GB2412846A

GB2412846A - Foldable and collapsible frame for a bunk bed or single bed or other item of furniture

Info

Publication number: GB2412846A
Application number: GB0406970A
Authority: GB
Inventors: Susan Raymie Jepson
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-03-27
Filing date: 2004-03-27
Publication date: 2005-10-12
Also published as: GB0406970D0

Abstract

A collapsible and foldable frame 10 for a bunk bed is disclosed. The frame includes members 12,14,16 which are pivotally connected to each other such that the bed can be collapsed (Figs.2-5) into a relatively small size for storage and transportation purposes. The frame comprises end supports in the form of two end support members 12 and lateral supports in the form of two lateral support members 14. The end support and lateral support members are connected to the support legs 16. Each end support member comprises a hinge 20 which includes locking members to selectively lock the end support in a linear configuration (Fig. 1) or to be unlocked during folding. Each lateral support member 14 comprises two sections 25,27 and a locking hinge (24,Fig.5) in order for the lateral supports to be foldable whilst in an unlocked configuration and locked in a linear configuration. The frame may be reinforced by members 18,31,33,36. The folding frame may be adapted for use with other items of furniture, e.g. a single bed or a table.

Description

24 1 2846

FOLDING FRAME FOR AN ARTICLE OF FURNITURE

Field of the Invention

The present invention relates to a folding frame for an article of furniture, an article of furniture including a folding frame and a method of constructing an article of furniture.

Background to the Invention

Articles of furniture, and in particular beds, generally comprise a permanent frame which generally comprises wood which is secured together using nails, screws or similar securement means. Accordingly, if the article of furniture needs to be moved, it takes a considerable amount of time to Reconstruct and reconstruct the article of furniture. In addition, the strength of the frame of the article of furniture may be weakened by the Reconstruction and reconstruction process.

In some situations, it may be desirable to only provide a bed in a location for a short period of time, for example a single night. Prior art frames are not suitable for such situations due to the construction time.

Furthermore, it may be advantageous for the frame to be compact in order to be easily transported whilst the article of furniture is being moved. For example, the army may require temporary accommodation in relatively remote locations. Accordingly, there is a requirement for relatively compact articles of furniture, in particular beds, which are easily assembled and are compact to transport.

It is an aim of the present invention to overcome at least one problem associated with the prior art whether referred to herein or otherwise.

Summary of the Invention

According to a first aspect of the present invention there is provided a folding frame for an article of furniture, the folding frame comprising lateral support means, end support means and support legs, the lateral support means and the end supports means being arranged, in a first configuration to support a support surface therebetween and the support legs being arranged, in the first configuration, to support the support surface spaced from the ground, the lateral support means and end support means being adaptable to enable the leg supports to move relative towards each other in order for the folding frame to form a second configuration.

Preferably the first configuration is an operative configuration where the article of furniture may provide or support a support surface. Preferably the second configuration is a storage configuration where the folding frame is compact and may be suitable for storage or transportation.

Preferably the support legs are secured to the end support means in the assembled configuration and in the storage configuration. Preferably the support legs are secured to the end support means whilst the folding frame is adapted from an operative configuration to a storage configuration. Preferably the end support means are pivotally secured to the support legs supports.

Preferably the support legs are secured to the lateral support means in the assembled configuration and in the storage configuration. Preferably the leg supports are secured to the lateral support means whilst the folding frame is adapted from an operative configuration to a storage configuration.

Preferably the folding frame comprises four support legs.

Preferably the end support means comprises a first end support member and a second end support member.

Preferably the lateral support means comprise a first lateral support member and a second lateral support member.

Preferably each lateral support member is pivotally connected between two support legs.

Preferably a first lateral support member is secured between a first and second support leg and a second support member is secured between a third and fourth support leg. Preferably each lateral support member comprises an elongate member and may comprise a tubular portion. Preferably each elongate member comprises a first section and a second section.

Preferably each lateral support member comprises a hinge member. Preferably the hinge member is located centrally along the longitudinal length of the respective lateral support member. Preferably a first end (or inner end) of each section is pivotally connected to the hinge member.

Preferably the first section and the second section are pivotally movable from a linear configuration to a side by side configuration.

Preferably each end support member is pivotally connected between two support legs.

Preferably each end support member comprises a hinge member. Preferably each hinge member is located centrally along the longitudinal length of the respective end support member. Preferably a first end (or inner end) of each section is pivotally connected to the hinge member.

Preferably the folding frame comprises reinforcement means in order to reinforce the folding frame, and more preferably the support surface, in the operative configuration.

The reinforcement means may comprise a reinforcement member extending diagonally across the folding frame in the operative configuration and preferably comprises two reinforcement members extending diagonally across the folding frame in the operative configuration.

Preferably a first reinforcement member secures between first and fourth support legs and the second reinforcement member secures between second and third support legs.

Preferably the two reinforcement members form a substantially X-shape in the operative position.

The two reinforcement members may be connected at an intersection means and preferably at a reinforcement plate of the intersection means. Preferably the reinforcement members are pivotally connected to the intersection means.

Preferably the or each reinforcement member may be pivotally connected to a support leg and preferably the or each reinforcement member is pivotally connected to two diagonally opposed support legs.

Preferably the or each end support member is arranged to fold on moving the folding frame from the operative position to the storage position and preferably fold such that one half of the or each end support member locates adjacent to the other half of the respective end support member.

Preferably the or each lateral support member is arranged to fold on moving the folding frame from the operative position to the storage position and preferably fold such that one half of the lateral support member locates adjacent to the other half of the respective lateral support member.

Preferably the or each reinforcement member is arranged to fold on moving from the operative position to the storage position and preferably fold such that one half of the reinforcement member locates adjacent to the other half of the respective reinforcement member.

Preferably an outer perimeter of the folding frame reduces as the folding frame means from the operative configuration to the storage configuration. The outer periphery may be defined as the outer most portion of the folding frame when viewed in a plan view or in a horizontal plane or horizontal cross-section which may be defined as being substantially perpendicular to the longitudinal axes of the support legs.

Preferably the article of furniture comprises a bed. The article of furniture may comprise a bunk bed.

The support surface may comprise a sheet and preferably a textile sheet.

The support surface may comprise a webbing.

The support surface may be arranged to extend between the lateral support members and the end support members.

The support surface may be resilient.

The end support members and preferably the hinge members of the end support members may be lockable in the operative configuration.

The lateral support members and preferably the hinge members of the lateral support members may be lockable in the operative configuration.

According to a second aspect of the present invention there is provided an article of furniture comprising a folding frame, the folding frame being in accordance with the first aspect of the present invention.

The article of furniture may comprise a bed. s

The article of furniture may comprise a bunk bed.

The article of furniture may comprise a bed wherein a raised support surface for the bed is provided together with a further support surface located thereunder in the first configuration. The further support surface may provide a support surface for a desk or table.

According to a third aspect of the present invention there is provided a method of constructing an article of furniture comprising folding out a folding frame in order to provide support means for a support surface for the article of furniture, the method comprising folding out end support means and lateral support means in order to provide support means for a support surface for the article of furniture, the method further comprising providing support legs to support the support surface spaced from the ground in an operative configuration.

The method may comprise folding the end support means and lateral support means outwardly from a central storage configuration.

Preferably the method comprises pivotally folding the end support means and the lateral support means relative to the support legs.

Brief Description of the Drawings

The present invention will now be described, by way of example only, with reference to the drawings that follow, in which: Figure 1 is a perspective view of an embodiment of a folding frame in an operative but unlocked configuration.

Figure 2 is a perspective view of an embodiment of a folding frame in a partially assembled configuration.

Figure 3 is a perspective view of an embodiment of a folding frame in a semi-assembled configuration.

Figure 4 is a perspective view of an embodiment of a folding frame in a partially stored configuration.

Figure 5 is a perspective view of an embodiment of a folding frame in a stored configuration.

Figure 6 is a side view of an embodiment of a folding frame in an assembled and unlocked configuration.

Figure 7 is an end view of a folding frame in an assembled and unlocked configuration.

Figure 8 is a plan view of a folding frame in an assembled and unlocked configuration.

Figure 9 is a side view of an embodiment of a folding frame in an assembled and locked configuration.

Figure 10 is a view of a folding frame in an assembled and locked configuration.

Figure 11 is a plan view of an article of furniture comprising an embodiment of a folding frame in an assembled and locked configuration.

Figure 12 is a perspective view of an article of furniture comprising an embodiment of a folding frame.

Figure 13 is a plan schematic view of an embodiment of a folding frame in an operative configuration.

Figure 14 is a plan schematic view of an embodiment of a folding frame in a storage configuration.

Figure 15 is a perspective view of an embodiment of an upper hinge member.

Figure 16 is a perspective view of an embodiment of a lower hinge member.

Figure 17 is a perspective view of an embodiment of an upper support bracket.

Figure 18 is a perspective view of an embodiment of a lower support bracket.

Figure 19 is a perspective view of another embodiment of a folding frame in an operative and locked configuration.

Figure 20 is a perspective view of another embodiment of a folding frame in a stored configuration.

Figure 21 is a side view of an upper end support member including a hinge member.

Description of the Preferred Embodiments

As shown in Figures 1 to 8, an article of furniture, in particular a bed comprises a frame. The frame 10 is a folding frame 10 such that all of the frame members remain connected to each other in both the assembled configuration (or operative configuration) and in a storage (or transportation) configuration. The frame members 12, 14, 16 are pivotally connected to each other such that the bed can be collapsed into a relatively small size for storage and transportation purposes. The frame does not require any additional securement means, for example screws etc. and all the securement means remain attached to the frame 10 in the storage configuration.

The folding frame 10 comprises end support means in the form of two end support members 12 and lateral support means in the form of two lateral support members 14. The end support members 12 locate at each longitudinal end of the bed whilst the two lateral support members 14 locate along each lateral side of the bed. The end support members 12 provide lateral support to the bed, i.e. they fix the lateral width of the bed. The lateral support members 14 provide longitudinal support to the bed, i.e. they fix the longitudinal length of the bed.

Whilst the present invention will now be described as a bunk bed it is appreciated that the folding frame 10 could be adapted for use with other items of furniture, and in particular a single bed.

The folding frame 10 for a bunk bed comprises a set (or two) end support members 12 for each bed level and a set (or two) lateral support members 14 for each bed level. A folding frame 10 for a single bed would only require one set (or two) end support members 12 and one set (or two) lateral support members 14. The end support members 12 and the lateral support members 14 are connected to support legs 16 which space and support the support members 12, 14 from the floor or ground.

The bed comprises four support legs 40,42,44,46 as shown in Figure 13. The first end support member 48 secures between the first support leg 40 and the fourth support leg 46 whilst the second end support member 50 secures between the second support leg 42 and the third support leg 44. The first lateral support member 52 secures between the first support leg 40 and the second support leg 42 whilst the second lateral support member 54 secures between the third support leg 44 and the fourth support leg 46. Finally, the first reinforcement member 56 secures between the first support leg 40 and the third support leg 44 whilst the second reinforcement member secures between the second support leg 42 and the fourth support leg 46. The first bed level is the same as the second bed level.

All of the support members 48, 50, 52, 54 are arranged to fold from a folded position to a linear position. The folding out of the support members urges the support legs 40, 42, 44, 46 away from each other and away from a central location. This central location may be defined by a reinforcement plate 36 which remains in a central location in both the storage configuration and the operative configuration. Accordingly, as the folding frame is unfolded, the dimensions of the frame increase in a longitudinal direction and in a lateral direction.

However, the height of the folding frame is substantially the same in the storage position and in the operative position and is defined by the length of the support legs.

Each end support member 12 comprises an elongate member, for example a section of a metal tube or pipe, and in particular a steel pipe. Each end support member 12 comprises a hinge member 20 which locates along the longitudinal length of the elongate member, and preferably is located centrally or half way along the elongate member. The hinge member 20 comprises locking means in order to selectively lock the end support member 12 in a substantially linear configuration or to be unlocked in order for the elongate member to fold. The hinge member may comprise a channel section. The end support member comprises two sections 21, 23 each of which is pivotally connected at one end to the inner portion of the channel section 22. The second ends of the two sections are each pivotally connected to a respective support leg 16.

When the two sections 21, 23 are in a linear configuration the outer edges of the channel section 22 locate adjacent to or abut the outer surface of each section 21, 23. This prevents any further pivotal movement in a first direction but enables pivotal movement in an opposite second direction. Once in a linear configuration a locking plate and preferably a channel shaped locking plate of the hinge member can be rotated around the longitudinal axes of the two sections 21, 23 in order to prevent pivotal movement in the second direction. Accordingly, this locks and retains the two sections 21, 23 in a substantially linear configuration.

Each section 21, 23 includes an end member which is rotatably engaged in the end of each section. The end member is connected to a bush section which is pivotally connected to the locking plate. A pin locates through an aperture in the locking plate in order to lock the locking plate relative to the section 21, 23. If the pin is removed, the bush members and locking plate can rotate through 180 and the pin can be reinserted through the aperture to lock the locking plate to the sections 21, 23 whilst allowing the sections 21, 23 to now be foldable into a storage configuration.

The end support members for the lower bed level are shaped such that they do not interfere with the upper end support members whilst moving to a storage configuration. In another embodiment, as described later, the legs 16 are shaped such that the lower bed level does not interfere with the upper bed level.

Each lateral support member 14 comprises two sections 25, 27 and a locking hinge member 24 in order for the lateral support members 14 to be foldable whilst in an unlocked configuration and locked in a linear configuration.

In one embodiment of a bunk bed arrangement only the upper bed level may include the locking hinge members 20 (see Figure 15) and the hinge members 26 (see Figure 16) on the lower level may not be lockable. Once the two end support members 12 of the upper level are locked then this locks the frame in the lateral direction and effectively locks the end support members 12 in a linear configuration.

Once the two end support members are locked the lateral spacing of the support legs 16 is fixed.

However, preferably all of the hinge members for the bunk bed are lockable.

The lateral support members are connected to the legs through brackets 32 and similarly the bracket also connect the end support members to the support leg (see Figure 17) In the lower bed level, if reinforcement members are present another bracket is used (see Figure 18).

Similarly, only the lateral support members 14 in the upper level require locking hinge members 24 since this effectively will lock the lateral support members 14 in the lower level. Accordingly, once the lateral support members 14 are locked in a linear configuration the spacing of the support legs 16 of the frame are fixed in a longitudinal direction.

The frame further comprises reinforcement means in the form of two reinforcement members 30. The reinforcement members 18 extend between two diagonally opposing support legs 16. The reinforcement means are pivotally connected to the support legs 16 and preferably are pivotally connected to brackets 32 mounted on the legs. The brackets 32 comprise limiting means in the form of an abutment surface 34 which only enables the reinforcement members 18 to pivot from a linear position in one direction, for example the reinforcement members can only pivot upwards from a linear (or horizontal) position relative to the support legs 16.

The reinforcement members 18 extend across the base of one bed level, for example the lower level, and form a substantially X-shaped configuration. Each reinforcement member 18 comprises two sections 31, 33. An outer end 35 of each section 31, 33 secures to a support leg 16 whilst an inner end 37 of each section 31, 33 secures to a reinforcement plate 36 which is located centrally. The inner ends 37 of the reinforcement sections 31, 33 are pivotally connected to the reinforcement plate 35 and enable each reinforcement member 30 to fold.

In use, from a locked configuration, the locking plates 19 of the hinge members 20 for the end support members 12 and lateral support members 14 on the upper bed level are rotated to an unlocked position to enable the end support members 12 and lateral support members 14 to be foldable.

The end support members 12 of the upper bed level are then folded downward and towards each other whilst the end support members 12 of the lower bed level are folded upwards and towards each other. The reinforcement members 18 also fold towards each other and upwards in order to reduce the lateral separation of the support legs 16.

Similarly, the lateral support members 14 of the upper level are folded downwards and towards each other and the lateral support members 14 of the lower bed level are folded upwards and towards each other. The reinforcement members 18 also fold upwards and towards each other in order to reduce the longitudinal separation of the support legs 16.

Accordingly, all of the end support members 12, lateral support 14 members and reinforcement members 18 fold inwardly and do not increase the height of the frame. The support legs 16 all simultaneously move relatively towards each other and inwardly in order for the folding frame 10 to have a compact storage configuration.

As shown in Figure 13 and Figure 14, the outer perimeter of the folding frame 10 is the operative configuration (Figure 13) is significantly greater than the outer periphery of the folding frame 10 in the storage configuration (Figure 14). The outer perimeter is taken as a horizontal plane (i.e. viewed in plan) and is substantially perpendicular to the longitudinal axes of the support legs 16 or in a plane parallel to the support surface, in the operative configuration. It can be seen that the lateral and longitudinal spacing of the leg supports reduces from the operative configuration to the storage configuration. All of the support members (the end support members, lateral support members and reinforcement members) fold upwardly or downwardly (depending upon the embodiment) in order for all of the support members to fold in half such that they extend in a direction parallel to the longitudinal axes of the support legs. Accordingly, in the storage configuration the support legs, end support members, lateral support members and reinforcement members all extend primarily in a single longitudinal direction. It is appreciated that the support members may be angled slightly from this longitudinal direction.

As shown in Figure 15, the lockable hinge member 20 for the end support member 12 (or lateral support member) comprises a channel shaped portion 22. The end of a first section of an end support member 12 is connected to the hinge member 20 by a pivot 50. Similarly, the end of a second section of the end support member 12 is connected to the hinge member 20 by a second pivot 52. This enables the two sections to pivot relative to each other and for the end support member to fold in half. The channel portion is provided with a cut out portion 53 which enables the ends of the two sections to pass or project therethrough in the storage position. In order to lock the two sections in the linear position (i.e. in the operative configuration) the channel portion is rotated around the longitudinal axes of the two sections and preferably through substantially 180 C in order to be in an inverted position. In this position the two sections cannot pivot relative to each other in a downwards direction since the edges of the channel portion will abut the outer surface of the two sections and thereby prevents any pivotal movement. The lockable hinge member 24 for the lateral support members 14 operates in the same way.

As shown in Figure 16, the hinge member 26 for the lower end support member (and lateral support member) is not lockable. Accordingly, the hinge member 26 simply provides a channel portion having two pivots 54, 56 for pivotally connecting the two sections of the end support members 12 (or lateral support member). The hinge member 26 provides an abutment surface which prevents the end support members (or lateral support members) pivoting downwardly from the linear position (i.e. the operative configuration) but enable the end support members (or lateral support members) to pivot upwardly and for the end support member (or lateral support members) to fold into a storage configuration.

The end support members 12 and lateral support members are secured to the respective support legs by support brackets 32, 33 as shown in Figure 17 and Figure 18. The support brackets 33 comprises two channel portions 62, 64 to correspond with one end support member and one lateral support member. A first channel portion 62 may be substantially perpendicular to a second channel portion 64 in order to support an end support member perpendicularly to the adjacent lateral support member. The support bracket 33 further comprises a sleeve or passageway portion 63 to enable the support leg to project therethrough. In use, the support leg 16 is vertical whilst the end support member 12 and lateral support member 14 are substantially horizontally but perpendicularly offset. The support bracket 33 includes fixing means in order to fix the support bracket 33 at a predetermined height on the support leg 16. The support bracket 33 further comprises two pivots in order to pivotally connect the lateral support member 14 and the end support member 12.

As shown in Figure 18, the support bracket 32 for the lower bed level comprises three channel portions in order to secure an end support member 12 a lateral support member 14 and a reinforcement member 18 to a support leg 16. Again, fixing means is provided to enable the support brackets 32 to be fixed to the support leg 16 at a predetermined height. The support bracket 32 includes three pivot members in order for the end support member 12, lateral support member 14 and reinforcement member 18 to all pivot relative to the support leg 16. In addition, each channel portion includes a cut away portion.

The frame 10 may have a support surface for completing each bed level in the operative position. For example, a layer of a flexible or resilient webbing may be secured between the end support members 12 and the lateral support members 14 in order to provide a support surface for a sleeping bag or other sleeping surface for example a mat or mattress. The webbing may be provided with cut-out many portions around the support legs 16 and hinge members 20, 24 such that the webbing does not interfere with the operation of the folding frame 10 and can be left in position whilst the folding frame 10 is in both the operative configuration and the storage configuration.

Another embodiment of a folding frame 10 for an article of furniture is shown in Figure 19 and Figure 20. The support legs 116 comprise an angled portion such that the longitudinal axis of a top portion 117 is offset from, but parallel to, a bottom portion 118. In particular, the support legs 116 or frame members 116 effectively are bent inwardly such that the upper ends of the support legs 117 are spaced closer together compared to the lower ends 118.

The angled support legs 116 enable the folding frame to be compact in the storage position (see Figure 20).

The folding frame does not have any reinforcement members and the support means (not shown) comprises a textile sheet with eyelets or attachment tabs located around the periphery thereof which loop around the end support members 112 and the lateral support members 114 of the lower bed level and the upper bed level of the bunk bed.

Since this embodiment does not include any reinforcement members the support brackets 120 are all identical. The support brackets 120 have two channel portions arranged perpendicularly in order to engage an end of an end support member 112 and an end of an adjacent lateral support member 114.

All of the locking hinge members 122 are substantially identical. The lower end support members 112 are arranged to fold upwardly whilst theupper end support members 112 are arranged to fold downwardly, as shown in Figure 20.

Similarly, the lower lateral support members 114 are arranged to fold upwardly whilst the upper lateral support members are arranged to fold downwardly. Since the support legs 116 are angled inwardly, this enables all the folding to occur and the upper support brackets 120 locate adjacent to each other in the collapsed or stored configuration.

Since the support legs 116 are bent or angled, all of the support members 112, 114 can be straight.

Figure 21 shows how a hinge member 122, and in particular an upper hinge member 122 for an end support member 112.

The end support member comprises two sections 126, 128 which have an inner end section 127, 129 and a bush section 130, 131. The bush section 130, 131 is pivotally connected to the locking plate 132. The bush has a radial channel 134 extending approximately 180 around the periphery thereof. In the locked configuration, a pin (not shown) is inserted through an aperture 136 in the locking plate 132 and locates through the radial channel 134 and into an aperture 138 provided in the inner end section 127, 129. When the pin is removed the locking plate 132 and bush sections 130, 131 can rotate relative to the inner end sections 127, 129 and the section 126, 128 of the end support member 112. Once rotated through 180 , again the pin can be inserted to lock the locking plate 132 and bush sections 130, 131 relative to the sections 126, 128 of the end support member 112. However, in this configuration the locking plate 132 does not prevent the sections 126, 128 of the end support member 112 pivoting about the pivot between the bush sections 130, 131 and the locking plate and hence the end support member 112 can be folded. All of the locking plates and support members may operate in the same way.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification

(including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features

disclosed in this specification (including any

accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A folding frame including 4 upright support means and X horizontal support means each having central hinges creating a structure that is collapsible and foldable

2. A [ - ing frame as claimed in Claim I whereas all the support means creating a structure to be used as a support means for anther article

3. A folding frame as claimed in Claim f where both the top and bottom horizontal support means are connected to every corner bracket by pivot pin

4. A folding frame as claimed in Claim 1 and where all horizontal support means of the top section have a rotational central hinge which itself

5. A folding frame as claimed in Claim 1 and 2 where all the horizontal support meads of the bottom section have a central hinge

6. A folding frame as claimed in Claim 1 where the folding frame can be used as a supporting structure for 2 sleeping bases to create a collapsible buckled

7. A folding frame as claimed in Claim 1 where the folding frame can be used as a support means for I sleeping base to create a collapsible single bed

8. A folding frame as claimed in Claim 1 and any preceding claim including use for any other article of furniture, stand or support stand for any of the aforesaid

9. A folding frame as claimed in Claim 3 where the horizontal support means is rotational

10. A folding frame as claimed in Claim 3 and 7 where the horizontal support means is locked into place by a rotating central locking hinge

ll. A folding frame as claimed in any preceding claim which is made from metal, plastics or wood or from a combination of these materials

12. A folding frame as claimed in all Claims preceding from I to 1 t in relation to its folding method