Abstract:
Disclosed are image scanning systems and methods including an imaging apparatus having a first image capture area with an image scannable area that is smaller than the image to be scanned, a second platen on which the image to be scanned is disposed, and an optical element to focus the image to be scanned within the image scannable area of the first image capture area.

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to capturing images and, more particularly, to capturing oversized images. 
     DESCRIPTION OF RELATED ART 
     Devices that scan images from paper sheets, or other media, may include an image scanning surface, e.g., a glass plate or platen, against which sheets may be automatically or manually positioned for image scanning or capturing. Such devices, sometimes referred to as “flatbed” devices, include copiers, scanners, facsimile machines and other document imaging apparatuses. These devices may include Automatic Document Feeder (ADF) systems to move and position single or multiple sheets against and away from platens and hold the sheets in position for image scanning. 
     Imaging apparatuses limit image sizes that may be scanned to be within some finite image scannable area, but in no case are flatbed device image scannable areas larger than the maximum size of platens. The imaging apparatuses may accomplish image scanning using either contact optics image sensors or translated linear sensor arrays such as a charge-coupled devices (CCD) in combination with reduction optics. Contact optics image sensor systems scan images without optical or electronic reduction of original image sizes. Reduction optics, in the case of translated linear sensors, often are positioned between platens and sensors to decrease one of the dimensions of scanned images to be comparable to a lengthwise dimension of a linear sensor array that is translated to scan the other image dimension. As an example, if an image on an 8.5 by 11 inch sheet of paper is being scanned, the 8.5 inch dimension may be optically reduced to 1 inch for an identically-dimensioned linear sensor array that is 1 inch in length. The linear sensor array then is translated to scan the 11 inch length of the paper sheet. Generated signals—which often are digitized—are processed and when desired are scaled back to the original size of the paper sheet for printing or other utilization. 
     All imaging apparatuses, whether contact image or translated linear sensors, have established maximum paper sizes that may be scanned. These maximum sizes often are dimensioned to accommodate essentially standard paper sizes, such as 8.5×11 inches, 8.5×14 inches, A4 (21.0×29.7 centimeters), etc. Even though image-scannable areas or platens are dimensioned for standard paper sizes and may readily accommodate smaller sizes, it sometimes becomes necessary to image scan paper sheets that are larger than standard sizes. In such cases, it has been necessary to image scan multiple portions of an oversized paper sheet and then stitch or reconstruct scanned images. 
     BRIEF SUMMARY OF THE INVENTION 
     An embodiment of the present invention provides an image scanning system including an imaging apparatus having a first image capture area with an image scannable area that is smaller than the image to be scanned. The system comprising a second platen against which the image to be scanned is disposed, and an optical element to focus the image to be scanned within the image scannable area of the first image capture area. 
     Another embodiment of the present invention provides a method for image scanning using an imaging apparatus having a first platen with an image scannable area that is smaller than an object having an image to be scanned. The method comprising disposing the object against a second platen and reducing an image of the object using an optical element to focus the image to be scanned onto the image scannable area of the first platen. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view of an optical system in a prior art image scanner; 
         FIG. 2  is a schematic for an optical train according to an embodiment of the invention; 
         FIG. 3  is a schematic for the optical train of  FIG. 2  on a plane intersecting axis A—A and perpendicular to the plane of the paper for  FIG. 2 ; 
         FIG. 4  is a simplified side view of a flatbed scanner combined, according to an embodiment of the invention, with an automatic document feeder; 
         FIG. 5  shown an optical element comprising a refractive system; and 
         FIG. 6  shown an optical element comprising a reflective system. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a prior art optical path  100  for an optical image scanner is shown. The illustrated prior art arrangement is for a folded optical path. Lens  101  focuses an image from an object against platen  102 , or other image capture area, onto sensor  103 . Objects from which images may be captured include sheets of paper and other media, photographs, photographic negatives and positives, documents, three-dimensional articles, and other objects one may desire scanned. Light ray  104  from platen  102  is reflected from first mirror  105 , second mirror  106  and then third mirror  107  before entering lens  101 . Lens  101 , mirrors  105 ,  106 , and  107  are mounted for movement so that a complete image from the object supported against platen  102  can be scanned and received at sensor  103  as a focused image. Lens  101  is a refractive element and mirrors  105 ,  106 , and  107  fold the optical path from platen  102  through lens  101  to sensor  103 , and thereby reduce linear lengths from platen  102  to sensor  103 . 
     Referring to  FIG. 2 , a schematic for optical train  200  according to an embodiment of the invention is shown. The schematic for optical train  200  is shown in plan view and is simplified for ease of illustration. As such,  FIG. 2  may represent either a single axis optical arrangement or a cylindrically-symmetric optical arrangement. In the case of a cylindrically-symmetric arrangement, the patterns for optical rays on all planes intersecting axis A—A, including those in  FIG. 2 , are the same. Alternatively, in the case of a single-axis optical arrangement, the patterns for optical rays on planes outside that of the paper for FIG.  2  and intersecting axis A—A could be different. For the embodiment discussed below a single-axis arrangement is shown in FIG.  2 . The optical path shown in  FIG. 1  also is a single-axis arrangement. 
       FIG. 3  shows a schematic for optical train  200  on a plane intersecting axis A—A and perpendicular to the plane of the paper for FIG.  2 . 
     Sensor  201  is shown in  FIGS. 2 and 3  at the bottom, and for the embodiment of the invention discussed below will be identified as a CCD sensor. Above sensor  201  is platen  202  against which an object may be placed for image scanning. This shown arrangement has optical element  203  contracting images from platen  202  onto sensor  201  which is shorter than platen  202  as shown in  FIG. 2 , and focusing images from platen  202  onto sensor  201  as shown in FIG.  3 . Optical element  203  may be a reflection system, a refractive system or a combination of reflective and refractive elements. 
     The combination of sensor  201 , platen  202  and optical element  203  schematically shown in  FIGS. 2 and 3  is used for many imaging apparatuses including flatbed scanners. Imaging apparatuses often use CCD arrays for sensor  201 ; the latter of which is moved, i.e., translated, out of the plane of the paper for  FIG. 2 , to image scan lengths of documents against platen  202 , with optical element  203  contracting the widths of the documents to the length of sensor  201 . 
     An embodiment consistent with the teachings of the invention provides another platen  204  spaced from platen  202 . Platen  204  is larger than platen  202  and accordingly may support larger objects for image scanning than platen  202 . Referring to  FIG. 2 , optical element  205  is interposed between platen  202  and platen  204 . Optical element  205 , contracts images from platen  204  to the size of platen  202  image scannable areas and in doing so focuses images onto platen  202 . Thus, oversized images for platen  202  are captured from platen  204  for image scanning using sensor  201 . 
     Optical element  205  may be a reflective system (FIG.  6 ), a refractive system ( FIG. 5 ) or a combination of reflective and refractive elements. Furthermore, optical element  203  and optical element  205 , despite possible differences in focusing power, do not have to be constructed of identical reflective, refractive, or combination type systems. Optical element  203  and optical element  205 , according to embodiments of the invention, may also comprise providing a single-axis optical arrangement and/or a cylindrically symmetric arrangement. 
     Referring to  FIGS. 2 and 3 , the illustrated embodiment utilizes single-axis optical arrangements for both optical element  203  and optical element  205 . Such an arrangement may efficiently be provided for a flatbed scanner having sensor  201 , optical element  203  and platen  202 , and an Automatic Document Feeder (ADF) having platen  204 . Referring to  FIGS. 2 and 3  the shown embodiment adds optical element  205  to the ADF such that the combination of optical element  203  and optical element  205  contract images to the width of sensor  201 . Optical elements  203  and  205  translate in unison to accomplish image scanning with sensor  201  of a page having a length that would fit against platen  202 . 
     Alternatively, optical element  203  may be a single-axis optical arrangement and optical element  205  may have a cylindrically-symmetric arrangement. In such cases, the combination of optical element  203  and optical element  205  contract images to the width of sensor  201  and optical element  205  further contracts the length of images to be scanned so they are focused at a plane corresponding to platen  202 . It should be appreciated that platen  202  is not necessary for capturing of the image by sensor  201  and, therefore, may be omitted and/or replaced by optical elements, or an image capture area otherwise defined, as desired. Again, such an arrangement may be incorporated in a combined flatbed scanner with an ADF. 
     Use of reduction optics causes decreased scanning resolutions. Imaging apparatuses that use reduction optics, such as those having linear array sensors, provide reduced resolutions over what could be provided by contact image sensors without reduction optics. These resolution reductions typically are not an operational-limiting factor because, for example, in the case of CCD linear array sensors, sufficiently high resolutions are available. Specifically, 200-300 dots per inch (dpi) or pixels per inch (ppi) resolutions are adequate for useful image scanning. These requirements are balanced against available image scanning apparatus system resolutions of 1200-2400 ppi. Referring to  FIG. 2 , optical train  200  with optical element  205  for the shown embodiment reduces resolution of the combination of platen  202 , optical element  203  and sensor  201  by the ratio of the dimension of the image scannable area of platen  202  to the dimension captured from platen  204 . For example, if the combination of platen  202 , optical element  203  and sensor  201  has a resolution of 1200 ppi and optical element  205  captures a dimension of 11 inches down to a dimension of 8.5 inches for platen  202 , then the reduced resolution is: 
         (       1200   ⁢           ⁢   ppi   ×   8.5   ⁢           ⁢   inches       11   ⁢           ⁢   inches       )     =     927.3   ⁢           ⁢   ppi         
 
This reduced resolution still is 3.1 times higher than that required for useful image scanning.
 
       FIG. 4  shows a perspective view of a combined flatbed scanner  400  and ADF  401  with optical element  205  diagrammatically shown in phantom for an embodiment of the invention. This embodiment provides a convenient arrangement for providing imaging apparatuses such as flatbed scanner  400  with a capability to capture oversized images.