Patent Publication Number: US-2004040675-A1

Title: Blind, especially for covering a glass pane of a window

Description:
[0001] The invention relates to a blind, especially for covering a glass pane of a window, according to the preamble of claim 1.  
       [0002] It is known to employ blinds for darkening, shading, or decorating windows. The basic principle resides in that the hanging is wound onto a winding rod and, as needed, can be unwound from the winding rod by a rotational movement.  
       [0003] DE 195 14 019 C2 describes a blind of the aforementioned kind. Here the hanging is comprised of a foil. The foil is provided with imprinted folds which impart to the foil in the unwound state a transversely extending wave profile. The lower free end of the foil is freely suspended in the downward direction. Accordingly, this blind is suitable only for a vertical window.  
       [0004] A similar blind is disclosed in DE 195 31 908 C2. Here, the hanging is also a foil with a wavy structure. For a slanted mounting of this blind, for example, on a skylight, the lower end of the foil, i.e., its terminal reinforcement, is provided with wheels on both ends with which the foil with this reinforcement can roll on the glass pane. A disadvantage is that this can result easily in canting so that the foil does not properly roll. This blind is not suitable for windows arranged at a flat angle or for horizontal windows.  
       [0005] Based on this, it is an object of the invention to further develop the blind of the aforementioned kind such that it is suitable for slanted or horizontal windows.  
       [0006] The technical solution is characterized by the features in the characterizing portion of claim 1.  
       [0007] The basic principle of the blind according to the invention resides in that the leading end of the hanging is coupled with regard to its movements with the movement of the two belts such that upon circulation of the belts the hanging is synchronously unwound from the winding core and that the leading end is entrained by the belts. All four end rollers have preferably the same diameter. Since with a corresponding positioning of the rollers the belts are guided forcibly parallel to the window pane, this means that the hanging is entrained accordingly, independent of whether a vertical, a slanted or even a horizontal window is concerned.  
       [0008] In this way, at any time and for any type of window it is ensured that the blind can be unrolled and subsequently can be rolled up again without problems.  
       [0009] It is basically conceivable to drive the belts by hand but the further embodiment according to claim 2 suggests an electric motor as a drive.  
       [0010] The further embodiment according to claim 3 suggests a technically simple rotary drive for the winding rod. The basic principle resides in that on the axle of the winding rod at each end a roller is fixedly supported, respectively. These rollers have preferably the same diameter as the end rollers for the two belts. The winding rod rollers are positioned in the area between the two end rollers of each belt and, in particular, between the carrying run and the return run of the belt. In this way, it is ensured that synchronously with the circulation of the belts also the rollers for the winding rod and thus the winding rod itself are caused to perform a rotary movement. In this way, a technically simple coupling of the movements is realized.  
       [0011] As already mentioned above, the further embodiment according to claim 4 suggests that the diameter of the winding rollers for the winding rod match the diameter of the end rollers for the belts.  
       [0012] The further embodiment according to claim 5 has the advantage that by means of the terminal rod extending transversely to the two belts the hanging is provided at its free end with the required stability and tension.  
       [0013] For hangings of greater lengths, the problem resides in that the hanging wound onto the winding rod during unwinding is reduced gradually with regard to its diameter and thus also with respect to its circumferential length. The leading end of the hanging is then transported at greater speed than the circulation of the winding device so that tension is caused within the hanging. For this reason, the embodiment according to claim 6 proposes a device for compensating the reducing winding circumference of the hanging on the winding rod caused by gradual unwinding. For this purpose, the following technical solutions are possible.  
       [0014] The embodiment according to claim 7 is based on a hanging with transversely extending wave structure. In this case, the winding rod has preferably a triangular or square cross-section. The basic idea resides in that the driven roller has a reduced circumference in comparison to the circumference of the hanging completely wound onto the winding rod. However, the circumference is greater than the circumference of the completely unwound hanging. This causes the effect that first the hanging is unwound to a greater extent then the leading end of the hanging is being transported by the belts. This is then used up again when the circumference of the wound hanging upon gradual unwinding becomes smaller than the circumference of the driven roller. Since the hanging has a wave structure, the wave structure, as a result of the tension provided within the wave structure, can essentially buffer this section of the hanging which section is initially unwound to a greater extent. Causing the circumferences of the drive roller, on the one hand, and of the wound hanging on the winding rod, on the other hand, to coincide can be realized approximately at half the maximum unwinding length. Of course, the matching circumferential length can also be adjusted as needed before or after half the maximum unwinding length.  
       [0015] One alternative to this—but also possibly an additional feature—is suggested by the configuration according to claim 8. The basic idea resides in that the different transport speeds are compensated by spring elements. In this way, the leading end of the hanging can be connected by springs with the belts. As an alternative, it is conceivable to support the rotary axle of the winding rod on a spring suspension. Both variants can be combined with one another.  
       [0016] The alternative according to claim 9 is based on a smooth structure for the hanging. In the case of these smooth hangings there is the special problem that, in contrast to hangings with a wave profile, sagging or tensions cannot be compensated and, therefore, in the latter case, there is the risk that the hanging will tear. For this reason, according to the variant of FIG. 9, it is supposed that the hanging, as a result of the special circumferential allowance, initially sags so that the excess length is then again used up toward the end.  
       [0017] The variant according to claim 10 finally ensures that by employing the spring elements the smooth hanging is tensioned in any winding position. With respect to the spring elements, the remarks in connection with claim 8 apply also.  
       [0018] The embodiment according to claim 11 suggests finally that the hanging is a foil. 
     
    
    
     [0019] Two embodiments of the blind according to the invention will be explained in the following with the aid of the drawings. It is shown in:  
     [0020]FIG. 1 a first embodiment of the blind with a wave structure;  
     [0021]FIG. 2 a side view of the blind in FIG. 1;  
     [0022]FIG. 3 a schematic enlarged view of the hanging together with the winding rod for the purpose of illustrating the wave structure of the hanging;  
     [0023]FIG. 4 a second embodiment of the blind with a smooth structure;  
     [0024]FIG. 5 a side view of the blind in FIG. 5;  
     [0025]FIG. 6 a schematic enlarged view of the hanging together with the winding rod for the purpose of illustrating the smooth structure of the hanging. 
    
    
     [0026] The blind is arranged between the two glass panes (not illustrated) of a window.  
     [0027] The blind has four rollers  1  wherein two rollers  1  form sequentially arranged roller pairs. Across the rollers  1  of each roller pair an endless belt  2  is guided, respectively. One of the four rollers  1  has a drive including an electric motor  3 .  
     [0028] On a winding rod  4 , extending transversely to the two belts  2  and having a triangular cross-sectional profile, a hanging  5  in the form of a thin foil is wound. This hanging  5  has a transversely extending wave structure as illustrated in FIG. 3. On the ends of the axle of the winding rod  4 , rollers  6  are fixedly arranged. Their diameter corresponds to the diameter of the rollers  1 . The winding rollers  6  are arranged between the carrying run and the return run of the respective belt  2 .  
     [0029] The leading end of the hanging  5  has a transversely extending terminal rod  7 . It is fastened with its two ends on the belts  2 , respectively.  
     [0030] The function of the blind is as follows.  
     [0031] In the wound-up state of the hanging  5  on the winding rod  4  the circumference of the roller  1  correlated with the electric motor  3  is smaller than the circumference of the hanging  5  wound onto the winding rod  4 . When starting up the electric motor  3 , the belts  2  are caused to rotate. Since the terminal rod  7  is connected fixedly with the belts  2 , the leading end of the hanging  5  is correspondingly entrained. This is illustrated in FIGS. 1 and 2 in dashed lines. Since the circumference of the hanging  5  on the winding rod  4  is initially greater than the circumference of the roller  1  correlated with the electric motor  3 , the hanging  5  is first unwound to a greater extent than the leading end of the hanging  5  is being transported by the belts  2 . As soon as the circumference of the hanging  5  on the winding rod  4  becomes smaller than the circumference of the roller  1  correlated with the electric motor  3 , the hanging  5  is unwound to a lesser extent than the leading end of the hanging  5  is being transported. In this way, the excess of unwound hanging  5  of the first phase is used up again. The relative differences in the transport speeds in this connection are compensated by the wave structure of the hanging  5 .  
     [0032] In order to provide a—certain—additional length compensation, compensation spring elements can be assigned to the connection of the terminal rod  7  with the belts  2  and/or the support of the axle of the winding rod  4 .  
     [0033] For winding up the hanging  5  the belts  2  are driven in the opposite direction.  
     [0034] The embodiment of FIG. 4 through  6  is based on a smooth hanging  5  which is wound onto a winding rod  4  of a round cross-section. The diameter of the hanging  5  wound completely onto the winding rod  4  is approximately identical to the diameter of the roller  1  driven by the electric motor  3  (in principle, it can also be greater or smaller). In contrast to the roller  1  with the wave structure of the hanging  5 , a compensation spring element  8  is arranged in this embodiment between the belts  2  and the terminal rod  7 , respectively. As an alternative, or in addition thereto, a compensation spring element can also be correlated with the axle of the winding rod  4 .  
     [0035] The function of the embodiment of FIGS. 4 through 6 is as follows.  
     [0036] By actuating the electric motor  3 , the belts  2  are caused to circulate. Since the circumference of the hanging  5  on the winding rod  4  decreases gradually and thus becomes gradually smaller than the circumference of the roller  1  correlated with the electric motor  3 , the leading end of the hanging  5  is transported to a greater extent than a supply of the hanging  5  is made available by the winding rod  4 . The result is that this length difference is compensated by the compensation spring elements  8 , as can be seen in FIGS. 4 and 5 when comparing the initial position (solid lines) with the end positions (dashed lines).  
     [0037] List of Reference Numerals  
     [0038] 1  roller  
     [0039] 2  belt  
     [0040] 3  electric motor  
     [0041] 4  winding rod  
     [0042] 5  hanging  
     [0043] 6  winding roller  
     [0044] 7  terminal rod  
     [0045] 8  compensation spring element