Patent Description:
A light emitting diode (LED) display screen includes a box assembly and a display screen mounted on the box assembly. The box assembly is assembled from a plurality of boxes. During field mounting, assembled boxes are deformed obviously, and there is a gap between two adjacent boxes, so display quality of the LED display screen is seriously affected. There is provided a tensioning mechanism in the related technology, by which the two adjacent boxes can be tensioned close to reduce the gap.

The tensioning mechanism includes a connection column connected withwith a box and a tensioning seat connected with another box. The connection column passes through the tensioning seat and is in threaded cooperation with a tensioning nut. The connecting column is sleeved with a spring. The spring is located between the tensioning seat and the tensioning nut. The tensioning nut is provided with a plurality of operation holes. An operation rod, an external tool, passes through an operation hole to screw the tensioning nut so as to apply a force to the spring, so that the tensioning nut is pressed on the connection column, and further the two adjacent boxes are tensioned close.

But the external tool is required for tensioning the two adjacent boxes close, resulting in a complex tensioning process. In addition, usage of the external tool leads to high cost of the LED display screen.

Examples of a bolt-type connecting device according to the prior art are known from <CIT>. And Examples of a connecting device for an LED display module according to the prior art are known from <CIT>.

A main objective of the present invention is to provide a tensioning mechanism of a box and a light emitting diode (LED) box assembly with the tensioning mechanism of the box, so as to solve the problem that in the related technology, an external tool is required for tensioning two adjacent boxes close, resulting in a complex tensioning process.

To achieve the objective, an aspect of the present invention provides a tensioning mechanism of a box. The tensioning mechanism of a box includes a tensioning structure including a base and a tensioning rod, wherein the base is provided with a mounting portion, the tensioning rod includes a tensioning pin and an operating portion connected with the tensioning pin, and the tensioning pin is movably arranged in the mounting portion in a penetrating manner; and a connecting member provided with a cooperating hole, wherein the tensioning pin includes a flat shaft, the flat shaft is able to being inserted into or moved out of the cooperating hole, and under the condition that the flat shaft is inserted into the cooperating hole, the flat shaft has a vertical tensioning position and a transverse unlocking position.

In some embodiments, the mounting portion is a mounting groove, the tensioning structure further includes a limiting member, and the limiting member is connected with the base and located at an opening of the mounting groove.

In the invention, the tensioning pin further includes a cooperating section arranged between the flat shaft and the operating portion, the tensioning structure further includes a positioning structure arranged between the cooperating section and the base, and the positioning structure enables the flat shaft to be kept at an insertion position for inserting into the cooperating hole or a move-out position for moving out of the cooperating hole.

In the invention, the positioning structure includes a positioning member, a first positioning hole and a second positioning hole, the first positioning hole is located between the second positioning hole and the flat shaft, the cooperating section is provided with the first positioning hole and the second positioning hole, the base is provided with the positioning member, when the positioning member cooperates the first positioning hole, the flat shaft is kept at the insertion position, and when the positioning member cooperates the second positioning hole, the flat shaft is kept at the move-out position.

In some embodiments, the positioning structure further includes a limiting hole provided on the base, the positioning member includes an elastic member and a positioning ball which are mounted in the limiting hole, the elastic member applies an elastic force to the positioning ball, a diameter of the first positioning hole and a diameter of the second positioning hole are both smaller than that of the positioning ball, and when the tensioning pin moves, a part of the positioning ball has a positioning position located in the first positioning hole or the second positioning hole and an avoiding position for avoiding the flat shaft.

In some embodiments, the base includes a base body as well as a first avoiding notch and a second avoiding notch which are arranged on the base body in a spaced manner, the first avoiding notch is located between the second avoiding notch and the flat shaft, the mounting portion is arranged on the base body, the first avoiding notch and the second avoiding notch are both located at one side of the mounting portion, when a part of the operating portion is located in the first avoiding notch, the flat shaft is located at the insertion position, and when a part of the operating portion is located in the second avoiding notch, the flat shaft is located at the move-out position.

In some embodiments, the tensioning rod is arranged in a bent manner so as to form the tensioning pin and the operating portion; and the limiting member includes a limiting piece.

In some embodiments, the connecting member includes a columnar section and a threaded section connected with the columnar section, a diameter of the columnar section is larger than that of the threaded section, the cooperating hole is provided on the columnar section, the columnar section is provided with a rotation stopping face, and a diameter of the flat shaft is smaller than that of the cooperating hole.

Another aspect of the present invention provides a LED box assembly, which includes a plurality of boxes and the above-mentioned tensioning mechanism of the box.

In some embodiments, the plurality of boxes cooperate one another in a spliced manner, there are a plurality of tensioning mechanisms for boxes, in the two boxes connected one above the other, one of the boxes is a first box and the other is a second box, and each of the first box and the second box includes a first side, a second side, a third side and a fourth side which are sequentially connected with one another; and the third side of the first box is connected with the first side of the second box by one of the tensioning mechanisms for boxes, the tensioning structure is arranged at the third side of the first box, the connecting member is arranged on the first side of the second box in a penetrating manner, and the third side of the first box is provided with an avoiding hole for avoiding the connecting member on the second box.

According to the technical solution of the present invention, the tensioning mechanism of a box includes the tensioning structure and the connecting member. The tensioning structure includes the base and the tensioning rod. The base is provided with the mounting portion, and the tensioning rod includes the tensioning pin and the operating portion connected with the tensioning pin. In this way, the operating portion enables the mounting personnel to conveniently conduct operations on the tensioning rod. The tensioning pin is movably arranged in the mounting portion in a penetrating manner. The connecting member is provided with the cooperating hole. In the disclosure, the tensioning pin includes the flat shaft, and the flat shaft is capable of being inserted into or moved out of the cooperating hole. Under the condition that the flat shaft is inserted into the cooperating hole, the flat shaft has the vertical tensioning position and the transverse unlocking position. Under the condition that the flat shaft is inserted into the cooperating hole, the flat shaft is capable of applying a force to a hole wall of the cooperating hole when being at the vertical tensioning position, and the flat shaft is incapable of applying a force to the hole wall of the cooperating hole when being at the transverse unlocking position. When two adjacent boxes are tensioned close, the connecting member may be connected with one of the boxes, the tensioning structure is connected with the other box, the tensioning rod is moved, then the flat shaft is inserted into the cooperating hole, the flat shaft is switched from the transverse unlocking position to the vertical tensioning position, and in this case, the flat shaft applies a force to the hole wall of the cooperating hole, so as to tension the two adjacent boxes close. Thus, when the two adjacent boxes are tensioned close, the two adjacent boxes may be tensioned close without an external tool (operation rod), thus simplifying a tensioning process and further reducing a gap. Therefore, the technical solution of the disclosure effectively solves the problem that in the related technology, an external tool is required for tensioning two adjacent boxes close, resulting in a complex tensioning process.

The drawings of the description, which form a part of the disclosure, are used to provide further understanding of the present invention, and illustrative embodiments of the present invention and the description thereof are used to explain the present invention, which are not intended to unduly limit the present invention. In the drawings:.

The above drawings include the following reference numerals:
<NUM>: tensioning structure; <NUM>: base; <NUM>: mounting portion; <NUM>: limiting hole; <NUM>: base body; <NUM>: first avoiding notch; <NUM>: second avoiding notch; <NUM>: tensioning rod; <NUM>: tensioning pin; <NUM>: flat shaft; <NUM>: cooperating section; <NUM>: operating portion; <NUM>: limiting member; <NUM>: positioning structure; <NUM>: first positioning hole; <NUM>: positioning member; <NUM>: elastic member; <NUM>: positioning ball; <NUM>: second positioning hole; <NUM>: connecting member; <NUM>: cooperating hole; <NUM>: columnar section; <NUM>: rotation stopping face; <NUM>: threaded section; <NUM>: box; <NUM>: first side; <NUM>: avoiding hole; <NUM>: second side; <NUM>: third side; and <NUM>: fourth side.

The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are merely a part rather than all of the embodiments of the present invention.

As shown in <FIG> and <FIG>, a tensioning mechanism of a box of the embodiment includes a tensioning structure <NUM> and a connecting member <NUM>. The tensioning structure <NUM> includes a base <NUM> and a tensioning rod <NUM>. The base <NUM> is provided with a mounting portion <NUM>, and the tensioning rod <NUM> includes a tensioning pin <NUM> and an operating portion <NUM> connected with the tensioning pin <NUM>. The tensioning pin <NUM> is movably arranged in the mounting portion <NUM> in a penetrating manner. The connecting member <NUM> is provided with a cooperating hole <NUM>. In the embodiment, the tensioning pin <NUM> includes a flat shaft <NUM>, and the flat shaft <NUM> is capable of being inserted into or moved out of the cooperating hole <NUM>. Under the condition that the flat shaft <NUM> is inserted into the cooperating hole <NUM>, the flat shaft <NUM> has a vertical tensioning position and a transverse unlocking position.

According to the technical solution of the embodiment, the tensioning rod <NUM> includes the tensioning pin <NUM> and the operating portion <NUM> connected with the tensioning pin <NUM>. In this way, the operating portion <NUM> enables the mounting personnel to conveniently conduct operations on the tensioning rod <NUM>. In the embodiment, the tensioning pin <NUM> includes the flat shaft <NUM>, and the flat shaft <NUM> is capable of being inserted into or moved out of the cooperating hole <NUM>. Under the condition that the flat shaft <NUM> is inserted into the cooperating hole <NUM>, the flat shaft <NUM> has the vertical tensioning position and the transverse unlocking position. Under the condition that the flat shaft <NUM> is inserted into the cooperating hole <NUM>, the flat shaft <NUM> is capable of applying a force upwardly to a hole wall of the cooperating hole <NUM> when the flat shaft <NUM> is at the vertical tensioning position, and the flat shaft <NUM> is incapable of applying a force to the hole wall of the cooperating hole <NUM> when the flat shaft <NUM> is at the transverse unlocking position. When two adjacent boxes are tensioned close, the connecting member <NUM> may be connected with one of the boxes, the tensioning structure <NUM> is connected with the other box, the tensioning rod <NUM> is moved, then the flat shaft <NUM> is inserted into the cooperating hole <NUM>, at this time, the flat shaft <NUM> is at the transverse unlocking position, then the flat shaft <NUM> is switched from the transverse unlocking position to the vertical tensioning position, and in this case, the flat shaft <NUM> applies a force upwardly to the hole wall of the cooperating hole <NUM>, so as to tension the two adjacent boxes close. Thus, when the two adjacent boxes are tensioned close, the two adjacent boxes may be tensioned close without an external tool (operation rod), thus simplifying a tensioning process and then reducing a gap. Therefore, the technical solution of the embodiment effectively solves the problem that in the related technology, an external tool is required for tensioning two adjacent boxes close, resulting in a complex tensioning process.

It should be noted that the flat shaft <NUM> of the embodiment has a long axis A1 and a short axis A2, the vertical tensioning position means that the long axis A1 of the flat shaft <NUM> is vertical, and the transverse unlocking position means that the short axis A2 of the flat shaft <NUM> is vertical. The flat shaft <NUM> switches between the transverse unlocking position and the vertical tensioning position by rotation.

As shown in <FIG>, to facilitate machining and shaping, the mounting portion <NUM> is a mounting groove. The tensioning structure <NUM> further includes a limiting member <NUM>, and the limiting member <NUM> is connected with the base <NUM> and located at an opening of the mounting groove. The limiting member <NUM> is capable of limiting the tensioning rod <NUM> on the mounting groove, so as to prevent the tensioning pin <NUM> from being separated from the mounting groove during movement in the mounting groove.

As shown in <FIG>, the tensioning pin <NUM> further includes a cooperating section <NUM> arranged between the flat shaft <NUM> and the operating portion <NUM>. The flat shaft <NUM> and the operating portion <NUM> are connected with two ends of the cooperating section <NUM> respectively. To enable the flat shaft <NUM> to be stably kept to be inserted into the cooperating hole <NUM> or moved out of the cooperating hole <NUM>, the tensioning structure <NUM> further includes a positioning structure <NUM> arranged between the cooperating section <NUM> and the base <NUM>. The positioning structure <NUM> enables the flat shaft <NUM> to be kept at an insertion position for insertion into the cooperating hole <NUM> or a move-out position for movement out of the cooperating hole <NUM>.

As shown in <FIG>, the positioning structure <NUM> includes a positioning member <NUM>, a first positioning hole <NUM> and a second positioning hole <NUM>. The first positioning hole <NUM> is located between the second positioning hole <NUM> and the flat shaft <NUM>, and the cooperating section <NUM> is provided with the first positioning hole <NUM> and the second positioning hole <NUM>. The base <NUM> is provided with the positioning member <NUM>. When the positioning member <NUM> matches the first positioning hole <NUM>, the flat shaft <NUM> is kept at the insertion position, and when the positioning member <NUM> matches the second positioning hole <NUM>, the flat shaft <NUM> is kept at the move-out position. In this way, when the positioning member <NUM> matches the first positioning hole <NUM>, the flat shaft <NUM> is capable of being stably kept at the insertion position, and when the positioning member <NUM> matches the second positioning hole <NUM>, the flat shaft <NUM> is capable of being stably kept at the move-out position. The positioning member <NUM> matches the first positioning hole <NUM> and the second positioning hole <NUM>, so that the positioning structure <NUM> has a simple structure and is economical.

As shown in <FIG>, the positioning structure <NUM> further includes a limiting hole <NUM> provided on the base <NUM>. The positioning member <NUM> includes an elastic member <NUM> and a positioning ball <NUM> which are mounted in the limiting hole <NUM>. The elastic member <NUM> applies an elastic force to the positioning ball <NUM>. In this way, the limiting hole <NUM> prevents the elastic member <NUM> and the positioning ball <NUM> from being separated from the limiting hole <NUM>, specifically, an opening of the limiting hole <NUM> is provided with an arc-shaped concave cavity, the arc-shaped concave cavity is stuck at a position over a radius of the positioning ball <NUM>, thus effectively preventing the positioning ball <NUM> from being separated from the limiting hole <NUM> under the action of the elastic force, and the positioning ball <NUM> and a hole wall of the limiting hole <NUM> are capable of limiting two ends of the elastic member <NUM>, so as to make the elastic member <NUM> stressed all the time. A diameter of the first positioning hole <NUM> and a diameter of the second positioning hole <NUM> are both smaller than that of the positioning ball <NUM>. When the tensioning pin <NUM> moves, a part of the positioning ball <NUM> has a positioning position located in the first positioning hole <NUM> or the second positioning hole <NUM> and an avoiding position for avoiding the flat shaft <NUM>. Specifically, when the positioning member <NUM> matches the first positioning hole <NUM>, a part of the positioning ball <NUM> is located in the first positioning hole <NUM>, thus limiting the cooperating section <NUM> vertically and horizontally. The limiting member <NUM> and a part of the positioning ball <NUM> work together to limit the cooperating section <NUM> between the positioning ball <NUM> and the limiting member <NUM>, thus preventing the cooperating section <NUM> from moving in the mounting groove. When the positioning member <NUM> matches the second positioning hole <NUM>, a part of the positioning ball <NUM> is located in the second positioning hole <NUM>, thus limiting the cooperating section <NUM> vertically and horizontally. The limiting member <NUM> and part of the positioning ball <NUM> may work together to limit the cooperating section <NUM> between the positioning ball <NUM> and the limiting member <NUM>, thus preventing the cooperating section <NUM> from moving in the mounting groove.

As shown in <FIG>, the base <NUM> includes a base body <NUM> as well as a first avoiding notch <NUM> and a second avoiding notch <NUM> which are arranged on the base body <NUM> in a spaced manner. The first avoiding notch <NUM> is located between the second avoiding notch <NUM> and the flat shaft <NUM>, and the mounting portion <NUM> is arranged on the base body <NUM>. The first avoiding notch <NUM> and the second avoiding notch <NUM> are both located at one side of the mounting portion <NUM>. When a part of the operating portion <NUM> is located in the first avoiding notch <NUM>, the flat shaft <NUM> is located at the insertion position, and when a part of the operating portion <NUM> is located in the second avoiding notch <NUM>, the flat shaft <NUM> is located at the move-out position. In this way, both the first avoiding notch <NUM> and the second avoiding notch <NUM> are capable of avoiding the operating portion <NUM>, so as to prevent the operating portion <NUM> from interfering with one side of the mounting portion <NUM>, so that the operating portion <NUM> is capable of standing on the base body <NUM>, an internal space of a box may be saved, and a structure in the box (such as a signal line or power line or control board) is more compact. The flat shaft <NUM> switches between the insertion position and the move-out position by movement.

As shown in <FIG>, to optimize a structural layout and facilitate production, manufacturing and mounting, the tensioning rod <NUM> is arranged in a bent manner so as to form the tensioning pin <NUM> and the operating portion <NUM>. In this way, the tensioning pin <NUM> is rotated by the operating portion <NUM> in a time-saving and labor-saving manner.

As shown in <FIG>, the limiting member <NUM> includes a limiting piece. The limiting piece has a simple structure and facilitates machining and shaping. Specifically, a side, facing the cooperating section <NUM>, of the limiting piece is provided with an arc-shaped groove, the arc-shaped groove matches the cooperating section <NUM> in shape, under the condition that the limiting member <NUM> and a part of the positioning ball <NUM> work together, the limiting member <NUM> is capable of being fitted to an outer side of the cooperating section <NUM>, resulting in a large contact area between the limiting member and the cooperating section and a better limiting effect.

As shown in <FIG>, <FIG>, <FIG> and <FIG>, the connecting member <NUM> includes a columnar section <NUM> and a threaded section <NUM> connected with the columnar section <NUM>. A diameter of the columnar section <NUM> is larger than that of the threaded section <NUM>, so that a stepped face is formed between the columnar section <NUM> and the threaded section <NUM>, the stepped face is capable of being locked on a side face of a box, and the threaded section <NUM> is conveniently connected with a box. To connect the threaded section <NUM> to a box more reliably, the connecting member <NUM> further includes a nut matching the threaded section <NUM>, so that the nut and the columnar section <NUM> are arranged on a partial structure of a box in a clamped manner. The cooperating hole <NUM> is provided on the columnar section <NUM>. In the process of screwing the nut on the threaded section <NUM>, to prevent the columnar section <NUM> from rotating relative to a box, the columnar section <NUM> is provided with a rotation stopping face <NUM>. A torque may be further shortened when the tensioning rod is rotated, thus saving more labor during tensioning. The flat shaft <NUM> is inserted into or moved out of the cooperating hole <NUM> smoothly, and a maximum diameter of the flat shaft <NUM> is smaller than that of the cooperating hole <NUM>. When the flat shaft <NUM> is inserted into the cooperating hole <NUM> and the flat shaft <NUM> is at the transverse unlocking position, the short axis A2 of the flat shaft <NUM> is close to the top wall of the hole wall of the cooperating hole <NUM>. The distance between the short axis A2 and the top wall of the hole wall of the cooperating hole <NUM> is smaller than a half of the difference between a length of the long axis A1 and a length of the short axis A2. When the flat shaft <NUM> is switched from the transverse unlocking position to the vertical tensioning position, the long axis A1 of the flat shaft <NUM> applies a force upwardly to the top wall of the hole wall of the cooperating hole <NUM>.

The disclosure further provides a light emitting diode (LED) box assembly. As shown in <FIG>, the LED box assembly includes a plurality of boxes <NUM> and the above-mentioned tensioning mechanism of the box. The above-mentioned tensioning mechanism of the box may solve the problem that in the related technology, an external tool is required for tensioning two adjacent boxes close, resulting in a complex tensioning process, so the LED box assembly with the tensioning mechanism of the box may solve the same technical problem.

As shown in <FIG>, two boxes <NUM> match each other in a spliced manner, and there are four tensioning mechanisms for boxes. Each of a first box and a second box is provided with two tensioning mechanisms of boxes. In the two boxes <NUM> connected one above the other, one of the boxes <NUM> is the first box and the other is the second box, and each of the first box and the second box includes a first side <NUM>, a second side <NUM>, a third side <NUM> and a fourth side <NUM> which are sequentially connected with one another. The third side <NUM> of the first box is connected with the first side <NUM> of the second box by a tensioning mechanism of a box, the tensioning structure <NUM> is arranged at the third side <NUM> of the first box, the connecting member <NUM> is arranged on the first side <NUM> of the second box in a penetrating manner, and the third side <NUM> of the first box is provided with an avoiding hole <NUM> for avoiding the connecting member <NUM> on the second box. The avoiding hole <NUM> enables the third side <NUM> of the first box to avoid the connecting member <NUM> conveniently, so that the connecting member <NUM> is capable of penetrating the third side <NUM> of the first box. Specifically, after the first box and the second box are connected one above the other, the mounting personnel pulls the operating portion <NUM> outward and then pushes the operating portion rightward to enable the flat shaft <NUM> of the tensioning pin <NUM> to be completely inserted into the cooperating hole <NUM> of the columnar section <NUM>, and then the mounting personnel pulls the operating portion <NUM> upward into the first avoiding notch <NUM>. In this case, the flat shaft <NUM> rotates from the transverse unlocking position to the vertical tensioning position, and the tensioning mechanism of th box may draw the first box at an upper position and the second box at a lower position close. The number of boxes <NUM> matching one another in a spliced manner may be not limited to two, but also four, six or more. The number of tensioning mechanisms of boxes may not be limited to four, but can also be increased or decreased according to the number of boxes <NUM> matching one another in a spliced manner.

In the description of the present invention, it should be understood that orientations or positional relationships indicated by the terms "front, rear, upper, lower, left and right", "transverse, vertical, perpendicular, and horizontal", "top and bottom", etc. are based on the orientations or positional relationships shown in the accompanying drawings and are only for facilitating the description of the present invention and simplifying the description, and in the absence of a statement to the contrary, the orientations do not indicate or implies that a device or element referred to must have a particular orientation or be constructed and operated in a particular orientation, and therefore will not be interpreted as limiting the scope of protection of the present invention; and the words "inside and outside" refer to inside and outside relative to an outline of each component itself.

For ease of description, spatial relative terms such as "over", "above", "on an upper surface" and "on" may be used herein to describe spatial positional relations of one device or feature with other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the device described in the drawings. For example, if the device in the drawings is inverted, the device described as "above" or "over" other devices or structures would then be positioned "below" or "under" the other devices or structures. Thus the exemplary term "above" may include two orientations of "above" and "below. " The device may also be positioned (rotated <NUM> degrees or at other orientations) in other different ways and the spatial relative description used herein is interpreted accordingly.

In addition, it should be noted that words "first" and "second" are used to define parts only for convenience of distinguishing corresponding parts. Unless otherwise stated, the above words have no special meaning, so they cannot be understood as limiting the scope of protection of the present invention.

Claim 1:
A tensioning mechanism of a box, comprising:
a tensioning structure (<NUM>) comprising a base (<NUM>) and a tensioning rod (<NUM>), wherein the base (<NUM>) is provided with a mounting portion (<NUM>), the tensioning rod (<NUM>) comprises a tensioning pin (<NUM>) and an operating portion (<NUM>) connected with the tensioning pin (<NUM>), and the tensioning pin (<NUM>) is movably arranged penetrating through the mounting portion; and
a connecting member (<NUM>), wherein the connecting member (<NUM>) is provided with a cooperating hole (<NUM>),
wherein the tensioning pin (<NUM>) comprises a flat shaft (<NUM>), the flat shaft (<NUM>) is able to being inserted into or moved out of the cooperating hole (<NUM>), and under the condition that the flat shaft (<NUM>) is inserted into the cooperating hole (<NUM>), the flat shaft (<NUM>) has a vertical tensioning position and a transverse unlocking position;
characterized in that, the tensioning pin (<NUM>) further comprises a cooperating section (<NUM>) arranged between the flat shaft (<NUM>) and the operating portion (<NUM>), the tensioning structure (<NUM>) further comprises a positioning structure (<NUM>) arranged between the cooperating section (<NUM>) and the base (<NUM>), and the positioning structure (<NUM>) enables the flat shaft (<NUM>) to be kept at an insertion position for inserting into the cooperating hole (<NUM>) or a move-out position for moving out of the cooperating hole (<NUM>), the positioning structure (<NUM>) comprises a positioning member (<NUM>), a first positioning hole (<NUM>) and a second positioning hole (<NUM>), the first positioning hole (<NUM>) is located between the second positioning hole (<NUM>) and the flat shaft (<NUM>), the cooperating section (<NUM>) is provided with the first positioning hole (<NUM>) and the second positioning hole (<NUM>), the base (<NUM>) is provided with the positioning member (<NUM>), when the positioning member (<NUM>) cooperates the first positioning hole (<NUM>), the flat shaft (<NUM>) is kept at the insertion position, and when the positioning member (<NUM>) cooperates the second positioning hole (<NUM>), the flat shaft (<NUM>) is kept at the move-out position.