JPH0788078A - Optical instrument for endoscope - Google Patents

Abstract

PURPOSE:To provide an optical instrument for an endoscope with which the examiner can focus the lens from the side of the hard parts on top of the scope after the hard parts including the optical instrument have been assembled, and which can cope with deep observation and achieve the maximum resolving power. CONSTITUTION:On top of the scope, installed are the illumination optical instrument 8 which irradiates light to observe the inside of the subject's body; the objective 9 which has the lens 12 to collect light reflected from the irradiated observed part; and the photographing element 14 to get an image from the light collected by that objective And the device 21 is provided so that the lens 12 of the objective 9 can be focused from the top of the scope.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an optical system of an endoscope, and particularly, when a fixed focus type objective optical system capable of photographing a wide range with a simple structure is used as a lens system of the objective optical system. The present invention relates to an endoscope optical system device capable of adjusting the focal position of the lens system.

[0002]

2. Description of the Related Art Endoscope devices include fiberscope type and electronic endoscopes, which will be briefly described with reference to FIG. In FIG. 6, the endoscope apparatus includes a monitor 1 for displaying an endoscopic image, an apparatus main body 2 including an operation control switch, and a scope 3 used by being inserted into a body cavity of a subject.
And. At the tip of the flexible tube 4 which is the insertion portion of the scope 3, a rigid portion 5 equipped with an optical system including a CCD camera, a forceps hole, a cleaning nozzle and the like is provided. On the other hand, on the proximal end side of the flexible tube 4, an operation unit 6 for performing an angle operation or the like which is a bending operation of the flexible tube 4 of the scope 3.
And a universal cord 7 for transmitting a video camera signal to the device body 2. Although not shown, inside the flexible tube 4, a light guide fiber bundle, an air supply tube, a water supply tube, a wiring cable, and the like are incorporated. Then, the rigid portion 5 is
Usually, as shown in FIG. 7, two illumination optical systems 8 and one objective optical system 9 and forceps holes 10 and two air / water feeding holes 1 are provided.
It is composed of 1 and 1.

The optical system of such an endoscope, particularly the objective optical system 9, is roughly classified into a single focus lens type and a zoom lens type. Further, the single focus lens type includes a focus adjustment type and a fixed focus type. The zoom lens type and the focus adjustment type single focus lens type are variously devised so that the magnification and the focus position can be changed from the operation section 6 of the scope 3 during surgery, but both have a complicated structure, Since the diameter of the tip, that is, the rigid portion 5 is large, and there are problems in durability, the fixed focus type single focus lens type is still mainstream as the objective optical system 9 of the endoscope. This fixed focus type single focus lens type is as shown in FIG.
FIG. 8 shows the objective optical system 9 and the forceps hole 10 of the rigid portion 5.
A sectional view taken along a line connecting the centers of the is shown. In FIG. 8, reference numeral 10 is a forceps hole, and reference numeral 12 is a lens system of the objective optical system 9. This lens system 12 is arranged inside a cylinder. A prism 13 is disposed behind the cylindrical objective lens system 12, and a light beam reflected by the prism 13 is detected by a solid-state image pickup device 14 such as a CCD, converted into an electric signal, and then a wiring cable 15 is used to detect the light beam. It is transmitted to the apparatus main body 2 via the universal code 7 to be imaged and displayed on the monitor 1. The lens system 12, the prism 13, and the solid-state image sensor 14 are accurately positioned and installed on the positioning member 16 made of metal or the like in the rigid portion 5. After that, the cap 17 made of resin or the like is attached. Reference numeral 18 is a cover glass provided on the cap 17, and reference numeral 19 is a fixing member that engages with the positioning member 16 and the cap 17. Reference numeral 20 is a waterproof O-ring made of rubber or the like.

The conventional fixed-focus type single-focus lens type of this type is a type of observation depth or a type of maximum resolution by changing the distance from the solid-state image sensor 14 such as CCD even if the same lens system 12 is used. Can be of any type. If the image distance (the distance between the lens and the image pickup surface) is shortened, the former type is used. Conversely, if the image distance is lengthened, the latter type is used. This is determined by the needs of the user and other needs, but the adjustment of the focus position had to be completed before the cap 17 was attached. Moreover, once assembled, changing the focus position is a fairly large-scale task, which is virtually impossible.

[0005]

In the conventional optical system device for an endoscope of this type, the focus position must be accurately adjusted when the lens system of the objective optical system is attached to the rigid portion to be assembled. There was a problem that it was rather troublesome work. In addition, there is a disadvantage that a large-scale dismantling work is required in the unlikely event that an adjustment failure occurs. In addition, even if the user is dissatisfied with the focal position when assembled, the focal position cannot be adjusted.

The present invention has been made in view of the above circumstances, and an object thereof is to adjust the focal position of the lens system even after the assembly of the rigid portion of the scope distal end portion including the optical system of the endoscope is completed. It is an object of the present invention to provide an optical system device for an endoscope having an objective optical system which can be formed from the side of a hard part and can be attached to both observation depth and maximum resolution.

[0007]

In order to achieve the above object, the present invention makes it possible to adjust the focal position of the lens system by configuring the optical system device of the endoscope as follows. That is,
An illumination optical system for irradiating light for observing the inside of a body cavity of a subject, an objective optical system having a lens system for condensing light reflected from an observation site irradiated with light, and the objective optical system An image pickup element for obtaining an image from light collected by the system, and a means for adjusting the focus position of the lens system of the objective optical system from the scope tip. It is what

[0008]

According to the above construction, in the endoscope optical system device, the member for adjusting the focal position of the lens system of the objective optical system is arranged at the distal end portion of the scope, that is, the hard portion. The focus position of the lens system can be adjusted even after assembly is complete, and it can be used for both types of observation depth-oriented and maximum resolution-oriented.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. The same members as those described in the related art are designated by the same reference numerals. FIG. 1 is for explaining an optical system device for an endoscope of the present invention, and is basically the same as FIG. 7. Therefore, in FIG. 1, two illumination optical systems 8 for irradiating light for observing the inside of the body cavity of the subject and one for condensing the light reflected from the observation site irradiated with the light are provided. The objective optical system 9, the centers C and D of the exit surface of each optical system, the forceps hole 10 and its center E are shown. A straight line connecting the objective optical system 9 and the forceps hole 10, that is, a line L connecting the center D and the center E is shown. In the following examples, the configuration of the objective optical system 9 will be described based on a sectional view taken along the line L.

FIG. 2 is a diagram showing an embodiment of the objective optical system of the endoscope optical system device of the present invention. In FIG. 2, the forceps hole 10 and the objective optical system 9 are mainly shown in the rigid portion 5 at the tip of the scope. The objective optical system 9 includes a lens system 12 arranged inside a cylinder and a prism 13 behind the lens system 12.
And a cover glass 18 provided on the cap 17 in front of the lens system 12. The objective optical system 9 collects the light irradiated by the illumination optical system and reflected from the observation site, and projects the collected light onto a solid-state image sensor 14 such as a CCD. The solid-state image sensor 14 detects a light beam, converts it into an electric signal, and transmits the electric signal to the apparatus main body by a wiring cable 15. This transmission is transmitted to the apparatus main body 2 via the universal code 7 as described above, and is imaged and displayed on the monitor 1. These lens system 12 and prism 1
3 and the solid-state imaging device 14 are accurately positioned and installed on the positioning member 16 made of metal or the like in the rigid portion 5. After that, a waterproof O-ring 20 is incorporated, and a cap 17 made of resin or the like is attached. Finally, the positioning member 16 and the cap 17 are fixed by the fixing member 19 that engages with the cap 17. In this embodiment, a long screw 21 is provided parallel to the longitudinal direction of the cylindrical objective lens system 12, and a worm gear 22 is attached to the tip of the long screw 21.
A rack gear 23 that engages with the worm gear 22 is provided on the outer circumference of the lens system 12 in the longitudinal direction.
The rotation of 1 allows the lens system 12 to move linearly along the groove 24. Reference numeral 25 is an O-ring, which is provided to keep airtightness.

FIG. 3 schematically shows the relationship between the long screw 21, the lens system 12 and the gear of this embodiment. In FIG. 3, a worm gear 22 is provided at the tip of the long screw 21, a rack gear 23 is provided on the outer periphery of the lens system 12, and the worm gear 22 and the rack gear 23 are engaged with each other. Therefore, by rotating the long screw 21, the lens system 12
Can be moved linearly in the longitudinal direction along the groove 24 (see FIG. 2). In this case, long screw 2
1 and the worm gear 22 are provided in a portion having a relatively large space in the tip side from the position where the solid-state image sensor 14 is installed, and therefore, the zoom lens type and the focus adjustment type single focus lens type described in the prior art are used. There is no need to thicken the tip of the scope.

FIG. 4 is a diagram showing another embodiment of the objective optical system of the optical system device for an endoscope of the present invention. FIG. 4 is a perspective view thereof, and its configuration is basically the same as that of FIG.
That is, the rigid portion 5 at the tip of the scope is shown with two illumination optical systems 8, one objective optical system 9, forceps holes 10, and two air supply / water supply holes 11. Further, the objective optical system 9 includes a cylinder 12 in which a lens system is disposed and a prism 13 behind the cylinder 12. Illumination optical system 8
The light reflected by the observation site is collected by the CCD and the collected light is passed through this prism 13 to the CCD.
And so on.
In this embodiment, a long screw 21 is provided in the direction parallel to the image pickup surface of the solid-state image pickup device 14 and perpendicular to the longitudinal direction of the cylindrical objective lens system 12, and the pinion gear 26 is provided at the tip of the long screw 21. Is provided. This pinion gear 26
A rack gear 23 that engages with is provided in the longitudinal direction on the outer circumference of the lens system 12, and the lens system 12 can be linearly moved in the longitudinal direction by rotation of the long screw 21.

The relationship between the long screw 21, the lens system 12 and the gear of this embodiment is schematically shown in FIG. In FIG. 5, a pinion gear 26 is provided at the tip of the long screw 21, and this is engaged with a rack gear 23 provided on the outer circumference of the lens system 12. Therefore, by rotating the long screw 21, the lens system 12 can be linearly moved in the longitudinal direction along the groove 24 (see FIG. 2). In this case, the long screw 21 must be provided in the direction perpendicular to the longitudinal direction of the cylindrical lens system 12. Therefore, the O on the side of the rigid part 5
Must be installed with ring 25. It can be seen from Fig. 2 that the installation position is a part with a relatively large space.
Is the same as the embodiment shown in FIG.

By using such an objective optical system 9, the focus position can be adjusted by simply rotating the long screw 21 even after the assembly of the endoscope is completed. Generally, when the focal point of the lens system is f, the object distance a (distance between the lens and the best object point) and the image distance b (distance between the lens and the imaging surface)
, And the relationship of 1 / f = 1 / a + 1 / b is established. Here, the best object point means where the object looks best. Also, the depth of field of the lens system, which is almost the same as the observation depth of the endoscope (the range that can be seen in focus)
Is the front side depth P1 centered on the best object point position

[0015]

[Equation 1] Rear depth P2

[0016]

[Equation 2] Given in. Here, δ is the minimum permissible circle of confusion, F is the F number of the lens. Therefore, when the same optical system is used, δ, F, and f are constant. Therefore, if a becomes large, the difference between P1 and P2, In other words, it turns out that the depth becomes deep.

For the above reasons, if a is small, the best object point becomes close to it, and it looks large and high resolution can be obtained. If a is large, the best object point becomes far, but the depth can be made deep. Therefore, by operating the long screw 21 according to the purpose, the objective optical system 9 having a desired focal position can be obtained. As described above, according to the present invention, the range of focus is relatively long, the structure is simple, and the features of the fixed-focus single-focus lens type are not lost,
By changing the focal position, it is possible to use either the observation depth-oriented type or the resolution-oriented type.

In the above embodiment, the lens system 12 is moved with respect to the solid-state image pickup device 14. Although the observation depth and the resolving power can be adjusted, the zoom magnification of the lens system may be adjusted by providing a structure in which only some lenses of the lens system are movable.

In the present invention, a direct-viewing type scope in which the solid-state image pickup device is arranged perpendicularly to the axial direction of the flexible tube,
The same can be applied to a side-view type scope in which an optical system is provided on the side of the rigid portion at the tip of the scope.

[0020]

As described above, according to the endoscope optical system apparatus of the present invention, the focus position of the lens system of the objective optical system is adjusted from the outside of the distal end portion of the scope even after the assembly is completed. Since it is possible to do so, depending on the user's request, it is possible to use either the observation depth-oriented type or the maximum resolution-oriented type.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an optical system device for an endoscope of the present invention.

FIG. 2 is a diagram showing an example of an objective optical system of an optical system device for an endoscope of the present invention.

FIG. 3 is a diagram schematically showing the relationship between the long screw, the lens system, and the gear according to the embodiment.

FIG. 4 is a diagram showing another embodiment of the objective optical system of the endoscope optical system device of the present invention.

FIG. 5 is a diagram schematically showing a relationship between a long screw, a lens system, and a gear according to another embodiment.

FIG. 6 is a diagram for explaining the outline of the endoscope device.

FIG. 7 is a diagram for explaining the outline of the distal end portion of the endoscope apparatus scope.

FIG. 8 is a diagram for explaining a conventional technique.

[Explanation of symbols]

 1 Monitor 2 Device Main Body 3 Scope 4 Flexible Tube 5 Rigid Section 6 Operating Section 7 Universal Code 8 Illumination Optical System 9 Objective Optical System 10 Forceps Hole 11 Air / Water Transmission Hole 12 Lens System 13 Prism 14 Solid-state Image Sensor 15 Wiring Cable 16 Positioning member 17 Cap 18 Cover glass 19 Fixing member 20 O-ring 21 Long screw 22 Worm gear 23 Rack gear 24 Groove 25 O-ring 26 Pinion gear

Claims (3)

[Claims] 1. An objective optical system having an illumination optical system for irradiating light for observing the inside of a body cavity of a subject, and a lens system for condensing light reflected from an observation site irradiated with light. And an image pickup device for obtaining an image from the light collected by this objective optical system at the tip of the scope, and a means for adjusting the focus position of the lens system of the objective optical system from the tip of the scope. An optical system device for an endoscope, which is provided. 2. A means for adjusting the focus position,
A long screw provided in the same direction as the moving direction of the lens system,
It has a worm gear installed at the tip of the long screw and rotated by rotation of the long screw, and a rack gear installed in the lens system and engaged with the worm gear to linearly move the lens system by rotation of the long screw. The optical system device for an endoscope according to claim 1. 3. A means for adjusting the focus position,
A long screw provided in the direction perpendicular to the moving direction of the lens system,
It has a pinion gear that is installed at the tip of this long screw and that rotates by rotation of the long screw, and a rack gear that is installed in the lens system and that engages with this pinion gear and moves the lens system linearly by rotation of the long screw. The optical system device for an endoscope according to claim 1.