JP2750861B2 - Actuator drive - Google Patents

Description

The present invention relates to an actuator driving device that drives a plurality of actuators using a shape memory alloy.

[Prior Art] In recent years, actuators using a shape memory alloy have been provided. A cable provided with a bending mechanism disclosed in Japanese Utility Model Laid-Open Publication No. 61-94001 is one of them. In this method, a plurality of actuators made of a shape memory alloy are arranged in a cable, and the cable is bent and driven by individually supplying current to each actuator.

In other words, an independent power supply line is connected to each of the plurality of actuators made of a shape memory alloy, and the operation of each actuator is controlled by selectively energizing or changing the amount of energized power through the independent power supply lines. ing.

[Problems to be Solved by the Invention] However, in the related art, since an independent power supply line is connected to each of the shape memory alloys constituting the actuator, the number of power supply lines is proportional to the actuator (shape memory alloy). And more. In other words, two wiring materials are required for each shape memory alloy, that is, twice as many wiring members as the shape memory alloy as a whole.

Generally, the electric resistance value of a shape memory alloy tends to be low, and the current value required for energization heating increases. For this reason, the power supply line is required to have a relatively high current capacity. Therefore, a thick wire is used for the wire of the feeder line.

Wiring a large number of wires having a large diameter in this way is a major obstacle in realizing a small and lightweight actuator. In addition, when the present invention is applied to a long object such as a cable or an endoscope, the length of the power supply line becomes considerably long accordingly, and in this case, there is a greater problem. In addition, when the current supply is prolonged or repeated, the amount of heat generated in the power supply line is accumulated, and heating may occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to simplify an electric power supply circuit for a plurality of actuators each including a shape memory alloy, and to further reduce the size and weight of the actuator. A drive device is provided.

[Means and Actions for Solving the Problems] To solve the above problems, the present invention provides an elongated flexible tube having a flexible insertion portion, and is disposed in the insertion portion of the flexible tube, An actuator driving device for a flexible tube having a plurality of actuators each having a shape memory alloy, wherein the actuator driving device extends in the insertion portion, connects the plurality of actuators, and supplies electricity to each of the actuators. A power supply line, power supply control means for controlling power supply to the actuator through the power supply line in series with and at least close to one of the actuators, and extending in the insertion portion, A driving line for performing an operation of causing the energization control unit to perform an operation, and a current capacity of the power supply line,
The current capacity of the driving line is set to be larger than that of the driving line, and the plurality of actuators are arranged in at least one row along the insertion axis of the insertion section, and both ends of each actuator are fixed in the insertion section. Accordingly, a plurality of actuators are arranged and printed in a line along the longitudinal direction of the insertion portion, and a power supply line for supplying power to each actuator from a power source is provided for each actuator. It is not necessary, and not only can the power supply line be omitted, but also the drive line for performing the operation of causing the energization control means to have a small diameter, and the volume ratio of the wiring material in the insertion portion can be reduced. Therefore, the weight and the diameter can be reduced.

Embodiment FIG. 1 shows a first embodiment of the present invention. A common power supply line (power supply path) 3, 3 (power supply path means) is connected to the power supply 1 via a heating prevention resistor 2. A plurality of actuators 4a, 4b, 4c are connected in parallel between the power supply lines 3, 3. Each of the actuators 4a, 4b, 4c is made of a shape memory alloy, and is heated and deformed by self-heating by energization. Each of these actuators
In 4a, 4b, 4c, energization control elements 7, 8, 9 as energization control means are respectively inserted in series. Each energization control element 7, 8, 9
Is made conductive by receiving an energization signal from the energization control terminals 11, 12, 13 of the energization control element driving means, for example, comprising a semiconductor switch.

Therefore, when energizing one of the actuators 4a, 4b, 4c to drive it, the energization control terminals 11, 8, 9 corresponding to the energization control elements 7, 8, 9 inserted in the actuators 4a, 4b, 4c,
An energization signal is provided from 12, 13 and the energization control elements 7, 8, 9 are made conductive. This will cause the selected actuator 4
a, 4b, 4c are energized and their actuators 4a, 4b, 4c
Causes self-heating and deforms.

Here, the power supply lines 3, 3 need to have a relatively large current-carrying capacity, that is, a relatively thick one, in order to flow a current necessary for causing the actuators 4a, 4b, 4c to generate self-heating. However, since the energization signals from the energization control terminals 11, 12, and 13 for energizing the energization control elements 7, 8, and 9 need only a small amount of current, the transmission line can be made of an extremely thin wire.

If the power supply lines 3 and 3 for individually energizing and heating the actuators 4a, 4b, and 4c are independently connected to each other, six power supply wires are required, and each of the power supply wires is relatively energized. It must be large and relatively thick.

However, according to the above configuration, the power supply line having a large current carrying capacity
The wires 3 and 3 need only be two wires and three extremely thin wires for transmitting a power supply signal to the power supply control elements 7, 8 and 9. Accordingly, the current-carrying circuit can be reduced in weight and size.

In particular, when the power supply 1 and the actuators 4a, 4b, 4c are installed far apart, the effects of power supply and reduction of the weight of the signal lines are remarkable.

The heating prevention resistor 2 prevents an excessive current from flowing through the power supply lines 3 and 3 to prevent the actuators 4a, 4b and 4c from being excessively heated. Only needs to be done.

FIG. 2 and FIG. 3 show a second embodiment of the present invention. This embodiment uses MOS field effect transistors 21 to 26 as the semiconductor switches of the conduction control elements. The current between the drain and the source of each of the transistors 21 to 26 is controlled by the voltage applied to the gate. It has become. The voltage applied to the gate is
Are provided through energization control terminals 11 to 16 corresponding to. Then, the transistor 21 with the voltage applied to the gate
To 26 conduct. As a result, power is supplied to the selected actuators 4a to 4f, and the actuators 4a to 4f generate self-heating and deform.

Further, each of the actuators 4a to 4f is formed in a coil spring shape, and is disposed on a bending portion 28 of the endoscope insertion portion 27 as shown in FIG. Actuators 4a-4f
Are arranged in series on the upper and lower sides of the curved portion 28 along the axial direction thereof, and are connected to each other through a fixture 29 between them. The transistors 21 to 26 for controlling the energization of the actuators 4a to 4f are mounted near the actuators 4a to 4f. The power supply lines 3, 3 and the signal lines 30, for transmitting energization signals to the transistors 21 to 26, are guided to the proximal side through the inside of the endoscope insertion section 27. Note that a thermal fuse 10 is inserted in the middle of the power supply lines 3 and 3.

In the case of incorporating the endoscope in this manner, the driving power supply 1
And the actuators 4a to 4f are installed very far apart. However, as described above, only two power supply lines 3, 3 having a large current carrying capacity are required, and a signal line 30 for transmitting a current carrying signal to each of the transistors 21 to 26. , ... need only be a very thin wire. Therefore, the diameter of the endoscope insertion portion 27 can be reduced.

In particular, since the MOS field effect transistors 21 to 26 are used as the conduction control elements, the signal lines 30, which apply a voltage to their gates, need to be extremely thin. Further, even when the number of actuators 4a to 4f is further increased to form a multi-joint, it is only necessary to increase the number of signal lines 30,.

FIG. 4 shows a third embodiment of the present invention. In this embodiment, phototransistors 31 to 33 are used as semiconductor switches of the conduction control element. Light is incident on each of the phototransistors 31 to 33 through an optical fiber 34, and the phototransistors 31 to 33 receive a specific light to be electrically operated. An operation of electrically conducting is performed. As a result, power is supplied to the selected actuator 4a to 4c,
4a to 4c generate deformation by self-heating.

Further, a filter rotator 36 having a plurality of filters 35a to 35c having different spectral characteristics is provided at the incident end of the optical fiber 34. Further, a light source 37 facing the incident end of the optical fiber 34 is provided in front of the filter rotator 36. Then, rotate the filter rotator 36 to select the filters 35a to 35c facing the incident end of the optical fiber 34,
The light from the light source 37 is split through the filters 35a to 35c, and the split light is incident on the optical fiber 34. Then, the light split into light of different wavelengths and incident on the optical fiber 34 reaches the respective filters 35a 'to 35c', but the respective filters 35a 'to 35c' transmit light of a specific wavelength adapted thereto. And the corresponding phototransistors 31 to
33, and the phototransistors 31 to 33 thereof are energized. And the actuators 4a ~
Electric power is supplied to the actuator 4c, and the actuators 4a to 4c self-heat and deform.

A normally-closed switch 38 is interposed in the middle of the power supply lines 3, 3 in this embodiment. The movable contact 39 of the switch 38 has a heating prevention coil 40 made of a shape memory alloy.
Are connected. Further, a bias spring 41 that constantly applies a bias pressure in a direction against the urging force of the heating prevention coil 40 is connected to the movable contact 39. And
Place the coil 40 near the actuators 4a to 4c,
When the actuators 4a to 4c are heated, they are deformed to open the movable contact 39 of the switch 38 and cut off the power supply.

The present invention is not limited to the above embodiment. For example, a multiplexer circuit may be used as driving means for selectively energizing the energization control element.

[Effects of the Invention] As described above, according to the actuator driving device of the present invention, a plurality of actuators are arranged in a line along the longitudinal direction of the insertion portion, and a power supply line that supplies power to each actuator from a power supply. Is not necessary for each actuator, and not only can the power supply line be omitted, but also the drive line for performing the operation of the power supply control means has a small diameter, and the wiring material occupying the insertion portion can be reduced. Since the volume ratio can be reduced, the weight and diameter of the insertion portion can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a first embodiment of the present invention,
FIG. 2 is a configuration diagram schematically showing a bending portion of an endoscope insertion portion to which the second embodiment of the present invention is applied, and FIG. 3 is a configuration schematically showing the second embodiment of the present invention. FIG. 4 is a block diagram schematically showing a third embodiment of the present invention. 1 ... power supply, 3 ... power supply line, 4a-4f ... actuator, 7,8,
9 energization control elements, 11-16 energization control terminals, 21-26 transistors, 31-33 phototransistors, 34 optical fibers, 35a-35c filters, 37 light sources.

Claims (1)

(57) [Claims] An elongated flexible tube having a flexible insertion portion;
An actuator driving device for a flexible tube, which is disposed in an insertion portion of the flexible tube and has a plurality of actuators each including a shape memory alloy, wherein the actuator driving device extends in the insertion portion and connects the plurality of actuators respectively. A power supply line for supplying electricity to each of the actuators; and a power supply control means for controlling power supply to the actuator through the power supply line in series with and near at least one of the actuators. And a drive line extending into the insertion portion and performing an operation of causing the energization control means to perform an operation. The current capacity of the power supply line is set to be larger than the current capacity of the drive line. And installing the plurality of actuators in at least one row along the insertion axis of the insertion portion. Actuator drive for both ends of the actuator flexible tube, characterized in that fixed to the insertion portion.