JPH11342104A - Zoom endoscope - Google Patents

Abstract

(57) [Problem] To provide a zoom endoscope that can maintain an appropriate distance to a subject with a tip hood at the time of close-up magnification observation and does not block the visual field at the time of wide-angle visual field observation. A distal end hood that protrudes forward and surrounds a distal end portion of an insertion portion in a tubular shape is provided so as to be able to advance and retreat in an axial direction, and the distal end is linked to a change in the focal length of objective optical systems and. The hood 70 is moved forward and backward.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom endoscope having a variable focal length objective optical system.

[0002]

2. Description of the Related Art In order to perform microscopic enlargement observation of a mucosal surface with an endoscope, it is necessary to lengthen the focal length of an objective optical system. Therefore, a zoom endoscope is used.

[0003] Such a zoom endoscope generally operates an objective optical system having a variable focal length built in the distal end of an insertion section by an operation wire which is operated to be advanced or retracted in the axial direction by operation from a hand side operation section. Let me.

[0004]

In general, when the focal length of the optical system becomes longer, the depth of focus becomes shallower, and the subject becomes out of focus even if it is slightly deviated from the best focus distance.

[0005] Therefore, when performing microscopic enlargement observation of the mucous membrane surface, a tip hood is often used in order to appropriately maintain the distance to the subject. However, if a tip hood suitable for securing the distance during such close-up magnification observation is attached to the tip of the insertion section, the peripheral portion of the viewing range will be obstructed by the tip hood when switching to the wide-angle field of view, hindering observation. There are inconveniences that arise.

Accordingly, an object of the present invention is to provide a zoom endoscope which can maintain an appropriate distance to a subject with a tip hood at the time of close-up magnification observation and which does not obstruct the visual field at the time of wide-angle visual field observation.

[0007]

In order to achieve the above object, a zoom endoscope according to the present invention has a zoom lens having a variable focal length objective optical system built in an observation window arranged on the distal end surface of an insertion portion. In the endoscope, a distal end hood that protrudes forward surrounding the distal end portion of the insertion portion in a tubular shape is disposed so as to be able to advance and retreat in the axial direction, and the distal end hood is interlocked with a change in the focal length of the objective optical system. Is made to advance and retreat.

It is preferable that the tip hood projects forward from the tip face of the tip body as the focal length of the objective optical system increases, and the tip hood moves forward from the tip body. When in the most protruding state,
The distal end surface of the distal end hood may coincide with a best focus position of the objective optical system.

[0009]

Embodiments of the present invention will be described with reference to the drawings. FIG. 5 shows the entire configuration of the zoom endoscope, in which an operation section 2 is connected to a base end of a flexible tubular insertion section 1, and a bending section 4 formed at a distal end portion of the insertion section 1 includes an operation section. By rotating the bending operation knob 3 provided on the 2, the bending operation knob 3 can be bent in an arbitrary direction by an arbitrary angle.

The distal end of the bending section 4 is connected to a distal end body 10 having an objective optical system and the like built therein. In the vicinity of the connection between the insertion section 1 and the operation section 2, a treatment instrument insertion port 5 which is an entrance of a treatment instrument insertion channel inserted and arranged in the insertion section 1 is protrudingly arranged. Reference numeral 6 denotes a zoom operation lever for performing a zoom operation.

A connector 8 is connected to a distal end of a flexible connecting pipe 7 connected to a rear portion of the operation section 2. The connector 8 supplies illumination light to a light guide fiber bundle for illumination, which will be described later, and a distal end. It is connected to a light source device and a video processor (not shown) for processing video signals picked up by a solid-state image pickup device built in the main body 10.

FIGS. 1 and 2 show the distal end portion of the insertion portion 1. FIG. 1 shows a close-up observation state, and FIG. 2 shows a normal observation state in which a wide-angle field of view is obtained. Reference numeral 12 in the figure denotes the tip body 1
0 is a treatment instrument insertion channel that is opened at the distal end surface of the treatment instrument.

The observation window 11 is disposed on the distal end surface of the distal end body 10, and a cover lens 20, which is the first lens of the objective optical system, is fitted therein. An illumination window (not shown) is arranged alongside the observation window 11.

An objective lens group 21 and a solid-state image sensor 24 are arranged inside the cover lens 20, and an image of a subject in front of the distal end main body 10 is formed on the image-capturing surface of the solid-state image sensor 24.

A fixed inner cylinder 28 is inserted into a fixed outer cylinder 27 fitted and fixed in a hole formed in the tip end body 10 in the axial direction.
Is directly fitted at the rear end and fixed with a fixing screw 29. On the front side, a space ring 30 is interposed and fixed between the two tubes 27 and 28, and both ends are located between the two tubes 27 and 28. A constant gap is secured over the entire length excluding the above.

The cover lens 20 is fixed to the distal end of the fixed inner cylinder 28 in a watertight manner, and a front lid 31 is joined to the space ring 30 so as to close the space between the side surface of the cover lens 20 and the distal end body 10. I have.

In the fixed inner cylinder 28, an objective frame 34 to which the objective lens group 21 is attached, and an image receiving section frame 35 to which the solid-state image sensor 24 for taking an observation image are attached.
They are inserted so as to be able to advance and retreat in the axial direction independently of each other.
A first compression coil spring 47 is interposed between the frames 34 and 35 to prevent rattling.

The objective lens group 21 is assembled and fixed in a lens barrel 36, and the lens barrel 36 is joined to the objective frame 34. However, the lens barrel 36 may be fixed to the objective frame 34 with screws.

The solid-state image sensor 24 is fixed to the tip of a flexible substrate 44 such as a TAB (Tape Automated Bonding) substrate. The cover glass 23 is joined to the front end surface of the solid-state image sensor 24, and the YAG The cut filter 22 is joined to the front end face of the cover glass 23.

In the flexible substrate 44, the solid-state image sensor 24
A buffer board on which electronic components constituting the drive circuit and the like are mounted is arranged, and a signal cable 45 is drawn out behind the buffer board.

A cylindrical cam cylinder 50 having first, second, and third cam grooves 51, 52, 53 formed on the outer peripheral surface of the fixed inner cylinder 28 is rotatably fitted around an axis. And
A slide tube 55 driven by the operation wire 25 and slid in the axial direction is disposed at a position surrounding the cam tube 50.

The distal end of the operation wire 25 is passed through a hole formed in the slide cylinder 55, and the retaining ring 5
7 is fixed. The slide cylinder 55 is slid rearward (rightward in the figure) as shown in FIG. 2 by an operation of operating the optical system operation lever 6 and pulling the operation wire 25 from the operation section 2 side.

Then, the operation wire 25 is turned in the opposite direction (that is,
When the slide cylinder 55 is moved forward, the slide cylinder 55 is slid leftward by the urging force of the second compression coil spring 58 disposed around the outer periphery of the fixed inner cylinder 28 as shown in FIG. Note that the urging force of the second compression coil spring 58 is set stronger than the urging force of the first compression coil spring 47 in the normal observation state.

A first pin 65 whose front end engages with the first cam groove 51 formed in the cam cylinder 50 without looseness is screwed into the slide cylinder 55 so as to protrude inward. ing.

A second pin 66 whose head engages with the second cam groove 52 is screwed and fixed to the objective frame 34 so as to protrude outward. The third pin 67 whose head engages with the third cam groove 53 is screwed and fixed so as to protrude outward. In the fixed inner cylinder 28, rectilinear grooves 68, 69 through which the second pin 66 and the third pin 67 pass are formed in a direction parallel to the axis.

FIG. 3 shows the first to third cam grooves 51 and 5.
FIG. 5 is a developed view showing an engaged state of the first and third pins 65, 66, 67 with the pins 65, 66, 67;
Is located in the proximity enlarged state (long focal length) shown in FIG.

When the operation wire 25 is pulled by operating the optical system operation lever 6 of the operation section 2 from the close-up state, the slide cylinder 55 resists the urging force of the second coil spring 58 as shown in FIG. The cam cylinder 50 is driven to rotate around the axis by the engagement between the first pin 65 and the first cam groove 51 which slides rearward and moves with it.

When the cam cylinder 50 rotates around the axis, the second and third pins 66 and 67 that engage with the second and third cam grooves 52 and 53 formed in the cam cylinder 50 move in the axial direction. Then, the objective frame 34 slides forward and the image receiving unit frame 35 slides backward, so that the focal length of the objective lens group 21 including the cover lens 20 decreases.

As described above, zooming and focusing are performed at the same time by moving the operation wire 25 forward and backward. For example, in the normal observation, the viewing angle is 120 ° and the observation distance is in the range of 5 to 100 mm. Corner 4
At 0 °, the observation distance is in the range of 2 to 4 mm, and a microscopic close-up observation state is established.

If the optical system operation lever 6 is stopped at an arbitrary intermediate position, the object frame 34 and the image receiving portion frame 35 driven via the operation wire 25 and the slide cylinder 55 stop at an intermediate position in the movement range. Thus, observation can be performed at an arbitrary magnification between the normal observation state and the close-up magnification observation state.

Note that the length of the first cam groove 51 is
The rotation angle of 0 is exactly 90 °, but the second and third
Both ends of the cam grooves 52 and 53 are the first cam grooves 51.
It is formed longer. As a result, the first cam groove 51
The first pin 65 engaged with the cam cylinder 50 serves as a stopper for regulating the rotation angle of the cam barrel 50.

A distal end hood 70 is disposed so as to surround the distal end portion of the distal end body 10 in a cylindrical shape. This tip hood 70
Is fitted slidably in the axial direction with respect to the outer peripheral surface of the distal end body 10.

The tip hood 70 is formed by integrally screwing a metal inner cylinder 71 fitted to the distal end main body 10 and an outer cylinder 72 made of electrically insulating plastic fitted to the outer surface thereof. Is formed. Note that the inner cylinder 71 may be formed of ceramic or the like.

Then, the tip hood 70 and the slide cylinder 55
Are connected by a connecting pin 77, and when the slide cylinder 55 moves in the axial direction, the tip hood 7 is moved therewith.
0 is configured to move.

That is, as shown in an enlarged view in FIG. 4, the connecting pin 77 is screwed into the upper half portion of the screw hole into which the first pin 65 is screwed, and is connected to the slide cylinder 55. The head of the connecting pin 77 fits into the hole formed in the inner cylinder 71 without looseness through an elongated hole 78 formed in a direction parallel to the axis.

Therefore, the operation wire 25
When the focal length of the objective optical system is changed by moving the
At the same time, the distal end hood 70 moves in the axial direction, and the position of the distal end surface A of the distal end hood 70 coincides with the distal end surface of the distal end body 10 in the normal observation state shown in FIG.

The tip hood 70 projects forward from the tip face of the tip body 10 as the focal length of the objective optical system becomes longer. When the tip hood 70 projects most from the tip body 10, the tip hood 70 extends. Tip surface A of
Coincides with the best focus position of the objective optical system in the state of closest enlargement.

Therefore, during normal observation, the tip hood 7
0 is retracted so that the wide-angle field of view can be observed without obstruction. At the time of close-up magnification, only the tip surface A of the tip hood 70 is lightly pressed against the mucous membrane, and very good focus and good proximity are obtained. Magnification observation can be performed.

The fitting surface between the inner cylinder 71 and the outer cylinder 72 and the fitting surface between the distal end body 10 and the inner cylinder 71 so as to prevent water from entering the connection pin 77 and the elongated hole 78 from the outside. In
O-rings 73, 74, 75, 76 for sealing are respectively mounted at positions before and after the connecting pin 77 and the elongated hole 78.

[0040]

According to the present invention, a distal end hood that surrounds the distal end portion of the insertion portion in a cylindrical shape and that protrudes forward is disposed so as to be able to advance and retreat in the axial direction, and interlocks with changes in the focal length of the objective optical system. The front hood can be retracted so that the field of view is not obstructed during normal observation of the wide-angle field of view, and the front hood can be protruded during close-up magnification observation to maintain an appropriate distance to the subject. If the tip surface of the tip hood is aligned with the best focus position of the objective optical system when the tip hood is in the state of being most protruded from the tip part main body, it is only necessary to lightly press the tip surface of the tip hood against the mucous membrane. Thus, it is possible to perform excellent close-up observation with very good focus.

[Brief description of the drawings]

FIG. 1 is a side cross-sectional view of a distal end portion of an insertion portion according to an embodiment of the present invention in a close-up enlarged observation state.

FIG. 2 is a side sectional view of a distal end portion of an insertion portion according to the embodiment of the present invention in a normal observation state.

FIG. 3 is a development view showing a shape of a cam groove according to the embodiment of the present invention.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is an external view showing the overall configuration of the zoom endoscope according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insertion part 10 Tip part main body 11 Observation window 20 Cover lens 21 Objective lens group 24 Solid-state image sensor 25 Operation wire 50 Cam cylinder 55 Slide cylinder 70 Tip hood 77 Connection pin 78 Slot

Claims (3)

[Claims] 1. A zoom endoscope having a variable focal length objective optical system built in an observation window disposed on a distal end surface of an insertion portion, wherein the distal end portion of the insertion portion is formed in a cylindrical shape and protrudes forward. A zoom endoscope, wherein a tip hood is provided so as to be able to advance and retreat in an axial direction, and the tip hood is advanced and retracted in conjunction with a change in a focal length of the objective optical system. 2. The zoom endoscope according to claim 1, wherein the distal end hood projects forward from the distal end surface of the distal end body as the focal length of the objective optical system increases. 3. The zoom endoscope according to claim 2, wherein when the tip hood projects most forward from the tip body, the tip face of the tip hood coincides with the best focus position of the objective optical system. .