stepladder

Abstract

To provide a step ladder which can be easily changed from a standing state to a folded state because one can fold it with only one hand in a natural posture.SOLUTION: A step ladder 10 includes an opening stop mechanism 7 that restricts the relative displacement of a pair of ladder bodies 2, 2 in standing state as step ladder, the opening stop mechanism 7 includes an arm member 70 that connects a pair of step bars 4, 4 that face each other and are spaced apart from each other in the pair of ladder bodies 2, 2, the arm member 70 includes a pair of arm bodies 71, 72 whose base ends are rotatably supported by the pair of step bars 4, 4 and whose tip parts are rotatably connected to each other, and the opening stop mechanism 7 includes a lever part 76 and an engaging part 78 as a deformable operation part in which the arm member 70 can be deformed from an extended state to a bent state near at least one of the pair of step bars 4, 4.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a step ladder, and more particularly to a locking mechanism in a step ladder.

Background Art

[0002] Conventionally, a step ladder that can be put into a closed state by folding it by operating a locking mechanism provided between ladder bodies constituting the step ladder has been used (see, for example, Patent Document 1). In such a step ladder, by the user lifting the operation part in the locking mechanism between the ladder bodies, the pair of ladder bodies can be brought close to each other to put the step ladder into a closed state.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the step ladder described in Patent Document 1, the user can change the step ladder from an open state to a closed state by simply lifting the operation part with one hand. However, for example, when the vertical position of the operation part is also at a high position because the height dimension of the step ladder is large, the user has to operate the operation part in an unnatural posture, which may deteriorate the usability.

[0005] The present invention has been made in view of the above circumstances, and the problem to be solved by the present invention is to provide a step ladder that can be easily changed from an open state to a closed state.

Means for Solving the Problems

[0006] Hereinafter, means for solving the above problems will be described.

[0007] The stepladder according to the present invention comprises a pair of ladder bodies, each having two support columns, one or more rungs spanning between the two support columns, and a top plate connecting the upper ends of the two support columns, which are connected at their upper ends so as to be rotatable relative to each other, and which can be transformed between a closed state in which the pair of ladder bodies are close together and a stepladder state in which the pair of ladder bodies are spaced apart at a predetermined distance, and is equipped with an opening stopper mechanism that restricts the relative displacement of the pair of ladder bodies in the stepladder state, the opening stopper mechanism comprises an arm member that connects a pair of rungs that are facing each other and moving closer together and further apart, the arm member comprises a pair of arm bodies whose base ends are rotatably supported by a pair of rungs and whose tip ends are rotatably connected to each other, and the opening stopper mechanism is equipped with an operating part near at least one of the pair of rungs, which can transform the arm member from an extended state to a bent state.

[0008] Furthermore, in the stepladder according to the present invention, it is preferable that the operating part comprises a lever part that is rotatably supported on at least one of the pair of rungs, and an engaging part that is provided on the lever part and is capable of engaging with the arm member.

[0009] Furthermore, in the stepladder according to the present invention, it is preferable that the lever portion has a flat surface on its upper side, the pivot axis of the lever portion is provided on the step that supports the lever portion, and that when the lever portion is not operated, the upper surface of the step that supports the lever portion and the flat surface of the lever portion are arranged on the same plane.

[0010] Furthermore, in the stepladder according to the present invention, it is preferable that two sets of arm members are provided on a pair of rungs, and that the lever portion is positioned between the two sets of arm members.

[0011] Furthermore, in the stepladder according to the present invention, it is preferable that the lever portion has a contact portion that contacts the rung supporting the lever portion when the lever portion is not being operated.

[0012] Furthermore, in the stepladder according to the present invention, it is preferable that two sets of arm members are provided on a pair of rungs, and that the operating section is configured as a connecting member that connects the two sets of arm members.

[0013] Furthermore, in the stepladder according to the present invention, it is preferable that the connecting member connects the two sets of arm members on the tip side of the arm body rather than on the pivot axis at the base end of the arm body.

[0014] Furthermore, in the stepladder according to the present invention, a pivot point is provided for when the arm body rotates, and it is preferable that the connecting member connects the two sets of arm members at the base end side of the arm body, rather than at the pivot point.

[0015] Furthermore, in the stepladder according to the present invention, it is preferable that the connecting member is located below the upper surface of the step rail that is adjacent to the connecting member when the stepladder is in a standing position.

[0016] Furthermore, in the stepladder according to the present invention, it is preferable that the connecting member is positioned above the pivot axis at the base end of the two sets of arm bodies when the stepladder is in use. [Effects of the Invention]

[0017] The stepladder according to the present invention has the effect of allowing the closing operation to be performed with one hand in a natural posture, making it easy to switch from the stepladder state to the closed state. [Brief explanation of the drawing]

[0018] [Figure 1] A perspective view showing the stepladder in the stepladder position according to the first embodiment. [Figure 2] A perspective view showing the opening locking mechanism of a stepladder according to the first embodiment. [Figure 3] A side view showing the stepladder in the stepladder position according to the first embodiment. [Figure 4] A side view showing the stepladder in the closed position according to the first embodiment. [Figure 5]Side view showing the closed state of the step ladder according to the first embodiment. [Figure 6] Perspective view showing the locking mechanism of the step ladder according to the second embodiment. [Figure 7] Side view showing the standing state of the step ladder according to the second embodiment. [Figure 8] Side view showing the closing state of the step ladder according to the second embodiment. [Figure 9] Side view showing the closed state of the step ladder according to the second embodiment. [Figure 10] Perspective view showing the locking mechanism of the step ladder according to the third embodiment. [Figure 11] Side view showing the standing state of the step ladder according to the third embodiment. [Figure 12] Side view showing the closing state of the step ladder according to the third embodiment. [Figure 13] Side view showing the closed state of the step ladder according to the third embodiment. [[ID=:25]] [Figure 14] Perspective view showing the locking mechanism of the step ladder according to the fourth embodiment. [Figure 15] Perspective view showing the locking mechanism of the step ladder according to the fifth embodiment. [Figure 16] Perspective view showing the standing state of the step ladder according to the sixth embodiment. [Figure 17] Side view showing the standing state of the step ladder according to the sixth embodiment. [Figure 18] Side view showing the closed state of the step ladder according to the sixth embodiment. [[ID=:41]] [Figure 19] Perspective view showing the ladder state of the step ladder according to the sixth embodiment. [Figure 20] Side view showing the ladder state of the step ladder according to the sixth embodiment.

Modes for Carrying Out the Invention

[0019] [First Embodiment - Step Ladder 10] First, a stepladder 10 according to the first embodiment of the present invention will be described using Figures 1 to 5. In the stepladder according to each embodiment of this specification, the axis of rotation of the ladder body 2·2 in each figure (the direction in which the rungs 4 are installed) is defined as the left-right direction of the stepladder, and the direction perpendicular to the left-right direction in the horizontal direction (the opening and closing direction of the ladder body 2·2) is defined as the front-back direction of the stepladder. In this embodiment, the lower left side in Figure 1 is the left side of the stepladder 10, and the lower right side in Figure 1 is the front of the stepladder 10 (the same applies to other embodiments).

[0020] As shown in Figure 1, the stepladder 10 according to this embodiment comprises a pair of ladder bodies 2 and 2 having common configurations. The ladder bodies 2 and 2 are arranged so that their lower ends are spaced apart from each other in a roughly V-shape when viewed from the side, and their respective upper ends are rotatably connected by hinges 6 and 6.

[0021] As shown in Figure 1, the hinge 6 has a first hinge portion 6a and a second hinge portion 6b that are rotatably connected by a pivot support portion 6c. The first hinge portion 6a and the second hinge portion 6b are fixed to the upper ends of the support columns 3 and 3 that are on the same side in the left-right direction (facing each other and moving closer together and further apart). This allows the hinge 6 to connect the opposing support columns 3 and 3 in a relative rotatable manner. In other words, the ladder bodies 2 and 2 are made rotatable in the direction of moving closer together and further apart from each other (the front-to-back direction of the stepladder 10).

[0022] Each ladder body 2 is equipped with a pair of elongated support columns 3-3. The support columns 3-3 are arranged in a roughly V-shape when viewed from the front, such that the distance between them increases from the top to the bottom. The stepladder 10 according to this embodiment is equipped with four support columns 3. Each support column 3 is bent at two points along its longitudinal direction for purposes such as ensuring strength, so that the cross-sectional shape perpendicular to the longitudinal direction is roughly U-shaped. In addition, an end fitting 3a is fixed to the lower end of each support column 3.

[0023] In the ladder body 2, a pair of hollow cylindrical members, called rungs 4, 4, ... are stretched between the two support columns 3, 3 at predetermined intervals. The rungs 4 are formed by cutting a straight extruded product having a predetermined cross-sectional shape to a predetermined length. Each rung 4 is fixed to the support column 3 between opposing inner surfaces by rivets. In the stepladder 10 according to this embodiment, each support column 3, rung 4, and top plate 5 are made of light metal, specifically aluminum or an aluminum alloy. It is also possible to fix the rungs 4 to the support column 3 using other fastening components such as bolts and nuts.

[0024] Each ladder section 2 is provided with a hollow cylindrical top plate 5-5 at its upper end. The top plate 5 is formed by cutting a straight extruded product having a predetermined cross-sectional shape to a predetermined length. The top plate 5 is fixed by rivets between the opposing inner surfaces at the upper ends of the support columns 3-3. In other words, the top plate 5 is provided in each ladder section 2 to connect the upper ends of the two support columns 3-3. It is also possible to fix the top plate 5 to the support columns 3 using other fasteners such as bolts and nuts.

[0025] The stepladder 10 can take on two main forms, depending on the angle formed by the pair of ladder bodies 2 and 2 (more specifically, the angle formed in a side view by the support columns 3 and 3 that move closer together or further apart due to the relative rotation of the ladder bodies 2 and 2, the same applies hereafter).

[0026] The first configuration, as shown in Figures 1 and 3, involves supporting the stepladder 10 with four support columns 3 at an angle of approximately 30 degrees between the ladder sections 2 and 2 (hereinafter referred to as the "stepladder state"). In the stepladder state, the stepladder 10 is used in a self-supporting state on the ground or floor. The second configuration, as shown in Figure 5, involves bringing the angle between the ladder sections 2 and 2 close to approximately 0 degrees (hereinafter referred to as the "closed state"). The closed state of the stepladder 10 is mainly used when storing or transporting it.

[0027] The stepladder 10 is equipped with an opening stopper mechanism 7 that defines the angle between the ladder bodies 2 and 2 and restricts their relative displacement (rotation) when in the stepladder state. In this embodiment, the opening stopper mechanism 7 is equipped with two sets of arm members 70 and 70 that connect a pair of treads 4 and 4 (the uppermost treads 4 and 4) that face each other and are spaced apart on the ladder bodies 2 and 2.

[0028] In the stepladder 10 according to this embodiment, each arm member 70 comprises a pair of arm bodies: a first arm body 71 and a second arm body 72. The base end (rear end) of the first arm body 71 is rotatably supported on the rung 4 of the rear ladder body 2 via a first support member 73. The base end (front end) of the second arm body 72 is rotatably supported on the rung 4 of the front ladder body 2 via a second support member 74.

[0029] The tip (front end) of the first arm body 71 and the tip (rear end) of the second arm body 72 are rotatably connected to each other. The connection between the first arm body 71 and the second arm body 72 in the two sets of arm members 70, 70 is connected by a rotating shaft 75.

[0030] A restricting portion 71a is formed at the tip of the first arm body 71 to restrict the relative rotation between the first arm body 71 and the second arm body 72. When the stepladder 10 is in the stepladder state and the arm member 70 is extended, the second arm body 72 comes into contact with the restricting portion 71a, so that the arm member 70 does not bend in a direction that would cause the rotation axis 75 to be displaced downward.

[0031] As shown in Figure 1, when the stepladder 10 is in the stepladder position, the rungs 4, 4 are connected by two sets of extended arm members 70, 70, so the ladder bodies 2, 2 do not rotate relative to each other in a direction that brings them closer or further apart. Therefore, the angle between the ladder bodies 2, 2 remains at approximately 30 degrees, and the stepladder 10 maintains its stepladder position.

[0032] In the stepladder 10 according to this embodiment, as shown in Figures 2 to 5, the opening stopper mechanism 7 is provided with a lever portion 76 and an engaging portion 78 near each of the pair of rungs 4, 4 connected by the arm members 70, 70, as operating parts that can deform from an extended state to a bent state for the arm members 70, 70.

[0033] As shown in Figures 3 to 5, the lever portion 76 is rotatably supported on the step 4 via a support portion 77 fixed along the step 4. A groove 77a is formed in the longitudinal direction of the support portion 77, and the pivot shaft 76b of the lever portion 76 is inserted into this groove 77a. The rotation of the pivot shaft 76b inside the groove 77a allows the lever portion 76 to rotate relative to the step 4. An operating piece 76a is formed at the tip (inner end in the front-rear direction) of the lever portion 76.

[0034] In this embodiment, the lever portion 76 is positioned between two sets of arm members 70-70. A rod-shaped engaging portion 78 is integrally assembled to the lever portion 76. The engaging portion 78 is positioned below the arm members 70-70 so that it can engage with the arm members 70-70.

[0035] When the user of the stepladder 10 wants to close the stepladder 10, as shown in Figure 4, they slightly lift the front ladder body 2 and rotate the operating piece 76a of the lever 76 upward. This causes the engaging part 78 to engage with the arm members 70-70, and rotates the first arm body 71 or the second arm body 72 so that the angle formed on the underside of the first arm body 71 and the second arm body 72 is 180 degrees or less. This makes it possible to deform the arm members 70-70 from an extended state to a bent state.

[0036] More specifically, a force is applied from below to the arm members 70, 70 via the lever portion 76 and the engaging portion 78, causing the first arm body 71 and the second arm body 72 to rotate relative to each other so that the rotation axis 75 is displaced upward. This releases the angle restriction of the ladder bodies 2, 2, and allows the ladder bodies 2, 2, to rotate so that the angle they form is less than approximately 30 degrees.

[0037] Then, due to the weight of the front ladder body 2, the ladder bodies 2 and 2 move closer together, and as the angle between the ladder bodies 2 and 2 approaches approximately 0 degrees, the stepladder 10 enters a closed state as shown in Figure 5. In this way, by bending the arm member 70, which consists of the first arm body 71 and the second arm body 72, when the stepladder is in a closed state with the ladder bodies 2 and 2 close together, the stepladder 10 enters a closed state.

[0038] Thus, when the stepladder 10 is in the stepladder state, the user can close the stepladder 10 by rotating the lever 76, which is the operating part, near the rung 4, and bending the arm member 70 in a natural posture with one hand. In other words, the user can close the stepladder 10 by lifting the front ladder body 2 and bringing it close to the other ladder body 2, and then lift and move the stepladder 10 with one hand. In other words, even if the height dimension of the stepladder 10 is large and the vertical position of the lever 76, which is the operating part, is also high, the user does not need to reach for the lever 76 in an unnatural posture, thus improving the usability of the stepladder 10.

[0039] As shown in Figures 3 to 5, the lever portion 76 has a flat portion 76d formed on its upper side. As shown in Figure 3, when the lever portion 76 is not operated, the upper surface of the step 4 supporting the lever portion 76 and the flat portion 76d of the lever portion 76 are positioned on the same plane. As a result, the lever portion 76 extends the upper surface of the step 4, expanding the tread surface and thus increasing the safety of the user when ascending or descending.

[0040] Furthermore, in this embodiment, the lever portion 76 is positioned between two sets of arm members 70-70 to prevent interference between the lever portion 76 and the arm members 70-70. In addition, the lever portion 76 has a contact portion 76c that contacts the foot rail 4 supporting the lever portion 76 when the lever portion 76 is not being operated. This makes it possible to position the lever portion 76 when it is not being operated.

[0041] In this embodiment, the arm members 70 can also be configured as a single set. Furthermore, the lever portion 76 and the engaging portion 78, which are the operating parts, can be provided on only one side of the pair of rungs 4-4. Also, in this embodiment, two sets of arm members 70-70 are attached to the rungs 4-4, but the arm members 70-70 may be attached at the same height to opposing surfaces of the adjacent and spaced-apart support columns 3-3 (the same applies to the subsequent embodiments).

[0042] [Second embodiment: stepladder 110] Next, a stepladder 110 according to the second embodiment of the present invention will be described using Figures 6 to 9. In each embodiment described below, the configuration of the ladder bodies 2·2 and hinge 6 that constitute the stepladder is the same as that of the stepladder 10 according to the first embodiment, so a detailed explanation will be omitted, and the differences will be described in detail.

[0043] The stepladder 110 according to this embodiment is equipped with an opening stopper mechanism 107 that defines the angle between the ladder bodies 2 and 2 and restricts their relative displacement (rotation) when in the stepladder state. The opening stopper mechanism 107 in this embodiment is equipped with two sets of arm members 170 and 170 that connect a pair of treads 4 and 4 (the uppermost treads 4 and 4) that face each other and are spaced apart on the ladder bodies 2 and 2.

[0044] In the stepladder 110 according to this embodiment, each arm member 170 comprises a pair of arm bodies: a first arm body 171 and a second arm body 172. The base end (rear end) of the first arm body 171 is rotatably supported on the rung 4 of the rear ladder body 2 via a first support member 173. The base end (front end) of the second arm body 172 is rotatably supported on the rung 4 of the front ladder body 2 via a second support member 174.

[0045] As shown in Figures 7 to 9, a first pivot piece 173a is formed at the lower part of the first support member 173, which serves as the pivot point when the first arm body 171 rotates to deform the stepladder 110 from the stepladder state to the closed state. Also, a second pivot piece 174a is formed at the lower part of the second support member 174, which serves as the pivot point when the second arm body 172 rotates to deform the stepladder 110 from the stepladder state to the closed state. As shown in Figure 7, when the stepladder 110 is in the stepladder state, the first arm body 171 is in contact only with the front end of the first pivot piece 173a. Similarly, the second arm body 172 is in contact only with the rear end of the second pivot piece 174a.

[0046] The tip (front end) of the first arm body 171 and the tip (rear end) of the second arm body 172 are rotatably connected to each other. The connection between the first arm body 171 and the second arm body 172 in the two sets of arm members 170-170 is connected by a rotating shaft 177. In addition, it is also possible to omit the rotating shaft 177 in the opening stopper mechanism 107 and simply connect the first arm body 171 and the second arm body 172 rotatably with rivets or the like (a configuration in which the connection between the first arm body 171 and the second arm body 172 in the arm members 170-170 is not connected on the left and right sides).

[0047] A restricting portion 171a is formed at the tip of the first arm body 171 to restrict the relative rotation between the first arm body 171 and the second arm body 172. When the stepladder 110 is in the stepladder state and the arm member 170 is extended, the second arm body 172 comes into contact with the restricting portion 171a, so that the arm member 170 does not bend in a direction that would cause the rotation axis 177 to be displaced downward.

[0048] As shown in Figures 6 and 7, when the stepladder 110 is in the stepladder position, the rungs 4, 4 are connected by two sets of extended arm members 170, 170, so the ladder bodies 2, 2 do not rotate relative to each other in a direction that brings them closer or further apart. Therefore, the angle between the ladder bodies 2, 2 remains at approximately 30 degrees, and the stepladder 110 maintains its stepladder position.

[0049] In the stepladder 110 according to this embodiment, as shown in Figures 6 to 9, the opening stopper mechanism 107 is provided near each of the pair of rungs 4, 4 connected by the arm members 170, 170, and includes a first connecting member 175 and a second connecting member 176 that connect the two sets of arm members 170, 170, as operating parts that can deform the arm members 170, 170 from an extended state to a bent state.

[0050] As shown in Figures 7 and 8, the first connecting member 175 and the second connecting member 176 are inserted into elongated holes formed in the first support member 173 and the second support member 174, respectively, and are supported so as to be able to move up and down within the first support member 173 and the second support member 174.

[0051] As shown in Figure 7, the first connecting member 175 connects the arm members 170-170 on the base end side of the first arm body 171, relative to the first pivot point piece 173a (more specifically, the front end of the first pivot point piece 173a). The second connecting member 176 connects the arm members 170-170 on the base end side of the second arm body 172, relative to the second pivot point piece 174a (more specifically, the rear end of the second pivot point piece 174a).

[0052] When the user of the stepladder 110 wants to close it, as shown in Figure 8, they slightly lift the front ladder body 2 and operate the first connecting member 175 (and the second connecting member 176) to displace it downwards. This causes the first arm body 171 to rotate around the front end of the first pivot piece 173a, which is the pivot point, and displace it to an angle that contacts the first pivot piece 173a (an angle parallel to the first pivot piece 173a), as shown in Figure 8. As a result, the arm members 170 can be deformed from an extended state to a bent state. This releases the angle restriction of the ladder bodies 2 and 2, allowing the ladder bodies 2 and 2 to rotate so that the angle formed by them is less than approximately 30 degrees.

[0053] Then, due to the weight of the front ladder body 2, the ladder bodies 2 and 2 move closer together, and as the angle between the ladder bodies 2 and 2 approaches approximately 0 degrees, the stepladder 110 enters a closed state as shown in Figure 9. In this way, by bending the arm member 170, which consists of the first arm body 171 and the second arm body 172, when the stepladder is in a closed state with the ladder bodies 2 and 2 close together, the stepladder 110 enters a closed state.

[0054] Thus, when the stepladder 110 is in the stepladder state, the user can close the stepladder 110 by bending the arm member 170 in a natural posture with one hand by operating the first connecting member 175 (second connecting member 176), which is the operating part, downward near the rung 4. In other words, the user can close the stepladder 110 by lifting the front ladder body 2 and bringing it close to the other ladder body 2, and then lift and move the stepladder 110 with one hand.

[0055] Furthermore, as shown in Figure 7, in the stepladder 110, the first connecting member 175 (second connecting member 176) is positioned below the upper surface of the rung 4 that is adjacent to the first connecting member 175 (second connecting member 176) when the stepladder is in the stepladder state. This prevents the first connecting member 175 (second connecting member 176) from obstructing the user's ascent and descent when the user is moving the stepladder 110 up or down. In this embodiment, it is also possible to use only one of the connecting members, the first connecting member 175 or the second connecting member 176, as the operating part.

[0056] [Third Embodiment: Step Ladder 210] Next, a stepladder 210 according to the third embodiment of the present invention will be described with reference to Figures 10 to 13. The stepladder 210 according to this embodiment is equipped with an opening stopper mechanism 207 that defines the angle between the ladder bodies 2 and 2 and restricts their relative displacement (rotation) when in the stepladder state. The opening stopper mechanism 207 in this embodiment is equipped with two sets of arm members 270 and 270 that connect a pair of treads 4 and 4 (the uppermost treads 4 and 4) that face each other and move closer together and further apart in the ladder bodies 2 and 2.

[0057] In the stepladder 210 according to this embodiment, each arm member 270 comprises a pair of arm bodies: a first arm body 271 and a second arm body 272. The base end (rear end) of the first arm body 271 is rotatably supported on the rung 4 of the rear ladder body 2 via a first support member 273. The base end (front end) of the second arm body 272 is rotatably supported on the rung 4 of the front ladder body 2 via a second support member 274.

[0058] The tip (front end) of the first arm body 271 and the tip (rear end) of the second arm body 272 are rotatably connected to each other. A restricting portion 271a is formed at the tip of the first arm body 271 to restrict the relative rotation between the first arm body 271 and the second arm body 272. When the stepladder 210 is in the stepladder state and the arm member 270 is extended, the second arm body 272 comes into contact with the restricting portion 271a, thereby preventing the arm member 270 from bending downward.

[0059] As shown in Figures 10 and 11, when the stepladder 210 is in the stepladder position, the rungs 4, 4 are connected by two sets of extended arm members 270, 270, so the ladder bodies 2, 2 do not rotate relative to each other in a direction that brings them closer or further apart. Therefore, the angle between the ladder bodies 2, 2 remains at approximately 30 degrees, and the stepladder 210 maintains its stepladder position.

[0060] In the stepladder 210 according to this embodiment, as shown in Figures 10 to 13, the opening stopper mechanism 207 is provided near each of the pair of rungs 4, 4 connected by the arm members 270, 270, and includes a first connecting member 275 and a second connecting member 276 that connect the two sets of arm members 270, 270, as operating parts that can deform the arm members 270, 270 from an extended state to a bent state.

[0061] As shown in Figure 11, the first connecting member 275 connects the two sets of arm members 270-270 on the tip side of the first arm body 271, beyond the pivot axis at the base end of the first arm body 271 (the pivot axis through which the first support member 273 rotates and supports the first arm body 271). Similarly, the second connecting member 276 connects the two sets of arm members 270-270 on the tip side of the second arm body 272, beyond the pivot axis at the base end of the second arm body 272 (the pivot axis through which the second support member 274 rotates and supports the second arm body 272).

[0062] When the user of the stepladder 210 wants to close the stepladder 210, as shown in Figure 12, they slightly lift the front ladder body 2 and operate the first connecting member 275 (the same applies to the second connecting member 276) to displace it upward. This causes the first arm body 271 to rotate around the pivot axis in the first support member 273, allowing the arm members 270-270 to deform from an extended state to a bent state. This releases the angle restriction of the ladder bodies 2-2, allowing the ladder bodies 2-2 to rotate so that the angle formed by them is less than approximately 30 degrees.

[0063] Then, due to the weight of the front ladder body 2, the ladder bodies 2 and 2 move closer together, and as the angle between the ladder bodies 2 and 2 approaches approximately 0 degrees, the stepladder 210 enters a closed state as shown in Figure 13. In this way, by bending the arm member 270, which consists of the first arm body 271 and the second arm body 272, when the stepladder is in a closed state with the ladder bodies 2 and 2 close together, the stepladder 210 enters a closed state.

[0064] Thus, when the stepladder 210 is in the stepladder state, the user can close the stepladder 210 by bending the arm member 270 in a natural posture with one hand by operating the first connecting member 275 (second connecting member 276), which is the operating part, upward near the rung 4. In other words, the user can close the stepladder 210 by lifting the front ladder body 2 and bringing it close to the other ladder body 2, and then lift and move the stepladder 210 with one hand.

[0065] Furthermore, as shown in Figure 11, in the stepladder 210, the first connecting member 275 (second connecting member 276) is positioned below the upper surface of the rung 4 that is adjacent to the first connecting member 275 (second connecting member 276) when the stepladder is in use. This prevents the first connecting member 275 (second connecting member 276) from obstructing the user's ascent and descent when the user is using the stepladder 210.

[0066] Furthermore, as shown in Figure 11, in the stepladder 210, the first connecting member 275 (second connecting member 276) is positioned above the pivot axis at the base end of the first arm body 271 (second arm body 272) when the stepladder is in use. As a result, when the stepladder is in use, the first connecting member 275 (second connecting member 276) is positioned above the pivot axis of the first arm body 271 (second arm body 272), making it possible to easily lift the arm members 270. In this embodiment, it is also possible to use only one of the connecting members, the first connecting member 275 or the second connecting member 276, as the operating part.

[0067] [Fourth embodiment: Step ladder 310] Next, a stepladder 310 according to the fourth embodiment of the present invention will be described with reference to Figure 14. The stepladder 310 according to this embodiment is equipped with an opening stopper mechanism 307 that defines the angle between the ladder bodies 2 and 2 and restricts their relative displacement (rotation) when in the stepladder state. The opening stopper mechanism 307 in this embodiment is equipped with two sets of arm members 370 and 370 that connect a pair of rungs 4 and 4 (the uppermost rungs 4 and 4) that face each other and move closer together and further apart in the ladder bodies 2 and 2.

[0068] In the stepladder 310 according to this embodiment, each arm member 370 comprises a pair of arm bodies: a first arm body 371 and a second arm body 372. The base end (rear end) of the first arm body 371 is rotatably supported on the rung 4 of the rear ladder body 2 via a first support member 373. The base end (front end) of the second arm body 372 is rotatably supported on the rung 4 of the front ladder body 2 via a second support member 374.

[0069] The tip (front end) of the first arm body 371 and the tip (rear end) of the second arm body 372 are rotatably connected to each other. The connection between the first arm body 371 and the second arm body 372 in the two sets of arm members 370-370 is connected by a rotating shaft 375. In addition, it is also possible to omit the rotating shaft 375 in the opening stopper mechanism 307 and simply connect the first arm body 371 and the second arm body 372 rotatably with rivets or the like (a configuration in which the connection between the first arm body 371 and the second arm body 372 in the arm members 370-370 is not connected on the left and right sides).

[0070] A restricting portion 371a is formed at the tip of the first arm body 371 to restrict the relative rotation between the first arm body 371 and the second arm body 372. When the stepladder 310 is in the stepladder state and the arm member 370 is extended, the second arm body 372 comes into contact with the restricting portion 371a, so that the arm member 370 does not bend in a direction that would cause the rotation axis 375 to be displaced downward.

[0071] As shown in Figure 14, when the stepladder 310 is in the stepladder position, the rungs 4, 4 are connected by two sets of extended arm members 370, 370, so the ladder bodies 2, 2 do not rotate relative to each other in a direction that brings them closer or further apart. Therefore, the angle between the ladder bodies 2, 2 remains at approximately 30 degrees, and the stepladder 310 maintains its stepladder position.

[0072] In the stepladder 310 according to this embodiment, as shown in Figure 14, the opening stopper mechanism 307 is provided with an operating part 376 that can deform the arm members 370-370 from an extended state to a bent state. The operating part 376 is rotatably mounted on the rotation axis 375.

[0073] When the user of the stepladder 310 closes the stepladder 310, the operating part 376 is rotated upward while being displaced above the rotation axis 375 (above the arm members 370-370). This causes the arm members 370-370 to deform from an extended state to a bent state. This releases the angle restriction of the ladder bodies 2-2, allowing the ladder bodies 2-2 to rotate so that the angle formed by them is less than approximately 30 degrees.

[0074] Then, the pair of ladder bodies 2 and 2 move closer together due to their own weight, and as the angle between the ladder bodies 2 and 2 approaches approximately 0 degrees, the stepladder 310 enters a closed state. In this way, by bending the arm member 370 when in the stepladder state, the stepladder 310 enters a closed state with the ladder bodies 2 and 2 close together.

[0075] Thus, when the stepladder 310 is in the stepladder position, the user can close the stepladder 310 by lifting the operating unit 376 above the rotation axis 375 (above the arm members 370-370) with one hand in a natural posture by bending the arm member 370. In other words, the user can close the stepladder 310 by lifting the front ladder body 2 and bringing it close to the other ladder body 2, and then lift and move the stepladder 310 with one hand.

[0076] Furthermore, as shown in Figure 14, in the stepladder 310 in its stepladder state, the operating unit 376 is positioned lower than the position of the operating unit 376 during operation (more specifically, below the rotation axis 375). This prevents the operating unit 376 from obstructing the user's ascent and descent when the user is moving the stepladder 310 up or down.

[0077] Regarding the configuration in which the operating section 376 is positioned lower than during operation when the stepladder 310 is in the stepladder state, a configuration different from that of this embodiment is possible. For example, by making the length of the operating section 376 longer than the distance between the arm members 370-370, it is possible to configure the device so that the operating section 376 does not displace below the arm members 370-370. Alternatively, by restricting the rotation range of the operating section 376 or by providing a member connecting the operating section 376 and the pivot shaft 375 on the outside of the arm members 370-370, it is also possible to configure the device so that the operating section 376 does not displace below the arm members 370-370.

[0078] Furthermore, the operating unit 376 may be configured not to displace from the operating position when the stepladder 310 is in the stepladder state (a configuration that maintains the same posture as during operation). For example, by restricting the position of the operating unit 376 so that it does not rotate, it is possible to configure the operating unit 376 not to displace from the posture during operation. Even in this case, when the stepladder 310 is in the stepladder state, the user can lift the operating unit 376 above the rotation axis 375, thereby bending the arm member 370 in a natural posture with one hand and closing the stepladder 310.

[0079] [Fifth Embodiment: Step Ladder 410] Next, a stepladder 410 according to the fifth embodiment of the present invention will be described with reference to Figure 15. The stepladder 410 according to this embodiment is equipped with an opening stopper mechanism 407 that defines the angle between the ladder bodies 2 and 2 and restricts their relative displacement (rotation) when in the stepladder state. The opening stopper mechanism 407 in this embodiment is equipped with two sets of arm members 470 and 470 that connect a pair of treads 4 and 4 (the uppermost treads 4 and 4) that face each other and move closer together and further apart in the ladder bodies 2 and 2.

[0080] In the stepladder 410 according to this embodiment, each arm member 470 comprises a pair of arm bodies: a first arm body 471 and a second arm body 472. The base end (rear end) of the first arm body 471 is rotatably supported on the rung 4 of the rear ladder body 2 via a first support member 473. The base end (front end) of the second arm body 472 is rotatably supported on the rung 4 of the front ladder body 2 via a second support member 474.

[0081] The tip (front end) of the first arm body 471 and the tip (rear end) of the second arm body 472 are rotatably connected to each other. The connection between the first arm body 471 and the second arm body 472 in the two sets of arm members 470-470 is connected by a rotating shaft 475.

[0082] A restricting portion 471a is formed at the tip of the first arm body 471 to restrict the relative rotation between the first arm body 471 and the second arm body 472. When the stepladder 410 is in the stepladder state and the arm member 470 is extended, the second arm body 472 comes into contact with the restricting portion 471a, so that the arm member 470 does not bend in a direction that would cause the rotation axis 475 to be displaced downward.

[0083] As shown in Figure 15, when the stepladder 410 is in the stepladder position, the rungs 4, 4 are connected by two sets of extended arm members 470, 470, so the ladder bodies 2, 2 do not rotate relative to each other in a direction that brings them closer or further apart. Therefore, the angle between the ladder bodies 2, 2 remains at approximately 30 degrees, and the stepladder 410 maintains its stepladder position.

[0084] In the stepladder 410 according to this embodiment, as shown in Figure 15, the opening stopper mechanism 407 is provided with an operating section 476 that can deform from an extended state to a bent state of the arm members 470, 470. The operating section 476 is assembled to the rotation shaft 475 via connecting plates 477, 477. Elongated holes 477a, 477a are opened in the connecting plates 477, 477, and the rotation shaft 475 is inserted through the elongated holes 477a, 477a. As a result, the operating section 476 is mounted to the rotation shaft 475 so as to be rotatable and able to move closer to and further away from it.

[0085] When the user of the stepladder 410 closes the stepladder 410, the operating part 476 is rotated upwards above the rotation axis 475, and then the operating part 476 is displaced upwards. This causes the arm members 470 to deform from an extended state to a bent state. This releases the angle restriction of the ladder bodies 2, 2, and allows the ladder bodies 2, 2, to rotate so that the angle formed by them is less than approximately 30 degrees.

[0086] Then, the pair of ladder sections 2 and 2 move closer together due to their own weight, and as the angle between the ladder sections 2 and 2 approaches approximately 0 degrees, the stepladder 410 enters a closed state. In this way, by bending the arm member 470 when the stepladder is in a stepped ladder state, the stepladder 410 enters a closed state with the ladder sections 2 and 2 close together.

[0087] Thus, when the stepladder 410 is in the stepladder position, the user can close the stepladder 410 by lifting the operating unit 476 above the rotation axis 475, allowing the arm member 470 to bend in a natural posture with one hand. In other words, the user can close the stepladder 410 by lifting the front ladder body 2 and bringing it closer to the other ladder body 2, and then lift and move the stepladder 410 with one hand.

[0088] Furthermore, as shown in Figure 15, in the step ladder 410 in its step ladder state, the operating unit 476 can be positioned lower than its position during operation by bringing it closer to the rotation axis 475. This prevents the operating unit 476 from obstructing the user's ascent and descent when the user is moving the step ladder 410 up or down.

[0089] [Sixth Embodiment: Step Ladder 510] Next, a stepladder 510 according to the sixth embodiment of the present invention will be described with reference to Figures 16 to 20. The stepladder 510 according to this embodiment can take on the following three forms depending on the angle formed by the pair of ladder bodies 2 and 2.

[0090] The first configuration is a stepladder state in which the ladder bodies 2 and 2 form an angle of approximately 30 degrees, and the stepladder 510 is supported by four support columns 3, as shown in Figures 16 and 17. The second configuration is a closed state in which the angle of the ladder bodies 2 and 2 is close to approximately 0 degrees, as shown in Figure 18. The third configuration is a ladder state in which the angle of the ladder bodies 2 and 2 is opened to approximately 180 degrees, as shown in Figures 19 and 20.

[0091] The stepladder 510 is equipped with a locking member 508 for maintaining the ladder configuration. The locking member 508 is rotatably supported by a rotating support portion 508a at the second hinge portion 6b. As shown in Figure 19, when the stepladder 510 is in the ladder configuration, the tip of the locking member 508 engages with a locking pin P formed on the first hinge portion 6a. This restricts the relative displacement of the ladder bodies 2·2, allowing the stepladder 510 to maintain the ladder configuration.

[0092] The stepladder 510 is equipped with an opening stopper mechanism 507 that defines the angle between the ladder bodies 2 and 2 and restricts their relative displacement (rotation) when in the stepladder state. The opening stopper mechanism 507 in this embodiment is equipped with two sets of arm members 570, 570 that connect a pair of treads 4 and 4 (the uppermost treads 4 and 4) that face each other and move closer together and further apart on the ladder bodies 2 and 2.

[0093] In the stepladder 510 according to this embodiment, each arm member 570 comprises a pair of arm bodies: a first arm body 571 and a second arm body 572. The base end (rear end) of the first arm body 571 is rotatably supported on the rung 4 of the rear ladder body 2 via a first support member 573. The first support member 573 has a fixing portion 573a to which the fixed portion 572a, which is the base end of the second arm body 572, is fixed when the ladder is in use.

[0094] Furthermore, the fixed portion 572a formed at the base end (front end) of the second arm body 572 is rotatably supported on the rung 4 of the front ladder body 2 via the second support member 574. In this embodiment, the fixed portion 572a of the second arm body 572 is detachably attached to the second support member 574 via fixing members such as bolts and nuts.

[0095] The tip (front end) of the first arm body 571 and the tip (rear end) of the second arm body 572 are rotatably connected to each other. The connection between the first arm body 571 and the second arm body 572 in the two sets of arm members 570-570 is connected by an operating section 575.

[0096] The first support member 573 has a restricting portion 573b formed therein for restricting the rotation angle of the first arm body 571. The second support member 574 also has a restricting portion 574a formed therein for restricting the rotation angle of the second arm body 572. When the stepladder 510 is in the stepladder state and the arm members 570 are extended, the first arm body 571 comes into contact with the restricting portion 573b and the second arm body 572 comes into contact with the restricting portion 574a, thereby preventing the arm members 570 from bending in the direction that would cause the operating portion 575 to be displaced downward. The restricting portion may be formed, for example, on the upper tip side of the first arm body 571, as long as the relative rotation of the first arm body 571 and the second arm body 572 is restricted so that the arm members 570 do not bend in the direction that would cause the operating portion 575 to be displaced downward.

[0097] As shown in Figures 16 and 17, when the stepladder 510 is in the stepladder position, the rungs 4, 4 are connected by two sets of extended arm members 570, 570, so the ladder bodies 2, 2 do not rotate relative to each other in a direction that brings them closer or further apart. Therefore, the angle between the ladder bodies 2, 2 remains at approximately 30 degrees, and the stepladder 510 maintains its stepladder position.

[0098] In the stepladder 510 according to this embodiment, as shown in Figures 16 and 17, the opening stopper mechanism 507 is provided with an operating section 575 that can deform the arm members 570-570 from an extended state to a bent state.

[0099] When the user of the stepladder 510 closes the stepladder 510, the operating part 575 is displaced upward. This causes the arm members 570-570 to deform from an extended state to a bent state. This releases the angle restriction of the ladder bodies 2-2, allowing the ladder bodies 2-2 to rotate so that the angle formed by them is less than approximately 30 degrees.

[0100] Then, the pair of ladder bodies 2 and 2 move closer together due to their own weight, and as the angle between the ladder bodies 2 and 2 approaches approximately 0 degrees, the stepladder 510 enters a closed state. In this way, by bending the arm member 570 when in the stepladder state, the stepladder 510 enters a closed state with the ladder bodies 2 and 2 close together.

[0101] As shown in Figures 19 and 20, when the stepladder 510 is in the ladder configuration, the second arm body 572 is rotated and displaced below the first arm body 571. The fixed portion 572a of the second arm body 572 is then fixed to the fixed portion 573a of the first support member 573. In this case, as shown in Figure 20, regardless of which ladder body 2 of the stepladder 510 is facing upwards when used in the ladder configuration, the operating portion 575 is positioned below the upper surface of the rung 4 to which it is fixed. This ensures that the operating portion 575 does not obstruct the user's ascent and descent when using the stepladder 510 in the ladder configuration, and allows for stable holding of the arm member 570. [Explanation of symbols]

[0102] 2 Ladder body 3 Post 3a End fitting 4 Stepper 5. Tabletop 6. Hinge 6a First hinge section 6b Second hinge section 6c Rotating support part 7 Opening stopper mechanism 10. Step ladder (first embodiment) 70 Arm member 71 First arm body 71a Regulating section 72 Second arm body 73 First support member 74 Second support member 75 Rotating shaft 76 Lever section (operating section) 76a Operation piece 76b Rotation shaft 76c Contact part 76d Plane part 77 Support part 77a Groove part 78 Engagement part (operation part) 107 Opening stopper mechanism 110 Step Ladder (Second Embodiment) 170 Arm member 171 First arm body 171a Regulatory section 172 Second arm body 173 First support member 173a First pivot piece 174 Second support member 174a Second pivot piece 175 First connecting member (operating part) 176 Second connecting member (operating part) 177 Rotation axis 207 Opening stopper mechanism 210 Step Ladder (Third Embodiment) 270 Arm member 271 First arm body 271a Regulatory section 272 Second arm body 273 First support member 274 Second support member 275 First connecting member (operating part) 276 Second connecting member (operating part) 307 Opening stop mechanism 310 Step Ladder (Fourth Embodiment) 370 Arm member 371 First arm body 371a Regulatory section 372 Second arm body 373 First support member 374 Second support member 375 Rotating shaft 376 Operating section 407 Opening stopper mechanism 410 Step Ladder (Fifth Embodiment) 470 Arm member 471 First arm body 471a Regulatory section 472 Second arm body 473 First support member 474 Second support member 475 Rotating shaft 476 Operating section 477 Connecting plate 477a Long hole 507 Opening prevention mechanism 508 Locking member 508a Rotating support part 510 Step Ladder (Sixth Embodiment) 570 Arm member 571 First arm body 571a Regulatory section 572 Second arm body 572a Fixed part 573 First support member 573a Fixing part 574 Second support member 575 Operation section P Lock Pin

Claims

1. A step ladder comprising two support columns, one or more rungs spanning between the two support columns, and a top plate connecting the upper ends of the two support columns, wherein a pair of ladder bodies are connected at their upper ends so as to be rotatable relative to each other, and the step ladder is transformable between a closed state in which the pair of ladder bodies are close together and a step ladder state in which the pair of ladder bodies are spaced apart at a predetermined interval, It is equipped with an opening stopper mechanism that restricts the relative displacement of the pair of ladder bodies when in a stepladder state, The opening stopper mechanism includes an arm member that connects a pair of rungs that are facing each other and are positioned closer together and further apart in the pair of ladder bodies. The arm member comprises a pair of arm bodies, the base end of which is rotatably supported by a pair of the rungs, and the tip portions of which are rotatably connected to each other. The opening stopper mechanism includes an operating part near at least one of the pair of rungs, which is capable of changing the arm member from an extended state to a bent state. The operating unit comprises a lever portion rotatably supported on at least one of the pair of footrails, and an engaging portion provided on the lever portion and capable of engaging with the arm member, The lever portion has a flat surface on its upper side. The pivot axis of the lever portion is provided on the step rail that supports the lever portion. A stepladder in which, when the lever is not operated, the upper surface of the step supporting the lever and the flat surface of the lever are positioned on the same plane.

2. A step ladder comprising two support columns, one or more rungs spanning between the two support columns, and a top plate connecting the upper ends of the two support columns, wherein a pair of ladder bodies are connected at their upper ends so as to be rotatable relative to each other, and the step ladder is transformable between a closed state in which the pair of ladder bodies are close together and a step ladder state in which the pair of ladder bodies are spaced apart at a predetermined interval, It is equipped with an opening stopper mechanism that restricts the relative displacement of the pair of ladder bodies when in a stepladder state, The opening stopper mechanism includes an arm member that connects a pair of rungs that are facing each other and are positioned closer together and further apart in the pair of ladder bodies. The arm member comprises a pair of arm bodies, the base end of which is rotatably supported by a pair of the rungs, and the tip portions of which are rotatably connected to each other. The opening stopper mechanism includes an operating part near at least one of the pair of rungs, which is capable of changing the arm member from an extended state to a bent state. The operating unit comprises a lever portion rotatably supported on at least one of the pair of footrails, and an engaging portion provided on the lever portion and capable of engaging with the arm member, Each pair of footrails is provided with two sets of the arm members. The lever portion is positioned between the two sets of arm members. A stepladder having a contact portion formed on the lever portion that contacts the rung supporting the lever portion when the lever portion is not being operated.

3. A step ladder comprising two support columns, one or more rungs spanning between the two support columns, and a top plate connecting the upper ends of the two support columns, wherein a pair of ladder bodies are connected at their upper ends so as to be rotatable relative to each other, and the step ladder is transformable between a closed state in which the pair of ladder bodies are close together and a step ladder state in which the pair of ladder bodies are spaced apart at a predetermined interval, It is equipped with an opening stopper mechanism that restricts the relative displacement of the pair of ladder bodies when in a stepladder state, The opening stopper mechanism includes an arm member that connects a pair of rungs that are facing each other and are positioned closer together and further apart in the pair of ladder bodies. The arm member comprises a pair of arm bodies, the base end of which is rotatably supported by a pair of the rungs, and the tip portions of which are rotatably connected to each other. The opening stopper mechanism includes an operating part near at least one of the pair of rungs, which is capable of changing the arm member from an extended state to a bent state. Each pair of footrails is provided with two sets of the arm members. The operating section is configured as a connecting member that connects the two sets of arm members, The connecting member connects the two sets of arm members at the tip of the arm body, relative to the pivot axis at the base end of the arm body. The aforementioned connecting member is located above the pivot axis at the base end of the arm body when the stepladder is in a stepladder state.

4. The stepladder according to claim 3, wherein the connecting member is located below the upper surface of the step rail that is adjacent to the connecting member when the stepladder is in a stepladder state.

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