Abstract:
A document handling device has a support frame with four legs, at least one of which is height-adjustable. The support frame includes a torsion meter and a display for displaying a torsion of the support frame. The display is arranged in a position where it is visible for a person adjusting the height of the at least one height-adjustable leg. In an embodiment, it is possible to perform state detection between subsequent droplet ejections, thereby obtaining a highly reliable inkjet process.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a Continuation of International Application No. PCT/EP2009/061939, filed on Sep. 15, 2009, and for which priority is claimed under 35 U.S.C. §120, and claims priority under 35 U.S.C. §119(a) to Application No. 08164734.9, filed in Europe on Sep. 19, 2008. The entirety of each of the above-identified applications is expressly incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a document handling device having a support frame with four legs, at least one of which is height-adjustable. 
         [0004]    2. Background of the Invention 
         [0005]    A document handling device, e.g. a printer, a copier or a scanner, typically comprises a number of mechanical components that need to be perfectly aligned and adjusted relative to one another or to a recording medium that is to be scanned or printed on in the device. Examples of such mechanical components are a guide rail for a reciprocating printhead carriage of an ink jet printer, a rotating mirror or an LED array in a laser printer, a scanning mirror assembly and/or a CCD array in a scanner and the like. Since both, the transport and guide device for the recording medium, e.g., paper, and the mechanical components are directly or indirectly mounted on the support frame, even a slight torsional deformation of the support frame may deteriorate the alignment and/or adjustment of the mechanical components, and this will have negative consequences on the function of the device, i.e. the quality of printed or scanned images. 
         [0006]    A torsion of the support frame is typically induced when the document handling device is installed on an uneven floor. A well-known counter measure for avoiding such torsion is to precisely level the support frame by compensating for the unevenness of the floor, so that the frame will be precisely level and torsion-free. 
         [0007]    U.S. Pat. No. 4,637,581 discloses a self-levelling support frame. 
         [0008]    JP 04/244 880 A discloses a printer, wherein any strain of a printer case is detected with a strain gauge. When the strain gauge detects an installment state where the printer case is likely to be subject to excessive bending force or torsional force, the strain gauge causes the control system of the printer to prevent printing operations until the strain has been relieved. 
       SUMMARY OF THE INVENTION 
       [0009]    It is an object of the present invention to provide a document handling device which facilitates the operation of installing the device and assures a proper function of the device. 
         [0010]    In order to achieve this object, the document handling device according to the present invention includes a support frame that comprises a torsion meter and a display for displaying a torsion of the support frame, the display being arranged in a position where it is visible for a person adjusting the height of the at least one height-adjustable leg. 
         [0011]    When this device is installed on an uneven floor, the display will show that the support frame is subject to a certain torsion. The operator may then adjust the height of the height adjustable leg until the display shows that the support frame is torsion-free. This does not necessarily mean that the support frame has been levelled, but at least the frame will be torsion-fee, so that a proper alignment and adjustment of the mechanical components and hence a proper function of the device will be assured. 
         [0012]    The present invention is particularly useful for large format printers or scanners capable of handling documents with the format A2 or larger. 
         [0013]    More specific features of the invention are indicated in the dependent claims. 
         [0014]    Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
           [0016]      FIG. 1  is a simplified perspective view of a document handling device according to the present invention 
           [0017]      FIG. 2  shows essential parts of a support frame of the device in a horizontal cross-section; 
           [0018]      FIG. 3  is a schematic view illustrating the function of a torsion meter; and 
           [0019]      FIG. 4  is a sectional view similar to  FIG. 2  but showing a modified embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0020]    The present invention will now be described with reference to the accompanying drawings, wherein the same reference numerals have been used to identify the same or similar elements throughout the several views. 
         [0021]    As is shown in  FIG. 1 , a document handling device, e.g. a printer, comprises a support frame  10 , which supports a casing  12  of the device. As is well known in the art, the casing  12  accommodates a number of mechanical components that have to be aligned and adjusted relative to one another with high precision in order to assure a proper function of the device. In order to maintain this proper alignment and adjustment, it is necessary to install the device in such a manner that the casing  12  and its support frame  10  will be torsion-fee. 
         [0022]    In the shown embodiment, the support frame  10  is formed by two side members  14  or  16 , each of which has two legs  18 , so that the support frame has four legs in total. One of the legs  18  of the side member  16  has a height adjusting mechanism  20  permitting adjustment of the height of that leg  18  so as to compensate for a possible unevenness of the floor on which the device has been installed. In the example shown, the height adjusting mechanism  20  is a manually operated screw-spindle mechanism. 
         [0023]    A torsion meter  22  is formed by a shaft  24  that extends over the entire width of the support frame (the direction in which this frame has its largest dimension) from the first side member  14  to the second side member  16 . The shaft  24  is rigidly connected to the first side member  14  by a socket  26  and is rotatably supported with its opposite end in the second side member  16 . An end portion of the shaft  24  which penetrates through the side member  16  carries a pointer  28  which, together with a scale  30  formed on the outer face of the side member  16 , forms a display for displaying a torsion of the support frame  10  as measured by the torsion meter  22 . 
         [0024]    It will be understood that a person manually operating the height adjusting mechanism  20  of the height adjustable leg  18  by can readily watch the display  28 ,  30 . 
         [0025]    As is shown in  FIG. 2 , the shaft  24  is formed by a tube that has by itself a high torsional stability. At the end facing the second side member  16 , the shaft has a reduced end portion  32 , which is supported in a bearing  34  and carries the pointer  28 . Thus, the shaft  24  is non-rotatably connected to the first side member  14  but is rotatable relative to the second side member  16 . 
         [0026]      FIG. 3  shows a side view of the second side member  16  of the support frame  10  in a state where this support frame is subject to a torsional deformation. The first side member  14  has been shown in broken lines in  FIG. 3  and in a slightly rotated position, as a result of the torsional deformation. Thanks to the rigidity of the shaft  24 , the pointer  28  will rotate relative to the second side member  16  together with the first side member  14  as has also been shown in broken lines in  FIG. 3 . As a result of the deformation of the support frame, the shaft  24  may also be subject to some bending strains, which, however, have no effect on the rotation relative to the second side member  16 . Thus, the amount of torsional deformation can be read on the scale  30 . 
         [0027]    It is preferred that the shaft  24  extends in the direction in which the support frame  10  has its largest dimension. Further, if a mechanical display is used where a pointer or the like is mechanically driven by the torsion meter, it is preferable that the pointer  28  is relatively long, so as to magnify the effect of the torsion. 
         [0028]    When an operator installs the device, he watches the display  28 ,  30  and rotates the height adjustment device  20  so as to reduce to zero the torsion shown on the display. When a state with zero torsion has been reached, it will be assured that the mechanical components that are directly or indirectly supported by the support frame  10  will be proper aligned and adjusted relative to one another, even when the support frame  10  and the casing  12  have a relatively lightweight and inexpensive construction with poor torsional strength. 
         [0029]      FIG. 4  illustrates a modified embodiment which differs from the embodiment shown in  FIG. 2  in that the bearing  34  for the shaft  24  accommodates a transmission, more specifically, a planetary gear transmission  36 , which translates the rotation of the shaft  24  relative to the side member  16  into a rotation of the pointer  28  by a significantly larger angle. In the example shown, the end of the shaft  24  is rigidly connected to a planet carrier  38 , whereas the pointer  28  is connected to a sun gear  40 , and the bearing  34  serves as an internally toothed hollow gear of the planetary transmission. Of course, any other type of mechanical transmission may be used as well. 
         [0030]    In yet another embodiment which has not been shown, the torsion meter may be an electronic device delivering an electric (analogue or digital) torsion signal which will be displayed on an electronic display. 
         [0031]    It is noted that the embodiment illustrated in  FIG. 1  includes a manually operated height adjusting mechanism  20 . One having ordinary skill in the art would also recognize that an automatic adjusting device, for example a motor, could also be used to accomplish adjusting of the legs  18 . 
         [0032]    The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.