Abstract:
A digital scanner for scanning sheet document along transport path. The scanner includes a transport mechanism for moving the document along the transport path and a platen. The transport path is designed to minimize sticking or jamming of the document at the platen and for providing a high quality digital scan of the document.

Description:
FIELD OF THE INVENTION 
     The present invention relates to digital scanners, and more particularly, to a digital scanner for scanning relatively stiff hard copy documents along a generally curved transport path. 
     BACKGROUND OF THE INVENTION 
     It is known to provided scanners for scanning of hard copy documents. Generally, this takes the form of a flat platen upon which individual documents are placed for scanning. However, this is quite limited and very manual intensive. It is also known to provide automatic feeders on a flatbed scanner whereby a plurality of documents are provided across the platen for scanning of the information thereon. In scanning of relatively stiff documents, such as photographic prints, a number of problems arise. The relatively stiff nature of the photographic print presents several problems with respect to transporting of the documents along a transport path. Another problem associated with photographic prints is the possibility of producing small scratches on the original photographic print. The producing of scratches or other imperfection to the surface of the photographic print can be quite upsetting to the owner as the original print often has sentimental value to the owner. This transporting problem increases when a hard copy photographic print is transported along a curved path. Thus it is important to maintain a photographic print in its best possible condition. Another problem associated with scanning of a relatively stiff hard copy document, is the sticking of the document against the platen which can result in poor image quality and/or potential jamming of the print within the machine. Another problem that may arise in transporting a photographic print along a curved transport path in a scanner is that the leading edge of the photographic print can catch very easily and thus get damaged and/or cause possible jams. 
     It is important in the scanning of photographic quality images, that the best possible quality image be obtained. If the photographic print is not maintained properly against the scanning platen, various image defects may result. For example, there is a possibility that a magnification shift will occur due to the fact that the print is not always kept at the same distance from the scanning device. Another problem is that the image may have a keystoning effect due to the print not being maintained against the platen during scanning. 
     Thus, there is a need to provide an automatic scanner for scanning a plurality of relatively stiff documents without damage to the document and maintaining a high degree of quality in the images that are captured. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention there is provided a digital scanner for scanning a sheet document comprising: 
     a transport path along which the documents travel; 
     a transport mechanism for moving the document along the transport path; 
     a platen having upper engagement surface, a leading edge and a trailing edge; 
     a sensor for digitally capturing an image on the document which is transported past the platen; 
     a first guide surface in the transport path adjacent the leading edge and a second guide surface in the transport path adjacent the trailing edge, the first guide surface and the upper engagement surface forming a first air gap, and the upper engagement surface and the trailing edge forming a second air gap as the document passes the platen. 
     In accordance with another aspect of the present invention there is provided a digital scanner for scanning sheet documents comprising: 
     a transport path along which the documents pass; 
     a transport mechanism for moving the document along the transport path; 
     a platen having an upper engagement surface, a leading edge and a trailing edge; 
     a sensor for digitally capturing an image on the documents which are transported past the platen; 
     a first guide surface in the processing path adjacent the leading edge, the first guide surface being positioned above the leading edge. 
     In accordance with yet another aspect of the present invention there is provided a digital scanner for scanning sheet documents comprising: 
     a transport path along which the documents pass; 
     a transport mechanism for moving the document along the processing path; 
     a platen having an upper engagement surface, a leading edge and a trailing edge; 
     a sensor for digitally capturing an image on the documents which are transported past the platen; 
     a pressure applying member disposed opposite the upper engagement surface for applying a pressure against the document as it moves past the upper engagement surface, the pressure applying member applying a substantially uniform pressure against the document. 
     In accordance with still another aspect of the present invention there is provided a digital scanner for scanning sheet documents comprising: 
     a transport path along which the documents pass; 
     a transport mechanism for moving the document along the processing path; 
     a platen having a upper engagement surface, a leading edge and a trailing edge; 
     a sensor for digitally capturing an image on the documents which are transported pass the platen; 
     the transport path including a first guide surface adjacent said leading edge and a second guide surface adjacent the trailing edge, the first and a first guide surfaces being substantially continuous and smooth. 
     In accordance with another aspect of the present invention there is provided a digital scanner for scanning a sheet document comprising: 
     a curved transport path along which the documents travel, the curved transport path comprising a channel having an outer guide surface and an inner guide surface; 
     a transport mechanism for moving the document along the transport path; 
     a scan gate located in the inner guide surface, the scan gate comprising an opening in the inner surface; 
     a sensor for digitally capturing an image on the document which is transported past the scan gate; 
     a biasing member for maintaining an area of the document to be scanned at the scan gate at a substantially constant distance with respect to the sensor as it passes by the scan gate. 
     These and other aspects, objects, features and advantages of the present invention will be more clearly understood and appreciated from a review of the following detailed description of the preferred embodiments and appended claims, and by reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the detailed description of the preferred embodiments of the invention presented below, reference is made to the accompanying drawings in which: 
     FIG. 1 is a schematic diagram of a scanning apparatus made in accordance with the present invention; 
     FIG. 2 is an enlarged schematic diagram illustrating the transport path of the scanner of FIG. 1; 
     FIG. 3 is an elevational view illustrating one side of the transport path of FIG. 3 as taken along the line  3 — 3 ; 
     FIG. 4 is a backside elevational view taken along the line  4 — 4  of FIG. 2; 
     FIG. 5 is an enlarged view of the area of the transport path of FIG. 2 illustrating the platen area where the documents are scanned; 
     FIG. 6 is an enlarged view of the platen area of FIG. 5 illustrated by lines  6 — 6 ; 
     FIG. 7 is a view similar to FIG. 2 illustrating a modified form of the present invention; 
     FIGS. 8 a - 8   c  are enlarged cross sectional views of the scanning area of the embodiment of FIG. 7 illustrating various stages of a document passing thereby; and 
     FIG. 9 illustrates an enlarged cross sectional view of the scanning area of a modified device made in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIGS. 1 and 2, there is illustrated a schematic view of a scanning apparatus  10  made in accordance with the present invention. The apparatus  10  is designed for scanning of documents so as to obtain a digital record thereof. The digital record allows the user to use the captured digital images in any desired manner as is done with such images. The apparatus  10  includes a transport path  12  along which documents are transported. In the particular embodiment illustrated, the transport path  12  comprises a narrow processing channel  14  having an inner guide surface  16  and an outer guide surface  18 . The processing channel  14  has an inlet  20  at which documents  25  are fed into the apparatus  10  and at exit  22  from which the documents  25  leave channel  14 . An automatic feeding apparatus/mechanism  24  is provided adjacent the inlet for sequentially feeding a plurality of stacked documents into the processing channel  14 . In the particular embodiment illustrated the feeding mechanism  24  is designed to feed a plurality of relatively stiff documents such as photographic prints of various sizes. A receiving tray  26  is provided adjacent the outlet for retaining the documents that pass through the scanning apparatus  10 . As can be seen, the transport path  12  has a generally curved configuration having a radius of curvature R. It is to be understood that radius of curvature R may be of any appropriate value that still allow the documents  25  to pass along the transport path  12 , yet not so severe as to cause damage to the documents  25  due to the curvature. In the particular embodiment illustrated, the radius of curvature R may range from one inch (2.54 cms) to infinity. In the particular embodiment illustrated, the radius of curvature R is about four (4) inches (10.16 cms) 
     Referring to FIGS. 3 &amp; 4, there is illustrated a plan view of the inner and outer guide surfaces  16 ,  18 , respectfully of channel  14 . A plurality of associated pairs of pinched rollers  28 ,  30  which extend into channel  14  are provided for transporting of the documents  25  through channel  14 . Each associated pair of pinch rollers  28 ,  30  extend a short distance D along the entire width W of the processing channel  14 . The plurality of pairs of pinch rollers  28 ,  30  are arranged in a plurality of spaced rows  32 ,  33 ,  34 ,  35  and  36 . Depending upon the width of the document  25  being passed through channel  14 , different pairs or pinch rollers  28 ,  30  will engage the document  25  for properly moving the document  25  along the transport path  12 . A glass platen  38  is located along the processing path  12  against which documents will be passed. A sensor  40  is provided in association with platen  38  for capturing of images on documents  25  as the documents passes by platen  38 . In the particular embodiment illustrated, sensor  40  comprises a CCD (charged coupled device) array capable of capturing color images of the documents passing thereby. Sensor  40  includes red, blue and green channels for capturing the three color primary channels such that colored images may be captured. The output of the sensor  40  is passed to a central processing unit  42  which typically takes the form of a computer. The captured digital images may be stored, transmitted and/or manipulated as desired. Typically, the captured digital images would be sent to a device for writing the information on to a storage medium. For example, a CD or computer disk. Alternatively, the data could be sent to an image storage device which could be the computer of the owner of the images, a printer for printing of the image, or simply to a long term storage device or facility whereby the images could be accessed at some later point in time. 
     Referring to FIGS. 5 and 6 there is illustrated in greater detail the area surrounding the platen  38  where the images on documents  26  are digitally scanned. As can be seen by reference to FIG. 6, the upper engagement surface  46  of platen  38  is positioned slightly below or above the adjacent sidewalls  43 ,  44  of guide surface  18  of the processing channel  14 . Thus, there is formed a small distance D 1  between the upper engagement surface  46  of the platen  38  and the surface  18  adjacent side walls  43 ,  44 . This is done so as to provide small air gaps  48 ,  50  at the leading and trailing edges  51 ,  53  of the platen  38 . This assists in minimizing sticking of the document  25  against platen  38  and also minimizes the possibility of the leading edge of the document from catching on to the leading edge  51  of the platen  38 . The end  55  of side wall  43  is positioned such that it abuts edge  51  of platen  38 . The side wall  43  which is slightly above the platen  38  whereas the sidewall  44  is slightly above platen  38 . Thus, an air gap is formed at both places minimizing sticking the photograph at either of the junctures therebetween. 
     A biasing member  47  is provided for biasing the document  25  passing thereby against the platen  38 . The biasing member  47  in the embodiment illustrated comprises a foam pad having a leading section  49  which is disposed adjacent the inner surface  16  such that the document  25  as it travels thereby will not hit the leading end  57  of the biasing member  47 . The foam pad  47  is configured such that trailing section  60  is closely adjacent to platen  38  such that it will cause document  25  to be firmly pressed the platen  38  so as to provide a controlled substantially constant distance with the sensor  40 , but not too firmly as to cause a jam. While in the embodiment illustrated, the biasing member is continuous across the width of the document  25 , it need not be continuous, but have a configuration so as to apply a substantially uniform pressure across the width of the document  25 . FIG. 6 illustrates how a document  25  will be slightly deformed in the area indicated by numeral  64  yet is spaced from the sidewalls  43 ,  44  as indicated. The biasing member  47  is shaped such that the area  54  is the area in which the sensor scans for obtaining of the digital record of the images on the documents. The inner and outer guide surfaces  16 ,  18  surrounding the rollers  28 ,  30  are designed such that they are substantially planar and smooth so that no protrusions are extending therefrom which could possibly scratch the document as it travels therethrough. The surfaces  16 ,  18  preferably have a kinetic coefficient of friction less than about 0.30, preferably less than about 0.22. In the embodiment illustrated the guide surfaces  16 ,  18  are made of a Teflon material. 
     In order to better understand the present invention, a brief description of its operation will now be discussed. First a plurality of documents, for example photographic prints, are placed in feed mechanism  24 . The feed mechanism  24  then sequentially feeds the documents into the inlet  20  and are transported along the transport path  12  in channel  14  by pinched rollers  28 ,  30 . The documents as they pass by the platen  38  are biased against the platen  38  such that the document maintains a constant distance from the sensor  40  during scanning. Due to the construction of the sidewalls  43 ,  44  with respect to the platen  38 , the small air gap  48 ,  50  formed adjacent the platen  38  minimizes potential sticking of the document as it passes thereby. The documents after having been scanned by sensor  40  are transported to the outlet  22  into the receiving tray  26 . 
     Referring to FIGS. 7 and 8 a - 8   c  there is illustrated a modified scanner made in accordance with the present invention with like numerals indicating like parts and operation as previously discussed. In this embodiment, a pair of biasing members  66 ,  68  are placed adjacent on both sides of the scan gate  70  for maintaining the area of the document  25  to be scanned at a substantially constant distance with respect to the sensor  40 . In this embodiment, the sensor  40  is provided on the internal guide surface  16  of channel  14 . The members  66 ,  68  maintains the area of the document  25  at a substantially constant distance with respect to sensor  40 . 
     Referring to FIGS. 8 a - 8   c , there is illustrated the position of a document  25  as it travels by scan gate  70 . A pair of biasing members  71 ,  73  are provided, one on the entrance side of the scan gate  70  and one on the exit side of the scan gate  70 . The biasing members  71 ,  73  bias the document against the guide surface  18 . Due to the curved configuration of the processing path  12 , the leading edge of the document  25  is substantially maintained against the guide surface  18 . Due to the stiffness of the document a small distance t results between the document  25  and back wall  18  of the channel. Thus, in this embodiment, the curvature of the processing path  14  assists in maintaining a substantially constant distance between the area of the document  25  being scanned and the sensor  40 . In the particular embodiment illustrated, the biasing members  71 ,  73  comprise a spring like member which apply a biasing force toward surface  18  but is sufficiently low as to allow the document  25  to pass the by without any adverse affect on the document  25 . It is to be understood that biasing members  71 ,  73  may comprise any desired structure. For example, but not by way of limitation, spring mounted rollers  76  could be used to bias the document as shown in FIG.  9 . 
     It is to be understood that various other embodiments may be made without departing from the scope of the present invention. The present invention being defined by the following claims. 
     Parts List 
       10 . scanning apparatus 
       12 . transport path 
       14 . narrow processing channel 
       16 . inner guide surface 
       18 . outer guide surface 
       20 . inlet 
       22 . exit/outlet 
       24 . automatic feeding apparatus/mechanism 
       26 . receiving tray 
       28 . pinched roller 
       30 . pinched roller 
       38 . glass platen 
       40 . sensor 
       42 . processing unit 
       43 . sidewall section 
       44 . sidewall section 
       46 . engagement surface 
       47 . biasing member/foam pad 
       48 . air gap 
       49 . leading section 
       50 . air gap 
       51 . leading edge 
       53 . trailing edge 
       54 . area 
       55 . end 
       57 . leading end 
       60 . trailing section 
       64 . numeral 
       66 . biasing member 
       68 . biasing member 
       70 . scan gate 
       71 . biasing member 
       73 . biasing member 
       76 . spring mounted rollers