JP3692670B2 - Endoscope lens device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens device used as an objective optical system of an endoscope, and particularly to a lens device having an antifogging function.
[0002]
[Prior art]
An endoscope is formed by connecting an insertion portion to be inserted into a body cavity or the like to a main body operation portion, and includes an illuminating means and an observation means for performing observation / inspection inside the body cavity or the like. The illuminating unit includes a light guide that includes an optical fiber bundle and transmits illumination light from a light source lamp of a light source device to which an endoscope is detachably connected. The light guide emitting end is provided so as to face the illumination means mounting portion formed on the tip body, and the illumination means mounting portion is mounted with an illumination lens for diverging illumination light from the light guide. On the other hand, the observing means is for extracting the in-vivo image information illuminated by the illuminating means to the outside, and this in-vivo image is optically imaged by an image guide in an eyepiece unit connected to the main body operation unit. The optical endoscope that observes the image in the body cavity by the operator's eye contact with the eyepiece and the imaging means are used, and the information on the body cavity image is converted into an electrical signal by the imaging means. There is an electronic endoscope in which an endoscope image is displayed on a monitor device after the signal is taken out and transmitted to a processor, and predetermined signal processing is performed on the basis of a signal from an imaging means by the processor.
[0003]
Whether it is an optical endoscope or an electronic endoscope, the distal end main body of the insertion portion is provided with observation means having an objective optical system at a position close to the illumination means. These lenses are composed of a plurality of lenses, and these lenses are mounted on a lens barrel. In the case of an optical endoscope, the incident end of the image guide is provided at the image forming position of the objective optical system, and in the case of an electronic endoscope, the imaging means is provided. Since the objective optical system is composed of a plurality of lenses, it is mounted on the observation means mounting portion as a lens device by mounting on the lens barrel. And in order to make the optical axis of the objective optical system and the imaging surface consisting of the incident end face of the image guide or the light receiving surface of the imaging means coincide with each other, a holding cylinder is provided, and the imaging plane is fixed to the holding cylinder The holding cylinder is fitted into the lens barrel. Further, in order to enable focus adjustment between the objective optical system and the image pickup means, the lens barrel is slidably fitted to the holding barrel, and after the focus adjustment is made, the lens barrel And the holding cylinder are fixed.
[0004]
[Problems to be solved by the invention]
Incidentally, 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, contaminants such as body fluid may adhere to the surface of the first lens exposed to the outside at the distal end of the insertion portion, and the observation field of view deteriorates due to the adhesion of the contaminants. Therefore, the insertion portion is provided with a lens surface cleaning mechanism for washing away the contaminants from the surface of the first lens. The lens surface cleaning mechanism is provided with a nozzle that ejects a cleaning fluid toward the outer surface of the first lens, and a cleaning liquid, usually cleaning water, is sprayed from the nozzle to wash away the contaminants, and then pressurized air To remove the cleaning water remaining on the lens surface.
[0005]
Since the distal end of the insertion portion, that is, the first lens is in a temperature state almost 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 imaging device exists. It may become higher than body temperature. On the other hand, the washing water is not particularly heated, and the washing water temperature is about room temperature. For this reason, when the washing 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 the curvature thereof is large, the temperature drop of the thinnest central portion or the vicinity thereof is the most remarkable among the first lenses, and the first lens has a concave surface. Cloudy or condensed in the central part. The central portion of the concave surface of the first lens is concentrated with light rays necessary for image formation. If even this portion is slightly cloudy, the image quality of the obtained observation image is drastically deteriorated and becomes extremely difficult to see. In addition to this, if the tip of the insertion portion is rapidly cooled, the first lens or the like may be clouded or dewed.
[0006]
Therefore, in a lens apparatus used as an objective optical system of an endoscope, an anti-fogging function for preventing the lens in the lens barrel, particularly the first lens, from being fogged or condensed is provided. ing. For this reason, for example, a device in which a gas that does not contain moisture, such as dry air or nitrogen gas, is sealed in the space in the lens barrel. However, because the lens barrel is provided with components such as an objective optical system, it is divided into several small spaces, and completely replaces the air in the lens barrel with a gas that does not contain moisture. In addition to being extremely difficult, there is a possibility that air containing moisture or moisture may enter the lens barrel for a long period of time, and it is not always possible to completely prevent moisture in the lens barrel. There was a problem.
[0007]
The present invention has been made in view of the above points, and an object of the present invention is to assure moisture-proof integrity in the lens barrel.
[0008]
[Means for Solving the Problems]
In order to achieve the above-described object, the present invention incorporates an objective optical system in a lens barrel that is provided at a distal end portion of an insertion portion of an endoscope and is fitted into a holding barrel to which an imaging surface is connected. A harmful light shielding plate is mounted in the lens barrel, and the harmful light shielding plate is composed of a desiccant plate made of a plate-like or sheet-like light non-transmissive member. To do.
[0009]
The drying agent plate, silica gel is dispersed in the olefin resin used as formed in a plate shape with ", it is possible to exhibit the moisture-proof for a long period of time, and since it formed into a desired shape preferred. Adverse the other light shielding plate, as a light non-transmissive member provided in the lens barrel, the diaphragm Riga, also fixing the lens positioned spacer and an end portion which is interposed like between the lens and the lens There is also a stopper ring, etc. The diaphragm and the harmful light shielding plate can be formed of a desiccant plate as they are, and in the case of a spacer, a stopper ring or the like, the desiccant plate can be attached to the inner surface or the like.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, FIG. 1 shows the appearance of the distal end portion of the insertion portion of the endoscope. In the figure, reference numeral 1 denotes an insertion portion, and a distal end portion of the insertion portion 1 is a distal end portion main body 1a made of a hard member, and the distal end portion main body 1a is curved in a desired direction over a predetermined length. An operable angle portion 1b is provided continuously, and further, although not illustrated, a flexible portion is provided continuously with the angle portion 1b. An illumination window 2 and an observation window 3 are provided on the distal end surface (or side surface) of the distal end main body 1a, a treatment instrument insertion channel 4 through which forceps and other treatment instruments are inserted is opened, and the observation window 3 is soiled. Sometimes, a nozzle 5 for injecting a cleaning fluid, for example, cleaning water and pressurized air, is provided toward the observation window 3. Here, the tip main body 1a has a high strength as a structural member and is generally formed of metal because the various members described above are fixed, and the metal is directly exposed to the outside. In order to prevent this, the tip portion main body 1a is covered with a cap 6 made of an electrically insulating member, and the joint between the tip portion main body 1a and the cap 6 is sealed with a sealing material. Accordingly, the illumination window 2, the observation window 3, the treatment instrument insertion channel 4 and the nozzle 5 are open to the cap 6.
[0011]
FIG. 2 shows a cross section of the tip portion main body 1a. A through-hole penetrating in the axial direction is provided at the site of the observation window 3 in the distal end main 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 the objective optical system are mounted, and a holding cylinder 12 is fitted into 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, and a solid-state imaging device 16 as an imaging means attached to the substrate 15 is joined to the prism 14. In addition, it is good also as a structure which connects a solid-state image sensor directly to a holding cylinder, without providing a prism.
[0012]
The lens configuration of the objective optical system provided in the lens barrel 11 shown in FIG. 2 includes four lenses L ₁ , L ₂ , L ₃ and L ₄ . Among these lenses L _{1 to} L ₄ , the first lens L ₁ located closest to the subject side is a plano-concave lens in which the subject side is a flat surface and the imaging side is a concave surface, and the flat side is exposed to the observation window 3. ing. The second lens L ₂ is located from the first lens L ₁ to the image 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} consists of a cemented lens. An annular harmful light shielding plate 17 is provided between the first lens L ₁ and the second lens L ₂ on the outer peripheral side, and harmful light is cut by the harmful light shielding plate 17. ing. Between the second lens L ₂ and third lens L ₃ spacer 11a made of protrusions provided on the inner surface of the lens barrel 11 is formed, and this spacer 11a and the third lens L ₃ A diaphragm 18 is interposed between the two. A stopper ring 19 for holding the lenses L _{1 to} L ₄ in a fixed manner is provided at a position on the image forming side of the fourth lens L ₄ .
[0013]
The lens barrel 11 equipped with the objective optical system described above is slidably inserted into the holding cylinder 12, and the objective optical system, the solid-state imaging device 16, and the lens barrel 11 are moved in the optical axis direction. It is possible to adjust the focus by adjusting the distance between the two. Then, the lens barrel 11 and the holding barrel 12 are fixed using an adhesive or the like in a state where focus adjustment is performed, but the inside of the lens barrel 11 is held airtight.
[0014]
First, a sealing material is filled between the lens barrel 11 and the first lens L ₁ . Here, the first lens L ₁ is incorporated in a state protruding from the tip of the lens barrel 11 by a predetermined length, and when the observation unit 10 is mounted on the tip body 1 a, the first lens L ₁ is attached to the cap 6. In the formed through-hole 6a, it arrange | positions in the position which corresponds with the surface of the cap 6. FIG. As a result, an annular recess is formed by the first lens L ₁ , the inner surface of the through-hole 6 a of the cap 6, and the tip surface of the lens barrel 11, and this recess is filled with the sealing material 20. In addition, a solid-state imaging device 16 mounted on the prism 14 and the substrate 15 is provided at a rear position of the holding cylinder 12, and this part is sealed with a sealing material 21 over almost the whole. Further, the sealing material 22 is also filled between the front end surface of the holding cylinder 12 and the peripheral barrel of the lens barrel 11 after the focus adjustment. As a result, the entire lens barrel 11 is sealed and kept airtight.
[0015]
Although the lens unit 11 is formed by incorporating _four lenses L _{1 to} L ₄ and other members in the lens barrel 11, the assembly work place of the lens unit is not a special moisture-proof space. For example, when these members are incorporated under high humidity conditions, the air inside the lens barrel 11 becomes wet. As a result, air containing moisture originally exists in the space in the lens barrel 11. If the lens barrel 11 is sealed in this state, moisture cannot be excluded inside. It is necessary to dry the inside at the stage before sealing. For this reason, nitrogen replacement may be conventionally performed, but the internal space of the lens barrel 11 is complicatedly partitioned by various members, and thus complete nitrogen replacement cannot be performed.
[0016]
From the above, in the present invention, the inside of the lens barrel 11 is dried using a desiccant, instead of performing nitrogen substitution. However, if the desiccant is accommodated inside the lens barrel, the lens barrel 11 is enlarged accordingly. If the lens barrel 11 is enlarged, the diameter of the insertion portion 1 is increased, so that the desiccant cannot be simply accommodated.
[0017]
Therefore, in the present invention, as the desiccant, as shown in FIG. 3, a desiccant plate P obtained by mixing a powder of silica gel S with a binder resin R and forming it into a plate shape or a sheet shape is used. Here, as the binder resin R, an olefin resin is used. Since the olefin resin has a low moisture transmission rate, the drying effect of the silica gel S is maintained for a long period of time. Further, the desiccant plate P can have any shape and thickness by molding. Furthermore, reflection of light can be prevented by applying a black paint having a hygroscopic property. Therefore, the desiccant plate P cannot be used as a member for transmitting light such as a lens. However, among the various members provided in the lens barrel 11 by forming into a required shape, It can be used as a non-permeable member. It is also possible to fix the light non-transmissive member to the light non-transmissive member by means such as adhesion.
[0018]
In the lens barrel 11, not only a lens constituting the objective optical system but also a light non-transmissive member that does not transmit light is provided. As the light non-transmissive member shown in FIG. 2, there are a harmful light shielding plate 17 and a diaphragm 18. These members are formed of an annular plate body, and their openings are light-transmitting members. However, the plate itself does not transmit light. The stopper ring 19 is also a light non-transmissive member. However, since the stopper ring 19 is used for positioning the lens, it needs to have high strength, and it must be prevented from being deformed even if it is pressed strongly against the lens.
[0019]
From the above, it is possible to use the desiccant plate P as an annular plate constituting the harmful light shielding plate 17 and the diaphragm 18. In this case, it is necessary to form the desiccant plate P as thin as possible and to increase the light absorption of the surface. Therefore, black paint is applied to both the front and back sides of the desiccant plate P, or at least a black pigment is mixed with the binder resin R. After mixing the black pigment with the binder resin R, the front and back surfaces are further applied 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 or 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 not bulky by forming it into a thin sheet.
[0020]
As described above, the harmful light shielding plate 17 and the diaphragm 18 are formed of the desiccant plate P, or the gas inside the lens barrel 11 is replaced by providing the stopper ring 19 with the desiccant plate P fixed thereto. Even without taking such measures, moisture in the lens barrel 11 can be removed reliably. Therefore, there is no possibility that the lenses L _{1 to} L ₄ in the lens barrel 11 are clouded or dewed when inspecting the body cavity, and a very good observation field of view can be obtained by the solid-state imaging device 16. Moreover, the lens barrel 11 is not increased in size because no special members are additionally provided in the lens barrel 11 and they are not particularly bulky.
[0021]
By the way, the observation unit 10 is mounted on the distal end main body 1 a, and the holding cylinder 12 is mounted on the distal end main body 1 a of the observation unit 10, and the angle portion 1 b on the proximal end side of the holding cylinder 12. A substrate 15 and a solid-state imaging device 16 are connected and provided in a space portion on the side of the connection. The most bulky portion of the observation unit 10 is a portion where the substrate 15 and the solid-state imaging device 16 are provided, and the portion mounted on the tip body 1a is more compact than that. Further, members other than the observation unit 10, such as the light guide and treatment instrument insertion channel 4 constituting the illumination means, have a substantially uniform shape in the axial direction. Therefore, even if the attachment portion of the holding cylinder 12 to the distal end portion main body 1a is made somewhat thick, it does not cause the insertion portion 1 to increase in diameter. Therefore, the outer diameter side of the holding cylinder 12 is enlarged by increasing the thickness of the portion of the holding cylinder 12 that is fitted to the lens barrel 11 and mounted on the distal end body 1a. The annular groove 23 is formed on the inner peripheral surface of the thickened portion, and the same desiccant plate P as described above is also formed between the groove 23 and the outer surface of the lens barrel 11. Alternatively, other desiccant 24 is provided. Thereby, the inside of the lens barrel 11 can be kept in a more dry state.
[0022]
By the way, among the lenses provided in the lens barrel, the concave surface of the first lens L ₁ is most easily fogged, so that it is particularly necessary to dry the space between the first lens L ₁ and the second lens L _2. Become. Therefore, what is necessary is just to comprise as shown in FIG. 4 in order to dry this site | part more efficiently.
[0023]
In the figure, reference numeral 30 denotes a lens barrel. Four lenses L _{1 to} L ₄ are mounted in the lens barrel 30, and the first lens L ₁ and the second lens L ₂ are further connected. A plane-parallel plate G is provided therebetween, and a predetermined space is formed 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 on the image forming side of the fourth lens L ₄ . A sealing member 35 such as an O-ring is attached to the outer peripheral surface of the plane parallel plate G, and the first lens is filled with the sealing member 35 and a sealing material filled between the first lens L ₁ and the lens barrel 30. The space between L ₁ and the plane parallel plate P is sealed. And the desiccant ring 36 which formed the above-mentioned desiccant plate P in the annular | circular shape is affixed on the inner surface of the spacer 31 so that it may adhere.
[0024]
Here, the spacer 31 maintains a distance between the first lens L ₁ and the plane parallel plate G, and the outer periphery of the first lens L ₁ is flat. Therefore, since the spacer 31 is also in surface contact with the harmful light shielding plate 32 that is in surface contact with the first lens L ₁ and also in the parallel plane plate G, even if the thickness thereof is extremely thin, The function as a spacer is fully demonstrated. Therefore, the desiccant ring 36 having a considerable thickness can be mounted inside the spacer 31, and the first lens L is a very limited space in the lens barrel 30 and is sealed. The space between ₁ and the plane parallel plate G is substantially completely dried by the desiccant ring 36 and becomes substantially completely dry.
[0025]
By configuring as above, even if the temperature changes rapidly in the first lens L ₁ of the outer surface such as, a risk that fogging and dew condensation occurs on the inner surface side of the first lens L ₁ is completely eliminated. Further, optical components on the imaging side from the joint surface of the plane parallel plate G other than the first lens L ₁ to the second lens L ₂ are sealed between the first lens L ₁ and the plane parallel plate G. Insulation effect is generated by the air. Therefore, even if there is a sudden temperature change on the outer surface side of the insertion portion, the temperature change is alleviated, so that the occurrence of fogging or condensation is also suppressed. Of course, the entire drying function of the lens barrel 30 can be further improved by forming the diaphragm 33 with the desiccant plate P, and the lenses L _{1 to} L ₄ and the plane parallel plate G are all protected against fogging. The
[0026]
【The invention's effect】
As described above, according to the present invention, among the members provided in the lens barrel, at least a part of the light non-transmissive member is constituted by the desiccant plate in which the desiccant is formed in a plate shape or a sheet shape. Even without nitrogen replacement, the lens barrel can be maintained in a dry state.
[Brief description of the drawings]
FIG. 1 is an external view showing a distal end portion in an insertion portion of an endoscope.
FIG. 2 is a cross-sectional view of an endoscope lens apparatus showing an embodiment of the present invention.
FIG. 3 is a cross-sectional view of a desiccant plate.
FIG. 4 is a cross-sectional view of a lens apparatus showing another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Insertion part 1a Tip part main body 3 Observation window 10 Observation unit 11, 30 Lens barrel 12 Holding cylinder 17, 32 Harmful light shielding plate 18, 33 Stopper 19, 34 Stopper ring 31 Spacer 35 Seal member 36 Desiccant ring L _{1 to} L ₄ lens P desiccant plate S silica gel R resin G parallel flat plate

Claims (5)

Provided at the distal end portion of the insertion portion of the endoscope, in which the objective optical system is built in the lens barrel inserted into the holding tube to which the imaging surface is connected,
An endoscope lens apparatus, wherein a harmful light shielding plate is mounted in the lens barrel, and the harmful light shielding plate is formed of a desiccant plate made of a plate-like or sheet-like light non-transmissive member .   2. The endoscope lens apparatus according to claim 1, wherein the desiccant plate is a plate formed by dispersing silica gel in an olefin-based resin. The lenses constituting the objective optical system are arranged in the order of the first lens and the second lens from the subject side, and the harmful light shielding plate is arranged between the first lens and the second lens. The endoscope lens apparatus according to claim 1. The endoscope lens apparatus according to claim 1, wherein the harmful light shielding plate is configured to prevent reflection of light . The desiccant plate is formed in a sheet shape on a spacer or a stopper ring for fixedly holding the objective optical system, which is provided to maintain a distance between optical components constituting the objective optical system. The endoscope lens apparatus according to claim 1 , wherein the lens apparatus is affixed.

Images