Abstract:
The present invention concerns a device in a chair, especially a chair with an adjustable back of the chair and head rest, in that in between a section of the head rest and an attachment section on the chair construction is arranged a connecting element with for example a rod, which by movement of the adjustable back of the chair is arranged to affect the angle of the head rest in relation to the back of the chair, and for the purpose of giving instructions on a head rest that by a blocking device and a coupling organ which come into effect in the reclined position of the back of the chair, either in a manual or automatic way.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a length-adjustable connecting element for a chair, with adjustable back of the chair and head rest, arranged between the head rest and the chair construction, which by movement of the adjustable back of the chair is arranged to affect the angle of the head rest in relation to the back of the chair, as the angle of the head rest may be altered by changing the effective length of the connecting element in the reclined position of the back of the chair.  
         PRIOR ART  
         [0002]    From WO 92/06621, which is incorporated herein as reference, a device for a chair with adjustable back of the chair and head rest is known, wherein the head rest may be adjusted in relation to the relative reclining positions of the back of the chair, using a telescopic length adjustable connecting element that stretches between the head rest and a suitable location on the chair. This device has relative complicated and expensive regulating organs and locking organs which must be operated through the upholstery of the chair, and they are difficult to make functioning in a satisfactory way.  
         PURPOSE OF THE INVENTION  
         [0003]    The basis of the present invention lies in the object of presenting a connecting element that comprises simple parts, that is robust and dependable and that is silent in use.  
           [0004]    An additional object of the present invention is to provide a connecting element with manual or automatic adjustment that may be adapted to any chair with a head rest, including such chairs having arched guides, and also such chairs with adjustable lower back support.  
         SHORT DESCRIPTION OF THE INVENTION  
         [0005]    The aforementioned objects are achieved by a device of the introductory given kind, which according to the invention is characterized by the features evident from the enclosed patent claim  1 .  
           [0006]    Additional features and advantages of the present invention will be apparent from the following description taken in association with the enclosed drawings, and the additional enclosed patent claims. 
       
    
    
     SHORT DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a phantom drawing of a chair according to the invention seen from the side, wherein the back of the chair is in a reclined position, simultaneously as the head rest is shown in a reclined position in dotted line.  
         [0008]    [0008]FIGS. 2-5 depicts different positions of the head rest in relation to the back of the chair, in one embodiment of the connecting element according to the present invention, in a length profile.  
         [0009]    [0009]FIGS. 6 and 7 depicts the connecting element in FIGS. 2-5 in a locked and an uncoupled position, respectively, in larger detail. 
     
    
     DESCRIPTION OF EMBODIMENTS  
       [0010]    On FIG. 1 the framework of a chair  1  of the type disclosed in WO 92/06621 is mainly shown, which chair  1  comprises an adjustable back of the chair  2  with an adjustable head rest  3 .  
         [0011]    It should be understood that the chair specified in FIG. 1 has a special adjustment of the head rest  3 . The head rest is active in that it maintains an upright position when the back of the chair is reclined. In the reclined position of the back of the chair this function of the head rest may be disconnected by pulling the head rest somewhat forward. The head rest may then be reclined.  
         [0012]    In FIG. 1 the back of the chair  2  is supported about an axis of rotation  9  making it possible for the back of the chair  2  to take different angular positions, as the back of the chair in the lower part at the same time has a connection joint  10  to the chair seat  5 , which is accomplish by a known movement mechanism  8 .  
         [0013]    In FIG. 1 a connecting element  18  with a rod  17  is also shown, which is attached at the top to a joint  19  on the head rest, and which in the lower part is attached to a joint  7  on a permanent part of the framework of the chair, in a distance from the axis of rotation  9 . The connecting element  18  with the rod  17  may take mainly two different length positions and has its shortest length amongst others when the back of the chair  2  is in an upright position, wherein the head rest  3  is almost an extension of the back of the chair  2 , and forms its largest angle (almost 180°) with the back of the chair. When the back of the chair  2  is reclined to the position shown in FIG. 1, the relative movement of the back of the chair  2 , and the connecting element  18  with the rod  17 , will imply that the head rest  3  is pulled forward to a steeper angle in relation to the back of the chair  2 . With the help of a mechanism, the connecting element may then be lengthened, so that the head rest may be reclined to the dotted position  3 ′.  
         [0014]    In FIGS. 2-5 one embodiment for a connecting element according to the present invention is shown.  
         [0015]    In this embodiment the connecting element  18  comprises groove  21 , blocking device  22  and coupling organ  24  which cooperate with each other so that the head rest  3  may be affected in the above mentioned ways by changing the length of the connecting element. The length of the connecting element  18  is further restricted in this embodiment by the stopping device  25  and track  26 .  
         [0016]    In FIGS. 6 and 7 it is shown in greater detail that the connecting element  18  comprises a guide  20  in the form of a circular cylinder, a blocking device  22  in the form of a sphere, a slider  23  and a stopping device  25 . The coupling organ  24  is in the form of a first track in slider  23 , wherein the coupling organ  24  has a more shallow part A and a deeper part B, which cooperate with the blocking device  22  and a groove  21  in guide  20 .  
         [0017]    Likewise, it may from FIGS. 6 and 7 be seen that the connecting element may comprise a track  26  in slider  23  with end restrictions C and D which cooperate with a stopping device  25  placed in a hole in guide  20 . The stopping device  25  is held in place in guide  20  by a spring ring  27  surrounding the guide  20 .  
         [0018]    The main parts of the connecting element, such as the guide  20 , the slider  23 , and the rod  17  may be produced in a mouldable material such as a plastic material.  
         [0019]    In an upright position of the back of the chair  2 , the blocking device  22  will fall down between the shallow position A in the coupling organ  24  in the slider  23  and the groove  21  in the guide  20 , due to gravity as is evident from FIG. 2. When the back of the chair  2  is reclined as shown in FIG. 3, the head rest function is locked. In the reclined position of the back of the chair  2  as shown in  4 , a small (manual) pull forwards of the head rest  3  will release the blocking device  22  out of clamp between the shallow position A in the coupling organ  24  and the groove  21 , down into the deeper position B of the coupling organ  24  due to gravity, and thereby uncouple the head rest as shown in FIG. 5. This implies that the slider  23  will move in the guide  20 , and not fall down between position A in the coupling organ and the groove  21  until in a new upright position of the back of the chair  2 . When the back of the chair  2  is reclined down again, the blocking device  22  will lock the slider  23  to the guide  20  and the head rest function is regained in cooperation with the connecting element  18 .  
         [0020]    The movement of the head rest  3  is further restricted in this embodiment by the movement of the slider  23  in guide  20  being restricted by the guiders stopping device  25 , which run in the gliders track  26  between the end restrictions C and D. This restricts the movement of the head rest forward, in upright position, as the slider  23  may not be moved further into the guide  20  than when the stopping device  25  stands against the end restriction C in track  26 , see FIG. 1 and FIG. 6. In the reclined position of head rest  3 , the movement both forward and backwards is restricted, where the latter is of most current interest in that the slider  23  moves in the direction out of the guide  20  until the stopping device  25  stands against end restriction D in then track  26 , see FIGS. 5 and 7.  
         [0021]    In the embodiment shown in FIGS. 2-5 the chair is further equipped with a driver  30  attached to the back of the chair in its one end and to the joint  19  on the head rest in its other end by a track  31 , as shown in FIG. 4. The driver  30  secures the head rest  3  against backward distortion in the reclined position, and brings the head rest  3  with it when the back of the chair  2  is raised up such that the slider  23  moves all the way down into the guide  20  in the upright position, making the blocking device  22  fall down between the groove  21  and position A in the coupling organ  24  again.  
         [0022]    In other embodiments the stopping device with track as described over may be arranged on other places in the connecting element than shown in the figures, or on other movable parts between the back of the chair  2  and the head rest  3 , such as for example on the arched guides of the head rest or as separate stopping devices similar to the driver  30 , or the function may be attended by the upholstery.  
         [0023]    The driver  30  may likewise be arranged on other places between the back of the chair  2  and the head rest  3 , or its function may be attended by the upholstery for example, or devices in the arched guides of the head rest. Further, the driver  30  may be constructed in other ways such as a wire or a similar flexible organ with a certain length.  
         [0024]    The connecting element may in its upper end be formed as a rod  17 , which is fastened in the joint  19  on the head rest. The rod part may have a shape which gives a suitable elastic flexibility. Alternatively the rod may be somewhat arched or contain at least one slight angle. Further, the rod  17  may be attached to the slider  23  in a way that allows rotation and/or variation of the angle between them.  
         [0025]    A person skilled in the art will understand that the embodiment over is only one example, and that the invention is restricted only by the claims enclosed. The guide  20  with slider may have another cross section than circular, such as for example oval or square. Likewise the blocking device  22  may be a roll or another element influenced by gravity. The coupling organ  24  and the groove  21  may have another suitable design adapted to the blocking device  22 , such as a simple v-formed track which secures the above mentioned function of the groove  21 , blocking device  22  and coupling organ  24 .  
         [0026]    Even if it is preferable both in technical production and in costs to produce most of the parts of the connecting element according to the invention from a mouldable plastic material, it will be understood that other materials such as metal or sintered materials may be used.