JP2018081270A - Optical device and endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical device capable of taking clear images by adequately preventing the occurrence of condensation even when focus switching is enabled.SOLUTION: Front group lenses 56a are divided into a first front group lens 56af located at a subject side, and a second front group lens 56ar located at an image side, and front group holding frames 55 are divided into and formed with a first front group holding frame 55f holding the first front group lens 56af and a second front group holding frame 55r holding the second front group lens 56ar. A sealed space 77 is formed with the first front group holding frame 55f holding the first front group lens 56af and the second front group lens frame 55r holding the second front group lens 56ar at a tip side than a transmission mechanism provided together with a rear group holding frame 57.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an optical device and an endoscope that can change the optical characteristics of an observation optical system.

  As is well known, an endoscope is widely used for observation, treatment, etc. of a living body (inside a body cavity) or inspection, repair, etc. in an industrial plant facility.

  In such endoscopes, fixed-focus imaging units are widely used. In general, a fixed focus type imaging unit includes a front group lens and a rear group lens, and the front group lens frame and the rear group lens frame that hold these group lenses are hermetically sealed with an adhesive or the like. It is connected to. Furthermore, the lens located at the forefront of the front lens group is processed with particularly high precision, and the lens processed in this way is fixed to the front lens group frame with an adhesive or the like, thereby taking an image. Airtightness of the observation optical system of the unit is ensured. It should be noted that high-precision processing on a fine lens causes a rise in cost, and thus is generally performed only on the lens located at the forefront.

  By the way, in recent years, in an endoscope, a focal length can be changed by moving the observation optical system in the direction of the photographing optical axis because of a zooming function for adjusting a focus of a photographed image or a magnification adjustment such as wide / telephoto. There is one using an imaging unit that can. In addition, the technique of the imaging unit which can change a focal distance in this way is used not only for an endoscope but for various photographing machines.

  As an optical device used for such a focus switching type imaging unit, for example, Patent Document 1 discloses a fixed lens frame that holds an objective lens (front group lens) disposed in front of a solid-state imaging element unit, and a lens. Inside the frame, a movable frame that holds a part of the lens (moving lens) that moves along the photographic optical axis, a connecting rod (operation rod) that protrudes from the movable frame, and a movable lens that moves forward and backward through the connecting rod An optical device including an actuator to be moved is disclosed.

WO2010 / 113658 publication

  However, like the technique disclosed in Patent Document 1 described above, the focus switching optical device needs to have a slit in the fixed lens frame for moving the connecting rod along the optical axis direction. Therefore, in the focus switching optical device, moisture easily enters the lens frame as compared with the focus fixing optical device.

  When the moisture that has entered the lens frame in this way fills the vicinity of the lens on the distal end side above a certain concentration, condensation occurs due to a rapid temperature change when the endoscope is used and the endoscope image is unclear. There is a risk that usability may be reduced. In particular, in an optical device used for an endoscope, a concave lens is generally arranged at the forefront in order to ensure a wide viewing angle, and moisture is filled in a wide gap formed by such a concave lens. In this case, condensation tends to occur.

  In addition, in recent years, image sensors (imaging devices) have been downsized and the number of pixels has been increased in order to improve the diagnostic ability through endoscopic observation. As a result, optical devices have been downsized and improved in performance. It is requested. In response to such a demand, if the optical device is downsized, the distance from the slit to the lens on the front end side is shortened, and condensation is more likely to occur.

  Here, it is indispensable to reduce the pixel pitch in order to reduce the size and increase the number of pixels of the image sensor. However, in order to take advantage of the performance of the image sensor with the reduced pitch, the F value of the optical system must be reduced. As a result, the optical device tends to be vulnerable to variations in lens processing. As a countermeasure, it is conceivable to correct image quality degradation due to processing variations by adjustment work during assembly. For example, in the configuration of the objective optical system disclosed in Patent Document 1, a concave lens and a convex lens are mixed in the front group holding frame. Therefore, the positive sensitivity and the negative power of the lens partially cancel each other, and the adjustment sensitivity is lowered. If the adjustment sensitivity is low, it is necessary to set a large adjustment margin, which may increase the radial size of the front group holding frame and the rear group holding frame, that is, increase the size of the product.

  The present invention has been made in view of the above circumstances, and provides an optical apparatus and an endoscope that can accurately prevent the occurrence of condensation and capture a clear image even when focus switching is enabled. For the purpose.

  An optical device according to an aspect of the present invention includes a front group lens disposed on a subject side, a rear group lens disposed on an image side of the front group lens, and the front group lens and the rear group lens. A movable lens disposed between the front lens group, a front lens group holding frame that holds the front lens group, a rear lens group holding frame that holds the rear lens group, a moving lens, and the inside of the rear lens group holding frame. A movable frame movable along the optical axis direction, and a transmission mechanism for transmitting a driving force for moving the movable frame from the outside to the inside of the rear group holding frame, and the front group lens is , A first front group lens located on the subject side, and a second front group lens located on the image side, and the front group holding frame holds the first front group lens. A first front group holding frame; a second front group holding frame for holding the second front group lens; And the rear group holding frame is sealed by the first front group holding frame holding the first front group lens and the second front group holding frame holding the second front group lens. It has a closed sealed space.

  An endoscope according to an aspect of the present invention includes the optical device at a distal end portion of an insertion portion that is inserted into a subject.

  According to the present invention, even when the focus can be switched, it is possible to accurately prevent the occurrence of condensation and capture a clear image.

Explanatory drawing showing the overall configuration of the endoscope Sectional drawing which shows the internal structure of a front-end | tip part and a bending part Sectional drawing which shows the structure of the imaging unit of the state which the moving lens unit moved to the front advance position Sectional drawing which shows the structure of the imaging unit of the state which the moving lens unit moved to the back retracted position A perspective view showing the imaging unit with the cover of the transmission mechanism removed The perspective view which shows the structure of a moving lens position correction frame The perspective view which shows the structure of an observation optical system unit The perspective view which shows the structure of a stopper member IX-IX sectional view of FIG. XX sectional view of FIG. Sectional drawing which shows the 2nd front group lens and the 2nd front group holding frame Sectional drawing which shows a 2nd front group lens and a 2nd front group holding frame concerning a 1st modification. Sectional drawing of an observation optical system unit concerning a 2nd modification. The perspective view which shows the structure of an observation optical system unit concerning a 3rd modification. Sectional drawing of an observation optical system unit concerning a 4th modification. The perspective view which shows the structure of an observation optical system unit concerning a 4th modification. The perspective view which shows the structure of an observation optical system unit concerning a 5th modification.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings relate to an embodiment of the present invention, FIG. 1 is an explanatory view showing the overall configuration of the endoscope, FIG. 2 is a cross-sectional view showing the internal configuration of the distal end portion and the bending portion, and FIG. FIG. 4 is a cross-sectional view showing the configuration of the imaging unit in a state in which the moving lens unit has moved to the advanced position, FIG. 4 is a cross-sectional view showing the configuration of the imaging unit in a state in which the moving lens unit has moved to the rearward retracted position, FIG. 6 is a perspective view showing the configuration of the moving lens position correction frame, FIG. 7 is a perspective view showing the configuration of the observation optical system unit, and FIG. 8 is a perspective view showing the configuration of the stopper member. 9 is a sectional view taken along the line IX-IX in FIG. 3, FIG. 10 is a sectional view taken along the line XX in FIG. 3, and FIG. 11 is a sectional view showing the second front group lens and the second front group holding frame.

  As shown in FIG. 1, an electronic endoscope system (hereinafter simply referred to as an endoscope system) 1 according to this embodiment includes an electronic endoscope apparatus (hereinafter simply referred to as an endoscope) 2 as an endoscope. The light source device 3, the video processor 4, and the color monitor 5 are electrically connected.

  The endoscope 2 includes an insertion portion 9 and an operation portion 10 in which the insertion portion 9 is extended. A universal cord 17 extending from the operation portion 10 is connected to the light source device 3 via a scope connector 18. It is connected to the.

  A coiled scope cable 19 is extended from the scope connector 18. An electric connector portion 20 is provided on the other end side of the scope cable 19, and the electric connector portion 20 is connected to the video processor 4.

  The insertion portion 9 includes a distal end portion 6, a bending portion 7, and a flexible tube portion 8 that are arranged in order from the distal end side. On the distal end surface of the distal end portion 6, a known distal end opening, an observation window, a plurality of illumination windows, an observation window cleaning port, and an observation object cleaning port are disposed (all not shown).

  An imaging unit, which will be described later, is disposed in the distal end portion 6 on the back side of the observation window. Moreover, the front end side of the light guide bundle which is not illustrated is arrange | positioned at the back side of the several illumination window.

  The light guide bundle is inserted and arranged in the universal cord 17 from the insertion portion 9 through the operation portion 10, and when the scope connector 18 is connected to the light source device 3, the illumination light from the light source device 3 is transmitted to the illumination window. Can be transmitted.

  The observation window cleaning port and the observation object cleaning port constitute openings of two cleaning tubes (not shown) that are inserted from the distal end portion 6 into the universal cord 17.

  These cleaning tubes are connected to a cleaning tank in which cleaning water is stored and a compressor (both not shown) on the light source device 3 side.

  The operation part 10 includes a bend preventing part 11 from which the insertion part 9 extends, a forceps port 12 disposed on the side part on the lower side, an operation part main body 13 constituting a grip part in the middle part, and an upper side A bending operation section 16 comprising two bending operation knobs 14 and 15 provided on the air supply / water supply control section 21, a suction control section 22, and a switch section that mainly operates an imaging function. 23 and an operation lever 24 for operating a zoom function for adjusting a magnification such as a focusing function or a wide / tele, for example, by moving a moving lens provided in an imaging unit, which will be described later, forward and backward. Is provided.

  The forceps port 12 of the operation unit 10 constitutes an opening portion of a treatment instrument channel (not shown) that is mainly inserted into the insertion portion 9 up to the distal end opening portion of the distal end portion 6.

  Next, the configuration of the distal end portion 6 of the endoscope 2 will be mainly described with reference to FIG.

  As shown in FIG. 2, an imaging unit 30 is disposed inside the distal end portion 6.

  The imaging unit 30 is fitted and arranged in a hard tip rigid member 25 and is fixed to the tip rigid member 25 by a set screw 27 from the side surface direction.

  In addition, an O-ring 28 for ensuring watertightness with the distal end hard member 25 is disposed on the outer peripheral portion on the distal end side of the imaging unit 30. A distal end cover 25 a constituting the distal end surface of the distal end portion 6 is bonded and fixed to the distal end side of the distal end rigid member 25.

  Note that the distal end opening, which is a hole formed in the distal end cover 25a, constitutes the opening of the treatment instrument channel 12b in the distal end 6 as described above.

  A plurality of bending pieces 26 constituting the bending portion 7 are connected to the proximal end side of the distal end rigid member 25, and the outer circumferences of the distal end rigid member 25 and the bending piece 26 are integrated by the distal end insertion portion rubber member 12a. Is covered. The distal end outer peripheral portion of the distal end insertion portion rubber member 12 a is fixed to the distal end rigid member 25 by a pincushion bonding portion 29.

  In addition, about members, such as the washing tube arrange | positioned at the front-end | tip part 6, the light guide bundle for illumination, since they are conventionally well-known structures, those description is abbreviate | omitted.

  Next, the detailed configuration of the imaging unit 30 will be described with reference to FIGS.

  As shown in FIG. 3 and FIG. 4, the imaging unit 30 of the present embodiment includes a solid-state imaging element unit 31 and an observation optical system unit 32 as an optical device connected to the front end side of the solid-state imaging element unit 31. , And is configured.

  The solid-state image sensor unit 31 has a solid-state image sensor holding frame 35, and the solid-state image sensor holding frame 35 has an optical member 36 such as a cover glass on the front side of a solid-state image sensor chip 37 made of a CCD, a CMOS, or the like. Is held through.

  A laminated substrate 38 is electrically connected to the back side of the solid-state image sensor chip 37 via an FPC (not shown).

  Furthermore, a plurality of communication lines branched from the cable 39 are connected to the laminated substrate 38. The cable 39 is inserted into the endoscope 2 and is electrically connected to the video processor via the electrical connector unit 20.

  In addition, a reinforcing frame 40 is connected to the outer peripheral portion of the base end of the solid-state image sensor holding frame 35, and a heat shrinkable tube 41 that covers the distal end portion of the cable 39 is provided on the outer periphery of the reinforcing frame 40.

  In the space formed by the reinforcing frame 40 and the heat-shrinkable tube 41 from the base end portion of the solid-state image sensor holding frame 35, the solid-state image sensor unit 31 is water-tightly held, and an adhesive for protecting it is used. The protective agent 42 is filled.

  The observation optical system unit 32 of the present embodiment includes a bifocal observation optical system 33 that realizes a focusing function or a zooming function by changing an optical characteristic (focal length) by moving an internal lens forward and backward. It is configured.

  More specifically, the observation optical system unit 32 includes a front group lens unit 45 positioned on the distal end side (subject side), and a rear group connected to the base end side (image side) of the front group lens unit 45. A lens unit 46, a moving lens position correction frame 47 interposed between the front group lens unit 45 and the rear group lens unit 46, and a movement in the moving lens position correction frame 47 in the direction of the photographing optical axis O. The movable lens unit 48 is configured to include a movable lens unit 48 and an actuator 49 that moves the movable lens unit 48 forward and backward.

  The front group lens unit 45 includes a front group holding frame 55 which is a fixed frame, and a front group lens 56 a made up of a plurality of fixed lenses held by the front group holding frame 55.

  The rear group lens unit 46 includes a rear group holding frame 57 that is a fixed frame whose front end is connected to the front group holding frame 55, and a plurality of rear group lens units 46 that are held on the photographing optical axis O on the base end side of the rear group holding frame 57. And a rear lens group 56b made of a fixed lens.

  The solid-state image sensor holding frame 35 is fitted on the base end side of the rear group holding frame 57 and fixed by an adhesive 35a, so that the solid-state image sensor unit 31 and the observation optical system unit 32 are connected. Yes.

  Further, a screw receiving portion 57g into which the front end portion of the set screw 27 is engaged is provided on the front end side of the rear group holding frame 57.

  Further, the rear group holding frame 57 is provided with a slit 57a penetrating the inner peripheral side and the outer peripheral side thereof. The slit 57 a extends in the same direction as the photographing optical axis O, and the front end side of the slit 57 a is opened at the front end of the rear group holding frame 57.

  Further, the rear group holding frame 57 is provided with a holding rod 57b protruding in the outer diameter direction on the proximal end side of the slit 57a, and the holding rod 57b is provided with an actuator holding hole 57c that penetrates in the same direction as the photographing optical axis O. Is provided.

  Further, the rear group holding frame 57 is provided with a stopper member 59 for defining a stop position on the base end side of the moving lens unit 48 in the photographing optical axis O direction.

  Specifically, on the front end side of the holding rod 57b, the rear group holding frame 57 is provided with protrusions 57f as a pair of wall portions (see FIGS. 5 and 10). These protrusions 57f extend so as to be parallel to each other along the photographing optical axis O direction on the base end side of the slit 57a, and the protrusions of these protrusions 57f extend in the photographing optical axis O direction. It is constituted by parallel planes.

  As shown in FIG. 8, the stopper member 59 is configured around a pipe-shaped stopper portion 59a in which a through hole 59b extending in the direction of the photographing optical axis O is opened. A key 59c disposed between a pair of protrusions 57f formed on the rear group holding frame 57 is integrally formed on one side of the stopper portion 59a in the radial direction. Further, on both sides of the key 59c, there are formed adhesive surfaces 59d that are directly brought into contact with the protruding end surfaces of the respective protrusions 57f by surface contact. Further, at key portions of the key 59c and the adhesive surface 59d, a notch portion 59e for reducing sliding resistance with each protrusion 57f etc. and introducing an adhesive between each protrusion 57f etc. Is provided. Further, an engagement hole 59f is provided on the other radial side of the stopper portion 59a, and a jig (not shown) for positioning the stopper member 59 with respect to the rear group holding frame 57 is provided in the engagement hole 59f. Can be engaged.

  The stopper member 59 has, for example, a key 59c disposed between the protrusions 57f of the rear group holding frame 57 that is positioned and fixed to the front group holding frame 55, and the protrusion end surfaces of the protrusions 57f. It is arranged in a state where the adhesive surface 59d is applied thereto. Thereafter, in a state in which the movable frame 65 (more specifically, an operating rod 65a of the movable frame 65 described later) is in contact with the stopper portion 59a, the stopper member 59 confirms the optical characteristics and the engagement hole 59f. Positioning is performed using a jig engaged with the. The stopper member 59 is fixed to the rear group holding frame 57 by introducing an adhesive through the notch 59e between the stopper 57 and the protrusion 57f.

  The moving lens position correction frame 47 is interposed between the outer peripheral side of the front group holding frame 55 and the inner peripheral side of the rear group holding frame 57.

  A front stopper 60 protruding in the outer diameter direction is provided on the distal end side of the moving lens position correction frame 47.

  The front stopper 60 has a recessed spring receiving portion 60a that opens on the rear side, and one end of a return spring 68 that is a compression spring is held in the spring receiving portion 60a.

  The moving lens position correction frame 47 is provided with a slit 61 that penetrates the inner peripheral side and the outer peripheral side thereof. The slit 61 extends in the same direction as the photographing optical axis O so as to overlap the slit 57 a of the rear group holding frame 57.

  The base end side of the slit 61 is opened at the base end of the moving lens position correction frame 47 (see FIG. 6).

  Further, as shown in FIGS. 6 and 7, the moving lens position correction frame 47 is provided with a guide portion 60 c as a pair of wall portions for guiding the movable frame 65 linearly. These guide portions 60c are formed in a plate shape extending along the both sides of the slit 61 from the base end side of the front stopper 60, and on the outer surface of each guide portion 60c, the protrusion 57f of the rear group holding frame 57 is formed. A recess 60d capable of accommodating the distal end side is provided. And each recess 60d accommodates the leading end side of each protrusion 57f, so that each side surface of the holding bar 57b, each side surface of each guide part 60c, each side surface of each protrusion 57f, and each of the front stopper 60 The side surface can form a substantially continuous plane (see FIG. 5).

  The moving lens position correction frame 47 is for performing stop positioning on the distal end side of the moving lens unit 48 in the direction of the photographing optical axis O, and the movable frame 65 (more specifically, the operating rod 65a) is a front stopper. In the state of being in contact with 60, it is positioned while confirming the optical characteristics, and is fixed to the rear group holding frame 57 via an adhesive or the like.

  The moving lens unit 48 includes a movable frame 65 that is a moving frame, and a moving lens 66 that is held by the movable frame 65.

  In the present embodiment, the movable frame 65 is disposed in the rear group holding frame 57, which is a fixed frame, via the moving lens position correction frame 47, and can be moved back and forth in the direction along the photographing optical axis O. Yes.

  The movable frame 65 is provided with an operating rod 65a that protrudes in the outer peripheral direction. The operating rod 65 a protrudes to the outer peripheral side of the rear group holding frame 57 through the slit 57 a of the rear group holding frame 57 and the slit 61 of the moving lens position correction frame 47.

  The operating rod 65a is disposed between the front stopper 60 and the stopper member 59. The operating rod 65 a is provided with a bearing portion 65 b facing the spring receiving portion 60 a on the side facing the front stopper 60.

  A shaft member 67 protruding into the return spring 68 in the spring receiving portion 60a is held on the bearing portion 65b. The operating rod 65a is biased toward the stopper member 59, which is the base end side, by the biasing force of the return spring 68.

  Thus, in this embodiment, between the front stopper 60 and the holding rod 57b, the slits 57a and 61, and the operation rod 65a protruding to the outer peripheral side of the rear group holding frame 57 via the slits 57a and 61, A transmission mechanism is formed around the ridge 57f and the guide 60c that guide the operating rod 65a along both sides of the slits 57a and 61, and this transmission mechanism applies the driving force from the actuator 49 to the rear group holding frame. Transmission from the outside of 57 to the inside is possible.

  Here, a cover 69 for closing the slits 57a and 61 by covering the above-described transmission mechanism is provided between the front stopper 60 and the holding rod 57b.

  For example, as shown in FIG. 5, the cover 69 is formed of a thin sheet metal member having a substantially U-shaped cross section. The front and rear ends of the cover 69 are bonded along the wall surfaces of the front stopper 60 and the holding rod 57b, and the U-shaped open ends are bonded along the wall surfaces of the guide portion 60c and the protrusion 57f. Thus, the rear group holding frame 57 and the moving lens position correction frame 47 are fixed.

  In this case, each side surface of the holding rod 57b, each side surface of each guide portion 60c, each side surface of each protrusion 57f, and each side surface of the front stopper 60 are disposed on substantially the same plane (FIG. 5). 7), each part of the cover 69 is fixedly bonded via an adhesive having a substantially uniform thickness. Further, as shown in FIG. 9, an adhesive or the like is filled in each recess 60 d (more specifically, a portion where each protrusion 57 f does not reach in each recess 60 d). The U-shaped open end 69 is continuously bonded to the rear group holding frame 57 and the moving lens position correction frame 47 without a gap. In addition, it replaces with filling of an adhesive agent etc., and arrange | positions the plate-shaped adjustment member in each recessed part 60d, The height of the adhesive surface in each recessed part 60d is made into the side surface of each guide part 60c, each protrusion part. It is also possible to match the side surface of 57f and each side surface of the front stopper 60. 5 and 10, the stopper portion 59a of the stopper member 59 is formed in a shape that follows the protruding shape of the front stopper 60 and the holding rod 57b, thereby preventing the cover 69 from being deformed. It is possible. And by attaching the cover 69 in this way, the slits 57a and 61 are closed in an airtight state.

  As shown in FIGS. 3 and 4, the actuator 49 has a guide tube 70 whose tip side is held in the actuator holding hole 57 c of the holding rod 57 b.

  In this guide tube 70, a push rod 71 that can project and retract from its tip is provided, and a head portion as a contact member that comes into contact with and separates from the operating rod 65a at the tip of this push rod 71. 72 is fixed.

  A distal end side of a drive wire 73 inserted into the guide tube 70 is connected to the push rod 71, and a shape memory element 74 made of a shape memory alloy is connected to the proximal end side of the drive wire 73.

  Furthermore, a push spring 75 for urging the push rod 71 toward the front stopper 60 with a stronger urging force than the return spring 68 is wound around the outer periphery of the drive wire 73 in the guide tube 70. .

  For example, the shape memory element 74 is set to be shrunk when heated and stretched when cooled, and is held in the guide tube 70 in a stretchable state. Further, the shape memory element 74 is provided with a heat source such as a Peltier element (not shown). The heat source can heat or cool the shape memory element 74 according to the operation state of the operation lever 24. Yes.

  The shape memory element 74 is not limited to a type that expands and contracts by heating or cooling using a heat source such as a Peltier element, and for example, a type that heats and contracts the shape memory alloy by energization is adopted. It is also possible.

  Then, when the shape memory element 74 is extended by cooling, the shape memory element 74 operates the drive wire 73 in a direction in which the urging force of the push spring 75 is released (that is, a direction on the distal end side along the photographing optical axis O).

  Thus, the distal end side of the push rod 71 protrudes from the guide tube 70 and presses the operating rod 65a against the urging force of the return spring 68 that is a compression spring.

  Therefore, the operating rod 65a moves to a position where it comes into contact with the front stopper 60. Along with the movement of the operating rod 65a, the movable frame 65 moves the moving lens 66 to the advance position for realizing a preset first focal length (for example, a wide first optical characteristic) (FIG. 3).

  On the other hand, when the shape memory element 74 is contracted by heating, the shape memory element 74 operates the drive wire 73 in a direction against the urging force of the push spring 75 (that is, a direction on the base end side along the photographing optical axis O).

  As a result, the distal end side of the push rod 71 is retracted into the guide tube 70. Therefore, the operating rod 65a is urged by the return spring 68 and moves to a position where it comes into contact with the stopper member 59.

  Along with the movement of the operating rod 65a, the movable frame 65 moves the moving lens 66 to a retracted position for realizing a preset second focal length (for example, the second optical characteristic of telephoto) (FIG. 4).

  In the observation optical system unit 32 having such a configuration, for example, as shown in FIGS. 3 and 4, the front group lens 56 a constituting the front group lens unit 45 is a first front lens located on the distal end side (subject side). The lens group is divided into a group lens 56af and a second front group lens 56ar located closer to the base end side (image side) than the first front group lens 56af.

  Here, the first front group lens 56af and the second front group lens 56ar are divided such that a lens having a predetermined length or more in the direction of the optical axis O is disposed at the forefront of the second front group lens 56ar. It is preferable. Therefore, for example, in the front group lens 56a of the present embodiment configured with four lenses, the third lens having the longest length in the optical axis O direction among these lenses is the second front group lens. It is divided so as to be arranged at the forefront of 56ar. When the front lens group 56a is divided so that the lens with the longest length in the optical axis O direction is arranged at the forefront of the second front lens group 56ar, depending on the specifications of the observation optical system unit 32, etc. There may be a case where one of the divided lenses is composed of only a single lens that does not form a group lens. Even in such a case, for the sake of convenience, the first front group lens 56af or the second front group lens is used. It shall be called 56ar.

  Further, the front group holding frame 55 constituting the front group lens unit 45 includes a first front group holding frame 55f corresponding to the first front group lens 56af and a second front group lens 56ar corresponding to the second front group lens 56ar. The front group holding frame 55r is divided and formed.

  The first front group holding frame 55f is constituted by a substantially cylindrical frame having a flange 55fa on the outer peripheral portion. The lenses constituting the first front group lens 56af are held (fixed) via an adhesive on the inner periphery of the first front group holding frame 55f. In this case, the lens located at the forefront of the first front group lens 56af is constituted by a concave lens for obtaining a wide viewing angle, and the size of the concave lens is processed with high accuracy. Then, the lens located at the forefront of the first front group lens 56af is processed with high accuracy and the peripheral portion of the lens is bonded and fixed via an adhesive, thereby the first front group holding frame. The front end side of 55f is airtightly closed. In the present embodiment, the first front group lens 56af held in the first front group holding frame 55f in this way is responsible for adjusting optical characteristics such as the angle of view.

  As shown in FIG. 11, the second front group holding frame 55r is configured by a substantially cylindrical frame having a flange 55ra on the outer periphery. Each lens constituting the second front group lens 56ar is held (fixed) via an adhesive on the inner periphery of the second front group holding frame 55r. In this case, by dividing the front group holding frame 55 into a first front group holding frame 55f and a second front group holding frame 55r, a lens (second front group) located in the middle of the front group lens 56a. The lens located at the forefront of the second front group lens 56ar can be directly operated from the front end side of the second front group holding frame 55r. It is possible to accurately apply the adhesive to the entire circumference of the film. Further, as described above, the lens having the longest length in the optical axis O direction (having a predetermined length or more) is disposed at the forefront of the second front group lens 56ar. Then, the tip side of the second front group holding frame 55r is hermetically closed by bonding and fixing a lens having a predetermined length or more in the direction of the optical axis O in this way. That is, by arranging a lens having a predetermined length or more at the forefront of the divided second front group lens 56ar, the second front group lens 56ar processes the dimensions of each lens with higher precision than necessary. Without this, the tip end side of the second front group holding frame 55r can be airtightly closed.

  As described above, the first front group holding frame 55f holding the first front group lens 56af and the second front group holding frame 55r holding the second front group lens 56ar are the same as the rear group holding frame 57. It is kept airtight on the tip side. Thereby, inside the rear group holding frame 57, a sealed space 77 whose front and rear are sealed by the first front group holding frame 55f and the second front group holding frame 55r is provided on the front side of the transmission mechanism. Is formed.

  Specifically, for example, as shown in FIGS. 3 and 4, a first extending portion 55fb having a substantially cylindrical shape is formed on the proximal end side of the first front group holding frame 55f. In addition, a second extension portion 55rc having an outer diameter smaller than the inner diameter of the first extension portion 55fb is formed on the distal end side of the second front group holding frame 55r. Further, a third extension portion 57h having an inner diameter larger than that of the first extension portion 55fb and extending toward the tip end side of the screw receiving portion 57g is formed on the tip end side of the rear group holding frame 57. .

  The second front group holding frame 55r is inserted into the rear group holding frame 57 from the front end side. At this time, the flange 55ra formed on the second front group lens frame 55r is arranged so that the base end surface abuts against a stepped portion 57e formed inside the base end side of the third extending portion 57h. . Further, the flange 55ra is disposed such that the outer peripheral surface abuts against the inner peripheral surface of the rear group holding frame 57 (more specifically, the base end side inner peripheral surface of the third extending portion 57h). The first extension 55fb formed in the first front group holding frame 55f is inserted into the third extension 57f, and the second extension formed in the second front group holding frame 55r. It arrange | positions so that the outer periphery of the part 55rc may be enclosed. Accordingly, the first front group holding frame 55f, the second front group holding frame 55r, and the rear group holding frame 57 have the first extending portion 55fb, the second extending portion 55rc, and the third extending portion. A part of each of the extending portions 57b is arranged to overlap, and a space having a substantially crank shape in cross section is formed between them.

  The second front group holding frame 55r is subjected to an adhesive injected between the flange 55ra and the step portion 57e after the optical axis of the held second front group lens 56ar is adjusted. Then, the rear group holding frame 57 is bonded and fixed.

  In this case, since the inside of the second front group holding frame 55r is hermetically closed by the held second front group lens 56ar, the inside on the front end side of the rear group holding frame 57 is adhesively fixed. It is closed in an airtight state by two front group holding frames 55r. That is, the frame body such as the second front group holding frame 55r is generally easy to process with low cost and high accuracy as compared with a lens or the like, and the second front group processed with high accuracy in this way. Since the holding frame 55r is bonded and fixed to the rear group holding frame 57, the inside of the front end side of the rear group holding frame 57 is accurately closed in an airtight state.

  In this case, by adjusting the optical characteristics and the like mainly by the first front group lens 56af as described above, the second front group holding frame 55r (second front group) is assembled when the rear group holding frame 57 is assembled. Adjustment of the optical axis of the lens 56ar) can be simplified (or omitted). Therefore, the second front group holding frame 55r can set a tight clearance with respect to the rear group holding frame 57, and the airtightness between the second front group holding frame 55r and the rear group holding frame 57 is also improved. It becomes possible to make it.

  Thus, after the inside of the front end side of the rear group holding frame 57 is closed by the second front group holding frame 55r, the first front group holding frame 55f has the flange 55fa on the front end surface of the rear group holding frame 57. Arranged to face each other. The first front group holding frame 55f is adjusted between the first extension portion 55fb and the third extension portion 57h after the optical axis adjustment of the held first front group lens 56af and the like. The space having a cross-sectional crank shape formed between the first extension portion 55fb and the second extension portion 55rc is integrally filled with the adhesive 58. Accordingly, the first front group holding frame 55f, the second front group holding frame 55r, and the rear group holding frame 57 are bonded with strong and high airtightness, and the stress due to the set screw 27 is temporarily Even if it acts on the screw receiving portion 57g of the group holding frame 57, peeling of the adhesive or the like is prevented. Further, since the outer peripheral surface of the flange 55ra of the second front group holding frame 55r is disposed so as to abut against the inner peripheral surface of the rear group holding frame 57, the stress caused by the set screw 27 is temporarily assumed. Even if it acts on the screw receiving portion 57g of 57, the deformation of the rear group holding frame 57 is suppressed, and the peeling of the adhesive or the like is more accurately prevented.

  In this case, since the inside of the first front group lens 56af is hermetically closed by the held first front group lens 56af, the front end of the rear group holding frame 57 is bonded and fixed to the first front group lens 56af. It is closed in an airtight state by the holding frame 55f. That is, the frame body such as the first front group holding frame 55f is generally easier to process at a lower cost and with higher accuracy than a lens or the like, and the first front group processed with high accuracy in this way. Since the holding frame 55f is bonded and fixed to the rear group holding frame 57, the tip of the rear group holding frame 57 is accurately closed in an airtight state.

  A closed space 77 capable of preventing moisture from entering through the slits 57a, 61 and the like is formed inside the front end side of the rear group holding frame 57 by being blocked by the first and second front group holding frames 55f, 55r. Is formed.

  Here, when the positive power and the negative power of each lens included in the front group lens unit 45 partially cancel each other, the adjustment sensitivity of the optical characteristics is lowered, and in order to compensate for the reduction of the adjustment sensitivity, the observation optical system unit 32 In order to suppress an increase in size, for example, it is preferable that the first front group lens 56af is configured only by a concave lens and the second front group lens 56ar is configured only by a convex lens. In this manner, by separating the concave lens and the convex lens by the first front group lens 56af and the second front group lens 56ar, not only the formation of the sealed space but also the adjustment of the optical characteristics can be facilitated. Further, it is possible to effectively suppress the enlargement of the observation optical system unit 32.

  According to such an embodiment, the front group lens 56a is divided into the first front group lens 56af located on the subject side and the second front group lens 56ar located on the image side, and the front group is held. The frame 55 is divided and formed into a first front group holding frame 55f that holds the first front group lens 56af and a second front group holding frame 55r that holds the second front group lens 56ar. A first front group holding frame 55f that holds the first front group lens 56af and a second front group that holds the second front group lens 56ar are located closer to the tip than the transmission mechanism provided alongside the holding frame 57. By forming the sealed space 77 by the lens frame 55r, it is possible to accurately prevent the occurrence of condensation and capture a clear image even when the focus can be switched.

  That is, the first front group holding frame 55f whose front end side is airtightly closed by the first front group lens 56af and the second front group holding frame 55r whose front end side is airtightly closed by the second front group lens 56ar. By forming a sealed space on the front end side of the rear group holding frame 57, even when moisture enters the observation optical system unit 32 through the slits 57a, 61, etc., the moisture is absorbed by the front group lens 56a. Reaching the tip side can be prevented accurately, and the occurrence of condensation can be prevented and a clear image can be taken.

  In this case, the lens held at the forefront of the second front group holding frame 55r is the lens having the longest length in the direction of the optical axis O among the front group lenses 56a. Even if each lens constituting the lens 56ar is not processed with high accuracy, the distal end side of the second front group holding frame 55r can be accurately airtightly closed. In other words, moisture can be prevented from entering the front end side of the front group lens 56a by an inexpensive and simple configuration in which only the lens held at the forefront of the first front group holding frame 55f is processed with high accuracy. Therefore, a sealed space 77 can be formed.

  Further, by covering the transmission mechanism having the slits 57a, 61 and the like with the cover 69, it is possible to effectively suppress the ingress of moisture into the observation optical system unit 32, and condensation on the front end side of the front group lens 56a. Can be prevented more accurately.

  In this case, the cover 69 can be bonded and fixed with an adhesive having a uniform thickness by forming the side surface of each guide portion 60c and the side surface of each protrusion 57f in a continuous plane. It is possible to suppress peeling and the like of the bonded portion.

  Here, for example, as shown in FIG. 12, an annular recess 55rb is provided on the inner peripheral side of the front end surface of the second front group holding frame 55r, and at the forefront of the recess 55rb and the second front group lens 56ar. It is also possible to fill an adhesive between the lens located. If comprised in this way, the front end side of the 2nd front group holding frame 55r can be sealed using sufficient quantity of adhesives, and the airtightness of the sealed space 77 can be improved more exactly. .

  Further, for example, as shown in FIG. 13, the cover 69 can be fixed by welding (welding portion 80) using laser welding or the like instead of the adhesive fixing using an adhesive.

  For example, as shown in FIGS. 14 and 15, a restricting portion 81 for preventing deformation of the cover 69 due to a spring back or the like is provided in the protruding portion 57 f, and the cover 69 is provided between the guide portion 60 c and the restricting portion 81. It is also possible to sandwich the open end of.

  Further, for example, as shown in FIG. 16, a restricting portion 82 parallel to the protrusion 57f is provided on the rear group holding frame 57, and the open end of the cover 69 is sandwiched between the protrusion 57f and the restricting portion 82. It is also possible.

  Furthermore, for example, as shown in FIG. 17, a groove 83 for inserting the open end of the cover 69 can be provided in the rear group holding frame 57.

  In addition, this invention is not limited to each embodiment described above, A various deformation | transformation and change are possible, and they are also in the technical scope of this invention.

DESCRIPTION OF SYMBOLS 1 ... Electronic endoscope system 2 ... Scope 3 ... Light source device 4 ... Video processor 5 ... Color monitor 6 ... Tip part 7 ... Bending part 8 ... Flexible tube part 9 ... Insertion part 10 ... Operation part 11 ... Breaking prevention part DESCRIPTION OF SYMBOLS 12 ... Forceps port 12a ... Tip insertion part rubber member 12b ... Treatment tool channel 13 ... Operation part main body 14,15 ... Bending operation knob 16 ... Bending operation part 17 ... Universal cord 18 ... Scope connector 19 ... Scope cable 20 ... Electric connector part DESCRIPTION OF SYMBOLS 21 ... Air supply / water supply control part 22 ... Suction control part 23 ... Switch part 24 ... Operation lever 25 ... Tip rigid member 25a ... Tip cover 26 ... Bending piece 27 ... Set screw 28 ... O-ring 29 ... Pincushion adhesion part 30 ... Imaging unit 31 ... Solid-state image sensor unit 32 ... Observation optical system unit (optical device)
33 ... Observation optical system 35 ... Solid-state image sensor holding frame 35a ... Adhesive 36 ... Optical member 37 ... Solid-state image sensor chip 38 ... Laminated substrate 39 ... Cable 40 ... Reinforcement frame 41 ... Heat-shrinkable tube 42 ... Protective agent 45 ... Front group Lens unit 46 ... Rear group lens unit 47 ... Moving lens position correction frame 48 ... Moving lens unit 49 ... Actuator 55 ... Front group holding frame 55f ... First front group holding frame 55fa ... Flange 55fb ... First extending portion 55r ... Second front group holding frame 55ra ... Flange 55rb ... Recess 55rc ... Second extension 56a ... Front group lens 56af ... First front group lens 56ar ... Second front group lens 56b ... Rear group lens 57 ... Rear group Holding frame 57a ... Slit 57b ... Holding rod 57c ... Actuator holding hole 57e ... Stepped portion 57f ... Projection 57g ... Screw receiving portion 57h ... Third extending portion 58 ... Adhesive 59 ... Stopper member 59a ... Stopper portion 59b ... Through hole 59c ... Key 59d ... Adhesive surface 59e ... Notch 59f ... Engagement hole 60 ... Front stopper 60a ... Spring receiving part 60c ... Guide part 60d ... Recess 61 ... Slit 65 ... Movable frame 65a ... Operating rod 65b ... Bearing part 66 ... Moving lens 67 ... Shaft member 68 ... Return spring 69 ... Cover 70 ... Guide tube 71 ... Push rod 72 ... Head part 73 ... Drive wire 74 ... Shape memory element 75 ... Push spring 77 ... Sealed space 80 ... Welding part 81 ... Restriction part 82 ... Restriction part 83 ... Groove part

Claims (8)

A front lens group disposed on the subject side;
A rear group lens disposed on the image side of the front group lens;
A moving lens disposed between the front group lens and the rear group lens;
A front group holding frame for holding the front group lens;
A rear group holding frame for holding the rear group lens;
A movable frame that holds the moving lens and is movable along the optical axis direction in the rear group holding frame;
A transmission mechanism for transmitting a driving force for moving the movable frame from the outside to the inside of the rear group holding frame;
With
The front group lens includes a first front group lens located on the subject side, and a second front group lens located on the image side,
The front group holding frame has a first front group holding frame that holds the first front group lens, and a second front group holding frame that holds the second front group lens,
The rear group holding frame is sealed by the first front group holding frame holding the first front group lens and the second front group holding frame holding the second front group lens. An optical device having a sealed space.   2. The optical device according to claim 1, wherein the lens held at the forefront of the second front group holding frame has the longest length in the optical axis direction among the front group lenses.   The optical device according to claim 1, wherein the transmission mechanism is covered with a cover. The transmission mechanism includes a slit that communicates the outside and the inside of the rear group holding frame, and wall portions that are provided along both sides of the slit,
The optical device according to claim 3, wherein each of the wall portions has a flat surface for bonding the cover.   The optical device according to claim 1, wherein a screw receiving portion for receiving a screw for fixing the optical device is formed on an outer periphery of the holding frame. A first extension formed on the base end side of the first front group holding frame;
A second extension portion formed on the distal end side of the second front group holding frame and having an outer diameter smaller than the inner diameter of the first extension portion;
A third extending portion formed on the front end side of the rear group holding frame and having an inner diameter larger than an outer diameter of the first extending portion;
Have
The first front group holding frame, the second front group holding frame, and the rear group holding frame are a part of each of the first extension part, the second extension part, and the third extension part. Are arranged to overlap,
2. The optical device according to claim 1, wherein at least an adhesive is filled in a space formed by an overlap between the first extension part and the third extension part.   The said 2nd front group holding frame has a flange in an outer peripheral part, The outer peripheral surface of the said flange is contact | abutted to the internal peripheral surface of the said rear group holding frame. Optical device.   An endoscope comprising the optical device according to claim 1 at a distal end portion of an insertion portion to be inserted into a subject.

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