JPH05253175A - Electrostatic type actuator - Google Patents

Abstract

PURPOSE:To provide the actuator which is elongated, shrunk or curved by the electrostatic force applicable to the front end curving mechanism of a catheter type medical treating apparatus having a very small tube diameter. CONSTITUTION:This electrostatic actuator 10 has electrodes 12 and 14 fitted to the opposite surface of an insulating elastic body 16. Two sheets of the electrodes 12 and 14 are arranged nearly parallel in such a manner that these electrodes partly face each other. Further, the actuator has a driving circuit 18 for selectively impressing voltages between the electrodes 12 and 14. The driving circuit 18 has a power source 22 and a switch 20 for changing over the impression and non-impression of the voltages.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator that uses electrostatic force to generate displacement.

[0002]

2. Description of the Related Art With the advancement of medical treatment, catheter-type medical devices (endoscopes, catheters for inserting blood vessels) are expanding their application range in view of their low invasiveness and simplicity. In order to expand the application of catheter-type medical devices, it is an important issue to reduce the diameter of the tube, and accordingly, the bending of the catheter tip and the novelty of the driving method are required. The narrowing of the tube diameter expands the examination and treatment capabilities of the lungs, gallbladder, etc., which could not be invaded in the past, by endoscopy and enables the insertion of a catheter into a thin blood vessel site. Further, by providing the distal end portion of the catheter with a bending function to form an active catheter, insertion into the thin tube portion can be facilitated.

[0003]

The applicable range of an endoscope or catheter-type medical device is limited by its tube diameter. It is well known that screening of the esophagus, stomach, duodenum, rectum, etc. is effective in detecting ulcers and early cancer.
Furthermore, for insertion into an organ having a small tube diameter or insertion of a catheter into a thin blood vessel, it is necessary to develop an endoscope or catheter having a small tube diameter suitable for the insertion. Further, as the diameter of the pipe is reduced, it is required to reduce the size and the diameter of the inspection / treatment tool installed in the endoscope or the catheter. A small-diameter endoscope needs to be able to bend its tip freely when it is inserted into a tubular organ in the body, and therefore it is necessary to develop a new drive system.

Conventionally, a mechanical method using a wire is generally used for mechanically bending the tip of the endoscope, and a bending means using a shape memory alloy (SMA) has been developed for the tip of the endoscope for a thin tube. However, in order to reduce the diameter of endoscopes or catheter-type medical devices, it is necessary to develop a new drive mechanism and tip bending mechanism that occupy a small volume, and therefore a new tip bending mechanism is required in principle.

An object of the present invention is to provide an actuator which can be applied to a tip bending mechanism of a catheter type medical device having a small tube diameter and which is extended / contracted or bent by an electrostatic force.

[0006]

An electrostatic actuator according to the present invention comprises a conductive member, which is partially opposed to each other and is arranged substantially in parallel, and an insulating elastic body interposed between the conductive members.
And a means for selectively applying a voltage to the conductive member.

[0007]

Next, regarding the electrostatic actuator of the present invention,
It will be described with reference to FIG. 1 showing the basic configuration. In the figure, (A) shows a natural state and (B) shows a contracted state. The electrostatic actuator 10 of the present invention has conductive members, that is, electrodes 12 and 14 attached to opposite surfaces of an insulating elastic body 16. The insulative elastic body 16 has a parallelogram-shaped cross section as shown in (A), and therefore the two electrodes 12 and 14 are arranged substantially parallel to each other so that a part thereof faces each other. Further, the actuator 10 includes a drive circuit 18 for selectively applying a voltage between the electrodes 12 and 14. Drive circuit 1
Reference numeral 8 has a power source 22 and a switch 20 for switching between application and non-application of voltage. When a voltage is applied between the electrodes 12 and 14, the two electrodes 12 and 14 are attracted to each other by an electrostatic force, and the insulating elastic body 16 is crushed as shown in FIG. Move to completely overlap. When the voltage application state is released, the electrode 1
The charges accumulated in 2 and 14 are discharged, and the original shape is restored by the restoring force of the elastic body as shown in (A).

[0008]

FIG. 2 shows a first embodiment of the electrostatic actuator of the present invention. A perspective view of a state in which no voltage is applied is shown in (A), and a cross section taken along line BB is shown in (B). In addition, a perspective view of a state in which a voltage is applied is shown in (C),
A cross section taken along line D-D is shown in (D). The electrostatic actuator of this embodiment has two cylindrical electrodes 32 and 34 arranged at the same center. The cylindrical electrodes 32 and 34 are provided on the outer peripheral surface and the inner peripheral surface of the cylindrical insulating elastic body 36. Since the outer peripheral surface and the inner peripheral surface of the insulating elastic body 36 are displaced from each other in the axial direction as shown in (B),
The inner electrode 34 and the outer electrode 32 are arranged in a state of being axially displaced from each other. When a voltage is applied between the inner electrode 34 and the outer electrode 32, as shown in (C) and (D), the inner electrode 3
4 is drawn inside the outer electrode 32, and the length of the entire actuator changes. The amount drawn at this time is determined by the magnitude of the applied voltage and the material constant of the insulating elastic body 36. By continuously changing the applied voltage, the total length of the actuator can be continuously changed. It is also possible to change the shape in a short time by changing the applied voltage in a pulsed manner. When the applied voltage is removed, the restoring force of the insulating elastic body 36 returns the actuator to the original state, that is, the state shown in (A) and (B).

A second embodiment of the electrostatic actuator of the present invention is shown in FIG. This embodiment basically has the same structure as the first embodiment and is an example in which the number of electrodes is increased to three.
In the figure, (A) is a perspective view of the actuator when no voltage is applied, (B) is a cross-sectional view taken along line BB, and (C) is a perspective view of the actuator when a voltage is applied. FIG. 1D is a sectional view taken along line D-D. The actuator of this embodiment has three cylindrical electrodes 42, 44 and 4 as shown in (A) and (B).
6 are provided coaxially with each other via the insulating elastic bodies 48 and 50, and are arranged axially offset from each other. When a voltage of the same magnitude is applied between the electrodes 42 and 44 and between the electrodes 44 and 46 in the same direction, the electrode 46 is placed inside the electrode 44 as shown in (C) and (D).
The electrode 44 is drawn inside the electrode 42, and the axial length of the actuator changes. With the actuator of this embodiment, a stroke (change in axial length) that is twice that of the first embodiment can be obtained.

A third embodiment of the present invention is shown in FIG. The present embodiment is a linear actuator 52 in which the actuators of the first embodiment or the second embodiment are arranged in series. Figure 4
In the figure, reference numeral 54 indicates the actuator shown in the first embodiment or the second embodiment. In this embodiment, a plurality of actuators 54 are arranged inside a tube 56 having elasticity. Partition plates 58 are arranged between the actuators 54 so that the inner electrodes of the actuators do not enter the outer electrodes of the adjacent actuators. Further, a connecting portion for stably disposing the actuator 54 is provided inside the tip of the tube 56. As shown in (B), the opening of the tube 56 is fixed to the support portion 62 without any slack when the actuators 54 therein are shortest (when a voltage is applied). When the voltage application to each actuator 54 is released, each actuator 54 becomes longer and the total length of the linear actuator 52 becomes longer, as shown in (A). Further, when a voltage is applied to each actuator 54, each actuator 54 becomes shorter and the tube 56 contracts, so that the total length of the linear actuator 52 becomes shorter.

FIG. 5 shows a catheter which can be bent using the linear actuator 52. The appearance of the catheter 64 is shown in (A), and the cross section taken along the broken line shown in (A) is shown in (B). As shown in (B), the catheter 64 has a flexible tube 66, and a plurality of linear actuators 52 are provided on its inner peripheral surface along its length direction. As a result, the linear actuators 5 in the lower half of the linear actuators 52 in the upper half of the drawing are
When 2 is shortened, the tip of the catheter 64 bends downward as shown in (C). On the contrary, when the linear actuators 52 in the lower half are made longer than the linear actuators 52 in the upper half, the distal end portion of the catheter 64 bends upward as shown in (D).

FIG. 6 shows a fourth embodiment of the electrostatic actuator of the present invention. The electrostatic actuator of this embodiment is
As shown in (A), it has a columnar center electrode 68 having conductivity and elasticity, and an elastic strip electrode 70 wound spirally around the center electrode 68. The surface of the strip electrode 70 is insulated. Further, as shown in (B), a step portion 70a is provided on the inner side of the step portion 70a, so that the step portion 70a is wound around the center electrode 68 at a constant pitch. When a voltage is applied between the center electrode 68 and the strip electrode 70 as shown in (C), each part of the strip electrode 70 is moved to the center electrode 68.
The lower end of the strip electrode 70 is attracted to the stepped portion 70.
The strip-shaped electrode 70 clamps the center electrode 68 while moving while contacting the top of a. When the center electrode 68 is tightened by the strip electrode 70, the center electrode 68 extends in the axial direction and its length is from h to h '.
Changes to. When the voltage application is released, the tightening by the strip electrode 70 is eliminated, so that the center electrode 68 has the original length h.
Return to.

FIG. 7 shows a fifth embodiment of the electrostatic actuator of the present invention. The electrostatic actuator of this embodiment is
As shown in (A), it has an insulating elastic body 72 whose thickness changes periodically along the length direction, and an upper electrode 74 and a lower electrode 76 having a V-shaped cross section are alternately arranged on the upper and lower surfaces thereof. It is provided in. When a voltage is applied between the upper electrode 74 and the lower electrode 76, the insulating elastic body 72 is crushed by the electrostatic attractive force acting between the upper electrode 74 and the lower electrode 76, as shown in FIG. As the angle changes, the tip portion 78 moves upward.

A sixth embodiment of the electrostatic actuator of the present invention is shown in FIG. The electrostatic actuator of this embodiment is
As shown in the sectional structure (A), it has an upper electrode 82 and a lower electrode 84 having a V-shaped cross section, and the ends of the upper electrode 82 and the lower electrode 84 are substantially parallel to each other via an insulating elastic body 86. It is provided. When a voltage is applied between the upper electrode 82 and the lower electrode 84, the insulating elastic body 86 is crushed and the upper electrode 82 and the lower electrode 84 come close to each other due to the electrostatic attraction between them. .. As a result, the actuator that was flexible in the state of (A) becomes stiff in the state of (B). When the voltage application is released, the actuator enters the state (A) and becomes flexible again.

A seventh embodiment of the electrostatic actuator of the present invention is shown in FIG. The electrostatic actuator of this embodiment is
As shown in the sectional structure (A), an insulating elastic body having an upper electrode 88 and a lower electrode 90 having a U-shaped cross section, and the upper electrode 88 and the lower electrode 90 being attached to side wall portions arranged in parallel with each other. It is connected via 92. When a voltage is applied between the upper electrode 88 and the lower electrode 90, as shown in (B), the sidewalls of the upper electrode 88 and the lower electrode 90 crush the insulating elastic body 86 by the electrostatic attraction and come close to each other. As a result, the total length of the actuator becomes longer and (A)
In this state, the flexible actuator becomes stiff. Further, when the voltage application is released, the actuator becomes the state of (A), becomes shorter and becomes flexible again.

[0016]

According to the present invention, there is provided an electrostatic actuator having a small size and a simple structure which can be applied to a tip bending mechanism of a catheter type medical device having a small tube diameter.

[Brief description of drawings]

FIG. 1 shows a basic configuration of an electrostatic actuator of the present invention.

FIG. 2 shows an electrostatic actuator according to a first embodiment of the present invention.

FIG. 3 shows an electrostatic actuator according to a second embodiment of the present invention.

FIG. 4 shows a linear actuator constructed by using the electrostatic actuator of FIG. 2 or 3, which is a third embodiment of the present invention.

FIG. 5 shows a bendable catheter constructed using the linear actuator of FIG.

FIG. 6 shows an electrostatic actuator according to a fourth embodiment of the present invention.

FIG. 7 shows an electrostatic actuator according to a fifth embodiment of the present invention.

FIG. 8 shows an electrostatic actuator according to a sixth embodiment of the present invention.

FIG. 9 shows an electrostatic actuator according to a seventh embodiment of the present invention.

[Explanation of symbols]

12, 14 ... Electrodes, 16 ... Insulating elastic body, 18 ... Drive circuit.

Claims (1)

[Claims] 1. A conductive member, a part of which faces each other and is arranged substantially in parallel, an insulating elastic body interposed between the conductive members, and means for selectively applying a voltage to the conductive member. An electrostatic actuator equipped.