JP2911051B2 - Bending section drive control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bending portion drive control device that performs a bending operation of a bending portion by a thermal transformation of a shape memory alloy disposed in a bending portion of an insertion portion.

[Related Art] In general, for example, in the case of an endoscope, an elongated insertion portion is inserted into a body cavity to observe the inside of the body cavity, and at the same time, performs a treatment process using a treatment tool as necessary. Alternatively, it is possible to insert the insertion portion into the bore and observe the inside of the bore.

Since the treatment site in the body cavity or in the lumen is rarely present in the direction of entry of the insertion section, when performing a treatment or the like, the bending section provided on the distal end side of the insertion section is bent. By operating, the distal end is directed to the above-mentioned treatment site.

As means for bending the bending portion, an operation wire is inserted into the insertion portion, one end of the operation wire is fixed to the distal end side of the curve, and the base end is connected to a bending operation knob provided on the operation portion. A technique is generally used in which the bending wire is pulled or loosened by the bending operation knob to bend the bending portion so that the distal end portion is directed to the observed portion.

However, in such a configuration, the structure must be complicated, the diameter of the insertion portion may be increased, and operability is difficult to improve because a relatively large operation force is required. is there.

Therefore, for example, Japanese Patent Application Laid-Open No. 63-292933 discloses that a shape memory alloy is provided in the bending portion, and the shape memory alloy is bent by energizing and heating the shape memory alloy, and the shape memory is bent. A technique has been disclosed in which the resistance value of an alloy is detected, and the amount of current supplied to the shape memory alloy is changed based on the detection result, thereby controlling the amount of bending of the bending portion.

[Problems to be Solved by the Invention] However, the above-mentioned memory alloy has a property that the electric resistance value with respect to temperature does not change linearly. That is, the twelfth
And until the T ₁ temperature from the low temperature side as shown in FIG., The resistance between the T ₂ of the high temperature side increases monotonically as with ordinary metal exhibits a positive temperature coefficient, but the T ₁ to T ₂ During the period, the resistance value decreases monotonically and shows a negative temperature coefficient.

Therefore, in general, in a control system that detects the resistance value R of the shape memory alloy and controls the bending angle of the bending portion, it is necessary to control the heating temperature T within the transformation temperature range of T _{1 to} T _2. For example, the transformation temperature region T shown in FIG.
_When the resistance values R of the points P ₁ and P ₂ deviating from _{1 to} T ₂ are detected, the heating temperature T is changed to the above-mentioned transformation temperature range T _{1 to} T ₂ even though the bending angle of the bending portion is already maximum or minimum. it is determined that there is within, the heating temperature T in order to further bend the bending portion which may result in erroneous operation in a direction deviating from the transformation temperature range T ₁ through T _2.

If the heating temperature T is further increased from the point P ₂ , not only the shape memory alloy will be covered with heating, but also the components such as lenses disposed around the shape memory alloy will be affected by heat and the durability will be reduced. Inconveniences such as inconvenience occur.

The present invention has been made in view of such circumstances,
It is an object of the present invention to provide a bending portion drive control device that cancels a change in resistance in a region outside a transformation temperature region of a shape memory alloy, eliminates erroneous operations, and improves the bending controllability of the bending portion.

Means for Solving the Problems According to the present invention, in a bending portion drive control device for controlling a bending angle of a bending portion provided in an insertion portion by a transformation operation by heating a shape memory alloy, a heating device for heating the shape memory alloy is provided. Means, a resistance value detecting means in which a resistance element having an absolute value equal to the temperature coefficient of a resistance value outside the transformation temperature region of the shape memory alloy is provided in series, and And heating control means for controlling the heating means.

[Function] According to the present invention, by connecting a resistance element having the same absolute value as the temperature coefficient of the resistance value outside the transformation temperature region of the shape memory alloy in series to the shape memory alloy, The resistance value does not change, and the resistance value changes only in the transformation temperature range that is the control range.

Embodiment An embodiment of the present invention will be described below 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 unit, FIG. 2 is a specific circuit diagram of a drive circuit and a resistance value detection circuit, and FIG. FIG. 4 is an overall schematic diagram of the endoscope apparatus, and FIG. 4 is a characteristic diagram of a heating temperature and a resistance value of the shape memory alloy.

Reference numeral 1 in FIG. 3 denotes an endoscope apparatus, which includes an electronic endoscope 2, a light source unit 3 for supplying illumination light to the electronic endoscope 2, and a signal processing circuit 4. And a monitor 6 connected to the video processor 5.

The electronic endoscope 2 has an elongated and flexible insertion portion 7.
A large-diameter operating portion 8 connected to the rear end of the insertion portion 7;
Universal cord 9 extending from the side of this operation unit 8
The connector 10 provided at the end of the universal cord 9 can be connected to a connector jack 11 provided on the video processor 5.

Further, on the distal end side of the insertion portion 7, a rigid distal end portion 12 and a bendable bending portion 13 are provided in order from the distal end side,
An objective lens system 14 is provided at the distal end portion 12, and an imaging surface of the solid-state imaging device 15 is disposed at an image forming position of the objective lens system 14.

Further, a light guide 16 having an emission end disposed at the distal end portion 12 of the insertion portion 7 is inserted through the insertion portion 7, the operation portion 8, and the universal cord 9.
It is fixed to. Light source unit 3 of video processor 5
The illumination light from the light source 17 provided at the light guide 16 is condensed by the lens 18 and then is incident on the incident end of the light guide 16.

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

On the other hand, the signal processing circuit 4 of the video processor 5 is provided with a clock signal generator 19 and a drive circuit 20. When a clock signal generated by the clock signal generator 19 is input to the drive circuit 20, The drive circuit 20 generates a drive signal for the solid-state imaging device 15. The drive circuit 20 includes a reset / horizontal transfer pulse generator 20a and a vertical transfer pulse generator 20b, and generates a reset pulse φ _H and a horizontal transfer pulse φ _V , respectively.

The vertical transfer pulse φ _V , reset / horizontal transfer pulse φ _R and horizontal transfer pulse φ _H are applied to the solid-state imaging device 15 via the signal line 21.

When a drive signal from the drive circuit 20 is applied to the solid-state imaging device 15, an optical image formed on the imaging surface of the solid-state imaging device 15 is photoelectrically converted, and this signal is subjected to signal processing provided in the video processor 5. The signal is input to the process circuit 22 of the circuit 4. This process circuit 22 captures the above signal,
A video signal is output to the monitor 6.

A pair of coil spring-shaped shape memory alloys (SMA) 23a and 23b are provided on the bending portion 13 of the insertion portion 7 at positions symmetrical about the axis of the bending portion 13 along the axial direction. When each of the SMAs 23a and 23b is heated by a control signal from the bending control unit 24 constituting the signal processing circuit 4 of the video processor 5, the SMAs 23a and 23b transform from the coarsely wound coil to the closely wound coil,
The bending portion 13 is bent in a predetermined manner.

Further, the bending angle signal data of the bending section 13 detected by the bending control section 24 is input to the process circuit 22,
A bending angle signal is superimposed on a video signal representing an endoscope image, and, for example, as shown in FIG. The displayed curvature information is displayed.

 FIG. 1 shows the configuration of the bending control section 24.

The angle signal output from the bending operation unit 25 is input to the PID controller 27 via the adder 26, and outputs a predetermined signal from the clock signal generator 19 to the PWM generator 28 that obtains source oscillation. The PWM generator 28 changes the palace width and outputs it to the drive circuit 29, and applies the output from the drive circuit 29 to the SMAs 23a and 23b.

On the other hand, the resistance setting detection circuit 30 detects the resistance values of the SMAs 23a and 23b and outputs the same to the adder 26 via the sample and hold circuit 31.

The adder 26 calculates a difference between the angle signal and a signal obtained by detecting the sampled and held resistance value, and outputs the difference to the PID controller 27 to perform feedback control.

FIG. 2 shows the drive circuit 29 and the resistance value detection circuit 30.

Negative resistance element R ₁ above SMA23a (or 23b), the dummy resistor R ₂ are connected in series, the dummy resistor R ₂ is connected to the drain side of the field effect (FE) transistor Q. Further, the SMA 23a (or 23b), the resistors R ₁ and R ₂
The resistors R ₃ and R ₄ are connected in parallel to form a bridge circuit 32.

Further, the PWM generator 28 is connected through a resistor R ₅ to the gate of the FE transistor Q. on the other hand,
The non-inverting input terminal of the differential amplifier OP is connected between the negative resistor R ₁ and the dummy resistor R _2, and the inverting input terminal of the differential amplifier OP is connected between the resistors R ₃ and R ₄ . .

As indicated by the solid line in FIG. 4, the SMA23a, the temperature coefficient of other than the transformation temperature region T ₁ through T ₂ and 23b is [Delta] R / Delta] t, the temperature coefficient of the negative resistance element R ₁ is - [Delta] R / Δt, that is, one having an absolute value equal to the temperature coefficient ΔR / Δt of the SMAs 23a and 23b is adopted.

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

The solid-state imaging device 15 provided at the endoscope tip 12 is driven by a drive circuit.
Phi _R is generated in the reset horizontal transfer pulse generator 20a and the vertical transfer pulse generator 20b in 20, when driven by the phi _H and phi _V, converts the optical image into an electrical signal, the process circuit 22 The video signal is generated by the process circuit 22.

The source oscillation from the clock signal generator 19 is input to the process circuit 22, and a horizontal synchronizing signal HD and a vertical synchronizing signal are generated from the source oscillation, and the synchronizing signal and the output signal of the solid-state imaging device 15 are used. Generate a standard video signal.

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

Then, the adder 26 of the bending control unit 24 detected the angle signal from the bending operation unit 25 and the resistance value detection circuit 30.
A difference signal from the current bending angle signal of the bending portion 13 based on the resistance value of the SMA 23a (23b) is obtained, and the PID controller 27 outputs a pulse corresponding to the difference signal to the PWM generator 28.

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

As shown in Figure 2, configuration when the pulse output from the PWM generator 28 is applied via a resistor R ₅ to the gate of the FE transistor Q of the drive circuit 29, FE transistor Q is the ON bridge circuit SMA23a (23
b), the resistors R ₁ and R ₂ are energized, and the SMA 23a (23b) is gradually heated.

Then, the SMA 23a (23b) is transformed from a coarsely wound coil shape, which is a memory shape, to a tightly wound coil shape, and this SMA 23a (23b) is transformed.
The bending section 13 incorporating b) is bent in a desired direction.

When the SMA23a (23b) is heated, the SMA23a (23b)
As shown by the solid line in FIG. 4, the resistance R in b) rapidly decreases in the transformation temperature range T _{1 to} T ₂ , and gradually increases in other regions with a positive temperature coefficient of ΔR / Δt. . On the other hand, the SM
Since the resistance value of the negative resistance R ₁ in series connection to the A 23a (23b) has a temperature coefficient of - [Delta] R / Delta] t, as indicated by the broken line in the Figure 4, the resistance value detected is above In a region other than the transformation temperature region T _{1 to} T ₂ , the temperature is constant without depending on the heating temperature T.

Resistance detection circuit connected to the output side of the bridge circuit
A voltage corresponding to the resistance value characteristic indicated by the broken line in FIG. 4 is applied to the non-inverting input terminal of the differential amplifier OP constituting 30.
On the other hand, inverted input terminal, for example, resistors R _3, partial pressures from between R ₄ as above SMA23a (23b) and negative corresponding voltage the reference voltage to the resistance value of the resistor R ₁ the curved portion 13 is in the vertical state Have been.

As a result, the differential by the voltage outputted from the amplifier OP can detect the current bending angle of the curved portion 13, also by resistance characteristics with respect to the heating temperature of the negative resistance R _1, the SMA23a (23b ) Is out of the transformation temperature range T _{1 to} T ₂ , the differential amplifier OP
Output voltage of the maximum or minimum bending angle of the bending portion 13 can be easily determined in the transformation temperature range T ₁ through T ₂ of the SMA23a to become constant (23b), the control is improved in.

Then, the sample-and-hold circuit 31 pulses corresponding to the resistance value corrected the detected based on the output voltage of the differential amplifier OP SMA23a the (23b) by negative resistance R ₁ as bending angle signal of the current bend 13 The signal is output to the adder 26 via the above-mentioned adder, and the feedback control is performed.

(Second Embodiment) FIGS. 5 to 7 show a second embodiment of the present invention, FIG. 5 is a sectional view of an endoscope insertion portion, and FIG. 6 shows a connection between a distal end hood and a wire. FIG. 7 is a specific circuit diagram of a drive circuit and a resistance value detection circuit.

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

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

Tip fixing member 45 provided on tip rigid portion 44 of insertion portion 42
The entrance ends of an image guide (IG) fiber 46 and a light guide (LG) fiber 47 are fixed, and are covered with a plastic cover 48.

A distal end hood 50 is stored in a storage portion 49 formed between the cover 48 and the distal end fixing member 45, and the distal end hood 50 is connected to an operation member provided on an operation portion (not shown) via a wire 51. By operating this operating member, the tip hood 50 can be moved in and out of the storage section 49 by remote control.

A bending piece 52 is provided on the bending portion 43 on the hand side of the distal end fixing member 45, and SMAs 23a (23b) are provided inside the bending piece 52 in a predetermined manner. The outside of the bending piece 52 is a bending portion outer skin 53
Further, the curved portion outer skin 53 is fastened to the outer periphery of a connecting pipe 54 connecting the rearmost bending piece 52 by a thread 55 and fixed by adhesion, and is also fixed through a flexible tube outer skin 56. It is connected to an operation unit (not shown).

Further, the drive circuit 29 and the resistance detection circuit 30 (see FIG. 1) in this embodiment are different from the SM circuit shown in FIG.
A bridge circuit incorporating A23a (23b) is configured.

The bridge circuit, the SMA23a and (23b) and the dummy resistor R ₂ are connected in series, and further, to the dummy resistor R ₂
The source side of the FE transistor Q is connected. Also,
The SMA23a (23b), the resistance R ₂ resistor R _3, R ₄ are connected in parallel, the SMA23a (23b), the non-inverting input terminal of the operation amplifier OP is connected between the dummy resistor R _2, also, the The resistance R ₃ and R ₄ are connected to the inverting input terminal of the differential amplifier OP.

The dummy SMAR ₂ has the same material as the SMA 23a (23b) and is set to the same resistance value, but is not heat-treated and does not transform.

Next, the operation of the embodiment having the above configuration will be described.

When the FE transistor Q is turned on and energized and heated, the SMA 23a (23b) transforms from a coarse coil to a tight coil, bending the bending piece 52 and bending the bending portion 43.

On the other hand, the SMA23a (23
b) The resistance of dummy SMAR ₁ connected in series with SMA23a is
Outside transformation temperature region T ₁ through T ₂ of (23b), the SMA23a
Has a (23b) is equal to the temperature coefficient [Delta] R / Delta] t (see FIG. 4), the two SMA23a (23b), the potential at the connection point P ₁ of R ₂ does not change in the transformation temperature range T ₁ through T ₂ .

Therefore, the change in the resistance value in the region other than the transformation temperature region T _{1 to} T ₂ is canceled, and only the resistance value in the transformation temperature region T _{1 to} T ₂ changes, so that the controllability is improved.

Further, in this embodiment, since the distal end hood 50 is housed in the distal end fixing portion 45 of the insertion portion 41 so as to be able to be freely inserted and removed, the trouble of attaching and detaching the distal end hood 50 one by one can be saved, and the handleability can be improved. Further, the thread 55 is wound around and fixed to the connecting pipe 54 connecting the bending section 52 of the rearmost part to the bending section outer skin 53, and the rear end of the bending section outer skin 53 is securely connected to the connecting pipe 54. Can be fixed.

(Third Embodiment) Figs. 8 to 11 show a third embodiment of the present invention, Fig. 8 is a schematic configuration diagram of a medical catheter, Fig. 9 is a schematic configuration diagram of a main part of the medical catheter, FIG. 10 is a sectional view taken along line XX of FIG. 9, and FIG. 11 is a sectional view taken along the line XI of FIG.

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

Reference numeral 62 in FIG. 8 denotes an insertion portion of the catheter 61. A balloon 63 formed of a bag-shaped elastic body is mounted on the outer peripheral surface of the distal end portion of the insertion portion 62.

Further, a proximal end portion 64 is provided at a proximal end portion of the insertion portion 62. A tube is attached to the outer peripheral surface of the proximal end 64.
65 and a connecting end 68 of a cable 67 to be described later.
Are provided respectively. One end of the tube 65 is connected to the balloon 63. Further, a cylinder 69 for supplying a fluid such as physiological saline into the balloon 63 is detachably connected to the base end of the tube 65.

An endoscope insertion port 70 is provided on the end face of the proximal end 64. The insertion section 72 of the vascular endoscope 71 formed by, for example, an electronic endoscope is inserted from the endoscope insertion port 70 into the tube of the catheter main body 61a.

The insertion portion 72 of the blood vessel endoscope 71 is formed by connecting a distal end rigid portion 74 to a distal end of a flexible tube 73. Further, one end of each of the universal cords 76 and 77 is connected to the proximal operation section 75 on the base end side of the insertion section 72.

The other end of the universal cord 76 is a connector
The other end of the other universal cord 77 is connected to a television camera unit 81 via a connector 80. This TV camera unit
A television monitor 82 is connected to 81.

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

That is, a pair of bending operation wire mounting holes 84a and 84b are provided in parallel at the position of 180 ° on the distal end surface of the tube wall portion of the insertion portion 62 in the proximity state. These bending operation wire mounting holes 84a and 84b extend in the axial direction. A bending operation wire 85 is inserted into each of the bending operation wire mounting holes 84a and 84b.

The bending operation wire 85 is formed of a shape memory material such as a linear shape memory alloy (for example, a nickel-titanium alloy or the like). The shape memory alloy of the bending operation wire 85 has, for example, a two-way shape memory effect, and is formed by forming a wire whose length is contracted by heating into an elongated shape.

That is, the bending operation wire 85 has the first memory shape (initial wire shape) on the high temperature side with the length L ₀ and the second memory shape on the low temperature side with the length L ₁ (L ₁ = L ₀ + ΔL). The memory shape (forced extension wire shape) is stored. In this case, after the shape memory alloy of the bending operation wire 85 is subjected to the shape memory processing on the high temperature side in the first memory shape on the high temperature side, for example, the shape memory alloy is forcibly extended to an elongated shape at room temperature about the body temperature, and the shape memory alloy on the low temperature side is obtained. Shape storage processing of the second storage shape is performed. Then, the bending operation wire 85 subjected to the shape memory processing in two directions
By heating the bending operation wire 85 to a transformation temperature of, for example, about 60 to 90 ° C. or more in a state where is held in the second storage shape, the first storage on the high temperature side having the length L ₀ is obtained. The shape (heat-shrinkable wire shape) is deformed (returned to shape).

As shown in FIG. 9, the bending operation wire 85 is folded back from a substantially central portion, and the folded wire constituting portions 85a and 85b on both sides thereof are inserted into the mounting holes 84a and 84b, respectively. Further, the center folded portion 85c of the bending operation wire 85 is fixed at the distal end surface of the tube wall of the insertion portion 62, and a front end fixing portion 86 of the bending operation wire 85 is formed.

Furthermore, one end of each of the lead wires 87a and 87b for energization is connected to the tip of each of the folded wire constituent parts 85a and 85b of the bending operation wire 85. In this case, the lead wires 87a, 87
b is formed of a shape memory material such as a shape memory alloy that has not been subjected to a shape memory process. Then, these lead wires 87a, 87b and both ends of the folded wire components 85a, 85b of the bending operation wire 85 are joined by welding or soldering, and the folded wire components 85a,
The respective ends of the lead wires 85b and one ends of the lead wires 87a and 87b are electrically connected.

Further, a connecting portion formed by welding or soldering between each end of each of the folded wire components 85a and 85b of the bending operation wire 85 and one end of each of the lead wires 87a and 87b is provided on the outer peripheral surface of the tube wall of the insertion portion 62. At positions corresponding to 88, side holes 89 are formed as shown in FIG. In this case, each end of the folded wire components 85a, 85b and the lead wires 87a, 87b
The outer diameters of the connecting portions 88, 88 with each one end are slightly enlarged at the time of joining work by welding or soldering. Also, these joints 88, 88 are inserted into the respective side holes 89, 89,
In this inserted state, the bending operation wire 85 is fixed by the adhesive S to form both end fixing portions 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 the cap.

The other ends of the lead wires 87a and 87b are connected to the bending operation wires 8 respectively.
5 is connected to an energization control unit 91 for controlling the amount of energization.
The energization control section 91 is connected to the catheter main body 61a via the cable 67. Further, the energization control unit 91
Is connected to an operation unit 93 via a cable 92.

The operation unit 93 is formed by, for example, a joystick 94. The joystick 94 can be moved to, for example, both sides of a neutral reference position, and is normally held at a predetermined reference position.

Further, each of the bending operation wires 85, 85
Built-in controller. Each of these controllers is provided with the same PWM energizing drive circuit as in the first embodiment, and operates the joystick 94, that is, the PWM of the controller in accordance with the operation direction and the amount of movement of the joystick 94 from the reference position. The drive circuit is controlled so that the bending direction and the bending amount of the curve 83 of the catheter main body 61a can be arbitrarily operated in a state corresponding to the movement amount of the joystick 94.

Next, the operation of the embodiment having the above configuration will be described.

First, the joystick 94 of the catheter 61 is normally held at the reference position. In this state, the controller of the power supply control unit 91 is held in the off state, so that the bending operation wires 85, 85 attached to the bending unit 83 of the insertion unit 62 are held in a state where power is not supplied. Therefore, since the bending operation wires 85, 85 is held in the second memory shape of the cold side of the length dimension L _1, a substantially linear regular shape state the curved portion 63 is not bent in the insertion portion 62 Is held.

Next, when the joystick 94 is appropriately operated from the reference position in the neutral state according to the moving direction and the moving amount when the hole in FIG. It is supplied to the bending operation wires 85, 85 and bent in a desired direction for insertion.

The inside power supply controller 91 is provided the first embodiment or the second embodiment similar to the resistance value detecting circuit 30 (see FIG. 1) is, SMA23a, at transformation temperature region T ₁ through T ₂ of 23b the curved Part 83
Can be easily controlled.

The scope of the present invention is not limited to endoscopes and catheters, and it goes without saying that the present invention can be applied to actuators using a shape memory alloy.

[Effects of the Invention] As described above, according to the present invention, the shape memory alloy cancels the resistance value change in a region outside the region where the transformation operation is performed. This eliminates erroneous operations such as overheating, and provides excellent effects such as greatly improving the bend controllability.

[Brief description of the drawings]

1 to 4 show a first embodiment of the present invention, FIG. 1 is a functional block diagram of a bending control unit, FIG. 2 is a specific circuit diagram of a drive circuit and a resistance value detection circuit, and FIG. Is an overall schematic diagram of an endoscope device, FIG. 4 is a characteristic diagram of a heating temperature and a resistance value of the shape memory alloy, FIGS. 5 to 7 show a second embodiment of the present invention, and FIG. FIG. 6 is a perspective view showing the connection between the distal end hood and the wire, FIG. 7 is a specific circuit diagram of the drive circuit and the resistance value detection circuit, and FIGS. FIG. 8 shows a third embodiment of the present invention, 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, FIG. FIG. 11 is a cross-sectional view taken along the line XI in FIG. 9, and FIG. 12 is a characteristic diagram of the heating temperature and the resistance value of the conventional shape memory alloy. 7,42,62 …… Insertion part, 13,43,83 …… Bend part, 23a, 23b ……
Shape memory alloy, 26 ... Heating control means (adder), 29 ...
Heating means (drive circuit), 30 ... resistance value detecting means, R
₁ , R ₂ ...... Resistance element.

Claims (1)

(57) [Claims] 1. A bending portion drive control device for controlling a bending angle of a bending portion provided in an insertion portion by a transformation operation by heating a shape memory alloy, comprising: heating means for heating the shape memory alloy; 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; and heating for controlling the heating means based on a signal obtained by detecting the resistance value of the shape memory alloy. A bending section drive control device, comprising: control means.