Abstract:
A sheet handling apparatus having a sheet input section, a sheet processing section, a sheet output section, a conveying mechanism adapted to convey sheets from the input section through the processing section to the output section, and a controller for the conveying mechanism. The controller is adapted to be switched between a feed through mode, in which the sheets are output by being fed through from the processing section to the output section, and a rewind mode, in which the sheets are output by being fed in a reverse direction from the processing section back to the input section.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a Continuation of International Application No. PCT/EP2014/055968, filed on Mar. 25, 2014, and for which priority is claimed under 35 U.S.C. §120. PCT/EP2014/055968 claims priority under 35 U.S.C. §119(a) to Application No. 13161057.8, filed in Europe on Mar. 26, 2013. The entire contents of each of the above-identified applications are hereby incorporated by reference into the present application. 
     
    
     BACKGROUND OF THE PRESENT INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a sheet handling apparatus having a sheet input section, a sheet processing section, a sheet output section, a conveying mechanism adapted to convey sheets from the input section through the processing section to the output section, and a controller for the conveying mechanism. 
         [0004]    2. Description of Background Art 
         [0005]    An example of a sheet handling apparatus of this type is a stand-alone scanner in which the processing section includes a scanning head for scanning an image that is present on the sheet. A printer may be mentioned as another example. 
         [0006]    An alternative type of sheet handling apparatus has a combined input and output section, and the conveying mechanism is adapted to convey the sheets from the input section to the processing section and, after processing, back from the processing section to the combined input and output section. This has the advantage that the operator may collect the processed sheets from the same side of the machine from which he has fed the sheets into the machine. On the other hand, this type has the drawback that the throughput is slightly reduced because the time needed for rewinding the processed sheet back to the input and output section delays the time at which the next sheet can be fed in. 
       SUMMARY OF THE INVENTION 
       [0007]    It is an object of the present invention to provide a sheet handling apparatus in which sheets, in particular sheets of different formats, can be handled reliably and efficiently. 
         [0008]    According to the present invention, the controller is adapted to be switched between a feed through mode in which the sheets are output by being fed through from the processing section to the output section, and a rewind mode in which the sheets are output by being fed in a reverse direction from the processing section back to the input section. 
         [0009]    In this apparatus, sheets which have a relatively small format may be handled in the rewind mode, which is most convenient for the operator. On the other hand, when processing a large format sheet, in particular a sheet which has a large dimension in the transport direction, it would be time-consuming to rewind the sheet to the input section. In this case, the apparatus may be switched to the feed through mode, so that the processed large format sheets will be output by feeding them forward to the output section in the same direction in which the sheets are fed in. As a consequence, a plurality of large format sheets may be fed through in close succession, so that a high throughput may be obtained. 
         [0010]    The present invention is particularly advantageous for apparatus that are designed for handling sheets with formats that vary in a large range, e.g. from A0 to A4. Then, the output section, which will be needed only for large format sheets does not have to be designed for handling small format sheets, which permits a low-cost design. The small format sheets, which will be rewound towards the input section can readily be taken out by the operator, so that the input section is not required to be capable of reliably guiding and collecting the small format sheets. 
         [0011]    More specific optional features of the present invention are indicated in the dependent claims. 
         [0012]    In a particularly preferred embodiment, the controller has a format information processing section capable of automatically selecting the mode of operation of the conveying mechanism dependent upon the format of the sheets. Preferably, the apparatus further has a sensor system capable of detecting the format of the sheets that are being fed or have been fed into the processing section, so that the detection of the sheet format and the selection of the mode of operation may be automated. In case of a scanner, the sensor system for the format detection may be formed by or incorporated in the scanning head. 
         [0013]    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 present invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the present invention will become apparent to those skilled in the art from this detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    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: 
           [0015]      FIG. 1  is a schematic side elevational view of a sheet handling apparatus according to the present invention; 
           [0016]      FIG. 2  shows the sheet handling apparatus of  FIG. 1  in a top plan view; 
           [0017]      FIG. 3  is a top plan view analogous to  FIG. 2  but illustrates the handling of small format sheets; 
           [0018]      FIG. 4  is a flow diagram of a decision process that is performed in a controller of the sheet handling apparatus; and 
           [0019]      FIG. 5  is a side elevational view of a sheet handling apparatus according to a different 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 an example of a sheet handling apparatus,  FIG. 1  shows a scanner  10  adapted to electronically scan images that are carried on sheets  12 ,  14 . The scanner  10  has a base part  16 , and a bridge part  18  between which a sheet transport path  20  is formed through which the sheets  12 ,  14  may be fed through from an input section  22  via a processing section  24  to an output section  26 . 
         [0022]    The input section  22  is formed by a slanting part of the top surface of the base part  16  on one side of the bridge part  18  and by a number of projecting curved guide bars  28  for the sheet  12 . The processing section  24  includes a scanning head  30  that is accommodated in the bridge part  18  and extends over the entire width of the apparatus so as to scan the sheets on their entire width when they are passed through. The output section  26  is formed by a cage that is designed to collect the sheets  14 . As in the example shown, the cage-like output section is formed by one or more bent wires, which define guide rails  32  for limiting the cage in a lateral direction and at its free end, as well as a support part  34  for guiding and supporting the sheet  14  in the vicinity of its width-wise center. 
         [0023]    Both the base part  16  and the bridge part  18  accommodate parts of a conveying mechanism  36  which, in the example shown, has two pairs of motor-driven conveying rollers  38 . 
         [0024]    An electronic controller  40  controls the scanning head  30  and the conveying mechanism  36  and also processes the image information received from the scanning head  30 . 
         [0025]    Of course, the scanning head  30  is not only capable of reading the image information carried on the sheets  12 ,  14  but also to detect the leading and the trailing edges as well as the lateral edges of the sheets. This information is processed in a format information processing section  42  of the controller  40  so as to automatically determine the format, i.e. the length in a transport direction and the width in a lateral direction, of the sheet that is being conveyed past the scanning head. 
         [0026]    In the example shown in  FIGS. 1 and 2 , the sheets  12 ,  14  have a relatively large format, e.g. A0. The bent wires forming the output section  26  are configured such that the large format sheet  14  can reliably be guided and supported in the cage. The format information processing section  42  of the controller  40  has detected the format of the sheet  14  and has, in particular, measured the length of the sheet when the trailing edge thereof has passed the scanning head  30 . Based on this information, the controller  40  has controlled the conveying mechanism  36  such that the conveying rollers  38  continue to rotate in the same direction, so that the sheet  14  is output by being fed through to the output section  26 . 
         [0027]    For comparison,  FIG. 3  illustrates a case where a sheet  12   a  with a relatively small format, e.g. A4, is fed in at the input section  22 . It can be seen here that, in comparison to the format of the sheet  12   a,  the cage forming the output section  26  has voids that are so large that the sheet  12   a  would most likely drop out if one attempted to collect the sheet  12   a  in the output section. However, in this case the controller  40  has detected that the sheet  12   a  has only a small format and therefore controls the conveying mechanism  36  such that, once the trailing edge of the sheet has passed the scanning head, the direction of rotation of the conveying rollers  38  is reversed, so that the sheet  12   a  is rewound towards the input section  22 , as has been indicated by arrows in  FIG. 3 . 
         [0028]    The sheet  12   a  can readily be taken out by the operator who has fed in this sheet. Since the length of the sheet  12   a  is relatively small, the time that is needed for rewinding and returning the sheet to the input section  22  is negligible and does not significantly reduce the throughput of the apparatus. 
         [0029]    And as is further shown in  FIGS. 2 and 3 , the bridge part  18  of the scanner has a control panel  44  permitting the operator to input settings and instructions, including settings for the mode of operation of the conveying mechanism  36 . In a preferred embodiment, the operator may select between a fed through mode in which all sheets, regardless of their size, are always output towards the output section  26 , a rewind mode, where all sheets are always output by being returned to the input section  22 , and an automatic mode in which the mode of operation is decided upon automatically, depending upon the detected format of the sheets. 
         [0030]    When the automatic mode has been selected, the controller  40  performs an algorithm that has been illustrated in  FIG. 4 . In a step S 1 , the sheet is drawn in from the input section  22 . Then, when the trailing edge of the sheet has just passed the scanning head  30 , the controller  40  reads the format of the sheet, especially the length of the sheet in the transport direction, in step S 2 . Then, in step S 3 , it is decided whether or not, the format (length) of the sheet is larger than a certain threshold value (max_rewind). For example, this threshold value may be set to about 30 mm, corresponding to the length of an A4-sheet supplied in portrait orientation and the length of an A3-sheet supplied in landscape orientation. When it is decided that the format is larger than max_rewind, the sheet is fed forward to the output section  26  in step S 4 . Otherwise, it is rewound to the input section  22  in step S 5 . 
         [0031]    The present invention is not limited to a sheet handling apparatus with the physical configuration shown in  FIGS. 1 to 3 . For example, as is shown in  FIG. 5 , the sheet transport path  20  may be curved, so that the input section  22  and the output section  26  may be disposed on the same side of the base part  16 . Nevertheless, although the sheets are always delivered on the same side, there is a distinction between the mode in which the sheets are fed through the transport path  20  into the output section  26  and the mode of operation in which they are returned to the input section  22 . 
         [0032]    If the sheet handling apparatus is a scanner, the scanning head  30  may be disposed on either side of the transport path  20 . In the example shown in  FIG. 5 , it is disposed on the bottom side, so that the sheets have to be supplied face-down. However, it should be understood that the scanner in  FIG. 5  could be disposed on the top side as well. 
         [0033]    The present 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 present 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.