backrest

The present invention relates to an item of seating furniture with a spring-mounted backrest.

Items of seating furniture with a spring-mounted backrest are known from the prior art. In the case of what are referred to as relaxing chairs, a user can lean with his weight against the backrest such that the latter is inclined rearwards and takes up a more pleasant position for the user. The backrest here is connected via a linkage to the seat surface in such a manner that the seat surface is inclined relative to a supporting structure. If the user by means of his bodyweight moves the backrest rearwards, the seat surface is inclined in such a manner that the bearing surface of the user' s posterior is located lower than the bearing surface of the thighs. The seat surface therefore slopes towards the backrest.

During the movement of the backrest, resetting means exert a resetting force on the backrest, said resetting force being directed counter to the force exerted by the user. The resetting force ensures that the backrest is moved again into the starting position when the force exerted by the user ceases, i.e. when the user moves forwards again. Different user weights mean that the resetting force is perceived to be well-balanced only by a few users. Heavy users perceive the resetting force to be too low, whereas light users perceive the resetting force to be too high. Therefore, a light user may move the backrest rearwards only by great effort, whereas a heavy user by means of his weight moves the backrest rearwards even if he does not desire this at all. By contrast, the invention is based on the object of providing an item of seating furniture with a greater degree of comfort for users of differing weight. This object is achieved by an item of seating furniture with the features of Claim 1. Embodiments of the invention are indicated in the dependent claims.

According to Claim 1, the item of seating furniture comprises setting means which are designed to set the resetting force. A user can set the resetting force according to his requirements by using the setting means. For example, a relatively heavy user can set a relatively high resetting force, and therefore said user has to apply a relatively high force in order to move the backrest rearwards. The relatively heavy user will not find this difficult because of his weight. The same item of seating furniture also provides a high level of comfort for a relatively light user. The relatively light user can use the setting means to set a relatively low resetting force, and therefore said user has no problem in moving the backrest rearwards counter to the resetting force. According to one embodiment of the invention, the resetting means can be supported on the seat surface. The term "seat surface" is understood here as meaning, in particular, supporting components and the bearing surface for the user' s posterior and for at least part of the thighs. The supporting components can be connected directly or indirectly to the bearing surface. The supporting components are immovable here relative to the bearing surface. The entire seat surface can therefore only be moved as a whole relative to the backrest and/or to the supporting structure of the item of seating furniture. The term "supporting structure" is understood here as meaning, in particular, components which support the seat surface and also components which support the backrest. The supporting structure may also be referred to as the base. The supporting structure may comprise standing means which are designed to stand the item of seating furniture on a flat surface.

In addition, the resetting means can be connected to the connecting means. The resetting force can be exerted on the backrest via the connecting means, for example a linkage.

During use of the item of seating furniture as intended, the resetting means can be arranged in particular below the seat surface. The resetting means can be supported in particular on an end region of the seat surface that faces the backrest.

According to one embodiment of the invention, the item of seating furniture can comprise a footrest which is pivotable into a region below the seat surface. Such a footrest is advantageous for an even higher level of comfort of the item of seating furniture. In particular when the user has leaned rearwards, the footrest can support the legs and/or feet of the user. The footrest can be coupled mechanically to the seat surface and/or the backrest in such a manner that, when the backrest moves from the first position into the second position, i.e. rearwards, the footrest under the seat surface is swung away upwards and is suitable for supporting the legs and/or the feet of the user. When the backrest moves into the first position, the footrest can be swung under the seat surface such that it does not annoy a user. In this connection, it is particularly advantageous if the resetting means are supported in the end region of the seat surface. This is because sufficient space then remains below the seat surface for the swung-in footrest. According to one embodiment of the invention, the connecting means can comprise a linkage. This linkage may also be referred to as a lever mechanism which couples the movement of the backrest to the movement of the seat surface.

According to one embodiment of the invention, the resetting means can be designed to exert the resetting force on the backrest during the entire pivoting operation of the backrest.

According to one embodiment of the invention, the resetting means can comprise a spring. According to one embodiment of the invention, the spring can have a pretension. The pretension can be set by the setting means.

According to one embodiment of the invention, the setting means can comprise a threaded rod and a gripping means which is screwable onto the threaded rod. The pretension can be set by the extent to which the gripping means is screwed onto the threaded rod. This is a particularly convenient manner for the user of setting the resetting force.

According to one embodiment of the invention, the threaded rod can have a left-handed thread. This is advantageous in particular if the setting means are arranged below the seat surface during use of the item of seating furniture as intended. Tests have shown that, by means of the fitting below the seat surface, most users experience an increase in the resetting force upon a rotation in the clockwise direction. This can be achieved by a left-handed thread.

According to one embodiment of the invention, the threaded rod can have a trapezoidal thread. The relatively large pitch of the trapezoidal thread is an advantage so that the desired resetting force can be set by relatively few revolutions. According to one embodiment of the invention, the spring can be designed as a helical spring with a plurality of turns. The number of turns per length unit can be inconstant here. As a result, different resetting forces can be set by means of the threaded rod and the gripping means.

According to one embodiment of the invention, the number of turns of the spring per length unit can increase continuously from one end to another end of the spring. Depending on the extent to which the gripping means has been screwed onto the threaded rod, the spring is pretensioned to a greater or lesser extent. Different resetting forces can thus be achieved by the continuous increase in the turns per length unit.

According to one embodiment of the invention, the turns can have different radii of curvature. This can likewise contribute to different resetting forces being able to be set particularly easily.

According to one embodiment of the invention, the radii of curvature can increase continuously from one end to the other end of the spring. In this case, the shape of the spring may also be referred to as conical.

The invention is described in more detail with reference to the attached figures, in which: Fig. 1 shows schematic illustrations of an item of seating furniture according to one embodiment of the invention in various positions; Fig. 2 shows schematic illustrations of the resetting means and setting means in the case of an item of seating furniture according to one embodiment of the invention;

Fig. 3 shows a schematic illustration of the item of seating furniture from Fig. 2 with differently set resetting means. Figures 1A to IE illustrate an item of seating furniture 100 with a backrest 101 and a seat surface 102. The backrest 101 is connected to the seat surface 102 via a linkage 103. A user can move the backrest 101 rearwards. This operation is illustrated in Figures 1A to IE. In Figure 1A, the backrest 101 is in a first position. In Figure IE, the backrest 101 is in a second position. The movement of the backrest 101 is converted via the linkage 103 into a movement of the seat surface 102. By means of this movement, the seat surface 102 changes its inclination relative to a supporting structure (not illustrated) to which both the backrest 101 and the seat surface 102 are fastened.

A resetting force acts on the backrest 101 in the direction of the first position. Said resetting force can be set by a gripping means 104.

Figures 2A to 2C more clearly illustrate how the resetting force is produced and how it can be adjusted. A helical spring 200, which is supported at one end of the seat surface 102, is provided. When the backrest 101 is moved from the first position in the direction of the second position, the spring 200 is compressed. If force is no longer exerted on the backrest 101 by the user, the resetting force of the spring 200 moves the backrest 101 into the first position again. The pretension of the spring 200 in the first position can be set by the gripping means 104. The gripping means can be screwed onto a threaded rod, as a result of which the spring is likewise compressed. The spring 200 has a progressive force increase. This means that the force which is required in order to deform the spring becomes greater the further the spring is compressed. This can be achieved, for example, by a conical spring shape or by a continuous change in the number of spring coils per length unit. Therefore, the further the gripping means 104 is screwed onto the threaded rod, the greater the force has to be in order to move the backrest 101. The resetting force can thus be set to the requirements of different users.

A comparison in Figures 3 and 2B makes it particularly clear how different resetting forces can be set. In the two figures, the backrest 101 is at the same angle with respect to the seat surface 102. However, in Figure 3, the gripping means 104 is screwed further onto the threaded rod, and therefore the spring 200 is further compressed and a greater force is required for moving the backrest 101.