JPH04126120A - Curved part driving controller - Google Patents

Abstract

PURPOSE:To cancel the resistance value variation in an area out of a transformation temperature area of a shape memory alloy and to eliminate the misoperation by providing a resistance element connected with the shape memory alloy in series in which an absolute value of a temperature coefficient of a resistance value in the outside of a transformation temperature area is equal to that of the shape memory alloy, and controlling a heating means, based on a signal which detects the resistance value of the shape memory alloy. CONSTITUTION:In a curved part 13 of an inserting part 7, a pair of coil spring- like shape memory alloys(SMA) 23a, 23b are provided in a symmetrical position centering around the axis center of the curved part 13, and when each SMA 23a, 23b thereof is heated by a control signal from a curvature control part 24, a loose winding coil is transformed to a close winding coil, and the curvature part 13 is curved to a prescribed state. To the SMA 23a (or 23b), a negative resistance element R1 is connected in series, and a temperature coefficient except transformation temperature areas T1-T2 of the SMAs 23a, 23b is DELTAR/DELTAt, and a temperature coefficient of the negative resistance area R1 is -DELTAR/DELTAt, that is, that which is equal with regard to a temperature coefficient and an absolute value of the SMAs 23a, 23b is adopted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a bending portion drive control device that performs a bending operation on a bending portion by thermal transformation of a shape memory alloy disposed in the bending portion of an insertion portion.

[Prior Art] In general, for example, in the case of an endoscope, an elongated insertion section is inserted into a body cavity to observe the inside of the body cavity, and if necessary, a treatment instrument is used to perform treatment. Alternatively, it is possible to insert the insertion section into a tube hole and observe the inside of the tube hole.

Since the treated areas within these body cavities and lumens are rarely located in the direction of entry of the insertion section, when performing treatment, etc., the curved section provided at the distal end of the insertion section should be bent. By creating a crosspiece, the distal end portion is directed toward the above-mentioned region to be treated.

The means for curving this bending section includes inserting an operating wire into the insertion section, fixing one end of this operating wire to the distal end side of the bending section, and connecting the proximal end to a bending operation knob provided on the operating section. However, a technique is generally used in which the bending operation knob is used to pull or relax the operation wire to curve the curved portion, thereby directing the tip toward the observed area.

However, such a configuration inevitably complicates the structure and may lead to an increase in the diameter of the insertion portion.
Since a relatively large operating force is required, it is difficult to improve operability.

Therefore, for example, in Japanese Patent Application Laid-open No. 63-292933,
disposing a shape memory alloy in the curved portion, heating the shape memory alloy with electricity to deform it to curve the curved portion, and detecting the resistance value of the shape memory alloy;
A technique has been disclosed in which the amount of curvature of the curved portion is controlled by changing the amount of current applied to the shape memory alloy based on the detection result.

[Problems to be Solved by the Invention] However, the above-mentioned memory alloy has a property that its electrical resistance value does not change linearly with respect to temperature.

That is, as shown in Figure 12, the resistance value shows a positive temperature coefficient and increases monotonically between the low temperature side and T1 and between T2 and the high temperature side, just like ordinary metals, but from T1 to T2, the resistance value increases monotonically. The resistance value decreases monotonically and shows a negative temperature coefficient.

Therefore, in a control system that detects the resistance value R of the shape memory alloy at −m and controls the bending angle of the bending portion, the heating temperature T must be controlled within the transformation temperature range T1 to T2. However, for example, when detecting the resistance value R at a point Pt and p2 which are outside the above-mentioned transformation temperature range T1 to T2 in FIG. The above transformation temperature range T1~
There is a possibility that the heating temperature T is determined to be within T2 and the heating temperature T is erroneously operated in a direction outside the transformation temperature range T1 to T2 in order to further curve the curved portion.

If the heating temperature T is further increased from the point P2,
Not only does the shape memory alloy tend to heat up too much, but it also causes inconveniences such as thermal effects on various components such as lenses disposed around the shape memory alloy, resulting in a decrease in durability.

The present invention has been made in view of the above circumstances, and provides a curved portion that cancels resistance changes in a region outside the transformation temperature range of a shape memory alloy, eliminates erroneous operation, and improves the bending controllability of the curved portion. The purpose is to provide a drive control device.

[Means for Solving the Problems] The present invention provides a bending portion drive control device that controls the bending angle of a bending portion provided in an insertion portion by a transformation operation by heating a shape memory alloy. means and
The heating is performed based on a resistance value detecting means provided in series with a resistance element having an absolute value equal to the temperature coefficient of the resistance value outside the transformation temperature range of the shape memory alloy, and a signal that detects the resistance value of the shape memory alloy. and heating control means for controlling the heating means.

[Function] According to the present invention, by connecting in series to the shape memory alloy a resistance element whose absolute value is equal to the temperature coefficient of the resistance value outside the transformation temperature range of the shape memory alloy, In this case, there is no change in the resistance value, and the resistance value changes only in the transformation temperature range that is the control range.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

1 to 4 show a first embodiment of the present invention, FIG. 1 is a functional block diagram of a bending control section, FIG. 2 is a specific circuit diagram of a drive circuit and a resistance value detection circuit, and FIG. 4 is a general schematic diagram of the endoscope device, and FIG. 4 is a characteristic diagram of the heating temperature and resistance value of the shape memory alloy.

Reference numeral 1 in FIG. 3 is an endoscope device, and this endoscope device 1 includes an electronic endoscope 2, a light source unit 3 that supplies illumination light to the electronic endoscope 2, and a signal processing circuit 4. The video processor 5 includes a video processor 5 and a monitor 6 connected to the video processor 5.

The electronic endoscope 2 includes an elongated and flexible insertion section 7, a large-diameter operation section 8 connected to the rear end of the insertion section 7, and an operation section 8 extending from the side of the operation section 8. A connector 10 provided at the end of the universal cord 9 is connectable to a connector jack 11 provided on the video processor 5.

Further, on the distal end side of the insertion section 7, a hard distal end section 12 and a bendable curved section 13 are provided in order from the distal end side, and an objective lens system 14 is provided on this distal end section 12. An imaging surface of a solid-state image element 15 is disposed at the imaging position of the lens system 14 .

Further, a light guide 16 having an output end disposed at the distal end 12 of the insertion section 7 is inserted through the insertion section 7, the operation section 8, and the universal cord 9, and its entrance end is fixed to the connector 10. There is. After the illumination light from the light source 17 provided in the light source section 3 of the video processor 5 is focused by the lens 18, it is incident on the incident end of the light guide 16.

When the illumination light from the light source 17 is emitted from the output end of the light guide 16 to illuminate a subject, an optical image of the subject is formed on the imaging surface of the solid-state image sensor 15.

On the other hand, the signal processing circuit 4 of the video processor 5 includes:
A clock signal generator 19 and a drive circuit 20 are provided, and when the clock signal generated by the clock signal generator 19 is input to the drive circuit 20, the drive circuit 2
At 0, a drive signal for the solid-state image sensor 15 is generated. This drive circuit 20 is composed of a reset pulse φH1, a horizontal transfer pulse generator 20a, and a vertical transfer pulse generator 20b, each of which has a reset pulse φH1 and a horizontal transfer pulse φV.
occurs.

This vertical transfer pulse φV, reset/horizontal transfer pulse φ
R and horizontal transfer pulse φH are applied to the solid-state image sensor 15 via the signal line 21.

When a drive signal from the drive circuit 20 is applied to the solid-state image sensor 15, the optical image formed on the imaging surface of the solid-state image sensor 15 is photoelectrically converted, and this signal is processed by the signal processing provided in the video processor 5. Process circuit 22 of circuit 4
is input. The process circuit 22 takes in the signal and outputs a video signal to the monitor 6.

Further, a pair of coil spring-like shape memory alloys (SMA) 23a and 23b are provided in the curved portion 13 of the insertion portion 7 at symmetrical positions with respect to the axial center of the curved portion 13 along the axial direction. When each of the 5MAs 23a and 23b is heated by a control signal from the bending control section 24 constituting the signal processing circuit 4 of the video processor 5, the coarsely wound coil transforms into a tightly wound coil, and the bending section 13 is turned into a predetermined shape. to curve it.

Further, the curved portion 13 detected by the curve control section 24
The bending angle signal data is input to the process circuit 22, and the bending angle signal is superimposed on the video signal representing the endoscopic image.For example, as shown in FIG. Curving information indicating that the bending angle is 30 degrees in the upward direction is displayed.

The configuration of the bending control section 24 is shown in FIG.

The angle signal outputted from the bending operation unit 25 is inputted to the PID controller 27 via the adder 26, and a predetermined signal is outputted to the PWM generator 28 which obtains source oscillation from the clock signal generator 19. This PWM generator 28 changes the pulse width and outputs it to the drive circuit 29, and the output from this drive circuit 29 is sent to the 5MA23.
a, 23b.

On the other hand, in the resistance detection circuit 30, the 5MA23a, 2
3b is detected and output to the adder 26 via the sample hold circuit 31.

This adder 26 calculates the difference between the angle signal and the signal obtained by detecting the sampled and held resistance value, and calculates the difference between the above-mentioned PID
It is output to the controller 27 for feedback control.

FIG. 2 shows the drive circuit 29 and resistance value detection port B30.

Negative resistance element R to the above 5MA23a (or 23b)
1. A dummy resistor R2 is connected in series, and this dummy resistor R
2 is connected to the drain side of the field effect (FE) transistor Q. Furthermore, the above 5MA23a (or 2
3b) A bridge circuit 32 is formed by connecting resistors R3 and R4 in parallel to resistor R1°R2.

Further, the PWM generator 28 is connected to the gate of the FE transistor Q via a resistor R5. On the other hand, the non-inverting input terminal of the differential amplifier OP is connected between the negative resistor R1 and the dummy resistor R2, and the differential amplifier OP
The inverting input terminal of is connected between the resistors R3 and R.

In addition, as shown by the solid line in FIG. 4, the above 5MA23a,
The temperature coefficient of 23b other than the transformation temperature range T1 to T2 is ΔR
/I411It, and the temperature coefficient of the negative resistance element R1 is -ΔR/Δt, that is, the 5MA23a, 23
A temperature coefficient having the same absolute value as the temperature coefficient ΔR/Δt of b is used.

Next, the operation of the first embodiment will be explained.

When the solid-state image sensor 15 provided at the endoscope tip 12 is driven by φR9φH and φV generated by the reset/horizontal transfer pulse generator 20a and the vertical transfer pulse generator 20b in the drive circuit 20, an optical image is generated. is converted into an electrical signal and output to a process circuit 22, which generates a video signal.

Source oscillation from one clock signal generator is input to this process circuit 22, and a horizontal synchronizing signal HD is output from this source oscillation.
and a vertical synchronizing signal, and a standard video signal is generated from these synchronizing signals and the output signal of the solid-state image sensor 15.

On the other hand, when bending the endoscope bending section 13 in a desired direction, an angle signal is output from the bending operation section 25 to the bending control section 24 .

Then, the adder 26 of the bending control section 24 calculates the current bending angle signal of the bending section 13 based on the angle signal from the bending operation section 25 and the resistance value of the 5MA 23a (23b) detected by the resistance value detection circuit 30. The difference signal between P
The ID controller 27 outputs a pulse according to the above difference signal.
Output to WM generator 28.

The PWM generator 28 modulates the pulse and outputs it to the drive circuit 29.

As shown in FIG. 2, when the pulse output from the PWM generator 28 is applied to the gate of the transistor Q of the drive circuit 29 via the resistor R5,
The 5MA 23a (23b) in which the E1-transistor Q refines the ONL bridge circuit, the resistors R1 and R2 are energized, and the 5MA 23a (23b) is gradually heated.

Then, the above-mentioned 5MA23a (23b) transforms from the memorized shape of a newly wound coil to a tightly wound coil, and this 5MA23a (23b)
The curved portion 13 into which the MA 23a (23b) is incorporated is curved in a desired direction.

When the above 5MA23a (23b) is heated, this 5MA23a (23b)
As shown by the solid line in FIG. 4, the resistance R of MA23a (23b) decreases rapidly in the transformation temperature range T1 to T2, and is 1! in other ranges. UR/1! The resistance value increases gradually with a positive temperature coefficient of Ut. On the other hand, the above 5MA23a (23b
) is the resistance value of the negative resistor R1 connected in series with -ΔR/
Since it has a temperature coefficient of Δt, the detected resistance value falls within the transformation temperature region T1, as shown by the broken line in FIG.
In the range other than ~T2, the heating temperature T remains constant without depending on it.

Resistance value detection circuit 3 connected to the output side of the bridge circuit above
A voltage corresponding to the resistance value characteristic indicated by the broken line in FIG. A voltage corresponding to the resistance values of the 5MA 23a (23b) and the negative resistor R1 in the vertical state is divided from between the resistors R3 and R4 as a reference voltage.

As a result, the current bending angle of the bending portion 13 can be detected by the voltage output from the differential amplifier OP, and the 5MA23a (23b) When the heating temperature T for deviates from the transformation temperature range T1 to T2, the output voltage of the differential amplifier OP becomes constant;
The maximum or minimum bending angle of the curved portion 13 in the transformation temperature range T1 to T2 of A23a (23b) can be easily determined, improving controllability.

Then, a pulse corresponding to the resistance value corrected by the negative resistor R1 of the 5MA23a (23b) detected based on the output voltage of the differential amplifier OP is used as a bending angle signal of the current bending portion 13 via the sample hold circuit 31. and is output to the adder 26 for feedback control.

(Second Embodiment) Figs. 5 to 7 show a second embodiment of the present invention, in which Fig. 5 is a sectional view of the endoscope insertion section, and Fig. 6 shows the connection between the tip hood and the wire. The perspective view and FIG. 7 are specific circuit diagrams of the drive circuit and the resistance value detection circuit.

In this embodiment, a shape memory alloy 23a (23b) similar to that of the first embodiment is disposed in a curved portion 43 provided in the insertion portion 42 of an endoscope 41 using an optical fiber. The bending portion drive control other than the configuration of the resistance value detection circuit incorporated in the bridge circuit, which will be described later, is the same as in the first embodiment.

Although not shown, the insertion section 42 is connected to a light source device via an operation section and a universal cord.

The input ends of an image guide (IG) fiber 46 and a light guide (LG) fiber 47 are fixed to a distal end fixing member 45 provided on a rigid distal end portion 44 of the insertion section 42, and covered with a plastic cover 48.

Five tip hoods are stored in a housing portion 49 formed between the cover 48 and the tip fixing member 45, and the tip hoods 50 are connected via wires 51 to an operation member provided on an operation section (not shown). By operating this operating member, the tip hood 50 can be taken in and out of the storage section 49 by remote control.

Further, the curved portion 43 on the proximal side of the distal end fixing member 45
A curved portion 52 is provided on the inside of the curved portion 52, and 5MA23a (
23b) are arranged in a predetermined manner.

The outside of the curved portion 52 is covered with a curved portion outer skin 53, and the curved portion outer skin 53 is tightened via a thread 55 and fixed by adhesive to the outer periphery of a joint pipe 54 that connects the rearmost curved portion 52. It is also connected to an operation section (not shown) via a flexible tube outer skin 56.

Further, the drive circuit 29 and the resistance detection circuit 30 (see FIG. 1) in this embodiment constitute a bridge circuit incorporating the above-mentioned 5MA 23a (23b) as shown in FIG.

In this bridge circuit, the 5MA23a < 23b) and a dummy resistor R2 are connected in series, and the source side of the FE1-transistor Q is further connected to the dummy resistor R2. In addition, resistors R3 and R4 are connected in parallel to the 5MA23a (23b) and the resistor R2, and the
The non-inverting input terminal of the differential amplifier OP is connected between the MA23a (23b) and the dummy resistor R2, and the resistor R3 and R4 is connected to the inverting input terminal of the differential amplifier OP.

The above dummy SMAR2 is the above 5MA23a (23b)
Although it has the same material and is set to the same resistance value, it has not been heat treated and will not undergo any transformation.

Next, the operation of the embodiment with the above configuration will be explained.

5MA23a (23b) is FE) transistor Q is ON
When heated with electricity, the coil transforms from a coarsely wound to a tightly wound coil, bending the curved portion 52 and bending the curved portion 43.

On the other hand, the above 5MA23a incorporated in the bridge circuit
The resistance value of the dummy SMAR1 connected in series with (23b) is the transformation temperature range T1 of the above 5MA23a (23b).
Other than T2, it has the same temperature coefficient ΔR#It (see Figure 4) as this 5MA23a (23b), and the potential at the connection point P1 of both 5MA23a (23b) and R2 is in the transformation temperature range T1 to T2. It does not change.

Therefore, changes in the resistance value outside the transformation temperature range T1-T2 are canceled, and only the resistance value between the transformation temperature range T1-T2 changes, resulting in improved controllability.

Furthermore, in this embodiment, the distal end hood 50 is housed in the distal end fixing portion 45 of the insertion portion 41 in a manner that it can be taken in and out freely, thereby saving the effort of attaching and detaching the distal end hood 50 one by one, improving the ease of handling. In addition, the curved portion outer skin 53 is attached to the rearmost curved portion 52.
By winding and fixing the thread 55 around the joint pipe 54 which is connected to the joint pipe 54, and gluing it, the rear end of the curved part outer skin 53 is connected to the joint pipe 54.
can be securely fixed.

(Third Embodiment) FIGS. 8 to 11 show a third embodiment of the present invention, in which FIG. 8 is a schematic configuration diagram of a medical catheter, FIG. 9 is a schematic configuration diagram of main parts of a medical catheter, 10 is a sectional view taken along the line XX in FIG. 9, and FIG. 11 is a partial sectional view of the XI section in FIG. 9.

The main body 61a of the catheter 61 is formed of a substantially circular tube (multi-lumen tube).

Further, reference numeral 62 in FIG. 8 is an insertion portion of the catheter 61. A balloon 63 formed of a bag-shaped elastic body is attached to the outer circumferential surface of the distal end of the insertion portion 62 .

Furthermore, a proximal end portion 64 is provided at the proximal end portion of this insertion portion 62 . A connecting end 66 of a tube 65 and a connecting end 68 of a cable 67, which will be described later, are provided on the outer peripheral surface of the proximal end 64, respectively. One end of the tube 65 is connected to the balloon 63. Further, the balloon 63 is attached to the proximal end of the tube 65.
A cylinder 69 for supplying a fluid such as physiological saline is removably connected therein.

In addition, an endoscope insertion lower 0 is provided on the end surface of the proximal end 64.
is provided. An insertion portion 72 of a blood vessel endoscope 71 formed by, for example, an electronic endoscope is inserted from the endoscope insertion lower 0 into the tube of the catheter main body 61a.

The insertion section 72 of the angioscope 71 is formed by connecting a rigid distal end portion 74 to the distal end of a visible tube 73 . moreover,
One end of each of universal cords 76 and 77 is connected to the proximal operation section 75 on the proximal end side of the insertion section 72.

The other end of one universal cord 76 is connected to a light source device 79 via a connector 78, and the other end of the other universal cord 77 is connected to a television camera unit 81 via a connector 80. A television monitor 82 is connected to this television camera unit 81.

Further, a curved portion 83 is provided at the distal end of the insertion portion 62 of the catheter main body 61a. This curved portion 83 has a configuration shown in FIGS. 9 and 10.

That is, the distal end surface of the tube wall of the insertion portion 62 has an angle of 180°.
a pair of curved wire attachment holes 84a at the positions of
84b are arranged in parallel in close proximity. These bending operation wire attachment holes 84a.

84b extends along the axial direction. A bending operation wire 85 is inserted into each of these bending operation wire mounting holes 84a and 84b.

The bending wire 85 is made of a shape memory material such as a linear shape memory alloy (for example, a nickel-titanium alloy). The shape memory alloy of this bending operation wire 85 has, for example, a bidirectional shape memory effect, and is made by forming a wire rod whose length shrinks when heated into an elongated shape.

That is, the bending operation wire 85 has a first memory shape (initial wire shape) on the high temperature side with a length dimension Lo, and a second memory shape (forced wire shape) on the low temperature side with a length dimension Lt (L1=Lo +JL). (stretched wire shape) is memorized. In this case, the shape memory alloy of the bending operation wire 85 is subjected to shape memory processing on the high temperature side using the first memory shape on the high temperature side, and then forcibly expanded to an elongated shape at room temperature, which is about body temperature, to form the shape memory alloy on the low temperature side. Shape memory processing of the second memory shape is being performed.

Then, in a state where the bending operation wire 85 that has been subjected to shape memory processing in two directions is held in the second memorized shape, the bending operation wire 85 is heated to a temperature higher than a transformation temperature of, for example, about 60 to 90°C. As a result, it is deformed (restored) to the first memorized shape (heat-shrinkable wire shape) on the high temperature side with the length dimension Lo.

Further, as shown in FIG. 9, this bending operation wire 85 is folded back from a substantially central portion, and folded wire constituent portions 85a and 85b on both sides thereof are inserted into reinstallation holes 84a and 84b, respectively. Furthermore, this bending operation wire 8
5 is fixed at the distal end surface of the tube wall of the insertion section 62, and a front end fixing section 86 of the bending operation wire 85 is formed.

Furthermore, a weight passing lead wire 8 is attached to each tip of both folded wire constituent portions 85a and 85b of this bending operation wire 85.
One end of each of 7a and 87b is connected. in this case,
The lead wires 87a and 87b are made of a shape memory material such as a shape memory alloy that has not been subjected to shape memory treatment. These lead wires 87a, 87b and both folded wire constituent parts 85a, 85 of the bending operation wire 85
The folded wire component portion 85a is connected to each tip portion of the wire portion 85a by welding or soldering.

Each tip of the lead wires 85b and one end of each of the lead wires 87a and 87b are electrically connected.

Further, on the outer circumferential surface of the tube wall portion of the insertion portion 62, there is a connection portion by welding or soldering between each tip portion of both folded wire constituent portions 85a, 85b of the bending operation wire 85 and one end portion of each lead wire 87a, 87b. In the position corresponding to 88,
As shown in FIG. 11, side holes 89 are formed respectively. In this case, the folded wire component parts 85a, 85b
The outer diameter of the connecting portions 88 and 88 between each tip of the lead wires 87a and 87b and one end of each of the lead wires 87a and 87b is slightly enlarged during the joining operation by welding or soldering. Further, these joint portions 88.88 are inserted into each side hole 89.89, and in this inserted state are fixed with adhesive S to form both end fixing portions 90.90 of the bending operation wire 85. .

Note that, for example, a cap (not shown) is attached to the distal end surface of the insertion portion 62, and the front end fixing portion 86 of the bending operation wire 85 is covered with this cap.

Further, the other ends of the lead wires 87a and 87b are connected to an energization control section 91 that controls the amount of energization of the bending operation wire 85. This energization control section 91 is connected to the catheter main body 61a via the cable 67. Furthermore, this energization control section 91 is connected to an operation section 93 via a cable 92.
is connected.

This operation section 93 is formed by a joystick 94, for example. The joystick 94 is operable to move, for example, to both sides of a neutral reference position, and is normally held at a predetermined reference position.

The energization control section 91 also includes each bending operation wire 85.
It has 85 built-in controllers.

These controllers have the same PW as in the first embodiment.
M energization drive circuits are provided respectively, and the PWM drive circuit of the controller is controlled according to the operation of the joystick 94, that is, the movement direction and the amount of movement of the joystick 94 from the reference position, and the amount of movement of the joystick 94 is controlled. In the matched state, the direction and amount of curvature of the curvature 83 of the catheter body 61a can be arbitrarily manipulated.

Next, the operation of the embodiment with the above configuration will be explained.

The joystick 94 of the catheter 61 is normally held at the reference position. In this state, the energization control section 91
Since the controller is held in the off state, the insertion section 6
Each bending operation wire 85.8 attached to the bending part 83 of No. 2
5 is maintained in a non-energized state. Therefore, this bending operation wire 85.85 is held in the second memory shape on the low temperature side of the length dimension L1, so that the bending operation wire 85.
3 is held in a normal, uncurved, substantially straight shape.

Next, when the hole shown in FIG. 8 is located at the branching site in the blood vessel 98, when the joystick 94 is operated appropriately according to the moving direction and the moving amount from the neutral reference position, the current curves and grips according to the operating amount. The actuating wire 85.85 is fed and bent in the desired direction for insertion.

A resistance value detection circuit 30 (see FIG. 1) similar to that of the first embodiment or the second embodiment is provided in the energization control section 91, and the curved portion 83 It is possible to easily control the direction of curvature.

It goes without saying that the scope of application of the present invention is not limited to endoscopes and catheters, but can be applied to actuators using shape memory alloys.

[Effects of the Invention] As explained above, according to the present invention, the resistance change in the region outside the region where the shape memory alloy is undergoing transformation operation is canceled, so that the shape memory alloy is not necessary. Excellent effects such as eliminating erroneous operations such as excessive heating and greatly improving bending controllability are achieved.

[Brief explanation of the drawing]

1 to 4 show a first embodiment of the present invention, FIG. 1 is a functional block diagram of a bending control section, FIG. 2 is a specific circuit diagram of a drive circuit and a resistance value detection circuit, and FIG. 4 is a diagram showing the characteristics of the heating temperature and resistance value of the shape memory alloy. FIGS. 5 to 7 show the second embodiment of the present invention. FIG. 6 is a perspective view showing the connection between the end hood and the wire, FIG. 7 is a specific circuit diagram of the drive circuit and resistance value detection circuit, and FIGS. 8 to 11 are a sectional view of the endoscope insertion section. A third embodiment of the present invention is shown, FIG. 8 is a schematic configuration diagram of a medical catheter, FIG. 9 is a schematic configuration diagram of main parts of the medical catheter, and FIG. 10 is a sectional view taken along the line XX in FIG. 9. FIG. 11 is a sectional view of section XI in FIG. 9, and FIG. 12 is a characteristic diagram of heating temperature and resistance value of a conventional shape memory alloy. 7.42.62...insertion part, 13,43.83...
Curved portion, 23a, 23b...shape memory alloy, 26...
- Heating control means (adder), 29... Heating means (drive circuit), 30... Resistance value detection means, R,, R2.
...Resistance element. Figure 2 Figure 4

Claims (1)

[Scope of Claim] A bending part drive control device that controls the bending angle of a bending part provided in an insertion part by a transformation operation caused by heating a shape memory alloy, comprising: heating means for heating the shape memory alloy; resistance value detection means provided in series with a resistance element having an absolute value equal to the temperature coefficient of the resistance value outside the transformation temperature range of the shape memory alloy; and controlling the heating means based on a signal detected from the resistance value of the shape memory alloy. A bending portion drive control device comprising: heating control means.