JP2005215345A - Optical system and endoscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical system with which the occurrence of the fogging of a lens, for example, an image defect or the like can be prevented even when it is exposed to high-humidity environment repeatedly or for a long time, and to provide an endoscope equipped with the optical system. <P>SOLUTION: The electronic endoscope is equipped with an insertion part flexible tube 1 inserted in the intravascular cavity of a living body so as to be used. The flexible tube 1 has an illumination means 4 and an imaging means 3 having an objective system 32 and an imaging device 31 installed on the base end side of the objective system 32, and taking the picture of a subject. The objective system 32 has an objective 320 and a member joined with the objective (optical component which does not require light transmitting property), and a coating film 329 containing a moisture absorbent, a colorant in dark color and organic binder is formed on at least a part of the surface of the optical component which does not require the light transmitting property. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical system and an endoscope.

  In the medical field, endoscopes are used for examination and diagnosis of the digestive tract and the like. This endoscope has an insertion portion (endoscopic flexible tube) to be inserted into a body cavity, and an operation portion that is installed on the proximal end side of the insertion portion and performs a bending operation on the distal end portion of the insertion portion. doing. The endoscope has a connection portion that extends from the operation portion and is connected to the light source device and the control device.

The insertion portion includes a flexible tube having flexibility so that the insertion portion can be inserted into a bent body cavity and follow the bending portion, and a bending portion that is bent at the distal end side thereof.
In addition, observation means including an objective lens is provided inside the distal end portion of the bending portion.

  By the way, every time it is used, the endoscope is subjected to cleaning, disinfection, sterilization processing, etc. At this time, if moisture enters and remains in the insertion portion (particularly, the distal end portion of the bending portion), Due to the temperature difference between the inside and the outside of the insertion portion, the objective lens is clouded or dewed, and as a result, there is a problem that observation of the observation site becomes extremely difficult.

  Therefore, it has been proposed to form a water-absorbing and anti-reflective coating on the surface of an optical element (a member that requires light transmission) constituting the optical system (see, for example, Patent Document 1). With such a configuration, it is possible to prevent the surface of the optical element from becoming clouded or water droplets from adhering even when steam enters the endoscope during autoclave sterilization with high-pressure and high-temperature steam.

  However, in the conventional method, since a film is formed on the surface of the optical element, there is a problem that light transmittance is reduced and it is difficult to image a subject. In addition, by repeating cleaning, disinfection, and sterilization treatment, the water-absorbing polymer contained in the coating deteriorates and turns yellow, and in that case, the color of the obtained image changes, which hinders image diagnosis. There's a problem.

JP 2000-152909 A

  An object of the present invention is to provide an optical system capable of preventing the occurrence of lens fogging, image defects, and the like even when repeatedly or exposed to a high humidity environment for a long time, and an endoscope including such an optical system. It is to provide.

Such an object is achieved by the present inventions (1) to (17) below.
(1) An optical system composed of a plurality of optical components including an optical component that does not require optical transparency,
An optical system, wherein a coating film containing a hygroscopic agent, a dark colorant, and an organic binder is formed on at least a part of the surface of the optical component that does not require light transmission.

  Thereby, even when it is repeatedly or exposed to a high humidity environment for a long time, it is possible to prevent the occurrence of fogging of the lens and, for example, an image defect.

(2) An optical system comprising a lens and a member bonded to the lens,
An optical system, wherein a coating film containing a hygroscopic agent, a dark colorant, and an organic binder is formed on at least a part of a surface of a member bonded to the lens.

  Thereby, even when it is repeatedly or exposed to a high humidity environment for a long time, it is possible to prevent the occurrence of fogging of the lens and, for example, an image defect.

  (3) The optical system according to (2), wherein the member bonded to the lens is a support member for the lens.

  Thereby, it is possible to prevent an increase in the number of parts and an accompanying increase in the size of the optical system.

(4) The optical system according to (2) or (3), wherein the lens is an objective lens.
Thereby, observation of an observation part can be performed suitably.

  (5) The optical system according to any one of (2) to (4), wherein the lens is an endoscope lens.

  The optical system of the present invention can be applied to various optical systems, but is particularly preferably applied to an endoscope lens system.

(6) The optical system according to any one of (1) to (5), wherein the coating film has an average thickness of 0.01 to 1 μm.
Thereby, favorable antireflection property and hygroscopicity can be imparted to the coating film.

(7) The optical system according to any one of (1) to (6), wherein the content of the hygroscopic agent in the coating film is 1 to 40 wt%.
Thereby, the vicinity of the optical system can be made sufficiently low in humidity.

  (8) The optical system according to any one of (1) to (7), wherein the hygroscopic agent is granular.

  Thereby, it can mix (disperse) more uniformly in the coating composition.

(9) The optical system according to (8), wherein the granular hygroscopic agent has an average particle diameter of 1 to 30 μm.
Thereby, the specific surface area can be sufficiently secured, and the moisture absorption capacity is further improved.

  (10) The optical system according to any one of (1) to (9), wherein the hygroscopic agent is mainly composed of magnesium sulfate.

  Magnesium sulfate is excellent in moisture absorption capacity, has good dispersibility in various resin materials, does not exhibit corrosiveness, deliquescence, etc. due to moisture absorption, is not easily crushed, and generates very little dust.

(11) The optical system according to (10), wherein the magnesium sulfate is represented by MgSO ₄ · nH ₂ O (where 0 ≦ n ≦ 3).
These magnesium sulfates are particularly excellent in moisture absorption capacity.

(12) The optical system according to any one of (1) to (11), wherein the dark color is black.
Thereby, the discoloration of the coating film can be made less noticeable.

(13) The optical system according to any one of (1) to (12), wherein the colorant is a pigment.
Thereby, the coating film can be easily colored.

(14) The optical system according to (13), wherein the pigment is granular.
Thereby, it can mix (disperse) more uniformly in the coating composition.

(15) The optical system according to (14), wherein the granular pigment has an average particle diameter of 1 to 10 μm.
Thereby, the dispersibility in a coating film can be made favorable.

  (16) The optical system according to any one of (1) to (15), wherein a content of the colorant in the coating film is 0.5 to 5 wt%.

  Thereby, the antireflection property of the coating film and the effect of making discoloration inconspicuous are preferable.

  (17) An endoscope comprising the optical system according to any one of (1) to (16).

  As a result, a clear image of a subject can be continuously obtained even when exposed to a high humidity environment repeatedly or for a long time.

  According to the present invention, even when exposed to a high-humidity environment repeatedly or for a long time, the lens is hardly fogged or condensed due to the dehumidifying effect of the coating film containing the hygroscopic agent.

  In particular, since the coating film is colored dark by the colorant, even when the organic binder is discolored, it is not noticeable. For this reason, for example, when applied to an endoscope, it is possible to prevent the occurrence of an image defect due to the discoloration of the organic binder, and to capture a subject satisfactorily over a long period of time.

  Hereinafter, an optical system and an endoscope of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

  FIG. 1 is an overall view showing an electronic endoscope (electronic scope) to which the optical system of the present invention is applied, and FIG. 2 is a longitudinal sectional view showing a distal end portion of the electronic endoscope shown in FIG. In the following description, in FIG. 1, the upper side is referred to as “base end” and the lower side is referred to as “tip”. In FIG. 2, the left side is the distal direction, and the right side is the proximal direction.

  An electronic endoscope 10 shown in FIG. 1 includes a bending portion 5 at a distal end, a long insertion portion flexible tube 1 having flexibility (flexibility), and a proximal end portion of the insertion portion flexible tube 1. Provided on the distal end side of the connection portion flexible tube 7, an operation portion 6 that is operated by the operator and operates the entire electronic endoscope 10, a connection portion flexible tube 7 connected to the operation portion 6, And the light source insertion portion 8 thus formed.

  The insertion portion flexible tube 1 is used by being inserted into a lumen of a living body. As shown in FIG. 2, the insertion portion flexible tube 1 includes an illumination unit 4 that irradiates a subject with illumination light, and an imaging unit 3 that captures an image of the subject.

  The illumination unit 4 includes a pair of optical fiber bundles (light guides) 41 and 41 disposed along the longitudinal direction of the insertion portion flexible tube 1 (and the connection portion flexible tube 7), and a distal end portion of the optical fiber bundle. Plano-concave lenses (projection lens systems) 42 and 42 are provided.

  The imaging means 3 has an objective lens system (optical system) 32 and an imaging element (CCD image sensor) 31 installed on the base end side of the objective lens system 32, and these are the distal end portion of the bending portion 5. It is installed in the hole 33 formed in 51. The image sensor 31 is connected to a signal line 311 arranged along the longitudinal direction of the insertion portion flexible tube 1 (and the connection portion flexible tube 7).

  An operation unit 6 is provided at the proximal end of the insertion portion flexible tube 1. The operation unit 6 is provided with operation knobs 61 and 62 on its side surface. When the operation knobs 61 and 62 are operated, a wire (not shown) disposed in the insertion portion flexible tube 1 is pulled, and the bending portion 5 is bent in four directions, and the direction can be changed. .

  Further, a connecting portion flexible tube 7 is connected to the operation portion 6. The optical fiber bundle 41 and the signal line 311 pass through the connecting portion flexible tube 7 and are connected to the light source insertion portion 8.

  The light source insertion unit 8 has a signal processing circuit 83 for processing an image signal therein. The light source insertion portion 8 has a light source connector 81 and an image signal connector 82 at the distal end thereof.

  Each optical fiber bundle 41 is connected to a light source connector 81. The signal line 311 is connected to the signal processing circuit 83, and the signal processing circuit 83 is connected to the image signal connector 82.

  These image signal connector 82 and light source connector 81 are respectively connected to a light source processor device (not shown). A monitor device (not shown) is connected to the light source processor device.

  In the electronic endoscope 10 having such a configuration, when the light source insertion unit 8 is connected to the light source processor device and the light source processor device is operated, light (illumination light) emitted from the light source processor device is converted into a light source connector. The light enters the optical fiber bundle 41 through 81. This light passes through the optical fiber bundle 41 and exits from the tip of the optical fiber bundle 41.

  The emitted light passes through the plano-concave lens 42 and is irradiated to the observation site (subject). At this time, the emitted light passes through the plano-concave lens 42 and is diffused and uniformed. As a result, the electronic endoscope 10 can illuminate the observation site uniformly over a wide range.

  The illuminated illumination light is reflected at the observation site and becomes reflected light that forms a subject image. Part of this reflected light is incident on the objective lens system 32. The reflected light is guided so as to form an image on the light receiving surface of the image sensor 31.

  The image sensor 31 receives the reflected light guided to the light receiving surface. As a result, a subject image is captured. The image sensor 31 outputs an image signal (CCD signal) corresponding to the captured subject image. This image signal is transmitted to the light source insertion unit 8 via the signal line 311.

  This image signal is input to the signal processing circuit 83 by the light source insertion unit 8. Then, the signal processing circuit 83 performs predetermined signal processing on the image signal. The image signal subjected to this processing is output to the light source processor device via the image signal connector 82.

  The output image signal is converted into a predetermined television signal by the light source processor. Therefore, when the monitor device is connected to the light source processor device, a television signal is input to the monitor device. As a result, the monitor device displays an image (electronic image) of the subject imaged by the image sensor, that is, a video endoscope monitor image.

Next, the objective lens system 32 to which the optical system of the present invention is applied will be described.
The objective lens system 32 shown in FIG. 2 has an objective lens (endoscope lens) 320 composed of four lenses 321 to 324. Specifically, the objective lens system 32 includes a first lens 321 installed at the distal end of the insertion portion flexible tube 1 and the center of the first lens 321 toward the base end side (image forming side). The objective lens 320 includes a second lens 322, a third lens 323, and a fourth lens 324 that are installed so that the axes (optical axes) substantially coincide with each other.

  The first lens 321 is constituted by a plano-concave lens having a flat front surface and a concave surface on the base end surface (image forming side). The first lens 321 is supported and fixed to the edge of the distal end opening 331 where the hole 33 is opened at the distal end of the bending portion 5 (insertion portion flexible tube 1). It is exposed to the outside of the tube 1.

The second lens 322 is a plano-convex lens having a flat tip surface and a convex base surface.
The third lens 323 and the fourth lens 324 are composed of cemented lenses.

  The second lens 322, the third lens 323, and the fourth lens 324 are each supported and fixed (bonded) to a cylindrical support body 325. Further, in this state, the support body 325 is inserted into the hole 33 and supported and fixed (joined) to the inside (hole 33) of the bending portion 5 via the cylindrical frame member 326.

  An interval ring 327 that defines the interval between the second lens 322 and the third lens 323 is provided.

  Further, an optical filter 328 that removes a high frequency component from the reflected light guided to the light receiving surface of the image sensor 31 is fixed (fixed) to the distal end surface of the image sensor 31.

  As described above, in the present embodiment, the objective lens (endoscope lens) 320, the support body 325, the frame member 326, and the spacing ring 327, which respectively support (members respectively joined to) the objective lens (endoscope lens), An objective lens system (optical system) 32 is configured by a plurality of optical components such as the optical filter 328.

  Each of the lenses 321 to 324 (objective lens 320) and the optical filter 328 are made of a material having optical transparency. Specific examples of the light transmissive material include various glass materials and various resin materials.

  The support 325, the frame member 326, and the spacing ring 327 are each preferably made of a resin material, particularly a relatively hard resin material. Specific examples thereof include polyethylene, polypropylene, polybutadiene, Polyolefin such as ethylene-vinyl acetate copolymer, polyvinyl chloride, polyurethane, polystyrene, polymethyl methacrylate, polycarbonate, polyamide, polyethylene terephthalate, polybutylene terephthalate, polyester, acrylic resin, ABS resin, AS resin, ionomer, polyacetal , Polyphenylene sulfide, polyether ether ketone and the like.

  Here, since the electronic endoscope 10 is used repeatedly, cleaning, disinfection, sterilization, etc. are performed after each use. When such cleaning, disinfection, sterilization, and the like are repeatedly performed, moisture may enter and remain inside the electronic endoscope 10 to increase the humidity. Similarly, when used in a high-humidity tropical region, the humidity inside the electronic endoscope 10 may increase with the passage of time of use.

  In these cases, when the humidity inside the electronic endoscope 10 (especially the hole 33) increases, the temperature difference between the inside and outside of the electronic endoscope 10 causes the objective lens 320, particularly the inner surface of the first lens 321 in particular. As a result, the image quality of the image of the subject is drastically lowered and becomes extremely difficult to see.

  As an example of the case where a temperature difference occurs between the inside and outside of the electronic endoscope 10 as described above, for example, the following case can be cited.

  That is, when the insertion portion flexible tube 1 is inserted into a body cavity such as the digestive tract and used, when a contaminated material such as a body fluid adheres to the surface of the first lens 321, the observation visual field is caused by the attachment of the contaminated material. Therefore, an operation of washing away the contaminated material from the surface (front end surface) of the first lens 321 using cleaning water or the like is performed.

  At this time, the first lens 321 has a temperature close to the body temperature in the body cavity or a temperature slightly higher than the body temperature due to the influence of the image pickup device 31 and the like housed therein, but the washing water is usually heated. Not at room temperature.

  For this reason, when cleaning water is sprayed on the surface of the first lens 321, the first lens 321 is rapidly cooled. As a result, a temperature difference occurs inside and outside the electronic endoscope 10 (particularly, inside and outside of the first lens 321).

  In view of this, the present inventor has intensively studied to make the objective lens 320 (first lens 321) less susceptible to fogging and condensation, and as a result, among the optical components constituting the objective lens system 32 as described above, the support body is provided. 325, a coating member 329 containing a hygroscopic agent (drying agent), a coloring agent, and an organic binder on the surface of a member to be joined to the objective lens 320 such as the frame member 326 and the spacing ring 327, that is, the hygroscopic agent and coloring. It was concluded that the coating film 329 in which the agent is supported (fixed) by the organic binder may be formed.

  The members bonded to these objective lenses 320 are optical components that do not require light transmission (hereinafter referred to as “light non-transmissive components”).

  Here, if such a coating film 329 is formed on the surface of a member that requires light transmission, such as the objective lens 320 or the optical filter 328, the transmittance of the light is reduced, and the object is exposed. Imaging becomes difficult. In addition, if the organic binder (polymer) contained in the coating film 329 is deteriorated and yellowed by repeated cleaning, disinfection, and sterilization, the color of the obtained image may be changed, which may hinder image diagnosis. There is sex. Further, when a member containing a hygroscopic agent is separately incorporated in the objective lens system 32, the number of parts may increase and the diameter (enlargement) of the distal end portion 51 of the curved portion 5 may be increased.

  On the other hand, in the present invention, a coating film (film) 329 is formed on at least a part of the surface of the light non-transmissive component (substantially the entire surface in the present embodiment) among the optical components constituting the objective lens system 32. .

  As a result, the electronic endoscope 10 is used in a high-humidity tropical region, repeatedly subjected to cleaning, disinfection, sterilization, etc., that is, repeatedly or exposed to a high humidity environment for a long time. Even when moisture enters and remains in the interior, the moisture absorbent takes in this moisture (absorbs moisture), and the inside of the hole 33 is maintained (held) at a low humidity. As a result, even when a temperature difference occurs between the inside and the outside of the electronic endoscope 10, it is possible to prevent the object lens 320 (especially the first lens 321) from being fogged or dewed, which is clear. A continuous subject image can be obtained continuously.

  Further, since the coating film 329 is colored in a dark color by the colorant, the reflection of light can be suppressed and the occurrence of flare can be prevented. Thereby, an image can be obtained clearly.

  Furthermore, even when the organic binder contained in the coating film 329 is discolored, the coating film 329 is colored, so that the discoloration is not conspicuous and the influence on the image can be suppressed. As a result, no image defect occurs, and the subject can be imaged satisfactorily over a long period of time.

  As the hygroscopic agent, for example, a substance that takes water molecules into the molecular structure as crystal water, a substance that holds water molecules by adsorption, or the like can be used.

  In particular, the hygroscopic agent can be easily and reliably mixed into the composition (coating composition) for forming the coating film 329, and the shape changes even when the moisture is absorbed (for example, deliquescence and liquefaction). Etc.) are preferred. Thereby, it is possible to suitably prevent an optical defect from occurring in the objective lens system 32.

  Examples of the moisture absorbent include aqueous metal salts such as magnesium sulfate, aluminum oxide, barium oxide, calcium oxide (quick lime), silicon oxide, calcium chloride, silica gel, silica alumina gel, zeolite, calcium hydroxide, and zinc hydroxide. , Sodium acrylate, water-absorbing polymer having an OH group (hydrophilic polymer), and the like, and one or more of them can be used in combination.

  Among these, as a hygroscopic agent, what has magnesium sulfate as a main component is suitable. Magnesium sulfate can irreversibly incorporate water molecules into the molecular structure as crystal water. For this reason, compared to substances that simply hold water molecules by adsorption (for example, silica gel, calcium chloride, zeolite, etc.), the amount of water absorption (moisture absorption) is large, that is, it has excellent moisture absorption capacity (dehumidification effect), Furthermore, it is difficult to release moisture due to changes in the usage environment (for example, temperature changes). For this reason, by using the hygroscopic agent mainly composed of magnesium sulfate, the electronic endoscope 10 can reliably lower the humidity inside the hole 33 even when exposed to a high humidity environment. Can be maintained.

Further, magnesium sulfate has the following advantages I to IV.
That is, I: excellent in hygroscopic capacity (for example, the amount of water molecules taken up, the uptake rate, etc.). II: Since the dispersibility in various resin materials is good, mixing into the coating composition can be performed easily. III: Since no corrosiveness or deliquescence is exhibited by moisture absorption, the coating film 329 does not change its shape. In addition, there is no optical effect. IV: Fracture hardly occurs and dust generation is extremely small.

As the magnesium _sulfate, MgSO 4 · _nH 2 O (provided that, 0 ≦ n ≦ 3) are preferably those represented by. That is, magnesium sulfate can be used in combination of one or more of anhydride, monohydrate, dihydrate, and trihydrate. These magnesium sulfates are particularly excellent in moisture absorption capacity.

  Such a hygroscopic agent may have any shape, but a granular shape is preferred. By using a particulate hygroscopic agent, it can be more uniformly mixed (dispersed) into the coating composition.

  In this case, the average particle diameter of the hygroscopic agent is not particularly limited, but is preferably about 1 to 30 μm, and more preferably about 2 to 20 μm. Thereby, while the said effect improves more, the specific surface area of a hygroscopic agent can fully be ensured, and the moisture absorption capability improves more.

  As the colorant, any one or two or more of various dark pigments and various dark dyes can be used in combination.

  Examples of the dark pigment include phthalocyanine pigments such as phthalocyanine green and phthalocyanine blue, azo pigments such as benzimidazolone brown, quinacridone pigments such as quinacridone maroon and quinacridone scarlet, perylene pigments such as perylene maroon, and dioxazine. Organic pigments such as dioxazine pigments such as violet, carbon black, lamp black, furnace black, ivory black, carbon pigments such as graphite and fullerene, chromate pigments such as chrome lead and molybdate orange, amber, brown oxidation Iron, zinc iron chrome brown, chromium oxide, cobalt green, cobalt chrome green, titanium cobalt green, cobalt blue, cerulean blue, cobalt aluminum chrome blue, iron black, manganese Oxide pigments such as cerite black, cobalt ferrite black, copper chrome black, copper chrome manganese black, hydroxide pigments such as viridian, ferrocyanide pigments such as bitumen, silicate pigments such as ultramarine blue, cobalt One type or two or more types of phosphate pigments such as violet and mineral violet, and other inorganic pigments can be used in combination.

Examples of dark dyes include metal complex dyes such as RuL ₂ (SCN) ₂ , RuL ₂ Cl ₂ , RuL ₂ (CN) ₂ , [RuL ₂ (NCS) ₂ ] ₂ H ₂ O, cyan dyes, One or two or more of azo dyes, blackberry dyes, chlorophyll dyes and the like can be used.

  Among these, as the colorant, a pigment is preferable. The pigment is preferable because it hardly changes or deteriorates over time. Further, by using a pigment as the colorant, the colorant can be more uniformly mixed into the coating composition, and color unevenness of the resulting coating film 329 can be prevented.

  Such a pigment may have any shape, but is preferably granular. By using the particulate pigment, the moisture absorbent can be kneaded into the coating composition more easily and reliably, and more uniformly mixed (dispersed) into the coating composition.

  In this case, the average particle diameter of the pigment is not particularly limited, but is preferably about 1 to 10 μm, and more preferably about 2 to 8 μm. If the average particle size of the pigment is too small, the pigment particles may agglomerate with each other and may be difficult to handle. On the other hand, if the average particle size of the pigment is too large, the pigment is dispersed in the coating composition. May decrease.

  Further, the color of the colorant, that is, the color (dark color) of the coating layer 329 is preferably black, dark blue, dark brown, dark green, or the like, and particularly preferably black. By coloring the coating film 329 black, the antireflection effect of the coating film 329 and the visual recognition effect of discoloration can be further improved.

  The coating film 329 as described above is prepared by, for example, preparing a coating solution by dissolving or dispersing a hygroscopic agent, a colorant, and an organic binder (dispersed polymer) in a solvent. It can form easily by apply | coating to the surface of the frame member 326 and the space | interval ring 327, and then solidifying or hardening.

  Examples of the organic binder include various thermoplastic resins and various thermosetting resins, for example, polyolefins such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), cyclic polyolefin, modified polyolefin, poly Vinyl chloride, polyvinylidene chloride, polystyrene, polyamide, polyimide, polyamideimide, polycarbonate, poly- (4-methylpentene-1), ionomer, acrylic resin, polymethyl methacrylate, acrylonitrile-butadiene-styrene copolymer (ABS resin) ), Acrylonitrile-styrene copolymer (AS resin), butadiene-styrene copolymer, polyoxymethylene, polyvinyl alcohol (PVA), ethylene-vinyl alcohol copolymer (EVOH), Polyester such as reethylene terephthalate (PET), polybutylene terephthalate (PBT), polycyclohexane terephthalate (PCT), polyether, polyether ketone (PEK), polyether ether ketone (PEEK), polyether imide, polyacetal (POM), Polyphenylene oxide, modified polyphenylene oxide, polysulfone, polyethersulfone, polyphenylene sulfide, polyarylate, aromatic polyester (liquid crystal polymer), polytetrafluoroethylene, polyvinylidene fluoride, other fluororesins, styrene, polyolefin, polychlorination Vinyl, polyurethane, epoxy, acrylic, silicone, polyester, polyamide, polybutadiene, transformer Various elastomers (thermoplastic elastomers) such as lysoprene, fluorine (fluororubber), chlorinated polyethylene, epoxy resin, phenol resin, urea resin, melamine resin, unsaturated polyester, silicone resin, polyurethane, etc. , One or more of these can be used in combination.

  Examples of the solvent include ketone solvents such as methyl ethyl ketone (MEK), acetone, diethyl ketone, methyl isobutyl ketone (MIBK), methyl isopropyl ketone (MIPK), cyclohexanone, methanol, ethanol, isopropanol, ethylene glycol, and diethylene glycol. (DEG), alcohol solvents such as glycerin, diethyl ether, diisopropyl ether, 1,2-dimethoxyethane (DME), 1,4-dioxane, tetrahydrofuran (THF), tetrahydropyran (THP), anisole, diethylene glycol dimethyl ether (diglyme) ) Ether solvents such as methyl cellosolve, ethyl cellosolve, cellosolve solvents such as phenyl cellosolve, hexane, pentane, heptane, Aliphatic hydrocarbon solvents such as chlorohexane, aromatic hydrocarbon solvents such as toluene, xylene and benzene, aromatic heterocyclic compounds solvents such as pyridine, pyrazine, furan, pyrrole and thiophene, N, N-dimethylformamide Amide solvents such as (DMF), N, N-dimethylacetamide (DMA), halogen compound solvents such as dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, esters such as ethyl acetate, methyl acetate, ethyl formate System solvents, sulfur compound solvents such as dimethyl sulfoxide (DMSO), sulfolane, and nitrile solvents such as acetonitrile and propionitrile, and one or more of these can be used in combination. .

  In the coating composition, if necessary, for example, a plasticizer, an inorganic filler, a pigment, various stabilizers (antioxidant, light stabilizer, antistatic agent, antiblocking agent, lubricant), X-ray contrast You may make it mix | blend (mix) various additives, such as an agent.

  The average thickness of the coating film 329 to be formed is not particularly limited, but is preferably about 0.01 to 1 μm, and more preferably about 0.1 to 0.7 μm. If the coating film 329 is too thin, the dehumidifying effect of the coating film 329 may not be sufficiently obtained depending on the content of the hygroscopic agent. On the other hand, even if the coating film 329 is made thicker than the above upper limit value. No further increase in effect can be expected.

  Further, by making the coating film 329 thin in this way, reflected light can be canceled out by light interference, and antireflection properties can be obtained. As a result, the occurrence of flare can be prevented. Thereby, a clear image can be obtained.

  The content of the hygroscopic agent in the coating film 329 is not particularly limited, but is preferably about 1 to 40 wt%, and more preferably about 1 to 30 wt%. If the content of the hygroscopic agent is too small, the inside of the hole 33 may not be made sufficiently low depending on the type of the hygroscopic agent and the conditions of the usage environment of the electronic endoscope 10. When there is too much content of an agent, there exists a possibility that the adhesiveness to the light-impermeable component of the coating film 329 may fall.

  Further, the content of the colorant in the coating film 329 is not particularly limited, but is preferably about 0.5 to 5 wt%, and more preferably about 1 to 3 wt%. If the content of the colorant is too small, depending on the type of the colorant, the coating film 329 may not be sufficiently colored, and the object of the present invention as described above may not be sufficiently achieved. When there is too much content of a coloring agent, there exists a possibility that the adhesiveness to the light-impermeable component of the coating film 329 may fall.

  In the electronic endoscope 10 having such a configuration, by performing autoclave sterilization, even if vapor enters inside through an O-ring, an adhesive, a resin part, etc., the objective lens system 32 has water absorption. Since the coating film 329 having the anti-reflection property and the anti-reflection property is formed, the invading vapor is surely absorbed by the coating film 329. As a result, the lens (first lens 321) is less likely to be clouded or condensed.

  In the present embodiment, the configuration in which the hygroscopic agent is dispersed in the coating film 329 has been described as an example. However, the present invention is not limited to this. For example, the coating film 329 may be formed of a water-absorbing polymer. Such a hygroscopic agent itself can also be formed as an organic binder.

  In this case, for example, the coating film 329 performs polycondensation reaction of at least one of inorganic alkoxide, inorganic alkoxide hydrolyzate, and hydrolyzate low molecular weight polycondensate with polyacrylic acid and the hydrolyzate. The coating liquid containing the catalyst to be promoted can be formed by coating the surface of the light non-transmissive component and heat-treating it.

  In this case, the colorant may be added to the coating solution. Thereby, the coating film 329 can be easily colored.

  In the present embodiment, the case where the coating film 329 is formed on the surfaces of the support 325, the frame member 326, and the spacing ring 327 has been described. However, in the present invention, at least one of these (one member) is used. A coating film 329 may be formed on the surface.

  In the present embodiment, the case where the coating film 329 is formed on almost the entire surface of the member has been described. However, in the present invention, the coating film 329 may be formed on at least a part of the surface of the member. Good. In this case, it is preferable to form the coating film 329 at least in a portion exposed to the hole 33 of the member.

  In addition, any desired component can be added to the objective lens system 32. For example, an annular member that defines the distance between the edge of the distal end opening 331 of the curved portion 5 and the frame member 326 is added, and the coating film 329 as described above is formed on the surface of the annular member. Also good.

  The optical system and endoscope of the present invention have been described above, but the present invention is not limited to this, and the configuration of each member (each part) can be replaced with any one having the same function. it can.

  In the above embodiment, the electronic endoscope has been described. However, it is needless to say that the endoscope of the present invention can be applied to an optical endoscope, and is not limited to medical use. It can also be applied to an endoscope used for (industrial use).

  In the above embodiment, the optical system according to the present invention is applied to an endoscope lens system, in particular, an objective lens system. However, the eyepiece lens system of the endoscope or irradiation for irradiating illumination light is described. The present invention may be applied to a lens system, and may be applied not only to an endoscope body but also to a camera lens system, a lens system of an endoscope accessory, and the like.

Next, specific examples of the present invention will be described.
1. Manufacture of electronic endoscope (Example 1)
First, the support body, the frame member, and the spacing ring as described above were prepared using polyphenylene sulfide (Torelina A504 manufactured by Toray Industries, Inc.).

  Next, a predetermined amount of a hygroscopic agent, a colorant and an organic binder were added to N, N-dimethylformamide (DMF), respectively, to prepare a coating composition.

  And after applying this coating composition to the surface of each member using a brush, it dried and solidified and formed the coating film (average thickness of 0.5 micrometer).

As the hygroscopic agent, MgSO ₄ · 2H ₂ O powder (average particle size 5 μm) was used. In addition, the content of the hygroscopic agent in the coating film was set to 1 wt%.

  Further, carbon black (average particle size 5 μm) was used as a colorant. Further, the content of the colorant in the coating film was set to 2 wt%.

  As the organic binder, a polyurethane-based thermoplastic elastomer (manufactured by DIC Bayer Polymer Co., Ltd., Pandex) was used.

  Next, using these members, an insertion portion flexible tube as shown in FIG. 2 was produced, and an electronic endoscope (an upper digestive tract endoscope) as shown in FIG. 1 was produced.

(Examples 2 and 3)
An electronic endoscope was manufactured in the same manner as in Example 1 except that the content of the hygroscopic agent in the coating film was as shown in Table 1.

(Examples 4 to 7)
An electronic endoscope was manufactured in the same manner as in Example 1 except that the type of moisture absorbent as shown in Table 1 was used.

(Examples 8 and 9)
An electronic endoscope was manufactured in the same manner as in Example 2 except that the content of the colorant in the coating film was as shown in Table 1.

(Examples 10 to 14)
An electronic endoscope was manufactured in the same manner as in Example 2 except that the types of colorants shown in Table 1 were used.

(Examples 15 and 16)
An electronic endoscope was manufactured in the same manner as in Example 2 except that the average thickness of the coating film was as shown in Table 1.

(Comparative Example 1)
An electronic endoscope was manufactured in the same manner as in Example 2 except that a coating film containing no hygroscopic agent was formed.

(Comparative Example 2)
An electronic endoscope was manufactured in the same manner as in Example 2 except that a coating film containing no colorant was formed.

(Comparative Example 3)
An electronic endoscope was manufactured in the same manner as in Example 1 except that no coating film was formed.

2. Evaluation The following evaluations were performed on the electronic endoscopes manufactured in each Example and each Comparative Example.

2-1. Durability Evaluation by Sterilization Treatment Sterilization treatment with ethylene oxide gas (concentration: 100%, humidity: 70% RH, time: 2 hours 45 minutes) was repeated 200 times.

For each electronic endoscope, after each sterilization treatment, the distal end of the insertion portion flexible tube is immersed in warm water of 40 ° C. for 10 minutes, and then cold water of 0 ° C. is sprayed onto the first lens, The image quality of the image was confirmed and evaluated according to the following four-stage criteria.
◎: No change in the image quality of the subject even after 200 sterilization treatments ○: There is a slight decrease in the image quality of the subject image after 200 sterilization treatments △: From about 150 sterilization treatments to the image quality of the subject image There is a decrease ×: The image quality of the subject has decreased from about 100 sterilization treatments 2-2. Durability evaluation by leaving in a high humidity environment The sample was left in a high humidity environment (temperature: 40 ° C., humidity: 90% RH) for 500 hours.

And about each electronic endoscope, after every 10 hours progress, after immersing the front-end | tip part of an insertion part flexible tube in 40 degreeC warm water for 10 minutes, 0 degreeC cold water is injected to a 1st lens, The image quality of the image was confirmed and evaluated according to the following four-stage criteria.
◎: No change in the image quality of the subject even after being left under high humidity for 500 hours ○: There is a slight decrease in the image quality of the subject image after being left under high humidity for 500 hours △: About 400 hours under high humidity Table 1 shows a decrease in image quality of the subject image after being left unattended: Decrease in image quality of the subject image after being left under high humidity for about 300 hours.

  As shown in Table 1, each of the electronic endoscopes (endoscopes of the present invention) of each example is capable of withstanding a sterilization process that is repeatedly performed while preventing deterioration of the image quality of the subject image. there were.

  On the other hand, the electronic endoscopes of the comparative examples all have extremely low quality because the image quality of the subject is deteriorated at an early stage by repeating sterilization treatment or leaving it under high humidity for a long time. It has become difficult.

It is a general view which shows the electronic endoscope (electronic scope) to which the optical system of this invention is applied. It is a longitudinal cross-sectional view which shows the front-end | tip part of the electronic endoscope shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electronic endoscope 1 Insertion part flexible tube 3 Imaging means 31 Imaging element 311 Signal line 32 Objective lens system 320 Objective lens 321 1st lens 322 2nd lens 323 3rd lens 324 4th lens 325 Support body 326 Frame member 327 Spacing ring 328 Optical filter 329 Coating film 33 Hole portion 331 Tip opening 4 Illuminating means 41 Optical fiber bundle 42 Plano-concave lens 5 Bending portion 51 Tip portion 6 Operating portion 61, 62 Operating knob 7 Connection portion Flexible tube 8 Light source insertion portion 81 Light source Connector 82 Image signal connector 83 Signal processing circuit

Claims (17)

An optical system composed of a plurality of optical components including an optical component that does not require light transmission,
An optical system, wherein a coating film containing a hygroscopic agent, a dark colorant, and an organic binder is formed on at least a part of the surface of the optical component that does not require light transmission. An optical system comprising a lens and a member bonded to the lens,
An optical system, wherein a coating film containing a hygroscopic agent, a dark colorant, and an organic binder is formed on at least a part of a surface of a member bonded to the lens.   The optical system according to claim 2, wherein the member bonded to the lens is a support member for the lens.   The optical system according to claim 2, wherein the lens is an objective lens.   The optical system according to claim 2, wherein the lens is an endoscope lens.   The optical system according to claim 1, wherein the coating film has an average thickness of 0.01 to 1 μm.   The optical system according to claim 1, wherein a content of the hygroscopic agent in the coating film is 1 to 40 wt%.   The optical system according to claim 1, wherein the hygroscopic agent is granular.   The optical system according to claim 8, wherein the granular hygroscopic agent has an average particle diameter of 1 to 30 μm.   The optical system according to claim 1, wherein the hygroscopic agent is mainly composed of magnesium sulfate. The optical system according to claim 10, wherein the magnesium sulfate is represented by MgSO ₄ · nH ₂ O (where 0 ≦ n ≦ 3).   The optical system according to claim 1, wherein the dark color is black.   The optical system according to claim 1, wherein the colorant is a pigment.   The optical system according to claim 13, wherein the pigment is granular.   The optical system according to claim 14, wherein the granular pigment has an average particle diameter of 1 to 10 μm.   The optical system according to claim 1, wherein a content of the colorant in the coating film is 0.5 to 5 wt%.   An endoscope comprising the optical system according to claim 1.

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