JP2001231741A - Observation unit mounting mechanism of endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow mounting of an observation unit in a manner that the length of a the rigid distal end section of an insertion section may be shortened by advancing an objective optical system into an insulation cap from a main body block of the distal end body. SOLUTION: The insulation cap 21 covering the end face of the main body block 20 is provided with an insertion hole 51 on which the observation unit 33 verges. This insertion hole 51 is formed to a structure having a large- diameter aperture 51a and a small-diameter aperture 51b and a level difference wall 51c therebetween. On the main body block 20 side, the circumference of an observation unit mounting section 20a from its front end is provided with a toric projecting line 52 which projects therefrom. This toric projecting line 52 is extended into the large-diameter aperture 51a of the insertion hole 51 in the insulation cap 21 and its front end butted against the level difference part 51c of the small-diameter aperture 51b. The inside surface of the toric projecting line 52 is overhung inward and its inner peripheral surface is formed as a holding wall 52a for fixedly holding a reference lens frame 40 and the reference lens frame 40 is stably held by the holding wall 52a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an observation unit mounting mechanism for mounting an observation unit having an objective optical system constituting an observation section at a distal end of an insertion section in an endoscope used for medical use or the like. is there.

[0002]

2. Description of the Related Art In general, an endoscope used for medical purposes or the like is a universal endoscope which is detachably connected to an insertion portion into a body cavity, a light source device, and the like, to a main body operation portion which is grasped and operated by an operator. It is roughly configured by providing a series of cords. The insertion portion is composed of a tip main body, an angle portion, and a flexible portion from the distal end due to its structure and function, and the flexible portion has most of the length from the side of the connecting portion to the main body operation portion. And bends in any direction along. The distal end main body is provided with an illuminating section, an observation section, and the like, and a treatment tool lead-out section for leading out a treatment tool such as forceps is opened. The angle section is used to direct the distal end body in an arbitrary direction. It can be bent by remote operation from the main body operation unit side.

As described above, at least the illumination section and the observation section are provided in the distal end body, and the exit section of the light guide made of an optical fiber bundle faces the illumination section, and this light guide is inserted into the insertion section. Through the main body operation unit and into the universal cord. On the other hand, an objective optical system is attached to the observation unit, and an image forming position in this objective optical system is
In the case of an electronic endoscope, a solid-state imaging device is arranged, and in the case of an optical endoscope, it is arranged so as to face an incident end of an image guide formed of an optical fiber bundle. And the signal cable or image guide connected to the solid-state imaging device also
Like the light guide, it is inserted into the insertion portion. In the following, description will be made assuming that the electronic endoscope is configured. However, if an image guide is provided instead of the solid-state imaging device and the signal cable, an optical endoscope can be used. Further, in addition to these, a treatment tool lead-out portion is opened in the distal end body, and a treatment tool insertion channel made of a flexible tube is connected to the treatment tool lead-out portion. The air / water supply tube connected to the washing nozzle provided toward the section is inserted.

[0004] Therefore, when configured as an electronic endoscope, the objective optical system and the solid-state imaging device are unitized, and
The observation unit is attached to an observation unit mounting portion formed on the distal end body. Here, the objective optical system includes an objective lens group including a plurality of lenses, and a filter, a prism, or the like may be disposed between the objective lens group and the solid-state imaging device. in any case,
Each lens and the solid-state imaging device constituting the objective lens group in the objective optical system must be arranged in a state where they are accurately positioned in the optical axis direction. If the positioning is not performed accurately, the image quality of the image will be degraded when the image is captured by the solid-state imaging device, for example, the focus will be out of focus. Each lens constituting the objective lens group is formed so as to have a predetermined design value, and they are arranged so as to provide a predetermined air gap in the optical axis direction or to join them. Due to problems such as manufacturing accuracy, when the optical system is actually assembled as an optical system, one of the objective lens groups must be displaced in the optical axis direction to perform focus adjustment.

In view of the above, one or a plurality of lenses constituting the objective lens group are fixedly attached to the observation unit mounting portion of the distal end main body, and the other lenses and the solid-state imaging device are arranged in the optical axis direction. By performing the position adjustment, the position is shifted to a position where the sharpest image can be obtained, that is, a position where the focus is accurately focused. For this purpose, the lens fixedly held by the observation unit mounting portion and the other lenses are mounted on separate lens frames.
The solid-state imaging device is fixed to the lens frame on the side where the position is adjusted. Therefore, in the following, the lens frame fixedly held on the observation unit mounting portion is set as the reference position, and the lens frame whose position is adjusted in the optical axis direction with respect to the lens mounted on the reference lens frame is adjusted. It is called the side lens frame.
Therefore, the position of the adjustment lens frame is adjusted in the optical axis direction in a state where the lens frame is mounted on the observation unit mounting portion. After the focus adjustment is performed, the lens frame is finally mounted using screws or an adhesive. Part will be fixed.

In recent years, it has been known to change the depth of focus, the imaging magnification, and the viewing angle of an object to be observed in accordance with the purpose of endoscopy. To this end, a part of the plurality of lenses constituting the objective optical system is formed as a movable lens movable in the optical axis direction, and by moving this movable lens, the depth of focus, the imaging magnification, the field of view, A configuration in which the angle and the like can be adjusted is conventionally known. In this case, the lens mounted on the reference lens frame is a fixed lens, and the lens mounted on the adjustment-side lens frame is a movable lens, and the movable lens is moved in the optical axis direction by appropriate driving means. I do. To adjust the lens position, the adjustment-side lens frame is moved in the optical axis direction while the movable lens is arranged at a predetermined position (for example, a position on the infinity side).

[0007]

The distal end of the insertion portion of the endoscope is a hard portion. In order to improve the operability of the insertion operation of the insertion portion and reduce the pain of the patient, it is desirable that the length of the hard portion at the distal end portion of the insertion portion in the axial direction be as short as possible. However, the rigid portion is a space for accommodating a non-bendable member (hereinafter referred to as a rigid built-in member) among the internal components of the insertion portion. Therefore, the position of the base end of the rigid built-in member determines the entire length of the distal end hard portion in the insertion portion. The observation unit is a unit in which an objective optical system, a solid-state imaging device, and the like are integrated, and the entire unit is a hard built-in member. Therefore, the length of the rigid portion at the distal end of the insertion portion usually depends on the length of the observation unit in the axial direction.

The present invention has been made in view of the above points, and an object of the present invention is to make it possible to mount an observation unit so as to shorten the length of a hard portion at the distal end of an insertion portion.

[0009]

In order to achieve the above-mentioned object, an insulating cap is mounted on the distal end surface of the distal end main body of the insertion portion, and the distal end main body is penetrated in the axial direction thereof. An observation unit mounting mechanism for an endoscope having a unit mounting portion, and fixedly holding a lens frame on which a lens positioned at least at the forefront of an objective optical system constituting the observation unit is provided in the observation unit mounting portion. In the periphery of the observation unit mounting portion, an annular ridge having a thickness equal to or less than the thickness of the insulating cap is formed from the distal end surface of the distal end body, and the lens frame is formed on the annular ridge. It is characterized in that a holding wall for fixedly holding is provided, and an insertion hole having a step portion covering an end face of the annular ridge portion is formed in the insulating cap.

[0010] In short, the observation unit is configured to be advanced into the insulating cap so that the base end thereof is displaced forward. Here, as the configuration of the objective optical system, there is a configuration in which all the lenses are mounted on a single lens frame, but at least two lens groups are mounted on independent lens frames. There is something. In any case, the tip of the lens frame is fixed to the holding wall. When the lens frames are separately provided, the lens frame on which the lens group located closest to the subject is mounted is not used as a reference lens frame for fixedly holding the lens frame on the holding wall. The group is mounted on an adjustment-side lens frame whose position can be adjusted in the direction of approaching / separating from the lens provided on the reference lens frame, and the reference lens frame and the adjustment-side lens frame are partially fitted to each other. State. Then, the inner diameter of the observation unit mounting portion of the main body block is made larger than the inner diameter of the holding wall formed in the annular ridge portion to secure a space for enabling the position adjustment of the adjustment-side lens frame. Some adjustment-side lens frames are provided with a fixed lens, but furthermore, a movable lens frame is provided on the adjustment-side lens frame so as to be movable in the optical axis direction, and by moving the movable lens frame, The depth of focus with respect to the observation target portion, the imaging magnification, the viewing angle, and the like can be changed according to the purpose of the endoscope inspection and the like.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. Needless to say, the present invention is not limited to this embodiment.

First, FIG. 1 shows a schematic configuration of the entire endoscope. As is apparent from FIG. 1, the endoscope 1 is generally configured by connecting an insertion section 3 into a body cavity or the like to a main body operation section 2 and pulling out a universal cord 4 from the main body operation section 2. Things. The insertion section 3 connected to the main body operation section 2 is divided into a front end main body 3a, an angle section 3b, and a flexible section 3c in order from the front end side in terms of function and structure.

The distal end body 3a is made of a hard member,
As shown in FIG. 2, an illumination unit 10, an observation unit 11, a treatment tool lead-out unit 12, and a cleaning nozzle 13 are provided on the distal end surface. Here, as shown in the figure, a plurality of illumination units 10 are generally provided on the left and right of the observation unit 11. The angle portion 3b can be operated to bend in up, down, left and right directions by an angle knob 5 provided on the main body operation portion 2 so as to direct the distal end portion main body 3a in a desired direction. Furthermore, the flexible portion 3c occupies most of the length of the insertion portion 3, and the flexible portion 3c is flexible in the bending direction.
In addition, the structure has crush resistance. Therefore, the flexible portion 3c bends in an arbitrary direction along the insertion path.

FIG. 3 shows a cross section of a portion on the distal end side of the insertion portion 3. As is apparent from this figure, the distal end portion main body 3a has a main body block 20 made of, for example, a metal, and a through hole is formed in a required portion of the main body block 20 to penetrate in the axial direction. An insulating cap 21 is attached to the tip end surface of the main body block 20, and is fixed to the main body block 20 by a set screw 22. Angle part 3b
It has a node ring structure in which a number of angle rings 23 are sequentially pivoted by pivot pins 24, and a cover member 25 is provided on the outer periphery of the node ring structure including the angle rings 23. Here, the cover member 25 is usually composed of an inner metal net and an outer skin layer made of an elastic material such as EPDM. The foremost ring of the angle rings 23, that is, the tip ring 23a is fitted and fixed to the main body block 20 constituting the tip main body 3a. Further, the base ring 23b located at the most proximal side of the angle ring 23 is fitted and fixed to a connection ring 26 for connecting the angle part 3b and the flexible part 3c by means such as soldering or welding. You. As a configuration of the flexible portion 3c, for example, a configuration can be adopted in which a metal net is provided on the outer periphery of a metal spiral tube, and a skin layer is formed on the outer periphery of the metal net. However, since these specific configurations are well known, their illustration and detailed description are omitted.

As shown in FIG. 4, the illuminating section 10 includes an illuminating lens 30 and a light guide 31 which are mounted in an illuminating section mounting hole 10a formed of one (or a plurality of) through holes provided in the main body block 20. The illumination lens 30 diverges the illumination light emitted from the end face of the light guide 31 so that a wide range can be illuminated. The light guide 31 is formed by bundling a large number of ultra-fine optical fibers, and a portion to be inserted into the illumination unit mounting hole 10a is inserted into a base 32, which comes out of the base 32 and is closer to the base end than the angle portion 3b. Toward the side, it is loosely bound using a flexible tube or the like and freely bent, and is extended into the universal cord 4 from the insertion section 3 through the main body operation section 2.

The observation section 11 comprises an observation unit 33, and as shown in FIGS. 5 and 6, an observation unit mounting section 20a which is provided in the main body block 20 so as to be opened so as to penetrate in the axial direction of the insertion section 3. Has an observation unit 33 provided so as to be supported. The observation unit 33 includes an objective optical system 34 inside and an optical path of the objective optical system 34.
A prism 35 for bending by 0 ° and an imaging means 36 arranged at an image forming position of the objective optical system 34 are provided. The objective optical system 34 includes a fixed lens group 37 composed of one to several lenses, and movable lens groups 38a and 38b each composed of one or more lenses movable in the optical axis direction. The imaging means 36 is composed of a solid-state imaging device arranged at an image forming position of the objective optical system 34 and its substrate,
A large number of wirings are connected to the board, and these wirings are bundled using a flexible tube, tape, or the like, and are connected as signal cables 39 from the insertion section 3 to the main body operation section 2.
Through the universal cord 4. The entire signal cable 39 has a structure that can be freely bent.

The fixed lens group 3 constituting the objective optical system 34
7 is mounted on the reference lens frame 40, and the two movable lens groups 38a and 38b
1F, 41L, these movable lens frames 4
1F and 41L are movably mounted in the optical axis direction on a lens support portion 41a of an observation unit support member 41 functioning as an adjustment-side lens frame, and the reference lens frame 40 on which the fixed lens group 37 is mounted is also an observation unit support member 41. Is fitted inside. As described above, the reference lens frame 40 and the movable lens frames 41F and 41L are supported by the observation unit support member 41 so that the optical axes of the entire objective optical system 34 are aligned. However, only a part of the reference lens frame 40 is accommodated in the lens support portion 41a of the observation unit support member 41, and the distal end side is fixedly supported by the main body block 20. Will be described later.

Arms 4 are provided on movable lens frames 41F and 41L.
2a and 42b are continuously provided.
Ring members 43a and 43b are formed at the distal ends of the a and b. Parallel to the optical axis of the objective optical system 34,
A cam shaft 44 is provided at a position distant from the objective optical system 34, and cam grooves 45 a and 45 b are formed at two locations on the circumferential body of the cam shaft 44 in the circumferential direction. The ring members 43a and 43b have cam pins 46a and 46b respectively engaged with the cam grooves 45a and 45b.
Are connected to each other. When the camshaft 44 is rotated in the forward and reverse directions, the cam pins 46a and 46b slide or roll along the respective cam grooves 45a and 45b, so that the cam pins 46a and 46b are connected via the ring members 43a and 43b and the arms 42a and 42b. The movable lens groups 38a and 38b mounted on the provided movable lens frames 41F and 41L are displaced in the optical axis direction. An electric motor 47 is provided to drive the camshaft 44, and the electric motor 47 is fixedly attached to the motor support portion 41b of the observation unit support member 41.

In the above configuration, as shown in FIG. 5 as the distal end hard portion length L, the distal end hard portion of the insertion portion 3 extends from the distal end surface of the distal end portion main body 3a to the distal end portion including the metal main body block 20. The whole body 3a and the angle part 3b
In the above, up to the base end of the distal ring 23a fitted to the main body block 20, specifically, the distal ring 23a
a and the next angle ring 23
It is up to the part. Therefore, the length of the distal end hard portion length L in the insertion portion 3 is determined by the length of the main body block 20 of the distal end ring 23a.
The length can be shortened or extended by adjusting the length of the protrusion from the base to the proximal end side. Here, the distal end hard portion length L depends on the axial length of the hard built-in member disposed therein.

The longest one of the hard built-in members is the observation unit 33. The observation unit 33 includes the objective optical system 3
4, a prism 35, an imaging means 36, and the like, all of which are rigid built-in members. In addition, an electric motor 47 is fixedly provided on the motor support portion 41b of the observation unit support member 41 for driving the movable lens groups 38a and 38b, and projects from the motor support portion 41b to the base end side. Therefore, these also constitute the observation unit 33, and the electric motor 47 is also a hard built-in member. That is, the observation unit 33 as a hard built-in member
Are fixed lens groups 36 when assembled in the insertion section 3.
From the tip of the reference lens frame 40 provided with
, And the length L of the hard distal end portion must be at least the same as the base end portion of the electric motor 47.

In addition, the base position of the electric motor 47 and the end position of the distal end hard portion length L cannot be accurately matched with the observation unit 33 installed in the insertion section 3. That is, the reference lens frame 40 is attached to the observation unit mounting unit 2.
In the state where the observation unit support member 41 is attached to the lens unit 0a, the observation unit support member 41 functioning as an adjustment-side lens frame is moved in the optical axis direction in order to perform focus adjustment. Most reference lens frame 40
It is necessary to take into account the position away from the. That is,
When actually performing focus adjustment in the objective optical system 34, it is necessary to take into account the maximum extra length required at the time of focus adjustment, based on the distance when the lenses at both ends are most separated.

Since the reference lens frame 40 must be fixed stably, the reference lens frame 40 is fixed to the main body block 20 made of metal. Since a high-frequency treatment instrument or the like is inserted through the treatment instrument insertion channel, it is necessary to prevent metal from being exposed at the tip of the insertion section 3 from the viewpoint of patient protection or the like. To this end, an insulating cap 21 is connected to the distal end body 10, and the insulating cap 21
The main body block 20 is covered so as not to be exposed to the outside.

The insulating cap 21 is for electrically insulating the main body block 20 by covering it.
As its original function, it does not substantially require a thickness dimension. However, the insulating cap 21 is fixed to the main body block 20 in a connected state by bonding or the like. Further, in order to prevent the insulating cap 21 from dropping off due to peeling of the adhesive or the like, the insulating cap 21 is fixed to the main body block 20 by set screws 22. Is done. Specifically, as shown in FIG. 7, a stepped through hole 2 through which a set screw 22 is inserted through an insulating cap 21 is provided.
1a is provided, a set screw 22 is inserted through the through hole 21a, and a screw hole 20b formed in the main body block 20 is screwed. Moreover, since the set screw 22 is also made of metal, the set screw 22 is also not exposed to the outside. For this purpose, the set screw 22 is inserted into the insulating cap 21 to a predetermined depth, and is then filled with the sealing material 50 so that the set screw 2
Cover the head of No. 2. Therefore, the insulating cap 21
Requires a thickness that allows the set screw 22 not to be exposed to the outside and that can be fixed by the set screw 22.

In view of the above, the insulating cap 21 needs to have a required thickness at the portion where the set screw 22 is fixed, but at other portions, for example, at the position where the observation unit 33 is mounted, such a thickness is required. Is not required. That is, even if the observation unit 33 is protruded inside the insulating cap 21, no particular trouble is caused. For this purpose, the insertion hole 51 facing the observation unit 33 formed in the insulating cap 21 has a stepped shape, the inner surface side, that is, the joining side to the main body block 20 is a large-diameter opening portion 51a, and the outer surface side is a small-diameter opening portion 51b. The large diameter opening 51a and the small diameter opening 51
A step wall 51c is formed between the step wall 51c and the step b. The thickness of the small-diameter opening 51b is a minimum thickness necessary for electrical insulation and strength retention.

On the other hand, on the main body block 20 side, an annular ridge 52 is provided so as to protrude from the distal end surface around the observation unit mounting portion 20a, and the annular ridge 52 is provided in the insertion hole 51 of the insulating cap 21. It extends into the large-diameter opening 51a, and its tip is a step 5 with the small-diameter opening 51b.
1c. And the annular ridge 52
Is projected inward, and its inner peripheral surface forms a holding wall 52a for fixedly holding the reference lens frame 40. Here, the length of the holding wall 52a in the axial direction is equal to the length of the reference lens frame 4.
The length is set to a value necessary to stably hold 0, but is set as short as possible within the range. The inner diameter of the holding wall 52a is smaller than the inner diameter of the observation unit mounting part 20a.
b is formed. The inner diameter of the observation unit mounting portion 20a is the lens support portion 41a of the observation unit support member 41.
Is inserted. The distal end surface of the reference lens frame 40 is also covered with a sealing material so as not to be exposed to the outside.

Therefore, the reference lens frame 40 is connected to the annular ridge 5
By moving the entire observation unit support member 41 back and forth while being fixed to the holding wall 52a provided in
Focus adjustment can be performed. Here, when performing focus adjustment, the position where the tip of the lens support portion 41a of the observation unit support member 41 abuts on the step 52b is the state where the optical path length of the objective optical system 34 is the shortest. A minimum optical path length and a maximum optical path length must be ensured. The base position of the electric motor 47 in the maximum optical path length state in the objective optical system 34 is the base position of the hard built-in member, and this position is set as the distal end hard portion length L. That is, the pivot portion between the tip ring 23a and the next angle ring 23 is set at that position.

The main body block 20 is set with the set screw 22.
Insulating cap 21 having the necessary thickness to fix it to
Observation unit mounting part 20 in main body block 20
a protruding annular ridge 52 that constitutes an extension of a, a holding wall 52a having a predetermined length is provided from the tip of the annular ridge 52, and the reference lens frame 40 is provided on the holding wall 52a.
Is extended and fixed, so that the entire observation unit 33 can be moved toward the distal end by the length of the reference lens frame 40 entering the insulating cap 21. Accordingly, the rigid built-in member can be disposed forward by that much, so that the distal end hard portion length L of the insertion portion 3 can be shortened, and more specifically, the pivoting position between the distal end ring 23a and the next angle ring 23 can be disposed forward. . As a result, the operability of inserting the insertion portion 3 into the body cavity is improved, and the pain of the patient is reduced.

In the above-described embodiment, some of the lenses constituting the objective optical system are used as movable lenses.
Although the movable lens is configured to move directly by the electric motor, the movable lens may be driven by a remote operation using a flexible shaft or the like, or each lens constituting the objective optical system may be configured as a fixed lens. it can. In these cases, the hard built-in member in the observation unit is located up to the position of the imaging unit. Therefore, the length of the distal end ring may be set so that the position of the pivotal connection between the distal end ring forming the angle portion and the next angle ring substantially coincides with the position of the mounting portion of the imaging means.

[0029]

As described above, the present invention has an effect that the observation unit can be mounted so that the length of the rigid portion at the distal end of the insertion portion can be shortened.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an endoscope showing one embodiment of the present invention.

FIG. 2 is an external view showing a distal end surface of an insertion portion of the endoscope in FIG. 1;

FIG. 3 is a longitudinal sectional view of the vicinity of a distal end of an insertion portion.

FIG. 4 is an explanatory diagram of a main part configuration of a lighting unit.

FIG. 5 is a sectional view taken along line AA of FIG. 2;

FIG. 6 is a configuration explanatory view showing a driving mechanism of an observation unit and a movable lens thereof.

FIG. 7 is an enlarged cross-sectional view at a position BB in FIG. 2;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Endoscope 2 Main body operation part 3 Insertion part 3a Tip main part 3b Angle part 3c Flexible part 10 Illumination part 11 Observation part 12 Treatment tool derivation part 20 Main body block 21 Insulating cap 22 Set screw 33 Observation part unit 34 Objective optical system 35 Prism 36 Imaging means 37 Fixed lens group 38a, 38b Movable lens group 40 Reference lens frame 41 Observation unit support member 41a Lens support section 41b Motor support section 41F, 41L Movable lens frame 44 Cam shaft 47 Electric motor 50 Seal material 51 Insertion hole 51a Large-diameter opening 51b Small-diameter opening 52 Annular ridge 52a Holding wall 52b Step

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02B 23/26 G02B 23/26 C

Claims (4)

[Claims] 1. A main body block comprising: a main body block;
An insulating cap that covers the distal end surface of the main body block, the distal end main body is provided with an observation unit mounting portion that penetrates in the axial direction, and an objective optical component that forms the observation unit in the observation unit mounting portion. In an observation unit mounting mechanism for an endoscope in which a lens frame on which a lens positioned at least at the forefront of the system is mounted is fixedly held, a distal end surface of the distal end main body is provided around the observation unit mounting portion. An annular ridge portion having a thickness equal to or less than the thickness of the insulating cap is formed from the above, and a retaining wall for fixedly holding the lens frame is provided on the annular ridge portion. An endoscope observation unit mounting mechanism, wherein an insertion hole having a stepped portion covering an end face of the portion is formed. 2. The objective optical system according to claim 1, wherein at least two lens groups are mounted on independent lens frames, and of these two lens frames, a lens frame mounted with a lens group positioned closest to the subject is mounted. No reference lens frame fixedly held on the holding wall, and another lens group is mounted on an adjustment-side lens frame whose position can be adjusted in a direction approaching / separating from a lens provided on the reference lens frame, and The reference lens frame and the adjustment-side lens frame are partially fitted to each other, and the inner diameter of the observation unit mounting portion of the main body block is larger than the inner diameter of the holding wall formed in the annular ridge. The endoscope observation unit mounting mechanism according to claim 1, wherein: 3. A lens group mounted on the reference lens frame is a fixed lens, and a movable lens frame on which at least one group of movable lenses is mounted is mounted on the adjustment-side lens frame so as to be movable in the optical axis direction. 3. The endoscope observation unit mounting mechanism according to claim 2, wherein: 4. The movable lens is composed of two lens groups that can be displaced in a direction approaching and moving away from each other, and both movable lens groups are integrated by a cam mechanism connected to a motor fixed to the main body block. 4. The endoscope observation unit mounting mechanism according to claim 3, wherein the endoscope observation unit mounting mechanism is configured to be displaced in the axial direction.