Patent Application
20100022841
The present application claims priority from Japanese Patent Application No. 2008-188186 filed on Jul. 22, 2008, the entire content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to an endoscope optical system device having an optical system which is provided on the top end side of an inserting portion of an endoscope and in which a plurality of optical elements are aligned, and an endoscope with the same.
2. Description of the Related Art
An endoscope used to observe/inspect a body cavity, or the like is equipped with an illuminating unit and an observing unit at an inserting portion that is inserted into the body cavity, or the like. The illuminating unit has a light guide for transmitting an illumination light emitted from a light source device. An illumination lens, from which the illumination light fed from the light guide is emergent, is fitted to a top end of the inserting portion. The observing unit has an objective optical system that is used to pick out image information in the body cavity to the outside, and displays the video image in the body cavity on a monitor device, or the like. The objective optical system consists of plural sheets of lenses. During the inspection, sometimes contaminants such as body fluids, or the like adhere to the lens, which is arranged at the top end of the inserting portion to expose to the outside, and thus the observation visual field becomes poor. Therefore, the contaminants are washed away by injecting wash water to the lens from a nozzle.
The inserting portion is employed during the inspection in a state that this portion is warmed up to about 40 to 50° C. by a heat generated from the solid-state imaging element, the light guide, etc. When the wash water whose temperature is low at about 10 to 20° C. is injected to an outer surface of the lens whose temperature is increased, the cooling of the lens is caused quickly. Thus, when moisture has entered into the inside of the objective lens, the formation of condensation occurs on the lens and is adhered onto the inner surface side of the lens. Therefore, such a problem existed that a picture quality of the observed video image deteriorates.
In order to prevent such formation of condensation on the lens, various proposals have been made (for example, see JP-A-61-107210, JP-A-5-281492). As shown in
Also, as shown in
However, in the endoscope 1 set forth in JP-A-61-107210, a layer of the adhesive 13 is provided merely between an outer peripheral surface of the top end cover lens 9 and an inner peripheral surface of the top-end cover lens containing recess 5 and between an outer peripheral surface of the filter 11 and an inner peripheral surface of the filter containing recess 7. Therefore, it is possible that the moisture, particularly, a water molecule passes through the layer of the adhesive 13 and enters into the inside. Also, in the optical system device 21 set forth in JP-A-5-281492, it is only the joining means (adhesive) for adhering the first optical element 25 and the second optical element 2 at the joined surfaces 29 that seals hermetically the air layer S in an airtight state. Therefore, it is impossible to say that the sufficient hermetic sealing can always be kept by merely adhering these narrow joined surfaces 29, and sometimes the moisture is ready to enter into the air layer S. Also, in some cases the above approach cannot be applied to adhere the moisture-resistant optical element whose moisture permeability is low but which cannot be used because of its low adhesive strength.
The present invention has been made in view of the above circumstances and it is an object of the present invention to provide an endoscope optical system device capable of preventing fogginess of an optical element caused due to a formation of condensation without fail by increasing airtightness of a top end portion of an endoscope, and an endoscope with the same.
In the endoscope optical system device constructed in this manner, the joined surfaces of the first optical element and the second optical element are adheres by the first adhesive, and peripheries of end portions of the joined surfaces are covered with the second adhesive with a moisture resistance. Therefore, such an event can be prevented without fail that moisture seeps in the joined boundary from the outside via the peripheries of the end portions of the joined surfaces and then enters into the air layer that is formed between the first optical element and the second optical element. As a result, the formation of condensation on the lens can be prevented in advance, and also a reduction in picture quality of the observed video image can be prevented.
Also, the adhesives that are excellent in each feature respectively are employed separately such that an adhering strength can be ensured by the first adhesive and also a moisture resistance can be ensured by the second adhesive whose moisture permeability is low. Therefore, the optical system device having a high airtightness and a high adhering strength can be constructed.
In the endoscope optical system device constructed in this manner, it prevents the air layer between the concave portion of the plane-concave lens of the first optical lens and the second optical lens from entering moisture from the outside of the endoscope. Thus, it is prevented from fogging caused by dew condensation of the plane-concave lens.
In the endoscope optical system device constructed in this manner, it becomes simple assembly steps, since it is unnecessary to adjust the position such as optical axis due to the parallel plate of the second optical element when the first optical lens joins the second optical lens.
the second adhesive is coated on a stepped portion which is formed by a difference between the outer diameter of the first and second optical elements in a case that the first and second optical elements are joined together.
In the endoscope optical system device constructed in this manner, the second adhesive whose moisture permeability is low is coated on the stepped portion formed when an outer diameter of the second optical element is set smaller than an outer diameter of the first optical element. Therefore, it can be prevented substantially that the external moisture passes through the second adhesive. As a result, such an event can be prevented that the moisture seeps in the air layer that is interposed between the first optical element and the second optical element. Also, the second adhesive never squeezes out outward in the diameter direction, and the optical system device can be constructed in compact.
In the endoscope optical system device constructed in this manner, the second adhesive is coated to fill the closed space that is formed between the first and second optical elements and the lens holder. Therefore, the moisture passing path can be restricted by shielding an outer air. As a result, such an event can be prevented more surely that the moisture seeps in the air layer that is interposed between the first optical element and the second optical element.
In the endoscope optical system device constructed in this manner, the optical system is the optical system that guides a light to the imaging element that fetches the image information. Therefore, the image in the body cavity can be converted into the electric signal and then output to the external device, and can be displayed on a monitor device, or the like.
In the endoscope optical system device constructed in this manner, the optical system is the optical system that emits an illumination light. Therefore, a desired part in the body cavity can be illuminated brightly, and the clear image in the body cavity can be picked up.
In the endoscope optical system device constructed in this manner, a moisture permeability of the second adhesive is set to 9 g/m2/24 h or less. Therefore, the sure moisture proof effect can be achieved.
According to the endoscope, the bright and clear image can be obtained.
According to the endoscope optical system device and the endoscope with the same, the joined surfaces of the first optical element and the second optical element are adhered together by the first adhesive, and peripheries of end portions of the joined surfaces are covered with the second adhesive with a moisture resistance. Therefore, such an event can be prevented without fail that the moisture seeps in the joined boundary from the outside via the peripheries of the end portions of the joined surfaces and then enters into the air layer that is formed between the first optical element and the second optical element. As a result, the formation of condensation on the lens can be prevented in advance, and also a reduction in picture quality of the observed video image can be prevented.
Embodiments of an optical system device of an endoscope and an endoscope with the same according to the present invention will be explained in detail with reference to the drawings hereinafter.
As shown in
As shown in
An observe unit 100 as an optical system device provided to the observation window 35 is constructed by incorporating an objective optical system into a lens holder 47. In order to fix the lens holder 47 to the top end hard portion 31a, a through hole that passes through from the top end cap 43 to the top end portion main body 41 in the axial direction is formed. An objective optical system consisting of a plurality of lenses, described later, as the optical element is fitted into the lens holder 47. Also, a prism 49 for turning an optical axis of the objective optical system at a right angle is joined/fixed to an end surface of the lens holder 47. Also, a solid state imaging element 53 as an imaging unit fitted to a substrate 51 is joined to the prism 49.
Next, an example of the objective optical system provided to the lens holder 47 is shown in
The first optical element G1 is formed as a plano-concave lens whose observation object side is shaped into a planar surface and whose focusing side (a side facing to the second optical element G2) is shaped into a concave surface, and the planar surface is exposed to the observation window 35. Also, the second optical element G2 positioned closer to the focusing side than the first optical element G1 is formed as the parallel plate. The second optical element G2 is joined hermetically to the first optical element (lens) G1 (in
Also, the third optical element G3 is formed as a convexo-concave lens whose concave surface is directed to the focusing side, and the fourth optical element G4 is formed as a convex lens. In this case, the third optical element (lens) G3 and the fourth optical element (lens) G4 constitute a cemented lens.
The first lens G1 and the parallel plate G2 are adhered firmly at joined surfaces 55 by a first adhesive 57 whose adhesive strength is high, and are joined hermetically together. Also, an outer diameter D of the first lens G1 is larger than an outer diameter d of the parallel plate G2. When the first lens G1 and the parallel plate G2 are joined together, a stepped portion 59 is formed on outer peripheries of end portions of the joined surfaces 55. When the first lens G1 and the parallel plate G2 are fitted into the lens holder 47, a closed space C is formed between an inner peripheral surface of the lens holder 47 and the first lens G1 and the parallel plate G2, and a second adhesive 61 whose moisture permeability is lower than the first adhesive 57 is coated on a full circumference of the closed space C. The a second adhesive 61 may be coated closely to cover at least a space between the first lens G1 and the parallel plate G2. The moisture resistance can be improved much more by providing the second adhesive to fill the closed space C.
The fitting operation of the optical elements G1, G2, G3 and G4 into the lens holder 47 will be made as follows. That is, the first lens G1 and the parallel plate G2 are adhered at the joined surfaces 55 by the first adhesive 57, and also the second adhesive 61 is coated on the stepped portion 59. Then, the first lens G1 and the parallel plate G2 are inserted into the lens holder 47 from the front surface side (the left side in
Both biocompatibility and chemical resistance are required of the first adhesive 57 that is used in the endoscope 30. As the first adhesive 57 whose main purpose is to adhere the first lens G1 and the parallel plate G2 firmly, an epoxy-based adhesive such as CS2340-5 (manufactured by Cemedine Co., Ltd), or the like, for example, is illustrated. A moisture permeability of the first adhesive 57 is set in a range of 45 to 90 g/m2/24 h (based on JIS Z0208).
Also, as the second adhesive 61 whose main purpose is to prevent a moisture, a fluorine-based adhesive with a low moisture permeability such as X-71-708 (manufactured by Shin-Etsu Chemical Co., Ltd: moisture permeability is 9 g/m2/24 h (after cured at 23° C./55% RH/7 days)), or the like, for example, and an organic polymer-based adhesive such as a polyolefin-based resin, or the like may be listed. The second adhesive 61 may have the moisture permeability of 9 g/m2/24 h or less. Although the concrete illustration is omitted, it was understood by experiment that, when the moisture permeability is about 15 g/m2/24 h, the influence of moisture permeation begins to appear. The certain moisture resistant effect could be achieved by the adhesive whose moisture permeability is 9 g/m2/24 h. In this case, because the outside of the second adhesive 61 is covered with the first adhesive 57, biocompatibility is not required of the second adhesive 61 and a margin of choice of the adhesive material can be enhanced.
The observe unit 100 is fitted to the top end hard portion 31a such that the lens holder 47 is inserted into the through hole provided from the top end portion main body 41 to the top end cap 43.
Next, an action of the observe unit (optical system device) 100 will be explained hereunder.
When the moisture is contained in the air layer S between the first lens G1 and the parallel plate G2, there is a possibility that the formation of condensation occurs. The first lens G1 is exposed to the observation window 35, and further the wash water is injected onto the surface from the nozzle 39. When the wash water is injected, the inner surface of the first lens G1, particularly the thinnest part of the lens, is cooled quickly by the wash water. As a result, the formation of condensation occurs intensively on the center thinnest portion on the inner surface side of the first lens G1, which may be not in obtaining the clear endoscope image.
For this reason, it is requested that the moisture should not be contained in the air layer S between the first lens G1 and the parallel plate G2. Also, it is requested that the air layer S should be sealed perfectly and held in such a state that no moisture enters into this air layer from the outside for a long term.
In the optical system device 100 of the endoscope 30, the first lens G1 and the parallel plate G2 are adhered at the joined surfaces 55 by the first adhesive 57 whose adhesive strength is high, and the second adhesive 61 whose moisture resistance is high (whose moisture permeability is low) is coated on the stepped portion 59 on the peripheries of the end portions of the joined surfaces 55. Therefore, the moisture that came from the outside can be blocked by the second adhesive 61 whose moisture resistance is high, and thus such an event can be prevented without fail that the moisture enters into the air layer S between the first lens G1 and the parallel plate G2. As a result, the formation of condensation on the first lens G1 can be prevented in advance, and also a reduction in picture quality of the observed video image can be prevented.
Next, a variation of the observe unit (optical system device) 100 will be explained with reference to
As shown in
Other operations and advantages are similar to those in the optical system device 100 in the first embodiment, and therefore their explanation will be omitted herein.
Next, an optical system device according to a second embodiment will be explained with reference to
As shown in
An emergent end 65 of a light guide 63 is positioned at the back (the right side in
When the moisture enters into the air layer S between the first lens G1 and the parallel plate G2 from the outside, in some cases the formation of condensation occurs on the first lens G1 and thus a luminous intensity of the illumination unit 200 is decreased. In the illumination unit 200 in the present embodiment, the first lens G1 and the parallel plate G2 are adhered at the joined surfaces 55 by the first adhesive 57 whose adhesive strength is high, and the second adhesive 61 whose moisture resistance is high (whose moisture permeability is low) is coated on the stepped portion 59 on the peripheries of the end portions of the joined surfaces 55. Therefore, the moisture that came from the outside can be blocked by the second adhesive 61 whose moisture resistance is high. As a result, the formation of condensation on the first lens G1 can be prevented in advance, and also the illumination of high luminous intensity can be provided.
Here, the optical system device of the present endoscope is not limited to the embodiments and the variation mentioned above, and variations, improvements, etc. can be applied appropriately. For example, in the above description, the explanation is made on the assumption that the parallel plate is employed as the second optical element. In this case, an infrared cut filter required when the solid state imaging element may be employed or another lens can be employed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-188186 | Jul 2008 | JP | national |
