JP3572976B2 - Endoscope with objective lens moving mechanism - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is provided in an insertion section of an endoscope used for medical use or the like, and makes at least one of an observation depth, an imaging magnification, a viewing angle, and the like variable in an objective optical system constituting an observation section. Therefore, the present invention relates to an endoscope with an objective lens moving mechanism in which at least one lens constituting an objective optical system is moved in an optical axis direction by remote control.
[0002]
[Prior art]
In general, endoscopes used for medical purposes are provided with a main body operation unit that is grasped and operated by a surgeon's hand and a universal cord that is detachably connected to an insertion unit into a body cavity and a light source device. It is roughly configured by providing the same. The insertion portion is composed of a distal end main body, an angle portion, and a flexible portion from the distal end side in terms of its structure and function, and the flexible portion has most of the length from the side of the connecting portion to the main body operation portion. Bends in any direction along. The distal end main body is provided with an illumination unit, an observation unit, and the like on the distal end surface thereof, and has an opening for a treatment tool lead-out unit for leading a treatment tool such as forceps. By bending the angle portion by remote operation from the main body operation portion side, the tip portion main body can be directed in an arbitrary direction.
[0003]
As described above, at least the illumination unit and the observation unit are provided on the distal end main body, and the emission end of the light guide made of an optical fiber bundle faces the illumination unit. And extended into the universal cord through the section. An objective optical system is mounted on the observation unit. When the objective optical system is configured as an electronic endoscope, a solid-state image sensor is arranged at an image forming position in the objective optical system. Here, the observation unit is usually arranged at a substantially central position in a vertical section of the distal end body, and one or a plurality of illumination units are provided at positions close to the observation unit. As a result, an observation field is formed at the approximate center position of the insertion section, and illumination light is applied to the entire field range centered on the observation field. In particular, when a hood is attached to the distal end of the insertion portion, it is possible to minimize the shading of the observation visual field by the hood.
[0004]
The objective optical system provided in the observation unit includes an objective lens group, and the objective lens group includes a plurality of lenses. Depending on the observation site, the purpose of the treatment, and the like, it is desirable to change the depth of focus with respect to the observation target portion, the imaging magnification, the viewing angle, and the like. Therefore, one or more lenses of the objective lens group are formed as movable lenses that can be moved in the optical axis direction, and by moving this movable lens, the depth of focus, the imaging magnification, the viewing angle, and the like can be adjusted. Is conventionally known. For this purpose, the fixedly held lens is provided on the fixed lens frame, the movable lens is mounted on the movable lens frame, and the movable lens frame is disposed in the fixed lens frame, and the fixed lens frame is guided. To move the movable lens frame in the optical axis direction.
[0005]
As a driving means for moving the movable lens in the optical axis direction, for example, it has been proposed to use a piezoelectric element, a shape memory alloy, or an artificial muscle. The distal end is connected to the movable lens, and the proximal end thereof is extended into the main body operation section. The control cable is configured to remotely move the movable lens in the optical axis direction. As a specific configuration of the control cable, a transmission member is inserted into a flexible sleeve, and the transmission member may be a wire for push-pull operation or a flexible wire for rotational drive. A shaft is used.
[0006]
Regardless of whether the transmission member is configured by using a wire or a flexible shaft, the movable lens is positioned at two positions: a position on the subject side and a position on the imaging side. That is, when the movable lens is positioned on the image forming side, the image forming magnification is reduced, but the depth of focus is increased. On the other hand, when the movable lens is positioned on the subject side, the imaging magnification increases, the viewing angle becomes narrow, and the depth of focus also becomes shallow. Therefore, the operator appropriately changes the position of the movable lens by driving the transmission member based on the location to be observed and what kind of diagnosis is performed. This operation is performed even when the insertion section is inserted into the body cavity.
[0007]
As described above, the movable lens can be moved in the optical axis direction according to the observation state, but in order to obtain a clear image, the movable lens must be accurately positioned at the above-described two positions. . In particular, since the depth of focus is shallow at the position of the movable lens on the subject side, even if the position is slightly deviated, the deterioration of the image becomes extremely large. Therefore, at least when the movable lens moves to the subject side, it must be accurately positioned. For this purpose, when the fixed lens of the objective lens group is mounted on the fixed lens frame, the fixed lens frame is provided with a spacer that projects a predetermined length in the optical axis direction on the side facing the movable lens in the fixed lens, In general, the movable lens is positioned by bringing the movable lens frame on which the movable lens is mounted into contact with the spacer.
[0008]
[Problems to be solved by the invention]
Incidentally, since the movable lens is driven by remote control, a control cable is connected to the movable lens frame, and the movable cable is moved in the optical axis direction by driving the control cable. Here, if the control cable is provided at two positions, for example, at 180 ° with respect to the movable lens, the movement in the optical axis direction can be performed smoothly, and the contact with the spacer can be performed with high precision. However, if two control cables are attached, the diameter of the insertion portion of the endoscope becomes large. In particular, in the angle portion, a necessary space must be secured in order to allow some movement of various members inserted therein during the angle operation, and two control cables are inserted. Generally, there is no space left. Therefore, one arm must be pulled out from the movable lens frame, and a control cable must be connected to this arm.
[0009]
With the above configuration, the movable lens frame is in a cantilever state, and when the movable lens is displaced, a driving force acts on a portion distant from the movable lens frame. Is positioned at a predetermined position on the movable lens side away from the position where the driving force acts. As described above, as a result of the difference between the portion where the force acts and the portion to be positioned, in order to accurately position the movable lens, that is, to stably contact the movable lens frame and the spacer, the movable lens frame is moved. It must be pressed strongly against the spacer. Here, since the connecting portion between the movable lens frame and its driving means is cantilevered by the arm, a force acts in a direction in which the movable lens frame tilts when performing positioning. Starting from a position where the movable lens is in contact with the movable lens is not smoothly performed, and the operability is deteriorated. In the worst case, the movable lens is locked.
[0010]
The present invention has been made in view of the above points, and an object of the present invention is to accurately position a movable lens at a predetermined position with a light force when positioning the movable lens at least at a stroke end position on the subject side. Another object of the present invention is to ensure smooth movement when driving the movable lens frame.
[0011]
[Means for Solving the Problems]
In order to achieve the above-described object, the present invention provides a method for fixing a fixed lens mounted on a fixed lens frame to a distal end main body of an insertion portion, and at least mounting a movable lens frame sliding on an inner surface of the fixed lens frame. An endoscope having an objective optical system having one movable lens and moving the movable lens frame in the optical axis direction by remote control, wherein an arm portion is extended to the movable lens frame. A drive shaft is connected to the arm part, and a stroke end regulating mechanism for positioning at least a stroke end position of the movable lens on the subject side is mounted on the drive shaft so as to be adjustable in the axial direction. The feature is that it has done.
[0012]
Here, the drive shaft can be constituted by a screw shaft. In this case, an arm portion is provided with a nut portion screwed to the screw shaft, and a flexible shaft is connected to the screw shaft. Is inserted into the sleeve, and the proximal end of the flexible shaft is rotated around the axis, whereby the screw shaft can be driven to rotate. In this case, another screw portion is provided at the tip of the screw shaft, and a stopper ring for regulating the stroke end position of the nut portion is screwed into the other screw portion, and the stopper ring is connected to another screw portion. By adjusting the screwing position, the stroke end position of the movable lens on the subject side can be set. Here, on the opposing surfaces of the stopper ring and the nut portion, joint surfaces extending in the axial direction are formed, and these joint surfaces are joined at the stroke end position of the movable lens. desirable. Further, it is more desirable to provide an imaging-side stroke end regulating mechanism for positioning a stroke end position on the imaging side in addition to the subject-side stroke end regulating mechanism on the drive shaft.
[0013]
The drive shaft is constituted by a slide shaft provided in parallel with the optical axis of the objective optical system, and at least a distal end of the slide shaft is formed with a threaded portion for coupling to the movable lens frame. It is also possible to provide a male thread part to be screwed into this female thread part, and to regulate the stroke end of the movable lens frame to a desired position by adjusting the screwing position of this screw. In this case, a connecting member was screwed into the base end of the slide shaft, an operation wire for pushing and pulling the slide shaft was connected to the connecting member, and the connecting member was connected to the fixed lens frame. A stroke end position regulating mechanism on the image forming side of the movable lens may be provided by contacting the regulating wall.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Therefore, embodiments of the present invention will be described below with reference to the drawings. In the following description, it is assumed that the objective optical system is configured as an electronic endoscope using a solid-state imaging device and the optical axis of the objective optical system is bent by 90 ° by a prism. The present invention can be applied to an optical endoscope in which an image guide is arranged at a position, and can be applied to an electronic endoscope which does not incorporate a prism even if a solid-state imaging device is used.
[0015]
First, FIG. 1 shows a schematic configuration of the entire endoscope. As is apparent from FIG. 1, the endoscope 1 is generally configured by connecting an insertion portion 3 into a body cavity or the like to a main body operation portion 2 and pulling out a universal cord 4 from the main body operation portion 2. Things. The insertion section 3 connected to the main body operation section 2 is divided into a front end main body 3a, an angle section 3b, and a flexible section 3c in order from the front end side in terms of function and structure.
[0016]
The distal end body 3a is made of a hard member, and on its distal end surface, as shown in FIG. 2, an illumination unit 10, an observation unit 11, a treatment tool lead-out unit 12, and a cleaning nozzle 13 are provided. The part 14 is open. The illustrated illumination unit 10 is provided at three locations so as to surround the observation unit 11, but the illumination unit 10 may be provided in an arbitrary number, and the jet water supply unit 14 is not necessarily provided. . The angle portion 3b can be bent in up, down, left, and right directions by an angle knob provided on the main body operation portion 2 so as to turn the distal end portion main body 3a in a desired direction. Furthermore, the flexible portion 3c occupies most of the length of the insertion portion 3, and the flexible portion 3c has a structure that is flexible in the bending direction and has a crush-resistant structure. Bends in any direction.
[0017]
FIG. 3 shows a cross section of a portion on the distal end side of the insertion section 3. As is apparent from this figure, the distal end portion main body 3a has a main body block 20 made of, for example, a metal, and a through hole is formed in a required portion of the main body block 20 so as to penetrate in the axial direction. An insulating cap 21 is attached to the end surface of the main body block 20, and is fixed to the main body block 20 by a set screw 22. The angle portion 3b has a node ring structure in which a number of angle rings 23 are sequentially pivoted by pivot pins 24. A metal net and fluoro rubber, EPDM, urethane are provided around the node ring structure composed of the angle rings 23. A cover member 25 including an outer layer made of rubber or the like is provided. Further, four operation wires 26 extend from the inside of the angle portion 3b toward the flexible portion 3c, and these operation wires 26 form a pair at the top and bottom, and at the left and right, respectively. When one is pulled and the other is extended, the angle portion 3b is bent in the vertical direction. When one of the pair of left and right operation wires is pulled and the other is extended, the angle portion 3b is curved in the left and right direction.
[0018]
The tip ring 23a located at the forefront of the multiple connected angle rings 23 constituting the angle portion 3b is connected to the main body block 20. Therefore, in the insertion portion 3, the portion from the distal end surface of the insulating cap 21 to the position of the pivotal connection between the distal end ring 23a of the angle portion 3b and the other angle ring 23 pivotally connected thereto is a hard portion. I have.
[0019]
As is well known, the illumination unit 10 irradiates the illumination light transmitted to the light guide toward the inside of the body cavity, and can observe the inside of the body cavity under the illumination light. The observation of the inside of the body cavity is performed by the observation unit 11, and the observation unit 11 is disposed approximately at the center of the distal end surface of the distal end main body 3 a of the insertion unit 3. As a result, the center position of the insertion section 3 substantially coincides with the center of the observation field of view, which is advantageous in terms of the operation of inserting the insertion section 3 into the body cavity, and also, for example, covering the tip main body 3a with a hood. In the case of wearing, for example, blurring of the observation visual field is suppressed to a minimum. The configuration of the observation unit 11 provided at the distal end of the distal end portion main body 3a will be described with reference to FIGS.
[0020]
First, in FIG. 4, reference numeral 30 denotes a lens assembly constituting an objective optical system, and the lens assembly 30 comprises a lens constituting an objective optical system provided on an observation unit mounting portion 11a provided on the main body block 20 (see FIG. 3). The lens assembly 30 includes an objective lens group 31. An optical path from the objective lens group 31 is bent downward by 90 ° by a prism 32. A solid-state imaging device assembly 33 including a solid-state imaging device 33a joined to a prism 32 and a substrate 33b is arranged at an image forming position of the objective lens group 31. In addition, a filter 34 having desired characteristics is provided between the objective lens group 31 and the prism 32, and an aperture (not shown) and the like are further provided in addition to these.
[0021]
As is clear from FIGS. 5 and 6, a part (one or a plurality) of lenses 31a constituting the objective lens group 31 is a movable lens movable in the optical axis direction, and the remaining lens 31b is fixed. Has become a lens. The fixed lens 31b is fixedly mounted on a lens support frame 35 constituting a fixed lens frame, and the lens support frame 35 is joined to the surface of the prism 32. Further, the movable lens 31a is mounted on the movable lens frame 36, and the movable lens frame 36 is slid along the inner surface of the lens support frame 35, whereby the movable lens 31a moves in the optical axis direction.
[0022]
In order to accurately match the optical axes of the movable lens 31a and the fixed lens 31b, the movable lens frame 36 provided with the movable lens 31a is movable in the optical axis direction in the lens support frame 35, and is movable in other directions. That is, it is fixedly held in a direction perpendicular to the optical axis and in a falling direction. In addition, in order to minimize the sliding resistance when moving in the optical axis direction, at least two sliding contact surfaces 36a are formed on the outer peripheral surface of the movable lens frame 36, and only the sliding contact surface 36a is used. By contacting the inner surface of the lens support frame 35, the contact area between the movable lens frame 36 and the lens support frame 35 is reduced. Thus, in the illustrated embodiment, two sliding contact surface portions 36a are provided at two positions, and they have a positional relationship of 180 ° with each other and have a predetermined width in the circumferential direction. An arm 37 is connected to the movable lens frame 36. The arm 37 is led out through a slit 35a provided in the lens support frame 35 in the optical axis direction. Is provided with a nut portion 38 continuously. Here, the dimension of the arm portion 37 in the width direction is substantially equal to the groove width of the slit 35a, thereby restricting the movement of the movable lens frame 36 in the rotation direction.
[0023]
With the above configuration, the movement of the movable lens frame 36 other than in the optical axis direction is almost completely restricted. The movable lens frame 36 moves in the direction of the optical axis by moving the nut 38 along the screw axis 40 in a direction parallel to the optical axis. The reason why the movable lens 31a is movable in the optical axis direction is to change at least one of the observation depth, the imaging magnification, the viewing angle, and the like.
[0024]
The movable lens 31a is movable by remote control on the main body operation unit 2 side. For this purpose, a protrusion 35b is continuously provided on the lens support frame 35, and a shaft support member 39 formed in a substantially cylindrical shape is continuously provided on the protrusion 35b. Here, the shaft support member 39 functions as a support unit that holds a driving unit of the movable lens frame 36. The driving means includes a nut 38 connected to the tip of the arm 37, a screw shaft 40, and a control cable 41 for driving the screw shaft 40 to rotate. The screw shaft 40 includes a screw rod portion 40a and a rotating shaft portion 40b. The rotating shaft portion 40b is rotatably and non-movably inserted into an insertion hole 39a formed in the shaft support member 39. The screw rod portion 40a protrudes a predetermined length forward from the shaft support member 39 by a predetermined length, and the nut portion 38 is screwed to a protruding portion of the screw rod portion 40a.
[0025]
The control cable 41 is configured by inserting a flexible shaft 43 made of a double contact coil into a sleeve 42 having flexibility. The distal end of the flexible shaft 43 is connected to the screw shaft 40 by a connecting member 44, and the distal end of the sleeve 42 is fixed to the shaft support member 39 by a connection ring 45. Therefore, when the base end of the flexible shaft 43 is rotated around the axis in the sleeve 42, the rotation is transmitted to the screw shaft 40, and the screw shaft 40 rotates, thereby connecting the nut portion 38 and the nut portion 38 thereto. The movable lens frame 36 moves. In order to fix the screw shaft 40 so as not to move in the axial direction during this time, the outer diameter of the connecting member 44 is larger than the diameter of the insertion hole 39a, and the rotary shaft portion 40b of the screw shaft 40 has a flange. A portion 40c is formed, and the connecting member 44 and the flange portion 40c are in contact with front and rear end surfaces of the insertion hole 39a.
[0026]
The control cable 41 extends from the insertion section 3 into the main body operation section 2. The base end of the flexible shaft 43 is connected to the rotating shaft 47, and the base end of the sleeve 42 is the casing of the main body operation section 2. Are fixedly held. A driven gear 48 is connected to the rotating shaft 47, and is meshed with a driving gear 50 provided on an output shaft of a motor 49. When the driving gear 50 is driven to rotate by the motor 49, the driven gear 48 is driven. As a result of the rotation of the gear 48 following the rotation, the rotation shaft 47 and the flexible shaft 43 connected thereto rotate around the axis, and the screw shaft 40 connected to the flexible shaft 43 is rotationally driven by remote control. Thus, the movable lens 31a moves in the optical axis direction. In order to control the operation of the motor 49, a control button 5 is provided on the main body operation unit 2, and the ON / OFF control of the motor 49 is performed by pushing the control button 5.
[0027]
Thus, the movable lens 31a can be displaced to two positions, that is, the imaging side position shown in FIG. 4 and the subject side position shown in FIG. At the imaging side position, the imaging magnification is small and the viewing angle is wide. On the other hand, when the movable lens 31a is disposed at the position on the subject side, the imaging magnification increases and the viewing angle decreases. In addition, the depth of focus of the movable lens 31a at each of these positions also changes, and the depth of focus becomes shallow at the position on the subject side. Then, with the insertion portion 3 inserted into the body cavity, the movable lens 31a is appropriately displaced to the above-described two positions depending on the observation site, what kind of diagnosis is to be performed, what kind of treatment is to be performed, and the like. Will be. Accordingly, the movable lens 31a is displaced by operating the control cable 41, and the movable lens 31a must be accurately positioned at the above-described two positions, that is, the imaging side position and the subject side position.
[0028]
Here, the drive mechanism of the movable lens 31a constituting the objective lens group 31 is provided by connecting to the control cable 41, the screw shaft 40 connected to the flexible shaft 43 of the control cable 41, and the movable lens 31a. And a nut 38 to be screwed with the screw shaft 40. When the flexible shaft 43 is rotated, the rotation is transmitted to the screw shaft 40, and the rotation of the screw shaft 40 causes the nut portion 38 to move in the axial direction. Therefore, the screw shaft 40 and the nut portion 38 constitute a means for converting the rotational motion into the linear motion. Only the movable lens 31a is driven by the control cable 41, and the movable lens frame 36 to which the movable lens 31a is attached. In addition, the movable lens frame 36 is guided by the lens support frame 35, and the position where the driving force acts is a nut portion 38 connected to an arm portion 37 extending from the movable lens frame 36.
[0029]
As described above, the movable lens 31a is moved by operating the control cable 41 and rotating the screw shaft 40. The movable lens 31a is always moved along the optical axis of the entire objective lens group 31, that is, the movable lens 31a is moved along with the fixed lens 31b. The optical axes must be kept aligned. It is for this reason that the sliding contact surface portion 36a of the movable lens frame 36 is slid along the inner surface of the lens support frame 35. Therefore, the sliding contact surface portions 36a provided at two places are substantially both with respect to the lens supporting frame 35. The surface is in contact. In addition, it is necessary to hold the movable lens 31a so as not to be displaced in the rotation direction unnecessarily during the movement. For this reason, the arm portion 37 is moved with respect to the slit 35a of the lens support frame 35 in the width direction, that is, in the rotation direction. It is inserted with almost no gap. As a result, the movable lens 31a is positioned extremely accurately, and movement other than in the optical axis direction is almost completely restricted.
[0030]
As described above, the movable lens 31a is caused to act on the nut portion 38 provided continuously with the one arm portion 37 extending from the movable lens frame 36, thereby moving the movable lens 31a between the image forming side position and the subject side position. The movable lens 31a is positioned very accurately at these two positions. Here, the positioning of the movable lens 31a at these two positions is performed between the screw shaft 40 and the nut portion 38. For this purpose, the screw shaft 40 is provided with a pair of stopper rings 51 and 52 at the front and rear. The stopper ring 51 constitutes a means for positioning the movable lens 31a at the image forming side position, and the stopper ring 52 constitutes a means for positioning the movable lens 31a at the object side position. However, since these stopper rings 51 and 52 do not directly position the movable lens 31a, in order to eliminate the effects of assembly errors of the members, etc. The positions of the stopper rings 51 and 52 can be adjusted even before the is mounted on the distal end body 3a of the insertion section 3.
[0031]
For this purpose, the stopper ring 51 is screwed to the screw rod portion 40a of the screw shaft 40. By adjusting the screwing position, the image-forming side position can be adjusted. However, if the nut portion 38 is rotated while the nut portion 38 is in contact with the stopper ring 51, the stopper ring 51 may rotate together. After being adjusted to a predetermined position, the stopper ring 51 is fixed to the peripheral body by attaching a set screw or by bonding, spot welding, or the like.
[0032]
On the other hand, the stopper ring 52 is not screwed directly to the screw rod portion 40a, but is screwed to a small-diameter second screw portion 40d provided so as to project forward from the screw rod portion 40a so that the position can be adjusted in the axial direction. Combine. Then, the second screw portion 40d is configured to be reverse-threaded or to change the feed pitch interval with respect to the screw rod portion 40a. As a result, even if the nut portion 38 is further rotated in a state where the nut portion 38 is joined to the stopper ring 52, there is no possibility that the stopper ring 52 rotates together. Here, at the position of the movable lens 31a on the subject side, the depth of focus in the objective lens group 31 becomes shallower, so that more accurate positioning is required as compared with the imaging side position, and even after the observation unit 11 is assembled. It is desirable that the position can be adjusted. This is why the stopper ring 52 is configured as described above, whereby the movable lens 31a can be extremely accurately positioned at the subject side position. The movable lens 31a is adjusted so as to have a predetermined interval with respect to the fixed lens 31b. Since the interval therebetween is predetermined by the lens configuration of the objective lens group 31, a spacer for holding the fixed lens 31b is provided. Is mounted on the lens support frame 35, and when the movable lens 31a is arranged at the position on the subject side, the movable lens frame 36 is set so as to contact the spacer, and the movable lens frame 36 contacts the spacer. Sometimes, it is more desirable to set the nut portion 38 so as to abut the stopper ring 52 at the same time.
[0033]
By the way, at the stop position of the nut portion 38, the end surface of the nut portion 38 may be joined to the end surface of the stopper ring. However, since the nut portion 38 is screwed, the nut portion 38 can be formed with higher precision. 7 can be configured as shown in FIGS. Thus, when the movable lens 31a is disposed at the position on the subject side, it is necessary to perform the positioning with higher accuracy. Therefore, in these figures, the nut portion 38 is positioned on the forward side, that is, with respect to the stopper ring 52 at the position on the subject side. The description will be made assuming that the positioning mechanism is configured. Note that the same configuration can be adopted at the image-forming side position. Further, as shown in FIG. 4 and the like, by attaching a protective cover 53 covering the screw shaft 40 and the nut portion 38 from the shaft support member 39 to the front portion of the lens support frame 35, the screw shaft 40 It is configured such that dust and other foreign matter do not enter into the threaded portion with the nut portion 38. Therefore, dust may adhere to the contact surfaces between the nut portion 38 and the stopper rings 51 and 52. Therefore, the movable lens 31a may be configured to be positioned by joining these end faces.
[0034]
Thus, the stopper ring 52 is formed with a protruding portion 52 a in the axial direction at a part in the circumferential direction, and the tip portion of the nut portion 38 is also provided with a corresponding protruding portion 38 a. I have. Joining surfaces 52T, 38T are formed on the both protruding portions 52a, 38a so as to face each other, and these joint surfaces 52T, 38T function as positioning walls for positioning the nut portion 38 at a predetermined position. Has become. As a result, the nut portion 38 is positioned by applying a pressing force in the rotational direction indicated by the arrow in FIG. 8, so that the position can be set extremely finely and can be reliably positioned at a predetermined position.
[0035]
As described above, it is the movable lens frame 36 provided with the movable lens 31a that is held at a predetermined position, but since the nut portion 38 on the side that drives the movable lens frame 36 is positioned, The nut portion 38 can be reliably held at a predetermined position. The movable lens frame 36 has considerable resistance to the movement since the sliding contact surface portion 36a moves along the lens support frame 35, but when the nut portion 38 is held at a predetermined position. Also, the movable lens frame 36 is always displaced to a predetermined position. As described above, although the movable lens frame 36 is originally positioned at the predetermined position, the nut portion 38 on the drive side is positioned instead of the movable lens frame 36 side. Therefore, the control cable 41 can be easily moved to each position on the subject side and the image forming side with a light load. Further, since no excessive force acts on the movable lens frame 36, when the operation of the control cable 41 is stopped, the movable lens frame 36 is accurately positioned at a predetermined position, so that the movable lens 31a is securely positioned at the predetermined position. Not only does not cause tilt and the like, but also there is no possibility that the focal position is shifted. In particular, at the object side position, since the positioning is performed by abutment between the joint surfaces 52T and 38T in the rotational direction, the stop position accuracy is extremely high, and the start when moving in the opposite direction is performed smoothly, and It is possible to reliably prevent a malfunction from occurring due to the application of a pressing force or the like.
[0036]
Further, as a configuration for moving the movable lens 31a in the optical axis direction, not only a configuration in which the flexible shaft is rotated to convert this rotational motion into a linear motion as in the above-described embodiment, but also As shown in FIGS. 9 and 10, the movable lens 31a may be moved by pushing and pulling a wire.
[0037]
In the figure, reference numeral 141 denotes a control cable, and the control cable 141 is formed by inserting a wire 143 into a sleeve 142. A slide shaft 140 as a drive shaft is inserted through a shaft support member 139 connected to the lens support frame 135. The slide shaft 140 is pushed and pulled by a wire 143 to move the movable lens frame 136 to the arm portion 137. Is moved in the axial direction. The movable lens 31a is normally held at the subject side position by the action of the spring 160, and the movable lens 31a is pulled by pulling the wire 143 against the urging force of the spring 160. It is configured to be displaced to the imaging side position.
[0038]
When such a configuration is adopted, the wall surfaces at both ends of the insertion hole 139a of the shaft support member 139 are used as reference surfaces 139b and 139c. The slide shaft 140 is provided with a flange portion 140 a at an intermediate position thereof, a connecting member 161 provided on the wire 143, and the connecting member 161 is screwed into the slide shaft 140. By making the outer diameter of the connecting member 161 larger than the inner diameter of the insertion hole 139a, the slide shaft 140 is restricted within the insertion hole 139a of the shaft support member 139 by the flange 140a and the connecting member 161. To reciprocate in the axial direction.
[0039]
In addition, the slide shaft 140 has a threaded portion 140b protruding from the distal end thereof, and a threaded portion 137a is screwed to the threaded portion 140b to be formed on the arm portion 137 connected to the movable lens frame 136. Then, by changing the screwing position of the screw, the position of the movable lens 31a at the subject side position can be adjusted. On the other hand, a female screw portion 140c is provided on the base end side of the slide shaft 140, a screw portion 161a is connected to the connecting member 161 and the screw portion 161a is appropriately screwed in and out, thereby forming the movable lens 31a on the image forming side. The position can be adjusted by position.
[0040]
9 shows the subject side position, in which the slide shaft 140 protrudes forward by the action of the spring 160, and the connecting member 161 connected to the wire 143 becomes the reference surface on the rear end side of the shaft supporting member 139. Since the connecting member 161 is screwed into the slide shaft 140, the position of the movable lens frame 136 at the image-forming side position is adjusted by appropriately screwing the connecting member 161 in and out. Can be. Further, when the wire 143 is pulled, the flange portion 140a of the slide shaft 140 is held at a position where the flange portion 140a contacts the reference surface 139b on the front end side of the shaft support member 139. This is the image-forming side position shown in FIG. 10, and the adjustment of the distance between the movable lens 31a and the fixed lens 31b at this image-forming side position is performed by using the screw portion 140c to provide the arm portion 137 of the movable lens frame 136. This can be performed by adjusting the screwing position of the slide shaft 140 with the screw portion 140b.
[0041]
Even with the above configuration, the mechanism for positioning the movable lens 31a at each position on the subject side and the image forming side is not a movable lens frame 136 on which the movable lens 31a is mounted, but a slide on the drive side thereof. It can be provided between the shaft 140 and the shaft support member 139 connected to the lens support frame 135, so that the positioning accuracy is good and the smoothness of operation when displacing from one side to the other side is secured. There is no danger of increased resistance to movement or locking.
[0042]
In addition, the position adjustment of the movable lens 31a at each of the image forming side and the subject side is performed by adjusting the positions of the screwing portions between the screw portion 140b and the arm portion 137 and between the connecting member 161 and the slide shaft 140. Is adjusted, the position of the movable lens 31a on the image side and the object side can be accurately adjusted after assembling the components constituting the observation unit 11.
[0043]
【The invention's effect】
Since the present invention is configured as described above, a drive shaft is connected to an arm portion extending from the movable lens frame, and a stroke end restriction for positioning at least a stroke end position of the movable lens on the subject side on the drive shaft. Since the mechanism is mounted so that the position can be adjusted in the axial direction, when the movable lens is positioned at least at the stroke end position on the subject side, it can be accurately positioned at a predetermined position with a light force, and the movable lens frame is driven. In some cases, such an effect is obtained that a smooth movement can be ensured.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an endoscope showing one embodiment of the present invention.
FIG. 2 is an external view showing a distal end surface of an insertion section of the endoscope in FIG. 1;
FIG. 3 is a vertical cross-sectional view near the distal end of an insertion portion.
FIG. 4 is a longitudinal sectional view showing a driving mechanism of a movable lens of an observation unit.
FIG. 5 is an exploded perspective view of the lens assembly.
FIG. 6 is a sectional view similar to FIG. 4, showing a state in which the movable lens has been advanced.
FIG. 7 is an operation explanatory view showing a state before engagement between a nut portion and a stopper ring.
FIG. 8 is an operation explanatory view showing an engagement state between a nut portion and a stopper ring.
FIG. 9 is a longitudinal sectional view showing a driving mechanism of a movable lens of an observation unit according to another embodiment of the present invention.
FIG. 10 is a longitudinal sectional view showing a driving mechanism of the movable lens of the observation unit in an operation state different from that of FIG. 9;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Endoscope 2 Main body operation part 3 Insertion part 3a Tip part main body 3b Angle part 11 Observation part 30 Lens assembly 31 Objective lens group 35 Lens support frame 35a Slit 35b Projection part 36 Movable lens frame 36a Sliding contact surface part 37 Arm part 38 Nut Part 38a Projecting part 38T Joint surface 39 Shaft support member 39A Insertion hole 40 Screw shaft 40a Screw rod part 40b Rotating shaft part 40c Flange part 40d Second screw part 51, 52 Stopper ring 52a Projecting part 52T Joint surface 136 Movable lens frame 137 Arm part 137a Female thread part 139 Shaft support member 139a Insertion holes 139b, 139c Reference surface 140 Slide shaft 140a Flange part 141 Control cable 142 Sleeve 143 Wire 160 Spring 161 Connection member 161a Screw part

Claims (7)

An objective optical system having a fixed lens mounted on a fixed lens frame and at least one movable lens mounted on a movable lens frame that slides on an inner surface of the fixed lens frame is provided at a distal end main body of the insertion section. In an endoscope having a configuration in which the movable lens frame is moved in the optical axis direction by remote control, an arm portion is provided to extend to the movable lens frame, and a drive shaft is connected to the arm portion and provided. An endoscope with an objective lens moving mechanism, wherein a stroke end regulating mechanism for positioning at least a stroke end position of the movable lens on the object side is mounted on the drive shaft so as to be position-adjustable in the axial direction. The drive shaft is constituted by a screw shaft, the arm portion is provided with a nut portion to be screwed to the screw shaft, a flexible shaft is connected to the screw shaft, and the flexible shaft is inserted into the sleeve, The endoscope with an objective lens moving mechanism according to claim 1, wherein the screw shaft is driven to rotate by rotating a base end portion of the flexible shaft around the axis. Another screw portion is provided at the tip of the screw shaft, and a stopper ring for regulating the stroke end position of the nut portion is screwed to the other screw portion, and the stopper ring is screwed to the other screw portion. The endoscope with an objective lens moving mechanism according to claim 2, wherein a position of a stroke end of the movable lens on the subject side is set by adjusting a position. On the opposing surfaces of the stopper ring and the nut portion, a joining surface extending in the axial direction is formed, and the two joining surfaces are joined at a stroke end position of the movable lens. The endoscope with an objective lens moving mechanism according to claim 3. A configuration in which the drive shaft is provided with a subject-side stroke end regulating mechanism that positions a subject-side stroke end position of the movable lens and an imaging-side stroke end regulating mechanism that positions an imaging-side stroke end position. The endoscope with an objective lens moving mechanism according to claim 1. The drive shaft is constituted by a slide shaft provided in parallel with the optical axis of the objective optical system, and at least a distal end of the slide shaft is formed with a screw portion for coupling to the movable lens frame, and a distal end of the slide shaft is formed. 2. A structure in which a male screw portion inserted into the female screw portion is provided, and a stroke end of the movable lens frame can be restricted to a desired position by adjusting a screwing position of the screw. An endoscope with the objective lens moving mechanism according to the above. A connecting member is screwed into the base end of the slide shaft, an operation wire for pushing and pulling the slide shaft is connected to the connecting member, and the stopper member is provided on a wall surface connected to the fixed lens frame. 7. The endoscope with an objective lens moving mechanism according to claim 6, wherein the movable lens is configured to be a stroke end position regulating mechanism on the image forming side of the movable lens.

Images