JPH10170794A - Lens device of endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold the inside of a lens barrel in a dry state even though nitrogen substitution is not executed by constituting at least a part of a light non- transmitting member out of members provided in the lens barrel of a desiccant plate being a platelike or sheet-like desiccant. SOLUTION: By using the desiccant plate obtained by mixing silica gel powder with an olefinic binder resin and molding the mixture like a plate or a sheet, and forming the desiccant plate as an annular plate body, the desiccant plate is used as a harmful light intercepting plate 17 and a diaphragm 18 as the light non-transmitting member provided in the lens barrel 11. When it is formed like the sheet, it is fixed on the surface of a stopper ring 19 by means of adhesion, etc. In the case the stopper ring is provided in order to arrange a plane parallel plate between 1st and 2nd lenses L1 and L2 with specified space from the 1st lens L1 , a desiccant ring being annularly formed desiccant plate is stuck to the internal surface of a spacer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens device used as an objective optical system of an endoscope, and more particularly to a lens device having an anti-fog function.

[0002]

2. Description of the Related Art An endoscope is provided with an insertion section inserted into a body cavity or the like connected to a main body operation section. However, in order to observe / examine the inside of a body cavity or the like, illumination means and observation means are used. It has. The illuminating means is made of an optical fiber bundle and has a light guide for transmitting illumination light from a light source lamp of the light source device to which the endoscope is detachably connected. An emission end of the light guide is provided so as to face an illumination means mounting portion formed on the distal end body, and an illumination lens for diverging illumination light from the light guide is mounted on the illumination means mounting portion. On the other hand, the observation means is for taking out the in-vivo image information illuminated by the illuminating means to the outside, and this in-vivo image is provided as an optical image by an image guide to an eyepiece provided in connection with the main body operation unit. Using an optical endoscope for observing the image inside the body cavity by the surgeon's eye contact with the eyepiece, and imaging means, which converts information about the image inside the body cavity into an electric signal. There is an electronic endoscope in which a video signal is taken out, transmitted to a processor, the processor performs predetermined signal processing based on a signal from an imaging unit, and then displays an endoscopic image on a monitor device.

Whether an optical endoscope or an electronic endoscope,
Observation means having an objective optical system is provided at a position close to the illumination means on the distal end main body of the insertion section. The objective optical system is usually composed of a plurality of lenses, and these lenses are lens mirrors. Attached to the cylinder. In the case of an optical endoscope, the incident end of the image guide is provided at an image forming position of the objective optical system, and in the case of an electronic endoscope, an image pickup means is provided at an image forming position. Since the objective optical system is composed of a plurality of lenses, the objective optical system is mounted on the observation means mounting portion as a lens device by being mounted on a lens barrel. Then, in order to make the optical axis of the objective optical system coincide with the image forming surface formed by the incident end face of the image guide or the light receiving surface of the imaging means, a holding cylinder is provided, and the image forming surface is fixed to the holding cylinder. The holding tube is fitted to the lens barrel. Further, in order to enable focus adjustment between the objective optical system and the imaging means, the lens barrel is slidably fitted to the holding barrel, and after the focus adjustment is performed, And the holding cylinder are fixed.

[0004]

The first lens located closest to the subject in the lens barrel is a plano-concave lens, and the concave surface is located in the lens barrel. For example, the first portion exposed to the outside at the tip of the insertion portion
Contaminants such as body fluids may adhere to the surface of the lens during the inspection, and the adhesion of the contaminants deteriorates the observation visual field. Therefore, the insertion portion is provided with a lens surface cleaning mechanism for cleaning contaminants from the surface of the first lens. This lens surface cleaning mechanism is provided with a nozzle for jetting a cleaning fluid toward the outer surface of the first lens, and jets a cleaning liquid, usually cleaning water, from this nozzle to wash away contaminants,
Then, pressurized air is blown to remove the cleaning water remaining on the lens surface.

[0005] The distal end of the insertion portion, that is, the first lens, is in a temperature state substantially equal to the body temperature in the body cavity, and in the case of an electronic endoscope, a heating element such as a solid-state image sensor is present. Therefore, the temperature may be higher than the body temperature. On the other hand, the washing water is not particularly heated, and therefore, the washing water temperature is about room temperature. Therefore, when the cleaning water is sprayed on the outer surface of the first lens, the first lens is rapidly cooled. As a result of the cooling of the first lens, if the air in the lens barrel contains moisture, fogging or condensation occurs on the inner surface side of the first lens.
Moreover, since the inner surface of the first lens is a concave curved surface and its curvature is large, the temperature of the first lens at or near the center where the thickness is thinnest becomes the most remarkable,
Clouding or dew is concentrated on the central portion of the concave surface of the first lens. Light rays necessary for image formation are concentrated in the central portion of the concave surface of the first lens. If the portion is slightly clouded, the image quality of the obtained observation image is rapidly reduced and becomes extremely difficult to see. In addition, when the tip of the insertion portion is rapidly cooled, the first lens and the like may be fogged or dew may be formed.

Accordingly, a lens device used as an objective optical system of an endoscope has an anti-fog function for preventing the lens in the lens barrel, particularly the first lens, from fogging and dew condensation. I try to make it. For this purpose, for example, dry air, nitrogen gas, etc.
A device in which a gas that does not contain moisture is sealed is conventionally known. However, since the interior of the lens barrel is provided with components such as an objective optical system, it is divided into several small spaces, and it is necessary to completely replace the air in the lens barrel with a gas that does not contain moisture. Is extremely difficult, and over a long period of time, air containing moisture or moisture may enter the lens barrel, and it is not always possible to completely prevent moisture in the lens barrel. There was a problem.

The present invention has been made in view of the above points, and an object of the present invention is to ensure the completeness of moisture prevention in a lens barrel.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a lens which is provided at the distal end of an insertion portion of an endoscope and which is inserted into a holding cylinder having an imaging surface connected thereto. An objective optical system is built in the lens barrel, and at least a part of the light non-transmissive member among the members provided in the lens barrel is formed of a plate-shaped or sheet-shaped desiccant plate. The feature is.

As a desiccant plate, a plate formed by dispersing silica gel in an olefin-based resin and using a plate is used.
This is preferable because it can exhibit a moisture-proof effect over a long period of time and can be formed into a desired shape. As the light non-transmissive member provided in the lens barrel, there are an aperture and a harmful light shielding plate, a spacer interposed between the lenses, a stopper ring for fixing the lens located at the end, and the like. There is also. The aperture and the harmful light shielding plate can be formed of a desiccant plate as it is, and in the case of a spacer, a stopper ring or the like, the desiccant plate can be adhered to the inner surface or the like.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. First, FIG. 1 shows an appearance of a distal end portion of an insertion portion of an endoscope. In the drawing, reference numeral 1 denotes an insertion portion, and a distal end portion of the insertion portion 1 is a distal end main body 1a made of a hard member. The distal end main body 1a is bent in a desired direction over a predetermined length. An operable angle portion 1b is continuously provided, and although not shown, a flexible portion is continuously provided on the angle portion 1b. Tip body 1a
An illumination window 2 and an observation window 3 are provided on the distal end surface (or side surface) of the device, and a treatment tool insertion channel 4 through which forceps and other treatment tools are inserted is opened. A nozzle 5 for jetting a cleaning fluid, for example, cleaning water and pressurized air toward the window 3 is provided. Here, the distal end portion main body 1a has a high strength as a structural member, and is generally formed of a metal because the above-described various members are fixed, so that the metal is directly exposed to the outside. In order to prevent this, the distal end body 1a is covered with a cap 6 made of an electrically insulating member, and the joint between the distal end body 1a and the cap 6 is sealed with a sealing material. Therefore, the illumination window 2, the observation window 3, the treatment instrument insertion channel 4, and the nozzle 5 are opened in the cap 6.

FIG. 2 shows a cross section of the tip body 1a. A through-hole penetrating in the axial direction is provided at the site of the observation window 3 in the distal end body 1a, and the observation unit 10 is mounted in the through-hole. The observation unit 10 has a lens barrel 11 on which a plurality of lenses constituting an objective optical system are mounted, and a holding barrel 12 is fitted to the lens barrel 11. A filter 13 and a prism 14 for bending the optical path by 90 ° are joined to the holding cylinder 12.
Is connected to a solid-state imaging device 16 as imaging means mounted on a substrate 15. Note that a configuration may be employed in which the solid-state imaging device is directly connected to the holding cylinder without providing a prism.

The lens configuration of the objective optical system provided in the lens barrel 11 shown in FIG. 2 includes four lenses L ₁ ,
It is composed of L ₂ , L ₃ and L ₄ . Each of these lenses L
The first lens L closest to the object side among _{1 to} L ₄
Reference numeral ₁ denotes a plano-concave lens having a flat surface on the object side and a concave surface on the image forming side, and the flat surface is exposed to the observation window 3. The second lens L ₂ is located from the first lens L ₁ on the object side is a plano-convex lens having a convex surface facing the image side. Further, the third lens L ₃ and the fourth lens L ₄ are constituted by cemented lenses. An annular harmful light shielding plate 17 is provided on the outer peripheral portion between the first lens L ₁ and the second lens L _2, and the harmful light shielding plate 17 cuts harmful light. ing. Between the second lens L ₂ and the third lens L ₃ , there is formed a spacer 11 a formed of a ridge provided on the inner surface of the lens barrel 11.
Diaphragm 18 is interposed between the 1a and the third lens L _3. Then, the position of the image forming side of the fourth lens L ₄ is a stopper ring 19 for fixedly holding the lens L ₁ ~L ₄ is provided.

The lens barrel 1 equipped with the above objective optical system
Numeral 1 is slidably inserted into the holding barrel 12, and the lens barrel 11 is moved in the optical axis direction to adjust the distance between the objective optical system and the solid-state imaging device 16 so as to focus. Adjustments can be made. Then, with the focus adjusted, the lens barrel 11 and the holding barrel 12 are fixed using an adhesive or the like, but the inside of the lens barrel 11 is kept airtight.

[0014] First, the lens barrel 11 and the sealing material is filled between the first lens L _1. Here, the lens barrel 11
And the tip incorporates a first lens L ₁ in a state of protruding a predetermined length, when mounting the observation unit 10 at the distal end portion main body 1a, the first lens L ₁ in the hole 6a formed in the cap 6 , Are arranged at positions corresponding to the surface of the cap 6. As a result, an annular concave portion is formed by the first lens L ₁ , the inner surface of the through hole 6 a of the cap 6, and the distal end surface of the lens barrel 11.
Is filled. Further, a solid-state imaging device 16 mounted on the prism 14 and the substrate 15 is provided at a position rearward of the holding cylinder 12, and this portion is almost entirely sealed with a sealing material 21. Furthermore, the space between the distal end surface of the holding barrel 12 and the peripheral body of the lens barrel 11 after the focus adjustment is performed is also filled with the sealing material 22. As a result, the entire lens barrel 11 is sealed and kept airtight.

The lens barrel 11 has four lenses L inside.
₁ but ~L ₄ and other members incorporated in the lens device is formed, the assembly workshop the lens device is not turned to the exceptional moisture space, for example, these members incorporated under humid conditions The lens barrel 11
The air inside becomes wet. As a result, air containing moisture originally exists in the space inside the lens barrel 11, and if the lens barrel 11 is sealed in this state, moisture cannot be eliminated inside. It is necessary to dry the inside before sealing.
For this reason, nitrogen replacement may be conventionally performed, but since the internal space of the lens barrel 11 is complicatedly partitioned by various members, complete nitrogen replacement cannot be performed.

As described above, in the present invention, instead of performing the nitrogen replacement, the lens barrel 11 is dried using a desiccant.
The inside is dried. However, when the desiccant is stored in the lens barrel, the lens barrel 1
1 becomes large. If the lens barrel 11 becomes large, the diameter of the insertion section 1 becomes large, so that it is not possible to simply store the desiccant.

Therefore, in the present invention, as a desiccant, FIG.
As shown in the figure, the silica gel S powder was
And a desiccant plate P formed into a plate shape or a sheet shape by mixing the same. Here, an olefin resin is used as the binder resin R. Since the olefin resin has a low moisture permeability, the drying effect of the silica gel S is maintained for a long time. The shape and thickness of the desiccant plate P can be arbitrarily determined by molding. further,
If a black paint having a hygroscopic property is applied, light reflection can be prevented. Therefore, the desiccant plate P cannot be used as a member for transmitting light, such as a lens, but is formed into a required shape, and among various members provided within the lens barrel 11, It can be used as a non-transmissive member. In addition, it is also possible to fix not to the light non-transmissive member itself but to a light non-transmissive member by means such as adhesion.

In the lens barrel 11, not only a lens constituting the objective optical system but also a light non-transmissive member which does not transmit light is provided. As shown in FIG. 2, the light non-transmissive member includes a harmful light shielding plate 17 and a diaphragm 18. These members are formed of an annular plate, and their openings are formed of light. , But the plate itself does not transmit light. The stopper ring 19 is also a light non-transmissive member. However, since the stopper ring 19 positions the lens, a high strength is required, and it is necessary to prevent deformation or the like even if the stopper ring 19 is strongly pressed against the lens or the like.

As described above, the desiccant plate P can be used as an annular plate constituting the harmful light shielding plate 17 and the diaphragm 18. In this case, the desiccant plate P needs to be formed as thin as possible, and its surface needs to have high light absorbency. Therefore, a black paint is applied to both the front and back surfaces of the desiccant plate P, or at least a black pigment is mixed with the binder resin R. After the black pigment is mixed with the binder resin R, the front and back surfaces are further coated with the black paint. Most preferably. On the other hand, the desiccant plate P cannot be used as the stopper ring 19 itself in terms of strength and the like, but can be fixed to the surface of the stopper ring 19 by means such as adhesion. In this case, the desiccant P is formed into a thin sheet so as not to be bulky.

As described above, the harmful light shielding plate 17 and the diaphragm 1
By forming the desiccant plate 8 as a desiccant plate 8 or fixing the desiccant plate P to the stopper ring 19, the lens barrel 1
The humidity in the lens barrel 11 can be reliably removed without taking measures such as replacing the gas inside the lens barrel 1.
Therefore, the lens L in the lens barrel 11 is inspected during the examination of the body cavity.
There is no danger of fogging or dew condensation on _{1 to} L ₄ , and a very good observation field of view can be obtained by the solid-state imaging device 16. Moreover, no special members are additionally provided in the lens barrel 11, and since they are not particularly bulky, the lens barrel 11 does not become large.

The observation unit 10 is mounted on the distal end main body 1a. Of the observation unit 10, a holding cylinder 12 is mounted on the distal end main body 1a. A substrate 15 and a solid-state imaging device 16 are connected to each other in a space on the side connected to the angle portion 1b. The most bulky part of the observation unit 10 is the part where the substrate 15 and the solid-state imaging device 16 are provided, and the part attached to the distal end body 1a is more compact. In addition, members other than the observation unit 10, such as a light guide and a treatment tool insertion channel 4 that constitute an illumination unit, have a substantially uniform shape in the axial direction. Therefore, even if the mounting portion of the holding cylinder 12 to the distal end main body 1a is made slightly thick, it does not cause the insertion portion 1 to have a large diameter. Therefore, the outer diameter side is enlarged by increasing the thickness of the holding tube 12, which is a portion fitted to the lens barrel 11, and which is attached to the inside of the distal end body 1a toward the outside. An annular concave groove 23 is formed on the inner peripheral surface of the thickened portion, and the same desiccant plate P as described above is provided between the concave groove 23 and the outer surface of the lens barrel 11. Alternatively, another desiccant 24 is provided. Thereby, the inside of the lens barrel 11 can be kept in a more dry state.

By the way, among the lenses provided in the lens barrel, since it is easy concave of the first lens L ₁ is the most cloudy, be dried in the space between the first lens L ₁ and second lens L ₂ Especially required. Therefore, in order to dry this portion more efficiently, the portion may be configured as shown in FIG.

In FIG. 1, reference numeral 30 denotes a lens barrel, and four lenses L _{1 to} L ₄ are provided in the lens barrel 30.
Is attached, and the first lens L ₁ and the second lens L
The plane-parallel plate G between ₂ provided, and forming a predetermined space between the plane-parallel plate G and the first lens L _1. In order to ensure this space, on the inner surface of the first lens L ₁ and spacer 31 of the annular interposed harmful between Matasupesa 31 and the first lens L ₁ A light shielding plate 32 is provided. The diaphragm 33 is disposed between the second lens L ₂ and the third lens L _3, and a stopper ring 34 is disposed at a portion on the image forming side of the fourth lens L ₄ . A seal member 35 such as an O-ring is attached to the outer peripheral surface of the parallel flat plate G, and the first lens is formed by the seal member 35 and a seal material filled between the first lens L ₁ and the lens barrel 30. sealing the space between L ₁ and the plane parallel plate P. And
On the inner surface of the spacer 31, a desiccant ring 36 in which the desiccant plate P described above is formed in an annular shape is attached and fixed.

Here, the spacer 31 is for maintaining a distance between the first lens L ₁ and the plane-parallel plate G.
The outer peripheral portion of the lens L ₁ is flat. Accordingly, the spacer 31 and the harmful light shielding plate 32 is in surface contact with the first lens L _1, also because by both surface contact parallel plate G, also the thickness thereof was extremely thin, scan The function as a pulser is fully demonstrated. Therefore, this spacer 31
Inside the can be fitted with desiccant ring 36 of substantial thickness, in the lens barrel 30, a very a limited space, yet sealed first and lens L ₁ and the plane-parallel plate G Is substantially completely absorbed by the desiccant ring 36, and becomes a substantially completely dry space.

With the above arrangement, the first lens L ₁
As was rapid temperature change on the outer surface side or the like of even a possibility that fogging and dew condensation occurs on the inner surface side of the first lens L ₁ is completely eliminated. The first lens L ₁ other than the plane parallel plate G
As for the optical components on the image forming side from the surface joined to the second lens L ₂ , the air sealed between the first lens L ₁ and the plane-parallel plate G has an adiabatic effect. Therefore,
Even if there are sudden temperature changes on the outer surface side of the insertion portion, those temperature changes are alleviated, so that the occurrence of fogging, dew condensation, and the like is also suppressed. Of course, by forming the diaphragm 33 with the desiccant plate P or the like, the overall drying function of the lens barrel 30 can be further improved, and the lenses L _{1 to} L ₄ can be improved.
The parallel flat plate G is also protected from fogging.

[0026]

As described above, according to the present invention, of the members provided in the lens barrel, at least a part of the light non-transmissive member is formed of a desiccant plate in which a desiccant is formed in a plate shape or a sheet shape. With this configuration, it is possible to maintain the inside of the lens barrel in a dry state without performing nitrogen replacement or the like.

[Brief description of the drawings]

FIG. 1 is an external view showing a distal end portion of an insertion section of an endoscope.

FIG. 2 is a cross-sectional view of a lens device of an endoscope showing one embodiment of the present invention.

FIG. 3 is a sectional view of a desiccant plate.

FIG. 4 is a cross-sectional view of a lens device showing another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Insertion part 1a Tip main body 3 Observation window 10 Observation unit 11, 30 Lens barrel 12 Holding cylinder 17, 32 Harmful light shielding plate
18, 33 aperture 19, 34 stopper ring 31 spacer 35 sealing member 36 desiccant ring L ₁ ~L ₄ lens P desiccant plate
S silica gel R resin G parallel flat plate

Claims (5)

[Claims] A lens barrel provided with an objective optical system in a lens barrel provided at a distal end portion of an insertion portion of the endoscope and inserted into a holding barrel having an imaging surface connected thereto; A lens device for an endoscope, wherein at least a part of a light non-transmissive member among members provided in a cylinder is formed of a plate-shaped or sheet-shaped desiccant plate. 2. The endoscope lens device according to claim 1, wherein the desiccant plate is formed by dispersing silica gel in an olefin-based resin and molding the desiccant plate into a plate shape. 3. A lens device for an endoscope according to claim 1, wherein said aperture as said light non-transmissive member or said harmful light shielding plate is constituted by said desiccant plate. 4. A spacer ring provided to hold optical components constituting the objective optical system at a predetermined interval, and a stopper ring for fixedly holding the objective optical system or a spacer constituting a light non-transmissive member. A lens device for an endoscope, wherein a desiccant plate is formed into a sheet and attached. 5. The endoscope according to claim 1, wherein an annular concave portion is formed between the holding tube and the lens barrel, and a desiccant is sealed in the concave portion. Lens equipment.