Detailed Description
In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The invention may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit or scope of the invention, which is therefore not limited to the specific embodiments disclosed below.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
Referring to fig. 1, a tissue closure system of an embodiment comprises a tissue closure device 1 and a conveyor. The tissue closure device 1 comprises a first clamping portion 10 and a second clamping portion 20, the first clamping portion 10 and the second clamping portion 20 being adapted to clamp tissue. The tissue is clamped between the first clamping portion 10 and the second clamping portion 20. Among them, tissues include, but are not limited to, the leaflets of the mitral valve, the leaflets of the tricuspid valve, etc.
At least two first clamping portions 10 and at least two second clamping portions 20 are provided, and the number of the first clamping portions 10 and the number of the second clamping portions 20 are equal. The tissue closure device 1 has a longitudinal central axis I-I, two first clamping portions 10 being arranged symmetrically about the longitudinal central axis I-I as an axis of symmetry and two second clamping portions 20 being arranged symmetrically about the longitudinal central axis I-I as an axis of symmetry. It will be appreciated that the first clamping portion 10 and the second clamping portion 20 are in one-to-one correspondence to clamp tissue.
Referring to fig. 2, the first clamping portion 10 includes a first clamping arm 110 and a supporting arm 120. The first clamping arm 110 is made of an elastic metal material, for example, the first clamping arm 110 is made of a nickel titanium alloy material, and provides a clamping force by the elasticity of the material itself. The support arm 120 is made of metal or polymer material.
The first clamping arm 110 and the support arm 120 are rotatably coupled, e.g., one end of the first clamping arm 110 is pivotally coupled to one end of the support arm 120 such that the support arm 120 can distract the first clamping arm 110, thereby allowing the first clamping arm 110 and the support arm 120 to move between an open position (as shown in fig. 2) and a closed position (as shown in fig. 1). In a natural state, the first clamping arm 110 and the support arm 120 are in a closed position. The support arm 120 should have a certain rigidity and toughness to be able to prop open the first clamping arm 110 in the open position to maintain the open state.
The rotatable connection of one end of the first clamping arm 110 to one end of the support arm 120 may be accomplished in a variety of ways. For example, the first clamping arm 110 is connected to the support arm 120 via a pivot, pin, living hinge, or the like.
In one embodiment, as shown in fig. 3, the first clamping arm 110 is a wire loop structure with an opening. For example, the first clamping arm 110 may be a wire loop with an opening, which is wound from nitinol. The support arm 120 includes a support body 121 and a connection portion 122 connected to the support body 121, and one end of the connection portion 122 away from the support body 121 is connected to the first clamping arm 110. In an embodiment, the connecting portion 122 and the supporting body 121 are integrally formed, and one end of the supporting body 121 is wound to form the connecting portion 122. The connecting portion 122 has a receiving cavity, the first clamping arm 110 penetrates the receiving cavity of the connecting portion 122, and two ends of the first clamping arm 110 are bent to form a wire loop with an opening. The first clamping arm 110 and the connecting portion 122 may pivot relative to each other. The first clamping arm 110 and the connecting portion 122 can pivot relatively without using a rotating shaft, a pin, or the like by the structures of the supporting arm 120 and the first clamping arm 110 themselves being mutually matched. The pivot connection reduces the use of parts such as a rotating shaft, a pin and the like, and can provide flexible rotation.
In one embodiment, as shown in fig. 3, the supporting body 121 and the connecting portion 122 are in a one-piece structure. The support arm 120 including the support body 121 and the connection portion 122 is integrally formed by elastic wire weaving.
In another embodiment, as shown in fig. 4, the support body 121 and the connection portion 122 are not a unitary structure. The connecting portion 122 is a machined metal part, and the connecting portion 122 and the supporting body 121 are connected by welding, mortise pressing, wire stitching or gluing, etc. In this way, during the opening process of the support arm 120, the support arm 120 is not deviated due to the limitation of the two sides of the first clamping arm 110, so as to ensure the smoothness of the opening and closing movement of the first clamping arm 110.
Referring back to fig. 3, in one embodiment, the first clamping arm 110 includes two support sections 111 and a connecting section 112, and the support sections 111 and the connecting section 112 are metal rods. Two ends of the connecting section 112 are respectively connected with two supporting sections 111, and one ends of the two supporting sections 111 far away from the connecting section 112 are not connected to form a wire loop structure with an opening. The end of the connecting section 112 is the free end of the first clamping arm 110. The support arm 120 is rotatably connected to the connecting section 112.
Referring to fig. 5 and 6 together, in one embodiment, each support section 111 includes a curved section 1112 and an extension section 1114 connected to the curved section 1112. Wherein an end of bending section 1112 remote from extension section 1114 is bent in a first direction such that the end of bending section 1112 remote from extension section 1114 and extension section 1114 are not in the same plane. And, as the end of bending section 1112 remote from extension section 1114 is bent in a first direction, connecting section 112 of first clamping arm 110 is away from the longitudinal central axis I-I of the tissue closure device.
As shown in fig. 6, in a natural state, the bending section 1112 is bent in a first direction, and the bending of the bending section 1112 makes an end of the bending section 1112 away from the extension section 1114 and the extension section 1114 not be in the same plane, so that the free ends of the two first clamping arms 110 are away from the longitudinal central axis I-I, i.e. the two connecting sections 112 of the two first clamping arms 110 are away from each other away from the longitudinal central axis I-I, so that the first clamping arms 110 are easy to open. The first direction, for example as shown in fig. 6, may be a bending away from the connecting section 112 of the other first clamping arm 110, and the end of the bending section 1112 away from the extension section 1114 is not in the same plane as the extension section 1114.
In one embodiment, extension segment 1114 is straight rod shaped and the location where extension segment 1114 connects to curved segment 1112 is in the same plane as extension segment 1114.
Referring to FIG. 7, in one embodiment, the extension segment 1114 includes a curved rod 1114A and a straight rod 1114B coupled to the curved rod 1114A, with the end of the curved rod 1114A distal from the straight rod 11114B being coupled to the curved segment 1112. Referring to fig. 6 and 8 together, in one embodiment, in a natural state (also referred to as a clamped state), the bending rod 1114A is bent in a second direction, so that a connection portion between the bending rod 1114A and the bending section 1112 of one first clamping arm 110 and a connection portion (a circle portion indicated by VI in the figure) between the bending rod 1114A and the bending section 1112 of the other first clamping arm 110 are relatively reliably abutted together to form an abutting portion. At the abutting position, the first clamping arms 110 have elasticity, so that the two first clamping arms 110 provide opposite abutting force to each other, and the two first clamping arms 110 are relatively reliably abutted together, which is beneficial to improving the reliability of clamping, so as to avoid falling off the tissue closing device 1 due to the systolic and diastolic movements of the heart. The second direction, for example, as shown in fig. 7, may be a direction outside the wire loop, i.e., the center of the curved rod 1114A itself is located inside the wire loop.
In an embodiment, the connection portion between the bending rod 1114A and the bending section 1112 of each first clamping arm 110 is in a straight rod shape, so that the areas of the portions of the two first clamping arms 110 that abut each other are larger and more reliably abut.
Referring to fig. 9, in one embodiment, the angle α of the bending bar 1114A is 5 ° to 15 °, so that the connection portions of the extension sections 1114 and the bending sections 1112 of the two first clamping arms 110 can reliably abut together. The angle α is an angle formed by intersecting the tangent line a and the tangent line B of the curved bar 1114A, and the intersection point is a. Tangent line a intersects the junction of curved rod 1114A and straight rod 1114B, and tangent line B intersects the junction of curved rod 1114A and curved segment 1112.
Referring to FIG. 10, in one embodiment, the angle β of the bending section 1112 is 10-60 to facilitate opening the first clamping arm 110, and the portion of the bending section 1112 that connects to the bending bar 1114A (i.e., the portion of the bending section 1112 that is coplanar with the bending bar 1114A) is made long enough to maintain the clamping action when the length of the bending section 1112 is constant. The angle β is an angle between an extension line C of a connection portion between the bending rod 1114A and the bending section 1112 and a tangent line D of the bending section 1112, and the tangent line D intersects with the extension line C at an intersection point b of the extension line C and the bending section 1112. The intersection point b is the tangent point of the tangent line D.
In one embodiment, the material of the supporting arm 120 is a resilient metal, for example, a nickel-titanium alloy is used to form the elastic sheet, and one end of the elastic sheet is bent and shaped to form the connecting portion 122.
In one embodiment, referring to fig. 11, the support 121 includes a curved section 123 and a straight section 124. One end of the curved section 123 is fixedly connected to the straight section 124, and the other end is rotatably connected to the first clamping arm 110. In one embodiment, the connecting portion 122 is connected to an end of the curved section 123 remote from the straight section 124, and the curved section 123 is rotatably connected to the first clamping arm 110 through the connecting portion 122. In another embodiment, as shown in fig. 12, one end of the connecting portion 1122 is connected to an end of the straight portion 124 away from the curved portion 123, and the straight portion 124 is rotatably connected to the first clamping arm 110 through the connecting portion 122.
Referring to fig. 13, in one embodiment, the length of the straight segment 124 is L1, the arc length of the curved segment 123 is L2 (not shown), and L2/l1=1/5 to 1/3. The lengths of the extension section 124 and the bending section 123 are set in such a way that, on the one hand, the length of the bending section 123 is prevented from being too large, so as to ensure that sufficient spreading force is transmitted to the first clamping arm 110, i.e. that the supporting arm 120 can provide a certain spreading force, so that the first clamping arm 110 can be spread in the opening process; on the other hand, the length of the curved section 123 is prevented from being too small, so that the curved section 123 can be further deformed (further curved) during opening to alleviate the problem of excessive stress. The intersection point c is the tangent point of the tangent line F.
With continued reference to fig. 13, in an embodiment, the angle γ of the bending section 123 ranges from 10 ° to 45 °, and in this angle range, the support arm 120 is guaranteed to transmit the spreading force to the first clamping arm 110 under a certain force, and the bending section 123 can deform to a certain extent to alleviate the problem of overstress. The angle γ refers to the angle between the extension line E of the straight section 124 and the tangent line F of the curved section 123, and the tangent line F intersects with the extension line E at the intersection point c of the extension line E and the curved section 123.
When the length of the support body 121 is determined, the greater the angle γ of the curved section 123, the smaller the capturing length of the support body 121, the more difficult it is to capture the tissue. When the angle γ of the curved section 123 is too small, it is difficult to easily open the first clamping arm 110 for action. Therefore, in an embodiment, the length of the straight section 124 is L1, the arc length of the curved section 123 is L2, l2/l1=1/5-1/3, and the angle γ of the curved section 123 is in the range of 10 ° to 45 °, so that the first clamping arm 110 is easier to open and capture tissue, and the operation is convenient, so that the operation is performed smoothly, and the operation time is reduced.
In an embodiment, the supporting body 121 may be a unitary structure made of a metal wire or sheet, and has a corresponding curved shape after being heat-set to form the curved section 123 and the extended section 124.
Returning to fig. 11, in one embodiment, the tissue closure device 1 further comprises a first anchor 130 and a second anchor 140. The first fixing base 130 and the second fixing base 140 are opposite in the axial direction, and are coaxially and alternately arranged.
One end of the first clamping arm 110, which is far away from the supporting arm 120, is fixedly connected with the first fixing base 130. The manner of fixing may be as known to those skilled in the art, including but not limited to welding, gluing, mortise pressing, wire stitching, etc. Specifically, the first clamping arm 110 is connected to the first fixing base 130 through the support section 111. One end of the straight rod 1114B of the support section 111, which is far away from the bending rod 1114A, is fixedly connected with the first fixing base 130, as shown in fig. 7. Referring to fig. 11 again, an end of the support arm 120 away from the first clamping arm 110 is rotatably connected to the second fixing base 140. The supporting body 121 is connected with the second fixing base 140 through a rotating shaft, a pin, a movable hinge or the like. For example, the supporting body 121 is rotatably connected to the second fixing base 140 through a rotating shaft 150.
In an embodiment, as shown in fig. 11, an end of the straight section 124 of the supporting body 121 away from the curved section 123 is rotatably connected to the second fixing base 140.
In an embodiment, as shown in fig. 12, an end of the curved section 123 of the supporting body 121 away from the section of the straight section 124 is rotatably connected to the second fixing base 140.
In an embodiment, through holes are formed in the middle portions of the first fixing base 130 and the second fixing base 140.
Referring back to fig. 2, in an embodiment, the second clamping portion 20 includes a second clamping arm 210, one end of the second clamping arm 210 is connected to the second fixing base 140, and the other end is a free end. When the first clamping arm 110 and the support arm 120 are in the closed position, the free end of the second clamping arm 210 is adjacent to the support arm 120, thereby clamping tissue between the second clamping arm 210 and the support arm 120.
In another embodiment, one end of the second clamping arm 210 is not connected to the second fixing base 140, but is connected to an end of the supporting arm 120 away from the first clamping arm 110.
The second clamping arm 210 is made of an elastic material such that the second clamping arm 210 has elasticity. The tissue is located between the resilient first clamping arm 110 and the resilient second clamping arm 210 and is resiliently compressed such that the clamping performance of the tissue closure device 1 is relatively stable. In one embodiment, the material of the second clamping arm 210 is nitinol.
In one embodiment, the second clamping portion 20 further includes an anchor 220. The anchor 220 is disposed on a surface of the second clamping arm 210 facing the support arm 120 and extends toward the support arm 120. The anchor 220 serves to capture tissue (e.g., leaflets) on the one hand, and on the other hand, when the tissue is captured, the anchor 220 pierces the tissue, and the first clamping arm 110, the second clamping arm 210, and the anchor 220 cooperate together to securely clamp the tissue.
The anchor 220 may be one or more. When the anchor 220 is plural, the plural anchors 220 are disposed on the second clamping arm 210 at intervals.
The number of the first clamping parts 10 and the second clamping parts 20 is two, the longitudinal central axis (coinciding with the longitudinal central axis I-I) of the first fixing seat 130 is taken as a symmetrical center, and the two first clamping parts 10 are symmetrically arranged at two sides of the first fixing seat 130. Specifically, the two first clamping arms 110 are symmetrically disposed at two sides of the first fixing base 130, the two supporting arms 120 are symmetrically disposed at two sides of the second fixing base 140, and one end of each supporting arm 120 is rotatably connected to the first clamping arm 110, and the other end is rotatably connected to the second fixing base 140. The two second clamping arms 210 are symmetrically disposed on two sides of the second fixing base 140 with the longitudinal central axis (coinciding with the longitudinal central axis I-I) of the second fixing base 140 as a symmetry center.
With continued reference to fig. 2, the tissue closure device 1 further includes a spacer 160. One end of the spacer 160 is connected to the second fixing base 140, and the other end extends axially in a direction away from the second fixing base 140 and the first fixing base 130.
The spacer 160 is a cage-like structure made of an elastic material, such as an elastic wire or an elastic polymer wire. In one embodiment, the spacer 160 is a cage-like structure woven from nickel titanium wire. In another embodiment, the spacer 160 is made of an elastic sponge or elastic silicone. In one embodiment, the spacer 160 is a balloon structure made of a polymeric material.
The spacer 160 can seal and fill the gap between two tissues, further improving the sealing performance. In addition, since the spacer 160 is made of elastic material, the spacer 160 has certain flexibility and deformability, and after the clamping, the spacer 160 can play a role in buffering, so that two tissues (such as two valve leaflets) to be clamped cannot be hard pulled together, and the clamping stress can be relieved.
The shape of the spacer 160 is not limited as long as it can perform the sealing and cushioning functions. In one embodiment, the spacer 160 is cylindrical. In another embodiment, the spacer 160 is a structure with axially opposite ends small and a middle large.
In one embodiment, the shape of the spacer 160 matches the shape of the first clamping arm 110 such that in the clamped state, the outer surface of the spacer 160 completely fills the wire loops of the first clamping arm 110, thereby improving the sealing effect.
In one embodiment, a film (not shown) is disposed on the spacer 160, and the film is wrapped on the surface of the spacer 160 to further improve the sealing effect.
The conveyor is used to convey the tissue closure device 1 to a target location and to release and cause the tissue closure device 1 to clamp the target tissue.
Referring to fig. 14 and 15 together, the conveyor includes a handle (not shown), a delivery sheath 310, and a lever 320. A handle is connected to the proximal end of the delivery sheath 310, the handle being provided with controls for operating the tissue closure device 1. The radially compressed tissue closure device 1 is received in the delivery sheath 310 and reaches the target site with the delivery sheath 310. The operation rod 320 is accommodated in the delivery sheath 310, and a proximal end of the operation rod 320 is connected to the control member, and a distal end thereof passes through the spacer 160 and the second fixing base 140 and extends to the first fixing base 130. The distal end of the operation lever 320 is detachably connected to the first fixing base 130. The detachable connection manner includes, but is not limited to, a threaded connection, for example, the through hole of the first fixing base 130 is a threaded hole, and the outer wall of the distal end of the operating rod 320 is provided with external threads to achieve the detachable connection.
The conveyor further includes a connector that is removably coupled to the distal end of the spacer 160. The connection member may be any structure that can be detachably connected to the spacer 160 as will be appreciated by those skilled in the art. For example, in one embodiment, the connector is a sleeve with an internal thread at the distal end that is received in the delivery sheath 310, and the spacer 160 is provided with a thread formation that is compatible with the sleeve to provide a removable connection.
As shown in fig. 16, the delivery device further comprises a control wire 330, wherein the control wire 330 is threaded through the delivery sheath 310, and the proximal end of the control wire 330 is connected to a control member, and the distal end of the control wire 330 is detachably connected to the second clamping arm 210. Control wire 330 controls the movement of second clamping arm 210 to capture the target tissue.
In one embodiment, in order to facilitate the operation rod 320 to pass through the second fixing base 140 and the first fixing base 130 in sequence via the spacer 160, a guide tube 170 having an inner cavity is provided inside the spacer 160, as shown in fig. 14. The guide tube 170 extends axially from the distal end to the proximal end of the spacer 160. The operation rod 320 passes through the inner cavity of the guide tube 170, passes through the second fixing base 140, and extends to the first fixing base 130.
Meanwhile, the guide tube 170 is provided, so that the spacer 160 can be supported to maintain structural stability of the spacer 160.
The delivery, release and closing procedure of the tissue closing device 1 is described taking the tissue to be closed as mitral valve leaflet. In one embodiment, AS shown in fig. 15, the distal end of delivery sheath 310 reaches left atrium LA by delivery sheath 310 traversing the femoral vein, inferior vena cava, to right atrium RA, and then penetrating septum AS. By manipulating the distal end of the delivery sheath 310 to reside in the centered position over the mitral valve MV, the tissue closure device 1 is then pushed out of the delivery sheath 310 by manipulating controls on the handle, as shown in FIG. 16. Further, referring to fig. 17, the tissue closing device 1 is pushed to the mitral valve MV position and the position is adjusted (if necessary) such that the first clamping arm 110 of the tissue closing device 1 is located at the side of the mitral valve leaflet close to the left ventricle LV. By operating the controls on the handle, the lever 320 is moved axially, causing the first clamping arm 110 to assume an open state to capture the leaflets. Next, the angle of the second nip 20 is controlled by the control wire 330 to capture the leaflet. When the second clamping portion 20 captures the leaflet, the lever 320 is moved axially to bring the support arm 120 and the second clamping portion 20 closer to each other and clamp the leaflet against the spacer 160. The two second clamping portions 20 and the two support arms 120 cooperate such that the anterior and posterior leaflet of the mitral valve MV are clamped, as shown in fig. 18, thereby achieving a reduction in the opening area of the mitral valve MV. After the clamping is completed, the control wire 330 is withdrawn, the connection between the operation rod 320 and the first fixing base 130 is released, the connection between the connecting piece and the spacer 160 is released, and the conveyor is withdrawn, so that the operation is completed.
During the opening of the first clamping arm 110, when the support arm 120 is of conventional construction, the force of the support arm 120 is analyzed as follows:
As shown in fig. 19a, the first clamping arm 110 is opened by sliding the operating lever 320 and the guide tube 170 relative to each other. T is the force exerted by the guide tube 170 on the shaft 150, and T generates two components: a component T1 parallel to the support arm 120 and a component T2 perpendicular to the support arm 120. T1 is transmitted along the support arm 120 to a position where the support arm 120 is rotatably coupled to the first clamping arm 110 to drive the first clamping arm 110 open. Assuming that there is no loss in force transfer within the support arm 120, t1=f. Where F is split into two components, a component F1 perpendicular to the first clamping arm 110 and a component F2 parallel to the direction of the first clamping arm 110, at the point where the support arm 120 is rotatably connected to the first clamping arm 110. Where f1=f×sin θ, t1=t×cos θ, where θ is the angle between the support arm 120 and the first clamping arm 110. From this, t=t1/Cos θ=f/Cos θ= (F1/Sin θ)/Cos θ=f1/(Sin θ×cos θ) =2×f1/Sin 2θ can be converted.
As can be seen from the above equation, as the angle θ increases, the force required to be applied to the guide tube 170 becomes smaller. As shown in fig. 19b, θ is 20 °. As shown in fig. 19c, θ is 40 °. As in fig. 19d, θ is 65 °. From fig. 19b to 19d, the force required to be applied to the guide tube 170 becomes smaller and smaller. And angle theta is minimal when the first clamping arm 110 and the support arm 120 are in the closed position. In the case of a certain distraction force F1, the force that needs to be exerted on the lever 320 is at its maximum. In the closed position, the angle θ is 1-10 °. When θ=10°, the force f1=10n of the support arm 120 is expanded, t1=58n is calculated, and the guide tube 170 needs to bear the force of the support arm 120 on both sides, so the force actually required on the guide tube 170 is 2×t1=108n. It can be seen that the guide tube 170 and the operating lever 320 are subjected to a very large force during the opening of the first clamping arm 110. Thus, the first clamping arm 110 needs to be opened under a large force, which on the one hand requires a great force operation by the doctor, which increases the risk of the operation; on the other hand, the risk of failure of the respective force-receiving members of the tissue closure device 1 is also increased.
The support body 121 of the tissue closure device 1 comprises a curved section 123 and a straight section 124. That is, in a natural state (a closed state in which the first clamping arm 110 and the support arm 120 are in a closed position), one end of the support arm 120 is curved. Whether the bending section 123 is rotatably connected with the first clamping arm 110 or the bending section 123 is connected with the second fixing base 140, the bending section 123 is provided, so that when the supporting arm 120 is used for stretching the first clamping arm 110, the component force of the supporting arm 120 which is decomposed to be vertical to the direction of the first clamping arm 110 is increased, and the force applied to the operating rod 320 and the guide tube 170 is reduced, thereby achieving the purpose of saving labor, being convenient to operate and easy to control, and improving the safety of operation.
In one embodiment, the degree of bending of the curved section 123 increases as the first clamping arm 110 and the support arm 120 move from the closed position to the open position. That is, the bending section 123 can guide the supporting arm 120 to deform towards the bending direction when the stress exceeds a limit, so as to play a role of buffering. When the support arm 120 is deformed to some extent, the first clamping arm 110 is more easily opened.
During implantation, the first clamping arm 110 and the support arm 120 of the tissue closure device 1 change from the closed position to the open position, and after tissue is captured, the first clamping arm 110 and the support arm 120 change from the open position to the closed position, thereby bringing the first clamping arm 110 and the second clamping portion 20 closer together such that tissue is clamped between the first clamping arm 110 and the second clamping portion 20. Since the support arm 120 of the tissue closure device 1 comprises the curved section 123 and the straight section 124, the component force applied by the support arm 120 to the opening direction of the first clamping arm 110 is increased during the opening process, so that the opening of the first clamping arm 110 is easier, thereby improving the safety of the handling system.
Further, due to the special structural design of the first clamping arms 110, the free ends of the two first clamping arms 110 are far away from the longitudinal central axis I-I, so that the first clamping arms 110 can be opened more easily, the supporting arms 120 can be used for supporting the first clamping arms 110 with smaller force, and the connecting sections 112 of the first clamping arms 110 can be moved in the direction far away from the longitudinal central axis I-I, so that the first clamping arms 110 can be opened.
Also, since the end of the curved section 1112 of the first clamping arm 110 near the extension section 1114 is in the same plane as the extension section 1114, the two first clamping arms 110 of the two second clamping sections 10 can reliably clamp the spacer 160 in the closed position to avoid falling off and maintain sealing performance.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.