 32 on the side end surface of the substrate 31 connected to the solid-state imaging device 11 are sealed with an adhesive 33. The cable holder 17 is also filled with an adhesive 33. These adhesives 33 are desirably epoxy adhesives that do not easily transmit vapor.
[0049]
The signal line 32 is provided with a net-like shield member 32a, and the shield member 32a and the cable holder 17 are connected to the same potential by solder or conductive adhesive. As a result, the cable holder 17 and the shield pipe 16, the imaging element frame 15, and the base end side metal member 23 are connected by welding, so that they are surely at the same potential.
[0050]
Furthermore, the other end side of the net-like shield member 32a of the signal line 32 falls to the ground. For this reason, since the solid-state image sensor 11 is covered and shielded by a grounded metal member, the structure of the solid-state image sensor 11 is less affected by the electromagnetic waves on the solid-state image sensor 11 and the emission of electromagnetic waves from the solid-state image sensor 11. ing.
[0051]
Here, the operation of the imaging unit 10 will be described.
When the element cover glass 24 is soldered to the imaging element frame 15 and then cooled, the element cover glass 24 is distorted in a state where the front end surface side (airtight inner side) is recessed. This is due to the difference in thermal expansion coefficient between the image sensor frame 15 and the element cover glass 24, and the image sensor frame 15 contracts greatly with respect to the element cover glass 24, and stress is applied to the element cover glass 24. Because it is added.
[0052]
Here, assuming that the base end lens 25 is surface-bonded to the front end surface side of the element cover glass 24 as in the prior art, the imaging element frame 15 repeats thermal expansion and contraction during autoclave sterilization. There is a possibility that the distorted portion of the cover glass 24 is repeatedly deformed and the surface bonding portion may be peeled off. However, in the present embodiment, the element cover glass 24 and the base end side lens 25 are not surface bonded, Since the lens centering member 26 is disposed with a predetermined gap, even if the distorted portion of the element cover glass 24 is repeatedly deformed, problems such as peeling do not occur.
[0053]
As described above, when the optical member is adjacent to the cover glass arranged on the imaging surface side of the solid-state imaging device, when autoclave sterilization is performed by providing a predetermined gap between the optical member and the cover glass. The occurrence of image defects can be reliably prevented by eliminating the peeling that occurs.
[0054]
Moreover, the surface of an optical member can be easily wiped and cleaned by dropping and arranging an optical member with respect to the cover glass arrange | positioned at the imaging surface side of a solid-state image sensor. This eliminates poor visual field due to dirt or the like and ensures a good visual field.
[0055]
Furthermore, since the space in which the optical lens constituting the objective optical system is arranged is joined by soldering, brazing, or welding, it is possible to reliably prevent water vapor from entering even if autoclave sterilization is performed. . This prevents deterioration of the lens, peeling of the lens coating, and adhesion of water droplets, and ensures a good visual field.
[0056]
In addition, since the periphery of the solid-state imaging device is electrically shielded, a good image with little noise can be obtained.
[0057]
It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention.
[0058]
[Appendix]
According to the embodiment of the present invention as described above in detail, the following configuration can be obtained.
[0059]
(1) In an electronic endoscope having an imaging unit configured by providing at least one metal frame member in which a plurality of optical members are arranged at one end,
A first optical member is hermetically bonded to one end of the metal frame member, and a second optical member adjacent to the first optical member is connected between the second optical member and the first optical member. An electronic endoscope disposed in the metal frame member via a positioning member that forms a predetermined gap therebetween.
[0060]
(2) The electronic endoscope according to appendix 1, wherein a fitting length between the positioning member and the second optical member is set to be shorter than an axial length of a side surface of the second optical member.
[0061]
(3) In an electronic endoscope having an imaging unit built in the distal end of the insertion portion,
The imaging unit is
A first optical member hermetically bonded to the metal frame member;
A second optical member disposed and fixed in the metal frame member;
A positioning member that is disposed in the metal frame member and that defines a predetermined gap between the first optical member and the second optical member to regulate the position of the second optical member;
An electronic endoscope comprising:
[0062]
(4) The electronic endoscope according to appendix 1 or appendix 3, wherein the endoscope is autoclavable.
[0063]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an endoscope provided with an imaging unit having a structure with good assembling properties by eliminating problems due to the influence of high temperature during high-pressure steam sterilization.
[Brief description of the drawings]
FIG. 1 to FIG. 5 relate to an embodiment of the present invention, and FIG. 1 is a diagram for explaining the configuration of an endoscope. FIG. 2 shows the configuration of an imaging unit built in the distal end portion of the endoscope. FIG. 3 is a diagram illustrating the relationship between the tip metal frame and the cover glass. FIG. 4 is a diagram illustrating the insulating frame. FIG. 5 is a diagram illustrating the relationship between the image sensor frame and the cover glass. Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Imaging unit 11 ... Solid-state image sensor 13 ... Tip metal frame 14 ... Insulation frame 15 ... Image sensor frame 16 ... Shield pipe 17 ... Cable holder 25 ... Base end side lens 26 ... Lens centering member

Claims (5)

  An image sensor for imaging a subject;
  A first optical member that covers an imaging surface of the imaging element;
  A metal frame member joined to the outer peripheral surface of the first optical member by soldering, brazing or welding;
  A second optical member for making light from the subject incident on the imaging surface;
  A positioning member provided in contact with the first optical member inside the metal frame member;
  A lens disposition recess for disposing the first optical member and the second optical member at a predetermined interval while having a through hole provided in the positioning member and forming an optical path to the imaging surface; ,
  An electronic endoscope characterized by comprising:   An image sensor for imaging a subject;
  A first optical member that covers an imaging surface of the imaging element;
  A metal frame member joined to the outer peripheral surface of the first optical member by soldering, brazing or welding;
  A positioning member provided in contact with the first optical member inside the metal frame member;
  A lens arrangement recess having a through hole provided in the positioning member and forming an optical path to the imaging surface;
  A second optical member disposed in the lens arrangement recess of the positioning member and held by the metal frame member via the positioning member so that a predetermined interval is formed with respect to the first optical member;
  An electronic endoscope characterized by comprising:   An image sensor for imaging a subject;
  A first optical member that covers an imaging surface of the imaging element;
  A metal frame member joined to the outer peripheral surface of the first optical member by soldering, brazing or welding;
  A second optical member for making light from the subject incident on the imaging surface;
  A positioning member provided in contact with the first optical member inside the metal frame member;
  A lens arrangement recess for arranging the first optical member and the second optical member at a predetermined interval;
  A through hole provided in the lens arrangement recess and forming an optical path to the imaging surface;
  An electronic endoscope characterized by comprising:   The electronic endoscope according to any one of claims 1 to 3, wherein the first optical member is distorted in a recessed state.   Soldering the outer peripheral surface of the first optical member covering the imaging surface of the image sensor and the inner peripheral surface of the metal frame member, joining by brazing or welding;
  Dropping a positioning member into an inner hole of the metal frame member so as to abut against the first optical member;
  Dropping the second optical member into the lens arrangement recess of the positioning member;
  Bonding and fixing the positioning member and the metal frame member and bonding and fixing the second optical member and the positioning member;
  A method of assembling an electronic endoscope, comprising:

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