JPH0251117A - Light guide for endoscope - Google Patents

Abstract

PURPOSE:To decrease the diameter of the light guide by making the fiber charging density relatively larger nearby the incidence end surface of an endoscope facing a light source than at the bending operation part in an optical propagation path. CONSTITUTION:The fiber charging density is set at least at the bending part 17 of the endoscope so as to maintain required flexuosity, and the fiber charging density in incidence surfaces 25 and 28 is made relatively larger than said fiber charging density to enable the light from the light source 13 to be photodetected with high incidence efficiency. Consequently, even when the total number of fiber element wires is decreased, the necessary quantity of illumination light is maintained and the diameter of the endoscope light guide is reduced.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an endoscope light disposed within an endoscope scope to illuminate dark observation areas such as inside a body cavity. The present invention relates to a guide, and more particularly, to a technology for reducing the diameter of a light guide.

(Prior Art) As is well known, there are two types of endoscopes: fiberscope type and electronic type.

The general structure of both is an endoscopic scope and a device main body. It is composed of a hand-held operation unit that has various proposal command functions for the central part.

A water supply tube, an air supply tube, a forceps passage, etc. are disposed in the scope guide section so as to pass through the guide section along the length direction.

In addition to each of these tubes, a light guide is also provided in the guide section of the scope. As is well known, this light guide is used to illuminate an observation site in a dark body cavity, and as shown in Fig. 4, a plurality of optical fibers l are covered with a tube jacket 2 such as a silicon tube. It will be done. Then, the light emitted from the light source provided in the device main body and condensed by the condensing lens is received by the input end face 3, guided to the distal end of the scope via the hand operation unit, and directed from the output end face to the observation site. It is designed to emit light.

The scope guide portion with such piping is inserted into a body cavity, and therefore needs to be made smaller in diameter. In addition, since the piping is frequently bent at various points during use, each piping must be constructed to be able to withstand frequent bending.

Therefore, as a light guide, the ratio of the cross-sectional area of the optical fiber 1 to the unit cross-sectional area in the tube jacket 2 (
The fiber packing density (hereinafter referred to as fiber packing density) is set to about 50%. Then, like this, sparsely insert the tube outer covering 2.
The state in which it is housed inside is almost uniform from the input end face 3 to the output end face.

(Problem to be Solved by the Invention) However, when the tube is sparsely housed in the tube jacket 2, the light from the light source that enters the input end face 3 is transmitted between the optical fibers 1. In space or in many light guides, the optical fiber 1 is hardened with an adhesive or the like near the incident end face, so the light is reflected or absorbed by the adhesive or the like. In other words, optical fiber element!
The incidence efficiency per unit of No. 1 was low, and it was a very wasteful state. For this reason, a larger number of optical fibers 1 than is actually required is required, and the light guide has to become thicker.

The present invention has been made in view of the problems of the prior art, and an object of the present invention is to provide a light guide for an endoscope that can be made smaller in diameter while maintaining the necessary amount of illumination light. It is.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention has a plurality of optical fibers bundled together and arranged as a light propagation path from a light source to the distal end of an endoscope. In the light guide for an endoscope, the fiber packing density is made relatively larger in the vicinity of the entrance end surface facing the light source than at least in the bending operation portion of the endoscope in the light propagation path. This is what I did.

(Function) According to the light guide for an endoscope having the above configuration, the fiber packing density is set so that the required flexibility is maintained at least in the bending operation portion of the endoscope, and the fiber packing By making the fiber packing density at the input end face relatively larger than the density, light from the light source can be received with higher incidence efficiency than when the fiber packing density is made uniform from the input end face to the output end face from which light is emitted. Therefore, even if the total number of optical fibers is reduced, the necessary amount of illumination light can be maintained, and the diameter of the endoscope light guide can be reduced.

(Embodiment) Hereinafter, an embodiment of the light guide for an endoscope according to the present invention will be described with reference to FIGS. 1 to 3.

FIG. 2 shows a schematic configuration of an endoscope apparatus to which an endoscope light guide according to the present invention is applied.

This endoscope apparatus is configured such that an endoscope 12 is detachably attached to a main body 11 of the apparatus.

The device main body 11 is provided with a light source 13 such as a Xe lamp. The light emitted by the light source 13 and condensed by the condensing lens 14 enters the light guide 17 while being intermittently blocked by the chopper 16 . In the endoscope 12, the light from the light source 13 is guided to the tip of the scope 18 by this light guide F. The light guided by the light guide 17 illuminates the inside of the body cavity of the subject (not shown). When this illumination reflected light is incident on a solid-state image sensor 19 such as a CCD through an objective optical system provided on the rigid part 18a at the tip of the scope, an electric signal corresponding to the amount of incident light is emitted from the solid-state image sensor 19. can get.

This electrical signal is sent to the main body 11 of the apparatus, and converted into a color video signal by the video processor 21. This video signal is
The signal is decomposed into three primary color signals of RGB by a DSC (digital scan converter), quantized, and recorded in the image memory 22. The video signal read out from the image memory 22 is converted back into an analog video signal and sent to the monitor 23.
Here, an image of the condition inside the body cavity of the subject is displayed.

In the endoscope apparatus having such a configuration, the light guide 17 has an overall and partial structure as shown in FIGS. 1 and 3.

This light guide 17 has a bundle shape and has a diameter of 2
Approximately 10,000 to 15,000 pieces of optical fiber 1 with a diameter of approximately 0 μm,
An optical fiber element 1 is housed in a tube jacket 2 made of a silicone tube so as to be freely movable. As shown in FIG. 3, the light/guide 17 is bound with a metal band jacket 28 instead of the tube jacket 2 by hardening it with adhesive or the like from the incident end face 25 to about the 2C layer. At the same time, it is bifurcated near the tip of the scope 18.

In such a light guide 17, the fiber packing density is changed in each part as follows.

The fiber packing density in the binding portion 28a bound by the metal band jacket 28 is set to 75 to 90%.

In this way, the method of configuring the fiber packing density in the binding part 28a to be in a high state is to control the amount of adhesive, or to bind the bundle of optical fibers 1 with the metal band jacket 28 without using adhesive. or each optical fiber strand 1
Possible methods include sharing the cladding layer.

From the end of the bundle 28a to the bifurcated point, the fiber packing density is lowered by 50 to 60% in the bundle 28a so that the optical fiber 1 is not damaged even when curved by about R5m. It is set to about.

The fiber packing density from the bifurcated point to the freely bendable curved portion 29 provided near the tip of the scope guide portion 27, in other words, to the vicinity of the angle piece 30 which becomes the fulcrum when curved, is 40~ It is set at 45% to further reduce the fiber packing density.

The fiber packing density is further reduced in the vicinity of the angle piece 30 than this fiber packing density, and the optical fiber strand 1 is in a state where it is less likely to be damaged during the bending operation.

Also, this is the section from the vicinity of this angle frame 30 to the exit end face 26 from which light is emitted, and includes the objective optical system and the imaging device! 9
Since the rigid portion 18a in which the fibers and the like are accommodated is not curved, it is possible to achieve a smaller diameter and higher density by increasing the fiber packing density to about 75 to 90%.

In this way, the light guide 17 in which the fiber packing density is changed in each part is better than the conventional example in which the fiber packing density is constant from the input end face 25 to the output end face 26. If the total number is the same, the cross-sectional area of the incident end face 25 will naturally become smaller. Therefore, the entrance end face 25
Assuming that the distribution (beam profile) of the focused light from the light source 13 focused by the condensing lens 14 in is a Gaussian beam with a beam diameter of about 2.5 mm as shown in FIG. 3, the light intensity is high. The center portion of the beam is effectively incident on the incident end face 25. In this way, the input end face 25
According to the light guide 17 in which the fiber packing density is increased near this end face.

Compared to the conventional example, a state in which the amount of light incident on one optical fiber strand l is high, that is, a state in which the incidence efficiency is high can be obtained.

Therefore, even if the number of optical fiber strands, the amount of light emitted from the light source 13, and the beam diameter at the incident end face 25 are the same as in the conventional example, the brightness is about 1.3 times that of the conventional example. In addition, the number of optical fiber strands has been reduced by 60%, and the thickness has been reduced to 80%.
Even if the brightness is reduced to about 0%, the same or higher brightness can be obtained.

Note that even when the light incident on the input end face 25 is not a Gaussian beam as described above, the same effect can be obtained by reducing the diameter of the incident beam.

In other words, even if the amount of light condensed by the condenser lens 14 is the same as in the conventional case, the light incident on the input end face 3 is reflected or absorbed by the adhesive between the optical fibers 1, as in the conventional case. This is because the loss caused by this is reduced.

〔Effect of the invention〕

As explained above, according to the light guide for an endoscope of the present invention, the fiber packing density is set so that the required flexibility is maintained at least in the bending operation portion of the endoscope. By making the fiber packing density at the input end face relatively larger than the fiber packing density, the light from the light source can be incident with higher efficiency than when the fiber packing density is made uniform from the input end face to the output end face from which light is emitted. Therefore, even if the total number of optical fibers is reduced, the necessary amount of illumination light can be maintained, and the diameter of the light guide for an endoscope can be reduced.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of changes in fiber packing density of a light guide for an endoscope according to the present invention, FIG. FIG. 3 is an external view showing an example of the vicinity of the incident end face of a light guide according to the present invention, and FIG. 4 is an external view showing an example of a conventional light guide. 1... Optical fiber strand 2... Tube jacket 13... Light source] 7... Light guide 25... Incident end face 26... Output end face 28... Metal band jacket

Claims (1)

[Claims] (1) An endoscope light guide formed by bundling a plurality of optical fiber strands and arranged as a light propagation path from a light source to a distal end of an endoscope, the light guide including at least 1. A light guide for an endoscope, characterized in that the fiber packing density near the entrance end face facing the light source is relatively greater than that at the bending portion of the endoscope.