Abstract:
A chair has a seat surface having a front region which is turned downwardly and is pullable rearwardly under the seat surface for reducing a seat depth.

Description:
BACKGROUND OF THE INVENTION 
     The present invention generally relates to chairs. 
     Modern chairs are frequently provided with seat depth adjustments, for adaptation of the seat surface of the chair to individual upper limb length of the people who have upper limb length deviating from normal sizes. 
     The seat depth adjustments which are presently known either have a relatively complicated construction or are not especially ergonomic during their use. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of present invention to provide a chair, in particular a work chair, with a seat depth adjustment means which is improved so that the seat depth adjustment has a very simple construction and is easy to operate. 
     In keeping with these objects and with others which will become apparent hereinafter, one feature of present invention resides, briefly stated, in a chair, in particular a work chair which has a seat surface whose front region is downwardly turned, and which under the seat surface for a reduction of the seat depth is pullable rearwardly. 
     Thereby the seat depth adjustment has a very simple construction and can be manufactured with low expenses. 
     Advantageously the front edge of the turned region is mounted on a slider which is displaced parallel to the seat surface. For easy adjustment of the seat surface by a person sifting on the chair, a rod can be mounted on the slider for forward and rearward pulling of the seat surface parallel to the front end of the seat surface. The rod can project at both sides slightly outwardly beyond the turned region of the seat surface, so that it can be used for adjustment of the seat depth simultaneously as a handle. 
     In order to guarantee an easy sliding of the slider arranged under the seat surface, the slider can be provided with a rod arranged under the seat surface and guided in a guide. The slider can slid especially well and without canting when it has two rods guided in at least two guides, symmetrically to a center. 
     For arresting the seat depth adjustment means in the desired position, the at least one rod and/or the guide can be provided with arresting elements. In an especially simple and cost-favorable manner, the arresting elements can be formed as synthetic plastic knobs or balls arranged on at least one rod or the guide, and engaging in depressions in the associated guide or rod. 
     The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of a seat surface with a seat depth adjustment from a chair according to the invention; 
     FIG. 2 is a side view of the seat surface with the seat adjustment of FIG. 1, but with a changed seating depth; 
     FIG. 3 is a perspective view of one embodiment of the seat depth adjustment device; 
     FIG. 4 is a detailed side cross-sectional view through the seat depth adjustment of FIG. 1 showing arresting element structure; and 
     FIG. 5 is a detailed side cross-sectional view through an additional embodiment of the seat depth adjustment according to the invention, showing a different arresting element structure. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 shows a seat surface  10  of a not shown chair. A slider  11  is arranged on its lower side and is displaceable parallel to the seat surface  10 . A front region  12  of the seat surface is downwardly turned and mounted by a rod  13  on the seat surface  10 . The rod  13  has a slot  16  extending in a longitudinal direction of the rod  13 . The front end of the seat .surface  10  can be inserted into the rod  13  through the slot  16 . By displacing the slider  11  forwardly or rearwardly the seat surface  10  can be elongated as shown in FIG. 2 or shortened as shown in FIG.  1 . 
     The slider  11  has two rods  14 , which are guided in two guides  15  shown in FIG.  3 . The guides  15  and the rods  14  are provided with arresting elements  50 ;  52 ,  52 ′ like those shown in the embodiments of FIGS. 4 and 5. The arresting elements  50 ;  52 ,  52 ′ are used for maintaining a desired seat depth fixed during use. In the embodiment shown in FIG. 4 the chair has a rod  14  that is not telescoping and the arresting elements comprise knobs  52  provided on the rod  14  and depressions  50  provided in the guides  15 , which are engageable in each other to prevent sliding of the rod in the guides. In the additional embodiment shown in FIG. 5 instead of knobs  52 , the balls  52 ′ are provided on the rod  14 . Alternatively the depressions could be provided in the rod and the guide could be provided with the knobs or balls. 
     FIG. 3 shows the slider  11  of FIG. 1 from below in a perspective view. The slider  11  is mounted on a base plate  30 , which in turn can be mounted on the lower side of the seat surface  10  of FIG.  1 . The rods  14 , which are displaceable parallel to the seat surface, are telescoping in the embodiment of FIG.  3 . At their one end they are connected with the rod  13 . The both outwardly projecting ends of the rod  13  enable a person who sits on the chair to arbitrarily adjust the seat depth simply and without great contortions. 
     It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above. 
     While the invention has been illustrated and described as embodied in a chair, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.