KR100956760B1 - Surgical instrument - Google Patents

Abstract

PURPOSE: A surgical instrument is provided to easily change the direction of an effector by bending a shaft through a controller. CONSTITUTION: A shaft(40) is combined with a handle(30). A bending unit(42) is formed in one side of the shaft. A driving unit(50) is mounted on the handle and includes a motor unit, a power supply unit and a controller. The controller controls the driving of the motor unit. A power transmission unit(70) transfers the driving force generated by the driving unit to the bending unit. The effector is combined with the end of the shaft. The direction of the effector is changed according to the curvature of the bending unit.

Description

Surgical Instrument

The present invention relates to a surgical instrument.

Medically, surgery means repairing a disease by cutting, slitting, or manipulating skin, mucous membranes, or other tissues with medical devices. In particular, open surgery to incise and open the skin of the surgical site to treat, shape, or remove the organs therein causes problems such as bleeding, side effects, patient pain, and scars.

On the contrary, instead of dissecting the skin, a small insertion hole is drilled, and through this, a medical device such as an endoscope, a laparoscope, a surgical instrument, a microsurgical microscope is inserted to allow surgery to be performed in the body. 'Laparoscopic surgery' or 'minimally invasive surgery' is in the spotlight.

Such a conventional surgical instrument 10 used for laparoscopic surgery has a structure in which the effector 16 is coupled to the end of the shaft 14 extending from the handle 12, as shown in FIG. If it is necessary to change the orientation of the effector 16 during the surgical procedure, conventional instruments allow a person to manually unlock the lock 18 and manually move the operator 26 so that a portion of the shaft 20 bends like a joint. It was then operated by locking the lock 18 again.

However, such a conventional manual operation method has to manually operate the locking device 18 and the operator 26 during the operation, it is necessary to operate the instrument 10 by using both hands, respectively holding the surgical instruments in both hands In the case there was a limit that can not operate the surgical instrument (10).

The background art described above is technical information possessed by the inventors for the derivation of the present invention or acquired during the derivation process of the present invention, and is not necessarily a publicly known technique disclosed to the general public before the application of the present invention.

The present invention provides a surgical instrument that can easily change the direction of the effector by bending the shaft simply by operating the controller. Technical problems other than the present invention will be easily understood through the following description.

According to an aspect of the present invention, a handle, a shaft coupled to the handle and extending in one direction, a bending portion formed on a portion of the shaft, mounted to the handle and generating a predetermined driving force Surgical instruments are provided that include a drive unit and a power transmission means for transmitting the driving force generated in the drive unit to the bending unit to bend the bending unit.

It may further include an effector coupled to the distal end of the shaft, the effector being operable to perform the operations necessary for surgery in accordance with user manipulation of the handle. In this case, the handle may be rotatably mounted, and may further include a rotation operator connected to the effector to rotate the effector about the extending direction of the shaft. The effector also includes a pair of jaws engaged with each other, and the handle may be coupled to a grip operator that is connected to the pair of jaws to allow the pair of jaws to open and close.

The bending part is formed adjacent to the effector, and the direction in which the effector is directed may be changed according to the bending of the bending part. In this case, the bending part may include a snake type joint.

The driving unit may include a motor unit, a power supply unit for supplying electric power for driving the motor unit, and a controller for controlling driving of the motor unit. The power supply may include a battery contained within the handle. The motor unit is located outside of the handle and can be connected to the handle by a driving force transmitting means. The controller may include a direction manipulator for controlling the driving of the motor unit to bend the bending part corresponding to the operation direction thereof.

The driving unit may include a hold function for driving the motor unit so that the bending unit is maintained in a bent state corresponding to the operation when the direction manipulator is operated in a predetermined direction, and the motor is configured to restore the bending unit to an initial state. It may further include a release operator for controlling the driving of the negative.

In this case, the direction operator is operated in two or more directions, and the motor unit may include a first motor driven in correspondence with the first operation direction of the direction operator, and a second motor driven in correspondence with the second operation direction of the direction operator. Can be. The bending part may be bent in the first direction according to the driving of the first motor, and may be bent in the second direction according to the driving of the second motor.

The power transmission means includes a first wire connecting two points facing each other in the first direction of the first motor and the bending part, and a second wire connecting two points facing each other in the second direction of the second motor and the bending part. It may include. In addition, the reaction apparatus may further include a reaction force blocking unit interposed between the first and second wires and the bending unit to block a reaction force to be restored to the original position from being transmitted to the first and second motors. The reaction force blocker may include a worm gear. The worm gear may include a worm and a worm wheel engaged with the worm, and the worm may be separated from the worm wheel in accordance with the operation of the release operator provided in the driving unit.

The shaft is detachably coupled to the handle, the power transmission means comprises a first power transmission means embedded in the shaft and a second power transmission means embedded in the handle, the first power transmission means as the shaft is coupled to the handle And the second power transmission means may be connected to each other.

Other aspects, features, and advantages other than those described above will become apparent from the following drawings, claims, and detailed description of the invention.

According to a preferred embodiment of the present invention, by mounting a drive unit such as a motor to the surgical instrument to bend the shaft simply by operating a controller such as a joystick, the direction of the effector easily even while holding the instrument with one hand Can be changed. In addition, since the shaft is bent while holding the instrument, the reaction force applied to the effector can be felt in the process of changing the direction of the effector, thereby realizing 'haptic feedback'.

As the present invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms including ordinal numbers such as first and second may be used to describe various components, but the components are not limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. When a component is said to be "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but other components may be present in the middle. It should be understood.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. As used herein, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described on the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

In the following description of the present invention with reference to the accompanying drawings, the same components are denoted by the same reference numerals regardless of the reference numerals, and redundant explanations thereof will be omitted. In the following description of the present invention, if it is determined that the detailed description of the related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

2 is a side view conceptually showing a surgical instrument according to an embodiment of the present invention, Figure 3 is a plan view showing a bending state of the bending portion according to an embodiment of the present invention, Figure 4 is 'A' of FIG. An enlarged sectional view of the part. 2 to 4, the handle 30, the rotation operator 32, the grip operator 34, the shaft 40, the bending part 42, the effector 44, the driving unit 50, and the direction operator ( 58, power transmission means 70, first wire 72, second wire 74 are shown.

In the present embodiment, instead of manually manipulating the shaft 40 of the surgical instrument to change the direction of the effector 44 coupled to the end of the shaft 40 by using a power such as a motor, By automatically bending, it is possible to easily change the direction of the effector 44 by simply operating a switch while holding the instrument, so that the user can sense the reaction force applied to the tip of the effector 44 in the process. That is, the haptic feedback can be felt.

That is, the instrument according to the present embodiment relates to a so-called 'motorized handheld instrument (Motorized Handheld Instrument)', and as shown in FIG. 2, the bending part 42 is formed at the distal end of the shaft 40, and FIG. As shown in FIG. 3, the bending part 42 is bent freely using the power of the motor, and the end of the instrument is easily bent by bending the shaft 40 using the force of a motor or the like in a manually operated instrument. Can move up, down, left and right.

As shown in FIG. 2, the instrument according to the present embodiment is based on a structure in which the shaft 40 extends to the manipulation handle 30, and a bending portion 42 that is bent freely at the end of the shaft 40. ) Is formed, the handle 30 is equipped with a drive unit 50 for generating a driving force to bend the bending portion 42, the drive unit 50 and the bending portion 42 is connected to the power transmission means 70 As the driving unit 50 drives, the bending unit 42 is bent in a desired direction.

To the end of the shaft 40 may be coupled to the effector 44 of the forceps form consisting of a pair of jaws, the effector 44 is cut, grip (grip) by the user by holding the handle 30 Various operations required for surgery such as rotation. To this end, the handle 30, the rotation operator 32 for causing the effector 44 to rotate about the extension direction of the shaft 40, the grip operator 34 for opening and closing the pair of jaws to perform a grip operation, etc. Operators corresponding to each operation of effector 44 may be combined.

As such, each operator and the effector 44 may be connected in various ways to implement various operations on the effector 44. For example, as shown in FIG. 2, a rotating operator rotatably coupled to the handle 30. 32 is connected to the shaft 40, so that the effector 44 connected to the shaft 40 and its end in accordance with the rotation of the rotary operator 32 can rotate, in the form of a lever to the handle 30 The grip operator 34 to be coupled may be connected to a pair of jaws and wires so that the tension is transmitted through the wires as the grip operator 34 is pulled to allow the effector 44 to grip. In addition, various connection methods may be applied according to the operation method of the effector 44 and the operation method of each operator.

The bending part 42 is formed in a part of the shaft 40 and serves as a joint to allow the shaft 40 to be bent in an arbitrary direction. In the embodiment shown in FIG. 2, an end portion of the shaft 40, That is, the case where the bending part 42 is formed in the part adjacent to the effector 44 is shown.

As described above, by generating and transmitting a driving force through the driving unit 50 to bend the bending unit 42, the portion after the bending unit 42, that is, the portion where the effector 44 is coupled, is predetermined. It is moved toward the direction, and thus the direction in which the effector 44 is directed by the bending of the bending portion 42 is converted.

That is, by operating the instrument according to the present embodiment not only can the effector 44 perform various operations (cutting, grip, rotation, etc.) necessary for surgery, but also by changing the direction in which the effector 44 is directed to the entire instrument. Various surgical operations can be performed on the desired surgical site without changing the direction. Furthermore, even when the direction of the instrument cannot be changed, the operation can be performed by bending the shaft 40 to change the direction in which the effector 44 faces.

As such, to bend a portion of the shaft 40, the bending part 42 according to the present embodiment may be implemented by combining various mechanisms such as hinges, pivots, bellows, and the like. Flexible joints can be implemented in the form of a so-called 'snake' type of speech.

The bending part 42 formed of the snake type can be bent in the desired direction by fixing the wire to the inner wall and transmitting tension through the wire as described later. For example, when pulling the wire on the left side and loosening the wire on the right side while fixing the four wires corresponding to the up, down, left, and right directions on the inner wall of the bending part 42, the bending part 42 ) Is bent to the left due to the tension of the wire.

The overall structure of the surgical instrument according to the present embodiment has been described above. However, the motor is not necessarily used for the driving unit 50 according to the present embodiment, and various driving force generating means capable of bending the bending unit 42 may be used. In addition, the driving force generated and transmitted from the driving unit 50 is not necessarily used to bend the bending unit 42, and may be used as driving force for various operations such as the operation of the effector 44.

Furthermore, the instrument according to the present embodiment is not necessarily limited to a manual type used by the user by hand, and the handle 30 is mounted on the surgical robot arm and may be implemented in such a manner that the driving force is received from the robot arm. It may be. Hereinafter, the operation of each part of the instrument will be described in more detail.

5 is a view showing a driving unit according to an embodiment of the present invention. Referring to FIG. 5, the shaft 40, the driving unit 50, the first motor 52, the second motor 54, the power supply unit 56, the direction operator 58, the release operator 60, and the first wire 72, second wire 74 is shown.

In FIG. 5, a case in which the driving unit 50 according to the present embodiment is implemented by coupling a pair of motors and wires to each motor will be described as an example.

The driving unit 50 according to the present embodiment may include a motor unit, a power supply unit 56, and a controller for controlling driving of the motor unit. In this embodiment, since the motor is used only for bending operation of the bending part 42, a motor having a capacity capable of generating power required for the bending part 42 may be used, and in this case, the motor may be accommodated in the handle 30. A motor of size can be used.

However, the motor unit according to the present embodiment is not necessarily to be accommodated in the handle, and by installing the motor unit outside the handle and connecting the motor unit to the handle by a driving force transmission means such as 'cable conduit', the driving force may be supplied from the outside. have.

The power supply unit 56 is a component for supplying power required to drive the motor. The power supply unit 56 may receive power from the outside, and a battery such as a battery or a rechargeable battery accommodated in the handle may be used to improve portability of the instrument. Can be. As described above, a small motor may be used to generate the power required for the bending of the bending part 42, and accordingly, the power supply unit 56 may also be designed with a smaller capacity, thereby driving the driving unit 50 at a lower cost. Can be configured.

The controller is a part for controlling the driving of the motor part. In this embodiment, a direction manipulator 58 such as a small joystick or a direction key is installed on the handle part 30 as a controller so as to correspond to the bending direction of the bending part 42. Intuitively, the bending part 42 may be controlled to be bent. For example, when the bending part 42 is configured to be bent in the up, down, left, and right directions, a joystick or the like which is operated in the up, down, left, and right directions may be installed so that the bending direction of the bending part 42 may be adjusted. By making the bending directions of the bending parts 42 coincide, the user can intuitively operate the direction operator 58 to bend the bending part 42.

As shown in FIG. 3, when the direction manipulator 58 is operated to the right R, the bending portion 42 is bent to the right R, and when the direction manipulator 58 is operated to the left L, Accordingly, the bending part 42 may be bent to the left side (L).

As described above, in order to bend the bending part 42 by operating the direction manipulator 58 in the up, down, left, and right directions to drive the motor, a pair of motor parts according to the present embodiment is shown in FIG. Motors 52 and 54 can be used.

That is, the first motor 52 is driven by operating the direction manipulator 58 in the vertical direction, and the second motor 54 is driven by manipulating the direction manipulator 58 in the left and right directions. The bending part 42 is bent in the vertical direction in accordance with the driving of the motor 52, and the bending part 42 is bent in the left and right directions in accordance with the driving of the second motor 54. The operation direction and the bending direction of the bending part 42 can be matched.

However, it is not necessary to set the operation direction of the direction operator 58 and the bending direction of the bending part 42 in the up-down direction and the left-right direction according to the present embodiment, and the direction operator 58 has two directions, that is, the first direction. Of course, it is also possible to match the bending portion 42 to be bent in the first direction and the second direction corresponding to the operation direction and the second operation direction.

Each point of the first and second motors 52 and 54 and the bending part 42 may be connected to a power transmission means 70 such as a wire. For example, the first motor 52 may include a first wire 72. The second motor 54 may be connected to two points of the bending part 42 by the second wire 74.

As in the above-described example, when the first motor 52 corresponds to the bending in the vertical direction and the second motor 54 corresponds to the bending in the left and right directions, the first wire 72 is connected to the first motor 52. May be connected to two upper and lower points of the bending part 42, and the second wire 74 connected to the second motor 54 may be connected to two left and right points of the bending part 42. Further, when the first motor 52 corresponds to the bending in the first direction and the second motor 54 corresponds to the bending in the second direction, the first wire 72 moves in the first direction of the bending part 42. The second wire 74 may be connected to two points that face each other, and the second wire 74 may be connected to two points that face each other in the second direction of the bending part 42.

Meanwhile, in addition to the direction manipulator 58, the driving unit 50 according to the present embodiment may have a 'hold' function and a 'release' function.

The hold function is a function that maintains the bent portion 42 in a curved state when the direction manipulator 58 is not touched. When the direction manipulator 58 is operated in a predetermined direction, the bending part 42 is operated to the operation. A function of locking the drive unit 50 to maintain the corresponding bent state.

In order to implement such a hold function, when the direction operator 58 is operated in a predetermined direction, power is continuously supplied to the motor unit so that the motors 52 and 54 stop without being operated by an external force. Alternatively, a motor having a sufficiently large cogging torque is selected so that the reaction force due to the bending of the bending part 42 does not operate the motors 52 and 54 reversely, so that the external force other than the operation of the direction operator 58 is selected. By means of which the motors 52 and 54 are not operated, or a stopper or the like is installed in the direction manipulator 58 so as to mechanically lock the direction manipulator 58 operated in a predetermined direction or separately. When the hold switch is pressed to install the hold switch, the operation of the direction operator 58 may be locked and the bending part 42 may be kept in a bent state.

In addition, the release function may be implemented in response to the hold function. The release function operates a release operator 60 such as a release button so that the shaft 40 bent to a predetermined state is automatically returned to its original state. As a result, the release operator 60 serves to drive the motor part so that the bending part 42 is restored to an initial state.

The release operator 60 may be embodied in a separate button form, or when the joystick is operated up, down, left, or right by adding a pressing function to the joystick, the release operator 60 may be a release operator when the joystick is pressed. It can be implemented in various ways, such as to operate as 60.

6 is a view showing a reaction force blocking unit according to an embodiment of the present invention, Figure 7 is a view showing the operating state of the release operator according to an embodiment of the present invention. 6 and 7, the shaft 40, the bending part 42, the driving part 50, the direction operator 58, the release operator 60, the first wire 72, and the second wire 74. , Reaction force block 76, worm 78, worm wheel 80 is shown.

In the present embodiment, when the bending portion 42 is bent by generating and transmitting power from the driving unit 50, the reaction force due to the bending of the bending portion 42 acts on the motor in reverse, so that the motor is damaged or malfunctions. In order to prevent this, the reaction force blocking part 76 is installed in the middle of the power transmission means 70.

That is, in connecting the drive part 50 and the bending part 42 with wires, the gears, such as the worm gears 78 and 80, are interposed in the middle of the drive part 50 from the driving part 50 toward the bending part 42 (forward direction). The driving force is transmitted, but in reverse, the reaction force due to the bending from the bending part 42 to the driving part 50 side (reverse direction) may be prevented from being directly transmitted to the motor.

As shown in FIG. 6, the bending portion 42 is provided between the first and second wires 72 and 74 and the bending portion 42 with a reaction force blocking portion 76 such as a worm gear 78 and 80 interposed therebetween. Can be prevented from being directly transmitted to the first and second motors 52 and 54 so as to prevent unnecessary load on the motor.

In this case, the force generated and transmitted from the motor does not directly act on the bending part 42, but the motor rotates the worm 78, and accordingly, the worm wheel 80 meshed with the worm 78. This rotation causes tension to act at each point of the bending part 42. As a result, the reaction force due to the bending of the bending part 42 may be prevented from being directly transmitted to the motor in reverse.

Meanwhile, as described above, the release operator 60 is installed in the driving unit 50 to drive the motor unit so that the bending unit 42 bent to a predetermined state is restored to an initial state, so that the curved shaft 40 is returned to its original state. The release function may be implemented. In addition, the release button may be operated to electronically return the shaft 40, and the release function may be implemented by mechanically separating the reaction force blocking unit 76.

That is, when using a worm gear in which the worm 78 and the worm wheel 80 are meshed as the reaction force blocking unit 76, the worm 78 is operated by operating the release operator 60 (see 'B' in FIG. 7). When mechanically separated from the worm wheel 80 and backed back (refer to 'B' in FIG. 7), the shaft 60 may be caused by the reaction force caused by bending the bending portion 42, that is, the elastic restoring force of the bending portion 42. Can be returned to its original position.

8 is a view showing a state in which the shaft is coupled to the handle detachably according to an embodiment of the present invention. Referring to FIG. 8, the handle 30, the rotation operator 32, the shaft 40, the driving unit 50, the power transmission unit 70, the worm 78, and the worm wheel 80 are illustrated.

In the instrument according to the present embodiment, the shaft 40 portion may be made disposable, and the handle 30 portion may be manufactured in a reusable structure. That is, by separately manufacturing the shaft portion 40 and the handle portion 30, 40 ', but configured to be removable from each other, the shaft portion 40 once used as needed, discarded and the new shaft handle 30 again ) To be reused.

In this case, the power transmission means 70 according to the present embodiment is separated into a first power transmission means 70 built in the shaft 40 side and a second power transmission means 70 'built in the handle 30 side. And the first power transmission means 70 in the process of coupling the shaft 40 to the handle 30 by forming coupling mechanisms corresponding to each other at each end of the separated power transmission means 70 and 70 '. ) And the second power transmission means 70 ′ may be connected to each other.

For example, by forming a protrusion at an end of the wire embedded in the shaft 40 side, and forming a groove in which the protrusion is matched at the end of the wire embedded in the handle 30 side 40 ', the shaft 40 is formed. By coupling to the handle 30, the wires may be coupled and connected to each other.

In addition, as described in FIG. 6, when the reaction force blocking portions 76 such as the worm gears 78 and 80 are installed in the shafts 40 and 40 ′, the worm 78 is provided on one side 40 ′ of the separated shaft. The other side 40 is provided with a worm wheel 80 engaged with the worm 78, so that the power transmission means 70 and 70 ′ naturally join each other due to the worm gear being engaged in the separation and coupling process of the shaft 40. You can also make connections.

However, the instrument according to the present embodiment does not necessarily have to separate the shaft from the portion adjacent to the handle, and by separating the middle portion of the shaft by connecting a part of the handle to the other part by configuring the shaft tip to be detachable from each other The shaft tip may be made disposable, and the handle and the shaft portion connected to the handle may be manufactured in a reusable structure.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It will be understood that the invention may be varied and varied without departing from the scope of the invention.

1 is a perspective view showing a robot surgical instrument according to the prior art.

Figure 2 is a side view conceptually showing a surgical instrument according to an embodiment of the present invention.

Figure 3 is a plan view showing a bending state of the bending portion according to an embodiment of the present invention.

4 is an enlarged cross-sectional view of portion 'A' of FIG. 3;

5 is a view showing a driving unit according to an embodiment of the present invention.

6 is a view showing a reaction force blocking unit according to an embodiment of the present invention.

7 is a view showing the operating state of the release operator according to an embodiment of the present invention.

8 is a view showing a state in which the shaft is detachably coupled to the handle according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

30: handle 32: rotation operator

34: grip operator 40: shaft

42: bending portion 44: effector

50: drive unit 52: first motor

54: second motor 56: power supply

58: direction operator 60: release operator

70 power transmission means 72 first wire

74: second wire 76: reaction force breaker

78: worm 80: worm wheel

Claims (14)

With a handle; A shaft coupled to the handle and extending in one direction; A bending part formed on a part of the shaft; A driving unit mounted to the handle and including a motor unit, a power supply unit for supplying electric power for driving the motor unit, and a controller to control driving of the motor unit; And a power transmission means for transmitting the driving force generated by the driving unit to the bending part to bend the bending part. And the controller comprises a direction manipulator for controlling the driving of the motor part to bend the bending part corresponding to the operation direction thereof. The method of claim 1, The distal end of the shaft is coupled to an effector (operator) is operated to perform the operation required for surgery in accordance with the user operation on the handle, The bending part is formed adjacent to the effector, the surgical instrument, characterized in that the direction of the effector is converted according to the bending of the bending part. The method of claim 2, The effector includes a pair of jaws engaged with each other, A rotation manipulator connected to the effector to allow the effector to rotate about an extension direction of the shaft; And a grip operator coupled to the pair of jaws to open and close the pair of jaws. delete delete The method of claim 1, And the driving unit has a hold function for driving the motor unit so that the bending unit is maintained in a bent state corresponding to the operation when the direction manipulator is operated in a predetermined direction. The method of claim 1, The driving unit, the surgical instrument, characterized in that further comprises a release (control) operator for controlling the drive of the motor unit to restore the initial state. The method of claim 1, The direction manipulator is operated in two or more directions, And the motor unit includes a first motor driven in correspondence with the first manipulation direction of the direction operator, and a second motor driven in correspondence with the second manipulation direction of the direction operator. The method of claim 8, The bending part is bent in the first direction according to the driving of the first motor, the surgical instrument, characterized in that bent in the second direction according to the driving of the second motor. 10. The method of claim 9, The power transmission means includes a first wire connecting two points facing each other in the first direction of the first motor and the bending part, and two points facing each other in the second direction of the second motor and the bending part. Surgical instrument comprising a second wire for connecting. The method of claim 10, The power transmission means further includes a reaction force interrupting part interposed between the first wire and the bending part to block a reaction force to be restored to the original position from being transmitted to the first motor. Surgical Instruments. The method of claim 11, The reaction force block is a surgical instrument, characterized in that it comprises a worm gear (worm gear). The method of claim 12, The worm gear includes a worm and a worm wheel engaged with the worm. And the worm is separated from the worm wheel in response to an operation of a release operator provided in the driving unit. The method of claim 1, The shaft is detachably coupled to the handle, wherein the power transmission means comprises a first power transmission means embedded in the shaft and a second power transmission means embedded in the handle, the shaft being coupled to the handle. And the first power transmission means and the second power transmission means are connected to each other.

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