JPH0644902B2 - Endoscope - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is equipped with a solid-state image sensor such as a CCD capable of performing endoscopic laser treatment at the tip of an insertion section, or a video camera attached to an eyepiece section. The present invention relates to an endoscope capable of projecting an observation image on a monitor.

[Problems to be Solved by Conventional Techniques and Inventions] Currently, laser light is used endoscopically for the purpose of incision resection of a diseased part in a body cavity such as the stomach or large intestine or coagulation of a bleeding part. It is widely known that an Nd-YAG laser that oscillates laser light in the infrared wavelength range is generally used as the laser.

By the way, for example, as shown in FIG. 5, when the electronic endoscope apparatus 1 and the Nd-YAG laser are used together, Nd-YA
The G laser is an electronic endoscope 4 inserted in the affected part 3 in the body cavity.
The laser device 8 is used by inserting the laser fiber probe 7 into the channel 6 provided in the insertion part 5 of the laser device 8.
The laser fiber probe 7 irradiates the affected area 3 in the body cavity with the Nd-YAG laser light from. Then, at the same time as the illumination light emitted from the light source device 9 through the light guide 10 to the affected part 3 in the body cavity and reflected, laser reflected light unnecessary for the observation is built in the tip of the insertion part 5 of the electronic endoscope 4. Since it is incident on the solid-state image sensor 12, the observation image displayed on the television monitor 16 is whitish through the signal line 14 and the video processor 15 extending from the side of the operation unit 13 of the electronic endoscope 4. It becomes hard to see.
In FIG. 5, reference numeral 11 is a solid-state image sensor cover glass.

Therefore, in order to solve the above problems, for example, Japanese Utility Model Laid-Open No. 62-142311 and Japanese Patent Laid-Open No. 62-129047.
It is disclosed in the publication. In these related technologies,
As shown in the figure, a method is used in which an objective lens system 18 is provided with a laser cut filter 17 for cutting laser light.

As the laser cut filter, by reflecting the light of the infrared absorption filter and the laser wavelength to reduce the transmittance of the laser light by absorbing the laser wavelength light,
Laser light reflection type filters that reduce the transmittance of laser light are already known.

When laser light is used in normal clinical practice, for example, Nd-YAG laser light of 50 W is used, and at this time, a filter having a laser transmittance of 0.01% is sufficient for observation. Images are supposed to be obtained. Further, when a higher quality observation image is required, or when 100 W of high-power Nd-YAG laser light is used, the laser transmittance is 1.0 × 10 ⁻³ % to 0.5 × 10 ^−5. Filter is needed.

At present, it is difficult to satisfy the required transmittance with only one of the infrared absorption filter and the laser reflection filter. For example, a general infrared absorption filter is KG5, CM500S, C500S.
Are commercially available and show a laser transmittance of about 10% at a thickness of 0.5 mm. To reduce the laser transmittance, it is sufficient to increase the thickness, but when actually incorporated in an endoscope objective lens system, the filter thickness cannot be expected to increase significantly due to space limitations. On the other hand, the laser reflection type filter is manufactured by applying a multi-layer coating on a white plate and has a transmission characteristic as shown in FIG. There is a limit to increasing the laser cut rate, because the transmittance characteristic is partially down (ripple) 19 in the visible part and the distortion of the transmission characteristic itself in the visible part disturbs the image color tone. The rate is limited to about 1%. Therefore, in order to achieve the required laser transmission,
Two or more types of laser cut filters must be used in combination.

Three types of combination patterns are conceivable: laser reflection filters, laser absorption filters, and a combination of laser reflection filters and laser absorption filters.

As shown in FIG. 7 (a), when the white plates coated with the laser reflective filters 20 and 20 each having a transmittance of 0.1% are used in combination, the laser light is 1/1
With a probability of 000, the light passes through the first laser reflection type filter 20, and the rest is removed. The laser light which has passed through the first laser reflection type filter 20 is converted into the first laser reflection type filter 20 and the second laser reflection type filter 2.
Between 0 and 0, multiple reflection occurs while transmitting 0.1% each time reflection occurs, and eventually the first laser reflection type filter 2
0, the laser light passing through the second laser reflection type filter 20 passes through the second laser reflection type filter 20 at a rate of 1/2. Therefore, the total transmittance when combining two laser reflection filters is 1/1000 ×
It becomes 0.05% from 1/2 = 1/2000.

As shown in FIG. 7 (b), when the infrared absorbing filters 22 and 22 each having a transmittance of 10% are combined, the total transmittance becomes 1%.

As shown in FIG. 7 (c), when a white plate coated with a laser reflection type filter 20 having a transmittance of 0.1% and a laser absorption filter 22 having a transmittance of 10% are combined,
The total transmittance is 0.01%.

Therefore, in order to guarantee the required laser transmittance,
It is wasteful to use a combination of a laser absorption type filter and a laser reflection type filter. As this combination, a method of coating a laser reflection type filter on the surface of a laser absorption type filter is already known. When such an infrared absorption type filter and a laser reflection type filter are combined and the arrangement direction is decided randomly, for example, the surface coated with the laser absorption type filter is placed on the back side of the insertion part, and the incident light is directly absorbed by the infrared absorption type filter. If the filter is installed so as to be incident on the filter, the reflected light containing a large amount of laser light having a relatively large amount of heat directly enters the infrared absorption filter. The infrared absorption filter absorbs a large amount of this laser light, so that an excessive amount of heat is accumulated and it is heated. The heating of this filter causes problems such as the influence of the temperature rise of the endoscope tip portion on the imaging system and the damage of the infrared absorption filter itself. In addition, when a large amount of laser light is incident on the infrared absorption filter, there is a case where the infrared absorption ability is deteriorated due to a performance problem, and the initially expected laser cutting effect cannot be obtained.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an endoscope that is safe and has a high laser cutting efficiency, by preventing the infrared absorption filter from being heated and from being deteriorated in performance.

[Means and Actions for Solving the Problems] In order to achieve the above object, the endoscope according to the present invention includes an absorption filter for absorbing light in a specific wavelength region, and the specific wavelength in an objective optical system. A reflection type filter that reflects light in a region is provided, and the reflection type filter is arranged closer to the subject side than the absorption type filter. With this configuration, after most of the incident laser light is reflected and removed by the reflection filter, the remaining laser light that has passed through the reflection filter enters the absorption filter and is absorbed and removed.

[Embodiment] FIGS. 1 to 3 relate to a first embodiment of the present invention.
FIG. 2 is a detailed cross-sectional view of the tip portion of the electronic endoscope, FIG. 2 is a schematic configuration diagram showing the electronic endoscope device when a laser device is used, and FIG. 3 is a comparative diagram showing a chamfered state.

As shown in FIG. 2, the endoscope device 31 includes an endoscope 32.
And a video processor 35 for processing a signal or the like sent from a solid-state image sensor 33 built in the endoscope 32 via a signal line 34, and a television for displaying the signal from the video processor 35 as an image. It is composed of a monitor 36 and a light source device 37 for supplying illumination light.

The endoscope includes an elongated and flexible insertion portion 38 and an operation portion 39 that is connected to the rear end of the insertion portion 38, and the operation portion 39 is provided inside the electronic endoscope 32. An insertion port 41 for the provided channel 40 is provided. Also,
A light guide 43 having a light distribution lens 42 at its tip is built into the insertion portion 38, and this light guide 43 is connected to the light source device 37. Further, an objective lens system 45 for forming an image of the reflected light from the subject 44 on the solid-state imaging device 33 is provided in the insertion portion 38, and a specific wavelength on the front surface is provided at the rearmost portion of the objective lens system 45. Like the infrared absorption filter 47 as an absorption filter that absorbs light in a specific wavelength range, the laser reflection filter 46 as a reflection filter that reflects light in a region is coated on the front surface of the laser reflection filter 46. A coated solid-state image sensor cover glass 48 is provided, and the solid-state image sensor 33 is fixed to the rear surface of the solid-state image sensor cover glass 48. Further, the laser fiber probe 49 of the Nd-YAG laser including the laser fiber probe 49 and the laser device 50 is inserted from the insertion opening 41 into the channel 40 of the endoscope 32.
Laser light is applied to the affected part 44 in the body cavity from the tip of the laser fiber probe 49.

As shown in FIG. 1, the distal end portion of the insertion portion 38 includes a cylindrical distal end portion main body 52 made of a hard member such as metal,
A cover member 53 is attached to the tip side of the tip body 52. The tip body 52 and the cover member 53
A through hole 54 for observation, the channel 40, and a through hole for illumination (not shown) are formed on the inner surface of the insertion portion 38 in parallel with the longitudinal direction of the insertion portion 38. A lens frame 55 is fitted on the tip side of the observation through hole 54. Then, a front objective sphere 56 as a part of the objective lens system 45 is held by the lens frame 55 so that its optical axis is parallel to the longitudinal direction of the insertion portion 38. A filter 57 is arranged behind the object front sphere 56. The filter 57
The rear face of the filter 5 is inscribed in the lens frame 55.
A pressing frame 58 for pressing 7 is continuously provided, and a lens frame 59 for holding the objective optical system 45 excluding the objective front sphere 56 and the filter 57 is provided by making the front part inscribed in the pressing frame 58. . Further, a laser reflection filter 46 is coated on the front surface of the infrared absorption filter 47 arranged at the rearmost part of the objective optical system 45, and the outer periphery of the rear surface is chamfered 60. The infrared absorption filter 47 coated with the laser reflection filter 46 is fixed by a lens retainer 61 provided on the outer periphery of the front surface and an adhesive 62 applied to the chamfered portion 60.

A cylindrical member 63 is exteriorly mounted on the rear side of the lens frame, and an inner diameter is increased via a step 64 on the rear side of the lens frame 59.

The step portion 64 has a laser reflection type filter 46 on the front surface.
The solid-state image sensor cover glass 48 coated with is fixed by mounting the outer periphery, and the solid-state image sensor 33 is fixed to the rear surface of the solid-state image sensor cover glass 48. A signal line 34 extends from the solid-state image sensor 33.

A laser fiber probe 49 is inserted in the channel 40. And the tip body 52
A flexible tube 65 is packaged on the outer side of the tube, and a flexible tube 66 is further packaged on the outer side.

With the above configuration, most of the incident light (illumination reflected light including laser light) indicated by the arrow 67 is reflected and removed by the laser reflection type filter 46 coated on the front surface of the infrared absorption type filter 47. It According to an experiment, the laser reflection filter 46 reduces the transmittance of laser light to about 1/1000.

The incident light from which the laser light is largely removed by the laser reflection type filter 46 then enters the infrared absorption type filter 47, where the laser light is further absorbed and removed. In the experiment, the infrared absorption filter 4
In No. 7, the transmittance of laser light is further reduced to about 1/10. Further, since the laser light reflected by the laser reflection type filter 46 coated on the solid-state imaging device cover glass 48 is absorbed by the infrared absorption type filter 47, multiple reflection does not occur.

As described above, according to the present embodiment, most of the laser light is reflected and removed by the laser reflection type filter 46 and is then incident on the infrared absorption type filter 47. The laser light is not excessively absorbed by 47, and therefore there is no possibility of heating or deterioration of performance.

In addition, in the present embodiment, the infrared absorption filter 47 has a third
Although chamfering 60 is performed as shown in FIG. 3A, it is also possible to chamfer the side coated with the laser reflective filter 46 as shown in FIG. 3B. However, usually in the chamfering or rounding process, the coating of the laser reflective filter 46 deteriorates in its reflective properties along the chamfered edge. This deteriorated portion may be generally considered to be about 50 μm, but when the coating surface of the laser reflection type filter 46 is fixed with a lens holder, the laser light directly enters the infrared absorption type filter 47 from the deteriorated portion. The inner diameter of the lens retainer must be set so as to completely mask this deteriorated portion.

As can be seen by comparing FIGS. 3 (a) and 3 (b), when the laser reflection filter 46 side is chamfered, the lens presser has a smaller inner diameter than the lens presser 61 of this embodiment. Therefore, in order to obtain the same inner diameter as that of the present embodiment, an infrared absorption filter having a large outer diameter must be used, and as a result, the distal end portion of the endoscope becomes large.

Therefore, by chamfering as in the present embodiment, the tip portion of the endoscope can be miniaturized, and the side coated with the laser reflection type filter and the side not coated can be easily identified.

It should be noted that this embodiment can be applied to other laser lights and infrared rays. Further, the same effect can be obtained not only in the electronic endoscope but also in a fiberscope capable of projecting an observation image on a monitor television by mounting a television camera or the like on the eyepiece.

FIG. 4 is a sectional view of the tip portion of the electronic endoscope according to the second embodiment of the present invention.

In the present embodiment, an infrared absorption filter 47 coated with a laser reflection filter 46 is arranged instead of the filter 57 in the first embodiment, and the solid-state imaging device cover glass 48 is coated with the laser reflection filter 46. However, most of the laser reflection type filter 46 coated on the front surface of the first infrared absorption type filter 47 is reflected, and the laser light transmitted without being reflected by the laser reflection type filter 46 is an infrared absorption type filter. Is absorbed and reduced by the filter 47 of FIG. Further, the laser light transmitted without being absorbed by the infrared absorption type filter 47 is a laser reflection type filter and an infrared absorption type filter coated on the infrared absorption type filter 47 arranged at the rearmost part of the objective lens system 45. It is reflected and absorbed at 46. Other configurations and actions are the same as those in the first embodiment, and effects can be obtained that are substantially the same as those in the first embodiment.

[Effects of the Invention] As described above, according to the endoscope of the present invention, since the laser reflection filter is provided in front of the infrared absorption filter, most of the incident laser light is reflected. Since it is incident on the infrared absorption filter,
The infrared absorption filter does not cause excessive accumulation of heat due to excessive absorption of laser light.

Therefore, there is an effect that it is possible to prevent the influence on the imaging system, the damage of the infrared absorption filter, and the reduction of the infrared absorption capability due to the temperature rise of the endoscope tip portion.

[Brief description of drawings]

1 to 3 relate to a first embodiment of the present invention.
FIG. 4 is a detailed cross-sectional view of the tip of the electronic endoscope, FIG. 2 is a schematic configuration diagram showing the electronic endoscope device when a laser device is used, and FIG. 3 is a comparative diagram showing a chamfered state. Is a cross-sectional view of a distal end portion of an endoscope according to a second embodiment of the present invention, FIG. 5 is a schematic configuration diagram showing a conventional electronic endoscope apparatus when a laser apparatus is used, and FIG. 6 is a laser reflection type. FIG. 7 is a diagram showing the transmission characteristics of the filter, and FIG. 7 is a comparative diagram showing a combination of a laser reflection type filter and an infrared absorption type filter. 33 ... Solid-state image sensor 44 ... Objective lens 46 ... Laser reflection type filter 47 ... Infrared absorption type filter 60 ... Chamfer

Claims (1)

[Claims] 1. An objective optical system is provided with an absorption filter that absorbs light in a specific wavelength region and a reflection filter that reflects light in the specific wavelength region, and the reflection filter is the absorption type filter. An endoscope characterized in that it is arranged closer to the subject than the filter.