Folding chair

Abstract: A folding chair includes a locking mechanism (10, 12, 15) for improved user safety. A locking bar (10) is mounted for limited movement on the underside of a seat panel (3). In the operation of opening the chair for use, the locking bar (10) automatically assumes a locking position in which it is located in a notch (15) formed in one leg frame (5). In order to close the chair, the user must first deliberately and manually dislodge the locking bar (10) from the notch (15). In another embodiment, a pair of folding leg frames (21, 22) are coupled together by a slotted sliding bar (27). A pin (29) which pivotally connects the seat panel (23) to one of the leg frames rides within the slot (28). The slot includes an angled locking portion (32) at one end which traps the pin (29) and thereby locks the leg frames in the open position. The lock is released by manually lifting the sliding bar so that the pin (29) re-enters the sliding portion (31) of the slot (28).

Description: This invention relates to a folding chair of the type comprising a pair of leg frames that are hinged together so that the chair may be folded substantially flat when not in use. In one chair of this general kind, a seat panel has one end hinged to one of the frames with the opposite end supported by the other frame when the chair is open for use. In another chair of this general kind, a seat panel and back support are hinged together to form a seat assembly that may be folded substantially flat, and the seat assembly is supported by the pair of leg frames. By their very nature, chairs of this type are inevitably prone to collapse during use. This can cause serious bodily injury. Additionally, the chair often collapses when it is lifted to be moved to another location. This is naturally inconvenient. Therefore, the aim of the invention is to realise a folding chair offering improved safety and/or convenience to the user. DE 94 00 541.9 U describes a folding chair having pairs of legs which can swivel and be fixed in relation to one another. A rear pair of legs can be displaced by means of a fixing rod mounted in guide slots provided in the two side pieces of the seat. The guide slot has the shape of a recumbent "L". In a functional position, the fixing rod is located in the upper end of the short side of the guide slot. To collapse the chair, the seat is slightly raised so that the fixing rod can be moved forwards in the long side of the guide slot. According to an aspect of the invention, a folding chair comprises a first frame that forms the rear legs of the chair and a second frame that forms the front legs of the chair, the first and second frames being pivotally connected so as to enable the chair to be folded substantially flat when not in use, and further comprises a seat panel that has one end pivotally connected to one of the frames and an opposite end engagable with the other of the frames whereby said other frame supports said opposite end of the seat panel when the chair is open for use. The chair is characterized in that a locking member is mounted on one of said other frame and said opposite end of the seat panel for limited movement relative thereto, and the other of said other frame and said opposite end of the seat panel includes a locking formation for receiving the locking member to lock the chair in the open condition, the limited movement of the locking member enabling the locking member to assume a locking position in which the locking member is located within the locking formation, and a release position in which the locking member is located outside the locking formation. The arrangement is such that the locking member automatically assumes the locking position in the action of opening the chair whereas the locking member must be manually moved into the release position in order to unlock and fold the chair. The above features ensure that the chair is locked automatically upon opening while, in order to collapse the chair, the user must first manually operate the locking member to unlock the chair. As a result, the folding chair of this first aspect of the invention incorporates a highly effective and safe locking mechanism whose operation is not dependent on the user remembering to lock the chair and which has a low probability of being accidentally released while the chair is in use. In a preferred embodiment, the locking member comprises a bar extending laterally across the width of the chair, and the locking formation comprises a groove or notch adapted to locate an edge of the bar. In order to achieve the required limited movement of the locking member, the opposite ends of the bar may be loosely trapped in respective recesses of a shape which permits movement of the bar between the locking position and the release position. These recesses may have a substantially triangular shape whereby the bar rests against one inclined side of the triangle in the locking position. The locking member is preferably biased into the locking position. The bias may arise under the action of gravity on the locking member or under the action of resilient means such as at least one spring element, or both. In the action of opening the chair for use, the locking member may be temporarily and automatically displaced from its bias position into the release position before being returned, by virtue of the biasing action, into the locking position in which the locking member engages the locking formation. In one design, the seat panel is hinged to the second frame that forms the front legs of the chair. In this design, the locking member is mounted on the seat panel and the locking formation is formed at the end of the first frame that forms the rear legs of the chair and supports the front edge of the seat panel. In this design, the first frame may engage the seat panel by means of pins that extend outwardly from the frame and slide within respective grooves formed at each side of the seat panel. Alternatively, the seat panel may be hinged to the first frame that forms the rear legs of the chair. In this case, the locking member is mounted on the second frame that forms the front legs of the chair and the locking formation is formed at the rear edge of the seat panel. The rear end of the seat panel is supported by the second frame when the chair is open for use. According to the aspect of the invention described above, the folding chair does not collapse when lifted up to be moved to a new location. This adds to the chair's convenience in everyday use. The invention is illustrated, but not limited, by the following description of preferred embodiments, given by way of example only, with reference to the accompanying drawings, in which: Figs 1 to 8 relate to a folding chair according to a first embodiment of the invention, wherein: Fig. 1 is a side view of the folding chair in its open state, Fig. 2 is a side view of the chair in its folded state, Fig. 3 shows a rear leg frame of the chair, Fig. 4 is an end view of the seat panel, Fig. 5 is an internal side view of the seat panel, Fig. 6 is a view of the locking mechanism with the locking bar in its locking position, Fig. 7 is a view of the locking mechanism with the locking bar in its release position, and Fig. 8 shows a modification of the locking mechanism. Referring firstly to Figs. 1 to 7, a first embodiment of the folding chair will be described. Fig. 1 shows the chair in its open condition and Fig. 2 in its closed or folded state. The chair comprises a pair of leg frames 1, 2 which are coupled together by means of a pivot connection, such as a hinge, at a point remote from the ends of the frames. The first leg frame 1 forms the rear legs of the chair and the second frame 2 forms the forward legs of the chair. In this embodiment, the second frame 2 also extends upwardly to form the back support of the chair. The back of the seat panel 3 is pivotally connected by means of a hinge to the second frame 2. The front of the seat panel 3 is supported by the upper end of the first frame 1 when the chair is open for use. Figs. 3 to 5 illustrate how the rear leg frame 1 is coupled to the seat panel. As shown in Fig. 3, the frame 1 comprises a pair of mutually parallel side members 5 that form the rearwardly extending legs. The side members 5 are connected together by a pair of cross bars 6. The upper ends of the side members 5 (as viewed in Fig. 1) include respective laterally outwardly extending pins 7, each of which may take the form of a screw or cylindrical stud or the like. As seen in Figs. 4 and 5 the seat panel 3 comprises a seating board 8 and a pair of side timbers 9. The inward faces of the side timbers 9 include a groove 11 that extends substantially the length of the side timber 9. The pins 7 of the leg frame 1 ride in the respective grooves 11 of the seat panel as the chair is opened and closed. When the chair is open for use, the pins 7 reside in the leftmost ends of the grooves 11, as viewed in Fig. 5. On the other hand, when the chair is fully folded, the pins 7 are located at the rightmost ends of the grooves 11, as viewed in Fig. 5. The chair is closed by lifting the front edge of the seat panel 3 upwardly and moving the same in the direction of the arrow 4 shown in Fig. 1. As the seat panel 3 moves towards the back support portion of the frame 2, the shorter frame 1 rides in the grooves 11 of the seat panel as the frames 1 and 2 close together in a scissors-like action. The locking mechanism in this embodiment comprises a locking bar 10 which is mounted on the underside of the seat panel towards the front edge thereof. In the locked condition, the locking bar 10 is located in notches 15 formed in the upper edges of the side members 5 of the shorter leg frame 1. The locking bar 10 extends laterally across the width of the seat panel. Its ends are located loosely in substantially triangular-shaped recesses 12 formed in the side members 9 of the seat panel. The locking bar is biased into the locking position shown in Figs. 5 and 6 under the action of gravity, as represented by the arrow 13 in Fig. 6. In this state, the locking bar rests on the inclined edges of the triangular recesses 12. In the operation of opening the chair, the leg frame members 5 slide along the grooves 11 in the seat panel, moving in the left direction as viewed in Figs. 5 to 7. As the ends of the leg frame members 5 approach the final position at the leftmost ends of the grooves 11, the locking bar 10 is temporarily moved upwardly being dislodged by the upper ends of the frame members 5. Immediately thereafter, the locking bar 10 drops down to the locking position in which the lower edge of the locking bar is located within the triangular notch 15 of each frame member 5. The chair is now in the locked condition shown in Fig. 6. The leg frame 1 is prevented from moving upwardly by the location of the pins 7 at the ends of the grooves 11 and to the left by the stop block 17. Movement of the leg frame members 5 in the rightward direction (as seen in the drawings) in an attempt to close the chair is prevented by the locking bar being located in the notches 15. The chair is thus locked automatically in the course of opening the chair for use. In order to close the chair, the user must temporarily dislodge the locking bar 10 from the notches 15 by moving the locking bar 10 into the release position, as shown by the arrow 14 in Fig. 7. The leg frame members 5 are then free to travel along the groove 11 to close the chair. Once the upper ends of the frame members 5 have passed the locking bar 10, the latter will drop back under the action of gravity to the bias position shown in Fig. 5. Fig 8 shows a modification of the locking mechanism in which resilient means are employed to bias the locking bar into the locking position. For this purpose, an angled plate 18 formed of spring steel sheet is mounted at each end of the locking bar 10. The plate 18 may be secured to the locking bar by means of one or more screws. Each plate 18 is arranged as shown whereby the bar 10 is moved to the release position against the spring action and returns to the biased position upon release. The invention may be embodied in numerous other ways without departing from the scope thereof. As an alternative to the described mounting arrangement for the locking bar of the first embodiment, the upper edge of the bar may be pivotally connected to the leg frame or seat panel. The movement of the locking bar between the locking and release positions may then be controlled by means of suitably positioned stopping members. In the described first embodiment, the second frame extends upwardly to form a back support for the chair. However, the principles of the invention are applicable equally to a chair in the form of a stool which has no back support. A chair in accordance with an aspect of the invention may also incorporate arm rests that are hinged to one or more of the leg frames, seat panel and/or back support in a manner that is known per se in the art.

Claims: A folding chair comprising a first frame (1) that forms the rear legs of the chair and a second frame (2) that forms the front legs of the chair, the first and second frames (1, 2) being pivotally connected so as to enable the chair to be folded substantially flat when not in use, and further comprising a seat panel (3) that has one end pivotally connected to one of said frames and an opposite end engageable with the other of said frames whereby said other frame supports said opposite end of the seat panel when the chair is open for use, characterized in that a locking member (10) is mounted on one of said other frame and said opposite end of the seat panel for limited movement relative thereto, and the other of said other frame and said opposite end of the seat panel includes a locking formation (15) for receiving said locking member (10) to lock the chair in the open condition, said limited movement of the locking member enabling the locking member to assume a locking position in which the locking member (10) is located within the locking formation (15), and a release position in which the locking member is located outside the locking formation, the arrangement being such that the locking member (10) automatically assumes the locking position in the action of opening the chair whereas the locking member must be manually moved into the release position in order to unlock and fold the chair. A folding chair according to claim 1, wherein said locking member comprises a bar (10) extending laterally across the width of the chair, and said locking formation comprises a groove or notch (15) adapted to locate an edge of said bar. A folding chair according to claim 2, wherein the opposite ends of said bar (10) are loosely trapped in respective recesses (12) of a shape which permits movement of the bar between said locking position and said release position. A folding chair according to claim 3, wherein each of said recesses (12) has a substantially triangular shape and said bar (10) lies adjacent one side of the triangle in said locking position. A folding chair according to any one of claims 1 to 4, wherein said locking member (10) is biased into said locking position under the action of gravity. A folding ohair according to any one of claims 1 to 4, wherein said locking member (10) is biased into said locking position under the action of resilient means (18). A folding chair according to any one of claims 1 to 6, wherein said other frame (1) engages said seat panel (3) by means of pins (7) that extend laterally outwardly from the frame (1) and slide within respective grooves (11) formed at each side (9) of the seat panel. A folding chair according to claim 7, wherein said first frame (1) constitutes said other frame.

Inventors: TSANG SHING CHI, TSANG SHING YIP, TSANG SING TAK, TSANG, SHING CHI, TSANG, SHING YIP, TSANG, SING TAK
Applicants: B T FURNISHING SDN BHD, B.T. FURNISHING SDN BHD
Application year: 2000
Main classification: A47C4
IPC codes: A47C4