JPH0716201A - Flexible tube - Google Patents

Abstract

PURPOSE:To provide a flexible tube small in diameter, which can be curved greatly in a given direction. CONSTITUTION:An IG fiber 26 and a LG fiber 28 are fitted in the inside of an insertion section. The IG fiber is disposed in center, and the LG fiber is disposed around the center. A heating means 30 is formed over the outside of the LG fiber 28, a pipe shaped member 22 is formed over the aforesaid heating means, and furthermore, an outer shielding tube 34 is formed over the aforesaid member. An optical lens 32 is attached to the tip end of the insertion section while being water-tight, so that built-in attachments are isolated from the outside by the optical lens 32 and the outer shielding tube 34. Besides, both the optical lens 32 and the outer shielding tube electrically insulate the built-in attachments. The pipe shaped member 22 is made of a shape memory alloy (for example, Ni-Ti), and has four deforming sections 24 extended in the longer direction at its tip end section. The deforming sections memory shapes that they are curved outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible tube having a curved distal end which is used in endoscopes and catheters.

[0002]

2. Description of the Related Art As such a flexible tube, as disclosed in, for example, Japanese Patent Laid-Open No. 4-61840, a tubular member made of a shape memory alloy that remembers a pre-bent shape is provided at the tip. There is something. In this flexible tube, the distal end portion is bent by heating and deforming the tubular member.

[0003]

In the above-mentioned flexible tube, the tip portion is deformed into the shape previously stored in the tubular member of shape memory alloy. That is, the bending direction of the tip is only one direction. Therefore, the endoscope using this flexible tube cannot observe or treat the inside of the lumen for the whole week.

Further, since the elastic urging member for returning the curve to the original is provided inside, the diameter reduction is limited. Furthermore, since the elastic force of the elastic biasing member hinders the bending operation by the shape memory alloy, the actually obtained bending amount is not so large. An object of the present invention is to provide a flexible tube having a small diameter that can be largely curved in any direction.

[0005]

A flexible tube of the present invention has a tubular member made of a shape memory member at a distal end thereof, and the tubular member has a plurality of parallelly extending distal ends divided by grooves. Each deforming portion has a different shape stored in advance and is deformed into that shape in accordance with the temperature, and further has a means for independently heating each deforming portion. There is.

[0006]

When the flexible tube is bent, the deforming portion corresponding to the bending direction is selectively heated by the heating means. The heated deforming portion is deformed into a shape stored in advance, for example, a shape curved outward. Therefore, the entire tip of the flexible tube bends in that direction.

[0007]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows an endoscope including the flexible tube of the present invention in an insertion portion. The endoscope 10 has a thin and long insertion portion 1
2 and an operation unit 14 connected to the proximal side of the insertion unit 12. The insertion portion 12 has a bending portion 20 at a tip end portion that can be bent in an arbitrary direction. The operation unit 14 includes an eyepiece unit 1.
6 is provided and an illumination light cable 18 is connected. The other end of the illumination light cable 18 is connected to a light source device (not shown).

As shown in FIG. 4, an image guide fiber (IG fiber) 26 and a light guide fiber (LG fiber) 28 are provided inside the insertion portion 12. The IG fiber 26 is arranged at the center, and the LG fiber 28 is arranged around it. The IG fiber 26 is guided through the inside of the insertion portion 12 to the eyepiece portion 16 of the operation portion 14. The LG fiber 28 is guided to the light source device through the inside of the insertion portion 12 and the illumination light cable 18. A heating means 30 is provided outside the LG fiber 28, a tubular member 22 made of a shape memory alloy is provided outside the heating means 30, and a jacket tube 34 is provided outside the tubular member 22. An optical lens 32 is provided at the tip of the insertion portion 12. The optical lens 32 and the outer tube 34 have a watertight structure, and the internal parts of the insertion part 12, that is, the IG fiber 26 and the LG fiber 2
8. The heating means 30 and the tubular member 22 are shielded from the outside. The optical lens 32 and the jacket tube 34 electrically insulate the built-in object.

The tubular member 22 is made of a generally known shape memory alloy (for example, Ni-Ti), and as shown in FIG. 2, the tip portion has four deformed portions 24 extending in the longitudinal direction.
have. These deformed portions 24 are formed by cutting the end face in a cross shape and providing four grooves linearly extending in the axial direction. As shown in FIG. 3, the deforming portion 24 remembers the shape that is curved outward. The shape memory process is performed by transforming the shape into a desired shape and performing heat treatment.
The shape recovery temperature set during heat treatment is preferably set between 37 and 50 ° C. The tubular member 22 is housed inside the insertion portion 12 in a state where the deformable portion 24 is linearly deformed after such heat treatment.

The heating means 30 is composed of a tubular insulating thin-film elastic body having a resistor serving as a heating wire. FIG. 6 shows the tubular thin film elastic body cut in the longitudinal direction and developed. In the thin film elastic body 38, four resistors 40 extending in the longitudinal direction are arranged at intervals. A lead wire 42 for supplying a current to each resistor 40 is connected to each resistor 40. The lead wire 42 is connected to the energization control device through the inside of the insertion portion 12 and the illumination optical cable 18.

The structure of the energization control device is shown in FIG. The energization pulse generation circuit 4 is supplied from the input unit 44 provided in the endoscope 10.
The input signal is input to 6, and the pulse width modulated signal is sent to the drive circuit 48. The drive circuit 48 includes a switching element such as a FET or a transistor, and heats the resistor 40. The deforming portion 24 of the tubular member 22 is deformed by heat transfer from the resistor 40, and the displacement is detected by the displacement sensor and fed back to the energizing pulse generating circuit 46 to control the bending amount.

In this embodiment, the IG fiber 26 and the LG fiber 28 are coaxially provided in the insertion portion 12 as shown in FIG. 4, but the IG fiber 26 and the LG fiber 28 are arranged in parallel as shown in FIG. In addition to this, a channel 36 may be provided for air supply, water supply, suction and insertion of a treatment tool.

Further, in this embodiment, the heating means 30 is provided inside the tubular member 22, but it may be provided outside the tubular member 22 as shown in FIG. With such a configuration, the insertion portion 12 can be made further thinner.

Next, the operation of this embodiment will be described.
The heating means 30 is operated by operating the energization control device provided on the hand side.
When the resistor 40 is selectively energized, the resistor 40 generates heat according to the amount of energization. The heat is applied to the resistor 4
It is transmitted to the deforming portion 24 of the tubular member 22 located at a position corresponding to 0, and the temperature rise due to the heat deforms the deforming portion 24 from the linear shape to the outwardly curved shape. Deformation part 2
The outer jacket tube 34 that has received the shape recovery force when the 4 deforms.
Is a built-in component (other deformation part 24, heating means 30, LG
Bend in the direction in which the force is applied together with the fiber 28 and the IG fiber 26). That is, the bending portion 20 bends in the direction of the heated deformation portion 24. When the energization is stopped during the bending operation or after reaching the maximum bending amount, the temperatures of the heating means 30 and the deforming portion 24 are lowered by natural cooling, and the bending portion 20
Is kept in the curved shape at that time.

The energizing operation will be described in more detail. Since a medical device such as an endoscope is used by inserting it into the body cavity of a living body, the shape memory alloy cannot be heated to a high temperature. Therefore, it is necessary to operate it efficiently at a low temperature. Therefore, an electric heating method utilizing the hysteresis of the shape memory alloy as shown in FIG. 10 can be considered. To obtain a certain displacement x1, it can be seen that T1 "is used during heating, but T1 'is used during cooling. Using this characteristic, if a large heating amount is added first and then the heating amount is reduced, T1 'Gets the displacement of x1.

That is, assuming that the time during which a signal for increasing the displacement is input from the input section 44 is TI, as shown in FIG. 9, the energizing pulse generating circuit 46 energizes in a specific pattern at a repeating cycle T. In this pattern, a pulse width TB is first generated so that the heating amount is increased, and then TM (<TB) is repeated for several pulses. This pattern occurs while a signal for increasing the displacement is being input.

Next, let TH be the time during which the signal for holding the displacement is input from the input section 44, and the pulse width TM is set so as to obtain a heating amount equal to the amount of heat that is naturally cooled during this period. Occur. At this time, the displacement sensor 52 sets the pulse width of TM. This is because the amount of heating required for holding (the difference between ΔT1 and ΔT2 in terms of temperature) varies depending on the amount of displacement.

Further, during the period TD during which the signal for reducing the displacement is input from the input section 44, the pulse width TS (<T
M) should be reduced. By such energization, it is possible to stop at an arbitrary position and obtain a large displacement at a low temperature.

A modified example of the energization control device is shown in FIGS. 11 and 12. The difference from the above-described energization control device is that the deforming portion 24 is directly energized and heated, and a circuit 56 for detecting the resistance value of the deforming portion 24 is provided, and the crest value of the drive pulse is changed according to the resistance value of the deforming portion 24. The point is that a variable voltage power supply 58 for changing is provided. As can be seen from FIG. 12, in this modification, T
The peak value of B is changed to V1, V2, and V3 to improve the responsiveness. Here, only TB was changed, but T
You may change M and TS.

In this embodiment, the IG fiber 26 and the LG fiber 28 have a very small diameter, the jacket tube 34 has a very thin wall, and the deformed portion 24 after deformation is originally formed by the elastic force of these members. There is no going back. Therefore, in order to deform the deformed portion 24 that has once deformed into the original linear shape or the shape bent in another direction, the energization control device is operated to change the deformed portion on the opposite side of the deformed portion 24 or another portion. The deformed part is heated.

In this embodiment, a unidirectional shape memory alloy is used as the material of the tubular member, but a bidirectional shape memory alloy may be used. In this case, the increase / decrease in the bending amount of the deforming portion is controlled by adjusting the amount of electricity supplied to the deforming portion.

As described above, according to this embodiment,
A small-diameter insertion portion that can be bent in an arbitrary direction is configured. Further, the elastic biasing member, which has been necessary to restore the bending so far, is no longer required, and the insertion portion can have a smaller diameter.

[0023]

According to the present invention, since it has a plurality of deforming portions that deform in different directions, the elastic biasing member that has been necessary to restore the curve is not necessary. Therefore,
A flexible tube having a small diameter that can be largely curved in an arbitrary direction is provided.

[Brief description of drawings]

FIG. 1 is a view showing a small-diameter endoscope having a flexible tube of the present invention.

FIG. 2 is a view showing a tubular member built in the insertion portion of FIG.

FIG. 3 is a diagram showing a state in which a deformed portion of the tubular member of FIG. 2 is deformed into a memory shape.

FIG. 4 is a view showing a cross section of the distal end portion of the insertion portion of FIG.

FIG. 5 is a diagram for explaining the structure of a modified example of the insertion portion.

FIG. 6 is a diagram for explaining a configuration of heating means.

FIG. 7 is a diagram for explaining the structure of another modification of the insertion portion.

FIG. 8 is a block diagram showing a configuration of an energization control device that supplies a current to a heating unit.

9 is a diagram showing a pulse waveform output by the energization pulse generation circuit of FIG.

FIG. 10 is a diagram showing hysteresis of a shape memory alloy for explaining the operation principle of the energization control device.

FIG. 11 is a block diagram showing a configuration of a modification of the energization control device.

FIG. 12 is a diagram showing a pulse waveform output by the energization pulse generation circuit of FIG. 11.

[Explanation of symbols]

12 ... Insertion part, 22 ... Tubular member, 24 ... Deformation part, 30 ...
Heating means, 40 ... Resistor.

Claims (1)

[Claims] 1. A flexible tube having a curved tip portion, wherein the tip portion has a tubular member made of a shape memory member, and the tubular member has a plurality of deformations extending in parallel and divided by grooves at the tip. Each deforming portion stores a different shape in advance and is deformed into that shape in accordance with temperature, and further has a means for independently heating each deforming portion. Flexible tube.