JP2010020104A - Lens unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens unit that can rapidly and stably perform a movement to a distal end side and a movement to a proximal end side of a movable lens frame by expanding and contracting an SMA wire. <P>SOLUTION: The lens unit 40 includes: a distal end side lens frame 41; a proximal end side lens frame 42; the movable lens frame 43 moved to the distal end side or the proximal end side; a first coil spring 46 having an urging force to arrange the movable lens frame 43 at a first observation position; a second coil spring 53 having an urging force greater than the first coil spring 46 to arrange the movable lens frame 43 at a second observation position; a pressing member 54; a contact member 55 fixed at a distal end of the pressing member; a guide pipe 56 including an inner hole 56i in which the second coil spring 53 and the pressing member 54 are disposed, and fixed to the proximal end side lens frame 42 which a proximal end face 55r of the contact member 55 contacts against; and the SMA wire 57 controlled to expand and contract by applied current and retaining the contact member 55 at an overheat prevention position when it contracts. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lens unit that varies the optical characteristics of an objective optical system disposed in an endoscope.

  Electronic endoscopes are widely used for in-vivo observation, treatment, etc., or inspection, repair, etc. in industrial plant equipment. In endoscopic observation, a device capable of changing optical characteristics such as a depth of focus, an imaging magnification, and a viewing angle with respect to an observation target is desired depending on an observation site or an observation purpose. In recent years, there has been known an imaging unit in which one or a plurality of optical lenses included in the imaging unit is configured to be movable in the optical axis direction so that optical characteristics can be adjusted and changed. ing.

For example, an endoscope disclosed in Patent Literature 1 is disclosed as a technique for changing an optical characteristic by moving a moving lens frame including an optical lens in an imaging unit provided in the endoscope. This endoscope makes it possible to reduce the size of the imaging unit having an actuator and to reduce the diameter of the distal end portion of the endoscope insertion portion, so that the moving lens frame that holds the moving lens that changes the optical characteristics is advanced and retracted. As an actuator device for movement, an urging spring and a shape memory alloy (hereinafter referred to as “SMA”) wire are used. In this endoscope, when the SMA wire is contracted by energization, the moving lens frame is moved backward against the urging force of the urging spring, and the energization to the contracted SMA wire is stopped and extended. The optical characteristic is varied by moving the moving lens frame forward by the biasing force of the biasing spring.
JP 2007-229155 A

  However, in the endoscope of Patent Document 1, the SMA wire is contracted to move the moving lens frame toward the rear third lens group, and the moving lens frame comes into contact with the positioning member, whereby the rear position of the moving lens frame is reached. Positioning is performed.

  When the moving lens is in contact with the positioning member, there are a case where the temperature of the SMA wire is within a predetermined temperature range and a case where the temperature of the SMA wire is overheated from the predetermined temperature. The extension of the SMA wire is left to natural cooling during non-energization. Therefore, when comparing the extension response when the overheated SMA wire is in a non-energized state and the extension response when the SMA wire heated in a predetermined temperature range is in a non-energized state, the overheated SMA wire is overheated. Further, the elongation response of the SMA wire is lowered. That is, if the SMA wire is overheated, when the user instructs to change the optical characteristic, a deviation occurs between the timing of the instruction and the change in the optical characteristic.

  The present invention has been made in view of the above circumstances, and provides a lens unit that can quickly and stably move the moving lens frame toward the distal end side and the proximal end side by expanding and contracting the SMA wire. It is aimed.

  The lens unit of the present invention includes a front end side lens frame that holds a plurality of first optical members, and an optical axis of the first optical member that is connected to the front end side lens frame and is held by the front end side lens frame. A proximal end side lens frame holding a plurality of second optical members having optical axes that coincide with each other, and a first optical member of the distal end side lens frame and a second optical member of the proximal end side lens frame. A moving lens frame that holds the third optical member and moves the third optical member toward the distal end side or the proximal end side of the optical axis, and a biasing force that moves the moving lens frame in the proximal direction. A first elastic member that disposes the moving lens frame at a first observation position; and a biasing force that is greater than the biasing force of the first elastic member, and moves the moving lens frame in the distal direction. A second elastic member for disposing the moving lens frame at a second observation position; A pressing member that is moved in the distal direction by the urging force of the second elastic member, a contact member that is fixed to the distal end portion of the pressing member and that has a distal end surface that contacts the moving lens frame, and the contact A distal end surface with which the proximal end surface of the member abuts, and includes an inner hole in which the second elastic member and the pressing member are slidably disposed, and are integrally fixed to the proximal end side lens frame, A guide pipe that sets the moving distance of the abutting member, and a characteristic that is fixed to the abutting member via the inside of the guide pipe and is controlled to expand and contract by being changed to a predetermined temperature by a current applied from an external power source. The pressing member to which the abutting member that abuts against the moving lens frame is fixed when being contracted is moved to the proximal side against the biasing force of the second elastic member. Together with the contact member A shape in which the base end surface of the material is separated from the distal end surface of the guide pipe by a predetermined distance, and the distal end surface of the contact member is held at a position separated from the moving lens frame moved to the first observation position by a predetermined distance. A memory alloy wire.

  According to this configuration, when the shape memory alloy wire is stretched in a non-tension state, the moving lens frame is pressed by the pressing member that fixes the contact member to the tip portion by the biasing force of the second elastic member. And held at the second observation position. On the other hand, when the shape memory alloy wire is switched to the contracted state, the pressing member moves to the proximal end side with the start of contraction. Then, the pressing force applied to the moving lens frame from the pressing member is released, and the moving lens frame moves to the proximal end side by the urging force of the first elastic member. Then, the contact member has a base end surface of the contact member spaced apart from the distal end surface of the guide pipe by a predetermined distance, and the distal end surface of the contact member is moved from the moving lens frame moved to the first observation position. When moved and held at a position separated by a predetermined distance, the moving lens frame is held at the first observation position. Thereafter, when the shape memory alloy wire is switched from the contracted state to the extended state, the moving lens frame is moved to the second observation position by the urging force of the second elastic member substantially simultaneously with the start of the natural cooling. I will do it.

  According to the present invention, it is possible to realize a lens unit that can quickly and stably move the moving lens frame toward the distal end side and the proximal end side by expanding and contracting the SMA wire.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 to 7 relate to one embodiment of the present invention, FIG. 1 is a configuration diagram showing the entire electronic endoscope system, FIG. 2 is a diagram for explaining the configuration of an imaging unit, and FIG. 3 is an arrow A in FIG. FIG. 4 is a diagram for explaining a process of fixing a ring member in which an SMA wire is fixed to the contact member, and FIG. 5 is a view when the contact member is arranged at the overheat prevention position. FIG. 6 is a diagram for explaining the positional relationship between the contact member and the guide pipe and the positional relationship between the contact member and the moving lens frame. FIG. 6 shows a contact member having a feature in the shape of the tip surface and a moving frame corresponding to the contact member. FIG. 7 is a diagram illustrating a configuration example of a moving lens frame having a convex portion and an operation thereof, and FIG. It is a figure explaining other structures.

As shown in FIG. 1, an electronic endoscope system 1 includes an electronic endoscope (hereinafter abbreviated as an endoscope) 2 having a lens unit described later, a light source device 3, a video processor 4, and a display. It is comprised with the color monitor 5 which is an apparatus. For example, the light source device 3 is provided with a power source unit as an external power source for applying a current to a shape memory alloy wire (hereinafter abbreviated as SMA wire) which is a wire shape memory alloy described later.
The endoscope 2 includes an insertion unit 9, an operation unit 10, and a universal cord 19 that extends from the operation unit 10.

  The insertion portion 9 is configured by connecting a distal end portion 6, a bending portion 7, and a flexible tube portion 8 in order from the distal end that is one end. A distal end opening, an observation window, a plurality of illumination windows, a cleaning nozzle, and the like (not shown) are disposed on the distal end surface of the distal end portion 6. On the back side of the observation window, an imaging unit, which will be described later, is provided in the distal end portion 6. In addition, a light guide bundle that transmits illumination light from the light source device 3 faces the back side of the plurality of illumination windows.

  The operation unit 10 includes an operation unit main body 11 that also serves as a gripping unit. The operation unit main body 11 includes a bending operation unit 14 that includes bending operation knobs 12 and 13, an air / water supply control unit 15, and a suction control unit 16. And a plurality of switches 17 that mainly operate an imaging function (for example, a zooming function). Reference numeral 18 denotes a forceps opening, through which a treatment tool such as a biopsy forceps is inserted.

  A scope connector 19 a is provided at the end of the universal cord 19, and the scope connector 19 a is detachably connected to the light source device 3. One end of the imaging device cable 20 is detachably connected to the side of the scope connector 19a. The other end of the imaging device cable 20 is detachably connected to the video processor 4.

The imaging unit provided in the tip 6 will be described with reference to FIGS.
As shown in FIG. 2, the imaging unit 30 includes an element unit 31 and a lens unit 40.
The element unit 31 mainly includes an imaging element 32, an element frame 33, a circuit board 34, a signal cable 35, and an imaging device exterior frame (hereinafter referred to as an imaging frame) 36.

  The imaging device 32 is a CCD (Charge Coupled Device), a CMOS (Complementary Metal-Oxide Semiconductor), or the like. For example, two cover lenses 37a and 37b, which are optical members, are bonded and fixed to the light receiving surface side of the image sensor 32. The second cover lens 37 b is disposed on the light receiving surface of the image sensor 32.

  The element frame 33 is formed of, for example, stainless steel, and the first cover lens 37 a is formed on the inner surface of the base end portion of the element frame 33 among the two cover lenses 37 a and 37 b disposed on the light receiving surface side of the image sensor 32. It is fixed integrally by bonding. That is, the image sensor 32 is fixed to the element frame 33 via the cover lenses 37a and 37b. On the inner surface of the distal end portion of the element frame 33, a proximal end portion of a later-described proximal end side lens frame 42 constituting the lens unit 40 is disposed. The base end side lens frame 42 and the element frame 33 are joined together by, for example, the solder 21 after completing the position adjustment such as focus.

  The circuit board 34 is a flexible printed board having flexibility, for example. Various electronic components (not shown) are mounted on the circuit board 34. The front end side of the circuit board 34 on which these electronic components are mounted is electrically connected to the image sensor 32.

  A plurality of signal lines 38 are inserted into the signal cable 35. The front ends of the plurality of signal lines 38 are connected to electrical connections (not shown) provided on the circuit board 34. A base end portion of the signal cable 35 is inserted through the insertion portion 9, the operation portion 10, and the universal cord 19 and extends into the scope connector 19a.

  The imaging frame 36 covers the imaging device 32, a circuit board 34 on which electronic components are mounted, a part of the signal cable 35 connected to the circuit board 34, and the like. The imaging frame 36 is formed in a predetermined shape, for example, by rounding or bending one rectangular thin plate made of stainless steel. Reference numeral 39 denotes a heat shrinkable tube, which covers the outer surface of the imaging frame 36 and constitutes the exterior of the element unit 31.

  Reference numeral 39a is an insulating sealing resin. The sealing resin 39a is filled in the space inside the imaging frame 36, and around the electrical connection portion between the circuit board 34 and the imaging device 32, around the electronic component mounted on the circuit board 34, and the cover lens 37b, The connection between the signal cable 35 and the circuit board 34 is sealed around the imaging element 32.

  As shown in FIGS. 2 and 3, the lens unit 40 includes a distal lens frame 41, a proximal lens frame 42, a moving lens frame 43, a distal position restriction frame 44, a proximal position adjustment ring 45, The first moving mechanism unit 51 and the second moving mechanism unit 52 are mainly provided.

  The first moving mechanism unit 51 is a mechanism that moves the movable lens frame 43 to the enlarged observation position that is the first observation position and holds the moving lens frame 43 at the first observation position. The first compression coil spring 46 that is a first elastic member; A guide pin 47 is provided.

  The second moving mechanism unit 52 moves the moving lens frame 43 to the wide-angle observation position that is the second observation position and holds the moving lens frame 43 at that position, and a contact member that will be described later by releasing this holding state. 55, the base end surface of the abutting member 55 is spaced a predetermined distance from the distal end surface of the guide pipe 56 described later, and the distal end surface of the abutting member 55 is a predetermined distance from the moving lens frame 43 moved to the first observation position. A second compression coil spring 53 that is a second elastic member, a tubular pressing member 54, and a contact member holding mechanism for holding at a separated position (hereinafter referred to as an overheating prevention position), The contact member 55, the guide pipe 56, and the SMA wire 57 are mainly configured.

  The front end side lens frame 41 holds a first optical lens group 61 that is a plurality of first optical members, a diaphragm, and the like. A tip position restricting frame 44 is fixed to the tip side lens frame 41.

  The base end side lens frame 42 holds a second optical lens group 62 that is a plurality of second optical members, a diaphragm, and the like. The second optical lens group 62 and the stop are provided on the base end side of the base end side lens frame 42. A male screw portion 42m is provided at a predetermined position on the outer peripheral surface of the base end side lens frame 42, and a base end frame convex portion 42a protruding outward from the outer peripheral surface is provided. A through hole 42b for fixing the guide pipe 56 parallel to the optical axis is formed in the proximal end frame convex portion 42a.

  The moving lens frame 43 holds at least one optical lens 63. The moving lens frame 43 has, for example, an engaging portion 43a that engages with the outer peripheral surface of the rear end side of the front end side lens frame 41 on the front end side.

  The engaging portion 43a of the moving lens frame 43 is provided with a moving frame convex portion 43b that protrudes outward from the outer peripheral surface. The moving frame convex portion 43b is formed with a sliding hole 43c into which one end portion of the guide pin 47 is inserted and a concave portion 43d in which one end portion of the first compression coil spring 46 is disposed. The moving frame convex portion 43b protrudes outside the outer peripheral surface of the base end side lens frame 42 through a notch groove 42c formed from the front end to the middle portion of the front end side outer peripheral surface of the base end side lens frame 42. The front end surface and the base end surface of the moving frame convex portion 43b are configured as a front positioning surface 43f and a rear positioning surface 43r.

  The distal end position regulating frame 44 is joined to the outer peripheral surface of the distal end side lens frame 41 by, for example, the adhesive 22. A distal end portion 42 d of the base end side lens frame 42 is disposed in the recess 44 a of the distal end position restricting frame 44. The tip 42d is joined into the recess 44a by the adhesive 23, for example.

  A stepped hole 44 b is formed on the distal end side of the distal end position restricting frame 44. The stepped hole 44b includes a recess 44c and a pin hole 44d. The diameter of the pin hole 44d is smaller than the outer diameter of the recess 44c. The other end of the guide pin 47 is fixed to the pin hole 44d. The other end of the first compression coil spring 46 is disposed in the recess 44c. The guide pin 47 is provided in parallel with the optical axis.

  The first compression coil spring 46 has an urging force that keeps the moving lens frame 43 in contact with the base end position adjustment ring 45 that sets the magnification observation position. The first compression coil spring 46 is inserted through a guide pin 47 protruding from the pin hole 44d. By inserting the guide pin 47 into the first compression coil spring 46, buckling or the like of the first compression coil spring 46 is prevented. Further, by inserting one end of the guide pin 47 into the sliding hole 43c, the movable lens frame 43 can be smoothly moved in the axial direction with the guide pin 47 as a guide. That is, in the present embodiment, the guide pin 47 serves as both a buckling prevention mechanism for the compression coil spring 46 and a guide mechanism for guiding the movement of the movable lens frame 43.

  The proximal end position adjusting ring 45 has an internal thread portion 45f that meshes with the external thread portion 42m of the proximal end side lens frame 42 on the inner peripheral surface thereof. The distal end surface of the base end position adjusting ring 45 constitutes a moving lens frame base end regulating surface 45a with which the rear positioning surface 43r of the moving frame convex portion 43b included in the moving lens frame 43 abuts. The base end position adjustment ring 45 is a member for setting an enlarged observation position, and is adjusted by, for example, an adhesive after adjusting the position of the focus or the like by turning.

  The guide pipe 56 includes an inner hole 56i, and the end of the second compression coil spring 53 and the pressing member 54 and the tip of the insulating tube 58 are disposed in the inner hole 56i. The second compression coil spring 53 and the pressing member 54 are slidably disposed in the inner hole 56i, and the insulating tube 58 is fixed to the inner hole 56i by, for example, adhesion.

  The outer peripheral surface from the proximal end side of the guide pipe 56 to the middle portion is covered with the distal end portion of the cover tube 59. The cover tube 59 covers the outer periphery of the insulating tube 58 and an electric cable 60 described later.

  The distal end side of the guide pipe 56 is disposed in a through hole 42 b formed in the proximal end frame convex portion 42 a of the proximal end side lens frame 42. At this time, the front end surface 56a of the guide pipe 56 protrudes a predetermined amount from the front end surface 42f of the base end frame convex portion 42a and is fixed by solder or adhesive. The base end surface 55r of the contact member 55 is in contact with the front end surface 42f.

  The second compression coil spring 53 disposed in the inner hole 56 i of the guide pipe 56 has a biasing force that is greater than the biasing force of the first compression coil spring 46. Specifically, the second compression coil spring 53 moves the moving lens frame 43 against the urging force of the first compression coil spring 46 in a state where the first compression coil spring 46 urges the moving lens frame 43. The front positioning surface 43f is brought into contact with the tip position restricting frame 44 to provide an urging force for maintaining the state. When the front positioning surface 43f of the moving frame convex portion 43b of the moving lens frame 43 comes into contact with the tip position regulating frame 44, the moving lens frame 43 is arranged at the wide-angle observation position.

The pressing member 54 disposed in the inner hole 56i of the guide pipe 56 has a tubular shape, and an abutting member 55 formed in a cylindrical shape with an insulating member is fixed to the tip portion. In the through hole 54 a of the pressing member 54, the SMA wire 57 guided through the through hole 58 a of the insulating tube 58 and the second compression coil spring 53 is inserted.
The SMA wire 57 has a characteristic that it contracts when heated by applying an electric current and expands when the application of electric current is stopped and cooled (natural cooling to room temperature).

  The middle portion 57m of the SMA wire 57 led out from the through hole 54a of the pressing member 54 is bent into a predetermined state after being inserted into the hole 64a of the ring member 64 as shown in FIG. The distal end side is extended from the side of the ring member 64 and is fixed by the adhesive 24. The ring member 64 to which the SMA wire 57 is fixed is fixed to the contact member 55.

  As shown in FIG. 4, the contact member 55 includes a pressing member fixing portion 55a that is a concave space, and a notch 55c that is formed from the opening 55b side to a midway portion of the side peripheral surface. The notch 55c communicates the pressing member fixing portion 55a with the outside.

  Here, the ring member 64 to which the middle portion 57m of the SMA wire 57 is fixed is disposed in the pressing member fixing portion 55a of the abutting member 55, and the abutting member 55 is externally fitted to the distal end portion of the pressing member 54. The abutting member fixing step of fixing with will be described.

  First, the SMA wire 57 extending from the hole 64 a of the ring member 64 is inserted into the through hole 54 a of the pressing member 54. Then, the ring member 64 is disposed on the front end surface of the pressing member 54.

  Next, an adhesive is applied to the tip of the pressing member 54 and the ring member 64. Then, as indicated by the arrow B, the ring member 64 and the distal end portion of the pressing member 54 are disposed in the pressing member fixing portion 55a. At this time, the SMA wire 57 extending from the side of the ring member 64 is disposed in the notch 55c.

  Thereafter, as the adhesive is cured, the contact member 55, the ring member 64, the SMA wire 57, and the pressing member 54 are integrally fixed as shown in FIGS. In this fixed state, the distal end side of the SMA wire 57 extends to the outside from the notch 55 c of the contact member 55. For this reason, the SMA wire 57 is prevented from being arranged on the base end face 55r side.

  As a result, the pressing member 54 in which the contact member 55 is fixed to the tip end portion is configured. The pressing member 54 is disposed in the inner hole 56i of the guide pipe 56 in which the second compression coil spring 53 is disposed.

  Instead of forming the cutout 55c on the side peripheral surface of the contact member 55, a through hole that communicates the pressing member fixing portion 55a with the outside may be formed. As a result, the SMA wire 57 can be reliably prevented from being arranged on the base end face 55r side.

  In addition, the distal end portion of the SMA wire 57 extending to the outside of the contact member 55 is inserted through an insulating tube (not shown), and, for example, the proximal end side of the bending portion 7 constituting the insertion portion 9 of the endoscope 2. Is connected to a grounding signal line (not shown) that is inserted through.

  On the other hand, the proximal end of the SMA wire 57 is disposed on the proximal end side of the bending portion 7 constituting the insertion portion 9 of the endoscope 2, and the proximal end is inserted into an electric cable 60 that supplies current to the SMA wire 57. The connected electric wire 60a is connected through a caulking member 65, for example. Therefore, when a current is applied to the SMA wire 57 from the power supply unit provided in the video processor 4 via the electric cable 60, the temperature of the SMA wire 57 rises and the SMA wire 57 contracts.

Here, the assembly process of the lens unit 40 will be described.
First, the process of assembling the frame body by assembling the frames 41, 42, 43, 44, the ring 45, and the first moving mechanism 51 will be described.

  In configuring the frame, the tip position restricting frame 44 is fixed to the tip side lens frame 41. At this time, one end of the guide pin 47 is fixed to the pin hole 44d. In addition, the base end position adjustment ring 45 is screwed into the male screw portion 42 m of the base end side lens frame 42.

  Next, the first compression coil spring 46 is disposed on the guide pin 47 provided on the tip position restriction frame 44 fixed to the tip side lens frame 41. A moving lens frame 43 is disposed on the rear end side of the front end side lens frame 41. At this time, the guide pin 47 is inserted into the sliding hole 43c formed in the moving frame convex portion 43b of the moving lens frame 43, and the first compression coil spring 46 is disposed in the concave portion 43d.

  Next, the distal end portion 42 d of the proximal end side lens frame 42 to which the proximal end position adjustment ring 45 is attached is disposed in the recess 44 a of the distal end position regulating frame 44. At this time, the moving frame convex portion 43b of the moving lens frame 43 is arranged in the cutout groove 42c formed in the base end side lens frame 42. Thereafter, the base end side lens frame 42 and the distal end position restricting frame 44 are fixed by, for example, the adhesive 22.

  Thus, a frame body in which the optical lens 63 is movably disposed between the first optical lens group 61 and the second optical lens group 62 is configured. In this frame, the moving lens frame 43 is moved to the second optical lens group 62 side of the base end side lens frame 42 by the urging force of the first compression coil spring 46. At this time, the rear positioning surface 43 r of the moving frame convex portion 43 b provided on the moving lens frame 43 is in contact with the moving lens frame base end regulating surface 45 a of the base end position adjusting ring 45. Here, the position of the optical lens 63 is determined by adjusting the position of the base end position adjusting ring 45. After the position adjustment is completed, the base end position adjustment ring 45 is integrally fixed to the base end side lens frame 42.

Next, a process of constructing the lens unit 40 by assembling the second moving mechanism 52 to the frame will be described.
First, when configuring the lens unit 40, a guide pipe 56 is prepared in which the insulating tube 58 and the cover tube 59 are fixed and the SMA wire 57 is inserted.

  Next, the guide pipe 56 is disposed in the through hole 42 b of the base end side lens frame 42. Then, the protrusion amount of the proximal end frame convex portion 42a of the distal end surface 56a of the guide pipe 56 from the distal end surface 42f is taken into consideration the position of the proximal end position adjustment ring 45, that is, the moving lens frame moving distance indicated by L1 in FIG. And fix.

  At this time, the protrusion amount is adjusted such that the abutting member moving distance indicated by L2 is longer than a predetermined amount set in advance from the moving lens frame moving distance indicated by L1 in FIG.

  This is because the moving frame convexity provided on the moving lens frame 43 as indicated by a two-dot chain line in a state where the base end surface 55r of the abutting member 55 is in contact with the distal end surface 56a of the guide pipe 56 as indicated by a solid line. When the rear positioning surface 43r of the portion 43b comes into contact with the moving lens frame base end regulating surface 45a of the base end position adjusting ring 45, it is between the rear surface 43e of the moving frame convex portion 43b and the front end surface 55f of the contact member 55. Further, by providing a preset gap t, it is possible to prevent the movement of the moving lens frame 43 to the enlarged observation position from being obstructed by contacting the contact member 55.

  Next, the second compression coil spring 53 is disposed in the inner hole 56 i of the guide pipe 56 integrated with the base end side lens frame 42. At this time, the SMA wire 57 is inserted into the inner hole of the second compression coil spring 53.

  Next, the SMA wire 57 is inserted into the through hole 54 a from the proximal end side of the pressing member 54, and the middle portion 57 m of the SMA wire 57 led out from the through hole 54 a on the distal end side is fixed to the ring member 64. Then, according to the above-described contact member fixing step, the ring member 64 to which the SMA wire 57 is fixed is disposed in the pressing member fixing portion 55a of the contact member 55, and the contact member 55 is connected to the tip of the pressing member 54. Secure to the part.

  That is, first, the ring member 64 is disposed on the distal end surface of the pressing member 54. At this time, the proximal end side of the SMA wire 57 is pulled to remove the slack. Then, an adhesive is applied to the tip of the pressing member 54 and the ring member 64. Next, the SMA wire 57 is aligned with the notch 55c, and the ring member 64 and the distal end portion of the pressing member 54 are disposed in the pressing member fixing portion 55a.

  Next, the proximal end side of the pressing member 54 at which the contact member 55 is disposed at the distal end is pushed into the inner hole 56 i against the urging force of the second compression coil spring 53. Thereafter, the front end surface 55f of the contact member 55 is disposed on the rear surface 43e side of the moving frame convex portion 43b.

  When the front end surface 55f is disposed on the rear surface 43e, the pressing member 54 is moved by the urging force of the second compression coil spring 53. Then, the front end surface 55f of the contact member 55 comes into contact with the rear surface 43e, and the moving lens frame 43 arranged at the enlarged observation position is moved to the wide-angle observation position by the urging force of the first compression coil spring 53. Then, the front positioning surface 43f of the moving frame convex portion 43b comes into contact with the tip position restricting frame 44, and the moving lens frame 43 is disposed at the wide angle observation position that is the normal observation position. In this state, the adhesive is cured. And the lens unit 40 is comprised when an adhesive agent hardens | cures. According to this lens unit 40, when no current is applied to the SMA wire 57, the moving lens frame 43 is disposed at the wide-angle observation position by the urging force of the second compression coil spring 53.

  According to the lens unit 40, the SMA wire 57 is folded back in the pressing member fixing portion 55a provided in the contact member 55 formed of an insulating member, and is extended from the side surface of the contact member 55. For this reason, insulation between the SMA wire 57 and the moving lens frame 43 can be ensured, and the SMA wire 57 can be prevented from being disposed on the base end face 55r side.

Next, an operation check of the lens unit 40 is performed, and a calibration value and overheating prevention position information are acquired.
The calibration value is a resistance value of the SMA wire 57 when the proximal end surface 55r of the contact member 55 reaches (contacts) the distal end surface 56a of the guide pipe 56, and the overheating prevention position information is an enlarged observation. This is a resistance value for placing the contact member 55 in the overheating prevention position, and by placing the contact member 55 in the overheating prevention position as shown in FIG. 5, the base end surface 55r of the contact member 55 is a guide. The first separation distance (t1) is separated from the front end surface 56a of the pipe 56, and the front end surface 55f of the contact member 55 is separated from the rear surface 43e of the moving frame convex portion 43b of the moving lens frame 43 by a second separation distance (t2). The separation distances t1 and t2 are values set based on the gap t.

  In order to perform an operation check, first, the distal end side and the proximal end of the SMA wire 57 are connected, and a current is applied to the SMA wire 57 from the power supply unit. Then, the SMA wire 57 starts to contract as the temperature rises. Then, as the SMA wire 57 contracts, the pressing member 54 provided with the contact member 55 that holds the moving lens frame 43 at the wide-angle observation position by the urging force of the second compression coil spring 53 is in the proximal direction, that is, enlarged. It is moved in the observation direction. In other words, the SMA wire 57 moves the pressing member 54 to which the contact member 55 is fixed in the proximal direction against the urging force of the second compression coil spring 53 when a current is applied. Thus, as described above, the moving lens frame 43 moves in the direction of the magnification observation position by the urging force of the first compression coil spring 46.

  Furthermore, as the temperature of the SMA wire 57 rises, the proximal end surface 55r of the contact member 55 approaches the distal end surface 56a of the guide pipe 56. At this time, the resistance value decreases with increasing temperature.

  When the proximal end surface 55r of the contact member 55 contacts the distal end surface 56a of the guide pipe 56, the contraction of the SMA wire 57 stops with this contact regardless of the temperature rise. That is, the resistance value does not change. The resistance value at this time is a value for notifying that the base end surface 55r of the contact member 55 has come into contact with the front end surface 56a of the guide pipe 56. Then, the resistance value is acquired as a calibration value, and the resistance value for stopping the proximal end surface 55r of the abutting member 55 at a predetermined distance before the distal end surface 56a of the guide pipe 56 based on the calibration value is overheated. Obtained as prevention position information.

  Here, the SMA wire 57 is contracted by controlling the SMA wire 57 with the resistance value acquired as the overheating preventing position information. And it is confirmed whether the contact member 55 is arrange | positioned in the overheating prevention position. That is, it is confirmed whether or not the predetermined gap is formed without the contact member 55 contacting the front end surface 56 a of the guide pipe 56 and the rear surface 43 e of the moving lens frame 43.

And if it confirms that the contact member 55 is arrange | positioned in the overheating prevention position, the application of the electric current to the SMA wire 57 will be stopped, and switching of an observation position will be confirmed. At this time, when the contact member 55 is disposed at the overheating prevention position, when the application of the current to the SMA wire 57 is stopped, the SMA wire 57 starts to expand due to natural cooling. Then, the moving lens frame 43 is moved from the enlarged observation position to the wide angle observation position by the urging force of the second compression coil spring 53.
Thereafter, the calibration value and the overheat prevention position information are registered as specific values of the lens unit 40 in the memory of the endoscope in which the lens unit 40 is mounted.

  When performing an endoscopic inspection with the endoscope 2 on which the lens unit 40 is mounted, the user performs a calibration process in which the base end surface 55r of the contact member 55 is brought into contact with the distal end surface 56a of the guide pipe 56 before the inspection. I do. The control unit (not shown) of the endoscope system 1 compares the resistance value acquired during the calibration process with the calibration value registered in the memory. When it is determined that there is no abnormality, the resistance of the SMA wire 57 is set so that the contact member 55 is disposed at the overheating prevention position during magnification observation based on the overheating prevention position information registered in the memory. Take control. When it is determined that there is “abnormal”, the user is notified and the endoscope is maintained.

  As described above, by acquiring the calibration value and the overheating prevention position information for each lens unit, the SMA wire resistance value is controlled based on the overheating prevention position information at the time of magnification observation. It is possible to prevent the SMA wire from being overheated by disposing the member at an overheat prevention position that does not contact the guide pipe and the moving lens frame.

  As a result, when the application of current to the SMA wire is stopped in order to switch from magnified observation to wide-angle observation during endoscopic observation, natural cooling is started and at the same time, the extension of the SMA wire is started to improve the optical characteristics. Changes can be made smoothly. In other words, it is possible to improve the stretch response when the user instructs to change the optical characteristics, and to change the optical characteristics at the timing of the instruction.

  Further, since the contraction of the SMA wire is specified to cancel the biasing force of the second compression coil spring when switching from wide-angle observation to magnification observation, the optical force by the first compression coil spring is released after the biasing force of the second compression coil spring is cancelled. The characteristics can be changed smoothly.

  By these, the movement of the moving lens frame to the distal end side and the proximal end side is performed by the urging force of the two types of compression coil springs without moving the moving lens frame directly by expansion and contraction of the SMA wire. It can be done quickly with stability.

  Furthermore, by holding the movable lens frame at the enlarged observation position with the biasing force of the first compression coil spring and holding at the wide angle observation position with the biasing force of the second compression coil spring, the temperature of the SMA wire is observed during observation. As the SMA wire contracts and expands due to the change of, the problem that the position of the moving lens frame changes can be solved.

  When the application of current to the SMA wire is stopped during observation, the moving lens frame is placed at the wide-angle observation position by the urging force of the second compression coil spring as the SMA wire extends. For this reason, even when the application of the current to the SMA wire is stopped, observation at a wide angle can be continuously performed.

  In the above-described embodiment, the front end surface 55f of the contact member 55 is configured to contact the rear surface 43e of the moving frame convex portion 43b of the moving lens frame 43. However, as shown in FIGS. 6 and 7, the contact lens and the moving frame convex portion are configured, and the moving lens frame having a clearance is pressed and held in a desired direction to be provided on the moving lens frame. Further, it is possible to prevent image vignetting due to the centering of the optical lens 63.

  FIG. 6 is a diagram illustrating a configuration example of a moving lens frame including a contact member having a feature in the shape of the front end surface and a moving frame convex portion corresponding to the contact member, and FIG. It is a figure explaining the other structure of the moving lens frame provided with the contact member with the characteristic and the moving frame convex part corresponding to the contact member, and its effect | action.

  As shown in FIG. 6, the contact member 55 </ b> D of the present embodiment has a curved surface portion 55 e that is a moving lens frame restricting portion at the tip. On the other hand, the moving frame convex portion 43b of the moving lens frame 43 is provided with a slope 43g which is a moving lens frame restricting portion with which the curved surface portion 55e abuts. According to this configuration, when the movable lens frame 43 is held at the wide-angle observation position by the urging force of the second compression coil spring 53, the curved surface portion 55e contacts the inclined surface 43g.

  As a result, the moving lens frame 43 is moved as indicated by the broken line within the clearance range, and is moved to the rear end side outer peripheral surface of the front end side lens frame 41 or the inner peripheral surface of the front end portion 42d of the base end side lens frame 42. Abut. For this reason, it is possible to prevent image vignetting that occurs when the position of the optical lens 63 shifts during observation.

  As shown in FIG. 7, the contact lens 55F is provided with a moving lens frame restricting portion and, for example, a conical shape portion 55g, and an engagement hole 43h into which the conical shape portion 55g is engaged is provided in the moving frame convex portion 43b. Also good. According to this configuration, when the movable lens frame 43 is held at the wide-angle observation position by the urging force of the second compression coil spring 53, the conical portion 55g is engaged in the engagement hole 43h to plant the same operation as described above. be able to.

  In addition, it is not limited to a curved surface part, a slope, a conical uneven part, etc., You may make it comprise a hemispherical part, a taper part, etc.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention.

Configuration diagram showing the entire electronic endoscope system The figure explaining the composition of an imaging unit Enlarged view of the portion indicated by arrow A in FIG. The figure explaining the process of fixing the ring member by which the SMA wire was fixed to the contact member The figure explaining the positional relationship between the contact member and the guide pipe and the positional relationship between the contact member and the moving lens frame when the contact member is disposed at the overheat prevention position. The figure explaining the example of 1 structure of a movable lens frame provided with the contact member characterized by the shape of a front end surface, and the moving frame convex part corresponding to the contact member, and its effect | action The figure explaining the other structure of the moving lens frame provided with the moving frame convex part corresponding to the contact member characterized by the shape of a front end surface, and the contact member

Explanation of symbols

2 ... Electronic endoscope 30 ... Imaging unit 40 ... Lens unit
41 ... Front end side lens frame 42 ... Base end side lens frame 42a ... Base end frame convex part 42b ... Through hole 43 ... Moving lens frame 43a ... Engaging part 43b ... Moving frame convex part 43c ... Sliding hole 43d ... Concave part 43e ... Rear surface 43f ... front positioning surface 43r ... rear positioning surface 46 ... first compression coil spring 47 ... guide pin 51 ... moving mechanism 52 ... moving mechanism 52 53 ... second compression coil spring 54 ... pressing member 54a ... through hole 55 ... Abutting member 55a ... Pressing member fixing portion 55b ... Opening 55f ... Tip surface 55r ... Base end surface 56 ... Guide pipe 56a ... Tip surface 56i ... Inner hole 57 ... SMA wire 58 ... Insulating tube 58a ... Through hole

Claims (8)

A tip side lens frame holding a plurality of first optical members;
A base end side lens frame holding a plurality of second optical members having an optical axis coinciding with an optical axis of the first optical member held by the front end side lens frame, which is connected to the front end side lens frame;
A third optical member disposed between the first optical member of the distal end side lens frame and the second optical member of the proximal end side lens frame is held, and the third optical member is moved to the distal end side of the optical axis or A moving lens frame to be moved to the base end side;
A first elastic member having an urging force to move the moving lens frame in the proximal direction, and disposing the moving lens frame at a first observation position;
A second elastic member having an urging force greater than the urging force of the first elastic member, moving the moving lens frame in a distal direction, and disposing the moving lens frame at a second observation position;
A pressing member that is moved in the distal direction by the urging force of the second elastic member;
A contact member having a front end surface that is fixed to the front end portion of the pressing member and that contacts the moving lens frame;
The abutting member has a distal end surface with which the proximal end surface abuts, and includes an inner hole in which the second elastic member and the pressing member are slidably disposed, and is fixed integrally to the proximal lens frame. A guide pipe for setting the moving distance of the contact member;
The movable lens is fixed to the abutting member through the guide pipe and has a characteristic of being controlled to expand and contract by being changed to a predetermined temperature by a current applied from an external power source. The pressing member to which the abutting member that abuts the frame is fixed is moved to the proximal side against the urging force of the second elastic member, and the abutting member is moved to the proximal end surface of the abutting member A shape memory alloy wire that is spaced apart from the distal end surface of the guide pipe by a predetermined distance and the distal end surface of the contact member is held at a predetermined distance from the moving lens frame that has been moved to the first observation position; ,
A lens unit comprising: further,
A front end position restricting frame that is fixed to the front end lens frame and that a front end abutting portion of the moving lens frame comes into contact with and restricts an arrangement position on the front end side of the moving lens frame;
A base end position adjusting ring that is arranged to mesh with the base end side lens frame and that a base end abutting portion of the moving lens frame comes into contact to regulate an arrangement position on the base end side of the moving lens frame;
The lens unit according to claim 1, comprising:   The lens unit according to claim 2, wherein a moving distance of the contact member is set longer than a moving distance of the moving lens frame.   A guide pin serving as a holding portion that holds the first elastic member and a guide portion that guides the movement of the movable lens frame in the distal direction or the proximal direction is provided in the distal position restriction frame. The lens unit according to claim 2. The contact member is
A ring arrangement part in which a ring member wound around a middle part of the shape memory alloy wire is arranged in the contact member;
A notch communicating the inside and outside of the abutting member to the outer peripheral surface extending from the opening side to the middle;
The lens unit according to claim 1, comprising:   The lens unit according to claim 1, wherein the contact member is an insulating member.   The lens unit according to claim 1, wherein the guide pipe and the guide pin are arranged in parallel to the optical axis.   2. The lens unit according to claim 1, wherein the moving lens frame and the contact member are provided with a moving lens frame restricting portion that moves the moving lens frame in a direction orthogonal to the optical axis.

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