Field of the Invention

This invention generally relates to a chair struc- ture of the type having at least one seat element and an associated back element which both are supported by a leg arrangement comprising front and rear legs whose free ends can be directly or indirectly applied against the chair-supporting structure, e.g. a floor, and which are articulated to one another and hence pivotable between, on the one hand, an unfolded position in which the free ends of the front and rear legs are maximally separated and, on the other hand, a folded-up position in which said leg ends are moved closer to one another. Background of the Invention

It is often the case that one and the same room has to serve many different purposes. For instance, lecture halls, assembly halls and similar meeting halls should on some occasions have chairs for the audience, e.g. when a lecture is to be held or a film shown, and on other occa¬ sions present a more or less empty floor, e.g. when a dance is to be held. Accordingly, specific and in some respects incompatible demands are placed on the chair structures used. On the one hand, moving the individual chair between the hall and the storeroom should be a sim¬ ple and expedient operation that, when need be, can be rapidly performed. In addition, the chair should take up but a minimum of space in the storeroom. On the other hand, the chair should be comfortable to sit on, which necessitates a design making the chair comparatively heavy. Furthermore, a frequent requirement is that it should be possible to easily arrange the chairs in per¬ fectly straight rows in the halls, which often is quite difficult with single chairs. For this reason, chair structures intended for lecture halls are today not seldom so designed that two or more seats and associated backs are built together.

Although a folding chair of the type stated by way of introduction meets the requirement of taking up a minimum of space when stored, prior-art folding chairs often do not provide the comfort required when used for periods of some length. Mostly, known folding chairs consist of sim¬ ple lightweight structures, primarily designed for allow¬ ing maximum ease of transportation between the lecture hall and the storeroom as well as taking up a minimum of space when stored. Moreover, prior-art folding chairs are all single chairs, i.e. having one seat and one back, and are thus placed in straight rows only with some diffi¬ culty. Objects of the Invention

The present invention aims at providing a chair structure that meets the above requirements, thus being particularly suitable for use in halls which should be able to accommodate a seated audience for long spells as well as to be rapidly evacuated. A basic object of the invention is, therefore, to provide a comfortable chair structure which is easy to move despite its comparatively heavy weight caused by the comfortable design and which takes up a minimum of space when moved and when stored owing to its folding construction. Another object of the invention is to provide a chair structure which easily is implemented with two or more seats and associated backs, thereby not only facilitating the arrangement of the chairs in the hall, but also reducing the time it takes to move the chairs between the site where they are used and the site where they are stored. Summary of the Invention

At least the basic object of the invention is achiev¬ ed by a chair structure in which movable elements are con¬ nected to the front as well as the rear legs and carry rolling elements, e.g. wheels, which occupy an inoperative position not lower than the level of the free ends of the legs when these are in the unfolded position, or which are forcedly maintained in an operative position at least

partly below the level of the leg ends in order to keep these raised from the chair-supporting structure, thereby allowing displacement of the chair by rolling on the roll¬ ing elements. Advantageous embodiments of the invention falling within the scope of the general inventive idea are recited in appended claims 2-7.

Further Elucidation of the Prior Art

US-3,495,868 discloses a folding chair in the form of a lightweight sun chair. However, this chair bears no resemblance to that of the present invention other than the provision of wheels, more precisely a single pair of wheels allowing the chair to move by rolling when in the folded-up position. The wheels of the chair known from US 3,495,868 are, however, fixedly connected to the frame structure of the chair, more specifically by being mounted on the ends of a stationary shaft forming part of the frame. In as far as they are at all associated with the legs of the chair, these fixed wheels are associated mere- ly with the rear legs, the front "legs" having no wheels or rolling elements at all. If the known chair is to be rolled, it therefore has to be totally collapsed to a folded-up position in which the rear legs have been retracted in relation to the wheels, enabling the chair to roll in a position in which the collapsed frame is close to the ground or the chair-supporting structure. Thus, the known chair cannot roll while still in the erected state. Brief Description of the Drawings In the drawings, FIG. 1 is a perspective view of an inventive chair struc¬ ture having two seats which are here in an inope¬ rative folded-up position, FIG. 2 is a simplified side view of the chair structure, the seats being in the folded-up position also here, and

FIG. 3 is a similar side view showing the seats in the unfolded position of use.

Description of a Preferred Embodiment

The chair structure illustrated in Fig. 1 comprises two seats 1, 1' and two backs 2, 2', which are built together so as to form a two-seater. The chair structure includes front legs 3 and rear legs 4, more precisely three front legs 3, 3' , 3" and four rear legs 4, 4' , 4" and 4"'. The free end of each leg 3, 4 is designated 5. Although the leg end 5 might be used as a contact surface to be directly applied against the supporting structure or floor, the legs are, in the preferred embodiment illu¬ strated, equipped with special foot-like supporting or contact plates 6 joined to the legs by means of a screw 7 screwed into a threaded hole (not shown) opening in the underside of the leg ends. Thus, the supporting plates 6 can be vertically adjusted in relation to the legs. It should here be emphasised that the supporting plate 6 is equated with the leg end 5 when reference is made to "the level of the leg ends" in the following description and the appended claims. An arm 8, serving as supporting means for a rolling element in the form of a wheel 9, is articulated to some of the chair legs. In the embodiment illustrated, two of the front legs, namely the legs 3' and 3", are connected to such an arm, while two rear legs, namely the legs 4 and 4", have such arms. The individual arm is connected to the assocatiated leg, e.g. the leg 3', by an articulation 10 in the vicinity of one end of the arm. The wheel 9 is arranged in the area of the opposite end of the arm. To be more precise, the wheel 9 is here rotatable about a pin in a holder 11 which in turn is connected to a bracket 12 on the arm by means of a vertical pivot pin which in known manner allows the wheel to pivot freely in optional angu¬ lar directions. The arm 8 that is articulated to a front leg cooperates with a stop lug 13 on a corresponding rear leg. Likewise, each arm connected to a rear leg cooperates with a stop lug 13' provided on the corresponding front leg of each pair of legs. In the folded-up storage posi-

tion (Figs 1 and 2), the free end of the arm 8 remote from the articulation 10 is located below the associated stop lug 13 or 13' .

It should be observed that the stop lugs 13 on the rear legs are thin compared with the stop lugs 13' on the front legs, while the articulation 10 of each arm connect¬ ed to a front leg is arranged on a spacer 14 whose thick¬ ness essentially corresponds to that of a rear leg. The rear legs, on the other hand, have no such spacers, and the individual arm 8 is thus applied directly against the lateral surface of the leg.

Although a wheel 9 is illustrated in the drawings, it is conceivable within the scope of the invention to use other rolling elements, such as balls, which like the wheels are able to provide a rolling action making it easier to move the chair on the supporting structure.

Each front leg 3 forms part of a side piece, general¬ ly designated 15, which in the area of an articulation 16 between the front and the rear leg of each pair is bent, such that an upper portion 17 thereof forms a supporting frame member for the back 2. The side piece 15 roughly has the shape of a J. The angle between the leg 3 and the frame portion 17 here is about 140°. In practice, this angle may vary, but should be 130-150°. The embodiment illustrated includes three side pieces 15 of which the central one is common to the two backs 2, 2'. On the out¬ side of the central side piece and on the inside of the two external side pieces, there is provided at least one projecting pin (not shown) anchored in the associated backs to provide a permanent connection between each side piece 15 and the associate back. Advantageously, an exten¬ sion arm 18, serving as an arm rest, may be provided on each side piece.

In the embodiment illustrated, the articulation 16 is formed of a throughgoing rod or tubular element common to all the pairs of legs and extending through holes in the legs. Each rear leg 4 is extended a certain distance above

the articulation 16 so as to support the seat 1 in an upper portion 19. More specifically, the upper portions 19 of rear legs nearby are connected to the associated seat 1 by pivot pins 20 arranged on a rigid frame 21 forming part of the seat 1. In the swung-down position of the seat shown in Fig. 3, the rear part of the frame 21 cooperates with stop means 22 on the side pieces 15. It should here be pointed out that each side piece 15 has, on at least one side, a stop means 23 located in the vicinity of the articulation 16 and serving to stop the rear leg 4 when unfolded in relation to the associated front leg.

A pivotable latch 25 is connected to the upper por¬ tion 19 of at least one of the four rear legs, e.g. one of the central legs 4' and 4", by an articulation 24 and exhibits a recess 26 which can be engaged by the stop means 22. The recess 26 is located at a considerable dis¬ tance from the free end of the latch, so that the latch will project a considerable distance from the rear side of the back when in the locking position, as shown in Fig. 2. Finally, it should be observed that all the front legs 3 are interconnected by a common first stiffening element 27 in the form of a flat bar. Likewise, the rear legs 4 are interconnected by a common second stiffening element 28 in the form of a flat bar or the like. Function of the Inventive Chair Structure

In the position shown in Fig. 3, the legs 3, 4 are swung to an unfolded position, in which the free ends of the legs equipped with the supporting plates 6 are maxi¬ mally separated. The latch 25 is disengaged from the stop means 22, and the seat 1 is swung down to a position of use, in which the rear part of the frame 21 is applied against the underside of the stop means 22. In this posi¬ tion, the chair stands firmly on the floor 29, the sup¬ porting plates 6 being in reliable frictional contact therewith. At the same time, all the wheel-supporting arms 8 are freely pivotable about the associated articulations, such that the wheels are merely resting on the floor. When

the seat 1 is thus swung down, the chair is comfortable to sit on.

When the chair is to be moved from the room where it is standing to a suitable storeroom, it is swung a certain distance in the forward direction, the supporting plates 6 of the front legs serving as points of articulation, while at the same time the person performing this operation puts one of his feet against the rear flat bar 28. The rear legs 4 will thus be swung clockwise about the articulation 16, shortening the distance between the supporting feet 6 of each pair of legs. When the legs 4 have been swung a sufficient distance, the latch 25 will come into engage¬ ment with the stop means 22, and the two legs of each pair will thus be locked in relation to one another. When the legs are thus folded up, also the arms 8 are swung about the associated articulations, such that the free end of each arm will finally come to be located below the asso¬ ciated stop lug 13 or 13' . Each stop lug 13 or 13' is so positioned that the wheels 9 are at least partly located on a level below an imaginary plane common to the support¬ ing plates 6, when the wheel-supporting arms 8 have been introduced below the respective lugs. As a result, the wheels 9 take over the supporting function of the support¬ ing feet 6, and the entire chair will thus be supported by the wheels when collapsed to the position shown in Figs 1 and 2. In this position, in which the chair takes up a minimum of space, the chair is easily rolled on the floor. The rotatable wheel suspension, allowing the wheels to be set in optional angular directions in relation to the chair, makes it particularly expedient to move the chair. When the chair, after being stored and rolled to a place of use, is to be unfolded to the position shown in Fig. 3, the easily accessible latch 25 is released from the engagement with the stop means 22, while at the same time the chair is slightly lifted from the floor. Because the total weight of the seats 1, 1' and the leg portions 19 exceeds that of the legs 4 projecting downwards from

the articulation 16, the legs will be swung about the articulation 16 to the maximally unfolded position, determined by the stop pin 23, in which the supporting plates 6 resume their supporting function. Then, the stop lugs 13, 13' slide along the upper side of the arms 8, and as soon as they have passed the free ends of the arms, the wheels will be free to move upwards to the level of the supporting plates 6. Advantages of the Invention A considerable advantage of the invention is that the seats and backs of the chair, as well as its other component parts, can be of solid design, providing com¬ fort as well as secure retention of the chair in the unfolded position. At the same time, the chair is rapidly and easily transported between the places of use and storage despite the fairly heavy weight necessitated by the solid design. Moreover, the unfolding and folding-up operations are very easily and rapidly performed. Because the side pieces 15 are angular as described above, the chair can be collapsed by simply being tilted forwards, the free ends or the supporting plates of the legs 3 serving as pivot joints. Another advantage is that the chair structure may comprise more than a single seat or back. Thus, the chair may in actual practice have two or more seats and backs, without there being any problems when the chair is to be moved. The more seats forming part of the structure, the more rapid the filling and the evacuation of a room. Within the scope of the invention, the production of chair structures having four, six or eight seats is thus envisaged.

Conceivable Modifications of the Invention

It goes without saying that the invention is not restricted to the embodiment described above and shown in the drawings. Thus, use can be made of rolling elements other than wheels and movable supporting means other than pivotable arms. The important thing is that the supporting means, when the chair is collapsed, forcedly retain the

rolling elements at least partly below the level of the leg ends or the supporting plates thereon in order to keep the legs raised from the chair-supporting structure, thereby enabling the chair to roll. Furthermore, the latch 25 mentioned above may be replaced by other means for locking the legs in relation to one another when in the folded-up position. Also, the chair can be supplemented with means, especially springs, facilitating the folding- up operation. Thus, a tension spring can be provided between a pair of legs 3 and 4 and is tensioned in the unfolded position of the chair, contributing to swinging the legs 4 clockwise about the articulation 16 when the chair is collapsed (analogously, a compression spring can be provided between the upper portion 17 of the side piece 15 and the upper leg portion 19). One or more springs of this type also have a dampening effect when the chair is unfolded. For the sake of simplicity, the stop lugs 13, 13' are illustrated in the form of simple rod-shaped ele¬ ments. Instead of such rod-shaped elements, use may, in actual practice, advantageously be made of elements, such as L-sections or U-sections, that also have a guiding function for the arms 8, so that these are at all times guided in a plane parallel to the legs 3, 4. The term "stop lug" is therefore to be interpreted in the broadest sense, encompassing every element against which the indi¬ vidual arm can be applied and operate in the manner described above.