Endoscope

Abstract

Endoscope having a bendable tube connected to a forward end member adapted to be inserted into a hollow body portion to be inspected and controlled from a control housing and an elongated flexible tube connecting the bendable tube and the control housing. The flexible tube has a thin tubular synthetic resin layer having a tubular net-like braid of non-metallic fibers embedded therein and another thin tubular synthetic resin layer having a tubular net-like braid of metallic fibers embedded therein, the superimposed resin layers coaxially covering the flexible core of the flexible tube, and the bendable tube comprises a tubular, knitted net-like braid of crimped synthetic fibers closely enveloping a bendable tubular core and a pliable resin tube closely enveloping the braid, thus providing adequate wall thickness for the flexible tube and the bendable tube while retaining sufficient flexibility and twist-resisting property.

Description

BACKGROUND OF THE INVENTION

The present invention relates to an endoscope, and more particularly to the novel and useful construction of the elongated flexible tube and the controllably bendable tube connecting the control housing of the endoscope to the forward end member thereof to be inserted into a hollow portion of a living body to be inspected by the endoscope.

An endoscope comprises in general a forward end member connected to a control housing through a controllably bendable tube and an elongated flexible tube. The controllably bendable tube is located adjacent to the forward end member and must have sufficient bendability and also sufficient strength against collapsing so that it can be bent in the desired direction and by the desired angle thereby permitting the forward end member to be easily inserted through a passage having complicated curvatures into a hollow portion to be inspected and directed to an object for the proper inspection thereof, while the elongated flexible tube is made yieldable to follow the curvature of the passage but resists twisting.

Optical systems are provided in the forward end member for illuminating the object to an eyepiece in the control housing or photographed by a camera provided in the control housing.

Since the passage through which the forward end member is inserted is relatively thin, the diameter of the forward end member as well as the bendable tube and the flexible tube must be made as small as possible while the inner diameter of the bendable tube and the flexible tube must be as large as possible in order to accomodate the light and the image transmitting optical systems and other elements.

The present invention aims at providing improved flexible and bendable tubes for an endoscope.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an endoscope with an elongated flexible tube which is sufficiently flexible but resists twisting while the wall thickness thereof is reduced to a minimum.

Another object of the present invention is to provide an endoscope with a bendable tube of sufficient bendability while the wall thickness thereof is at a minimum.

The above objects are achieved in accordance with the present invention by an elongated flexible tube characterized by a thin tubular synthetic resin layer having a tubular net-like braid made of non-metallic fibers embedded therein and a thin tubular synthetic resin layer having a tubular net-like braid made of metallic fibers embedded therein, the two layers being superimposed and closely enveloping a flexible tubular metallic core member thereby affording sufficient flexibility and twist-resisting property to the elongated flexible tube at minimum wall thickness so that sufficient space is provided in the interior of the elongated flexible tube. The bendable tube has a tubular net-like braid knitted of crimped synthetic fibers and closely enveloping a bendable tubular core, a pliable resin tube being laid closely around the braid to provide sufficient bendability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a general side view of a conventional endoscope;

FIG. 2 is a fragmentary longitudinal sectional view of the elongated flexible tube of the endoscope of FIG. 1;

FIG. 3 is a fragmentary longitudinal sectional view of another known flexible tube of an endoscope;

FIG. 4 is a fragmentary longitudinal sectional view of an elongated flexible tube constructed in accordance with the present invention;

FIG. 5 is a fragmentary plan view of the braid used in the tube shown in FIG. 4;

FIG. 6 is a fragmentary side view partly in section showing the construction of the bendable tube of a known endoscope;

FIG. 7 is a fragmentary side view of a bendable tube constructed in accordance with the present invention; and

FIG. 8 is a fragmentary side view shown the procedure of producing the braid used in the bendable tube of FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1 showing a conventional endoscope, the elongated tubular endoscope element has a forward end member 1 connected to control housing 2 through an elongated yieldably flexible tube portion 3 and a controllably bendable tube portion 4. The controllably bendable tube 4 is located adjacent to the forward end member 1 and controlled by an operating handle 5 through connecting means such as strings (not shown) so that the forward end member 1 is directed to the desired direction with respect to an object for the proper inspection thereof.

A viewing window 6 and an illuminating window 7 are provided in the wall of the forward end member 1. An elongated light conducting optical system (not shown) extends through the tube 4 and the tube 3 from the illuminating window while the rearward end 8 thereof extends beyond the control housing 2 so as to be connected to an external light source (not shown).

An objective lens and a reflecting prism (not shown) in the forward end member 1 at the viewing window 6 and an image transmitting optical system (not shown) permits an image to be viewed through an eyepiece 9 provided in the control housing 2.

In the prior art construction of the elongated flexible tube 3 shown in FIG. 2, a helically wound thin strip of metal 10 is laid closely around an oppositely helically wound thin strip of metal 11 so as to form the core of the elongated flexible tube 3. A pliable tube 12 made of a material such as polyvinyl chloride resin is laid closely around the helically wound thin strip 10.

FIG. 3 shows another example of a known flexible tube 3' which comprises a helically wound thin strip of metal 11 forming the core of the elongated flexible tube 3', a tubular net-like metallic braid 13 closely laid around the strip 11 and a pliable tube 12 laid closely around the braid 13.

The elongated flexible tube 3 of FIG. 2 has a relatively great wall thickness and poor yieldability. The tube 3' of FIG. 3 has also a relatively great wall thickness although the yieldability is slightly improved in comparison with that of the tube 3.

In accordance with the present invention, an elongated flexible tube 3" shown in FIG. 4 comprises a helically wound thin strip of metal 11 similar to that shown in FIG. 2. A tubular net-like braid 14 made of non-metallic fibers such as cotton, silk or plastic is laid coaxially around the strip 11, and soft synthetic resin compound is applied to the braid 14 by coating with or dipping in the molten resin compound so as to form a thin resin layer 15 in which the braid 14 is embedded and which engages the strip 11.

In the like manner, a tubular metallic braid 16 of piano wires or stainless steel wires is laid closely around the layer 15, and soft synthetic resin compound is applied to the braid 16 by coating or dipping so as to form a thin resin layer 17 in which the braid 16 is embedded.

In a similar manner, a thin resin layer 18 with a braid 19 of non-metallic fibers embedded therein is provided around the resin layer 17.

The number of layers may be increased so as to form the desired thickness of the wall in which resin layers having embedded braids of non-metallic fibers and the resin layers having the braid of metallic fibers alternate.

FIG. 5 shows an example of the braid used in the present invention.

As to the resin compound, any resin compounds can be used insofar as they have sufficient pliability and are harmless to the living body.

The elongated flexible tube 3" has appropriate flexibility and resiliency as well as sufficient yieldability and twist resistance while its wall thickness is held to a minimum. The longitudinal end of the tube 3" remote from the bendable tube constitutes a terminal portion of the tubular endoscope element which is secured to the control housing 2.

FIG. 6 shows a known bendable tube 4 of an endoscope connected to the forward end member 1. It comprises a tubular core consisting of short tubular segments 20 connected by pivot pins 20a, a pliable tube 21 made of polyvinyl chloride or Neoprene laid closely around the core, a metallic braid 22 of stainless steel or piano wires closely laid around the pliable tube 21 and a pliable outer shell 23 made of an elastomeric material such as polyvinyl chloride or rubber. Therefore, the wall thickness of the tube 4 is relatively great thereby reducing the space utilizable to locate the various elements therein.

In accordance with the present invention, the bendable tube 4' shown in FIG. 7 is provided with a thin wall which affords sufficient bendability and resistance against collapsing and twisting.

The core of the tube 4' consists of a tubular segments 20 joined by pivot pins 20a as in FIG. 6. A tubular braid 24 of knitted crimped synthetic fibers such as nylon fibers is laid closely around the core, and a pliable tube or outer shell 25 made of soft synthetic resin compound closely envelopes the braid 24.

The tube 4' has a relatively small wall thickness while it has sufficient bendability and resistance against collapsing and twisting.

The pliable tube 25 may be formed by dipping the braid 24 in the molten synthetic resin compound or by coating the braid 24 so that the synthetic resin compound is impregnated into the braid 24.

FIG. 8 shows an example of the process for forming the braid 24. A cylindrical form 26 having an inner diameter greater than the outer diameter of the core in the tube 4' is placed around the core, and the crimped fibers 24a are wound around the form 26 so as to form a net-like structure. Thereafter, the form 26 is withdrawn, thereby permitting the net-like structure of fibers 24a to contract into engagement with the core by the crimping effect or by appropriate heat treatment.

Claims

We claim:

1. In an endoscope including a control housing and an elongated tubular element having one longitudinally terminal portion secured to said housing, another longitudinally terminal portion remote from said housing and formed with a viewing window, and a longitudinal, flexible portion intermediate said terminal portions, said intermediate portion having a tubular, flexible, metallic core, the improvement of said intermediate portion which comprises:

a. a first, tubular, synthetic resin layer substantially coaxially engagingly superimposed on said core;

b. a second, tubular, synthetic resin layer substantially coaxially superimposed on said first layer;

c. a first tubular, net-like braid of non-metallic fibers embedded in one of said resin layers; and

d. a second tubular, net-like braid of metal fibers embedded in the other resin layer.

2. In an endoscope as set forth in claim 1, wherein the tubular element has a bendable portion longitudinally intermediate said other longitudinally terminal portion and said flexible portion thereof, the endoscope including operating means on said housing for bending said bendable portion, the bendable portion having a tubular core adapted to be bent by said operating means and an outer shell of elastomeric material, the improvement in said bendable portion which comprises a tubular, net-like braid of crimped synthetic fibers closely enveloping said core and being closely enveloped by said shell.