Digitizer with masking apparatus

#The present invention relates generally to a digitizer and in particular to a digitizer having a mask for reducing the affects of stray light.

#Digitizers convert optical densities of an image on a data medium to a digitized signal representative of the image recorded on the data medium. Such digitizers generally include an illuminator and a light sensitive element. The illuminator provides light that is directed towards the data medium. The light sensitive element accumulates photons based on the various optical densities of various portions of the recorded image on the data medium. The light sensitive element converts such accumulated photons into an associated analog electric charge. Electric processing circuitry accepts such an analog signal and converts it to a corresponding digital signal. The digital signal may be stored, retrieved, transferred, and processed in any variety of ways similar to other electronic data.

#The light sensitive element in such a digitizer typically has a fixed field of view. When reading data from a data medium that has a width less than an associated length of the illuminator, excess illumination occurs beyond the edges of the data medium yielding undesirable flare. This flare may adversely affect the performance of the light sensitive element and hence the quality of the overall digitizing process. Some masking mechanisms have been developed to mask the outer edge of the illuminator based on a width of the data medium to be digitized. However, such methods linearly transport the mask between the illuminator and the light sensitive element requiring a complex mask transport system. In addition, there is not a simple and efficient way to automatically position the mask based on the width of the data medium. Accordingly, there is a need in the art for a simpler and less expensive masking mechanism to reduce flare where the mask is rotated about a central axis.

#Advantages of the present invention will be apparent from the following detailed description of exemplary embodiments thereof, which description should be considered in conjunction with the accompanying drawings, in which:

#FIG. 1 is a simplified block diagram of a digitizer consistent with the invention;

#FIGS. 2A and 2B are perspective views of one embodiment of a mask consistent with the invention where the mask is affixed to an illuminator; and

#FIG. 1 illustrates a simplified block diagram of a digitizer 100 consistent with the invention. The digitizer 100 generally includes an illuminator 101, a lens 104, a light sensitive element 106, and electrical processing circuitry 114 including an analog to digital converter 108 and a processor 112. In general, the digitizer 100 converts optical densities of an image on a data medium 102 to electrical signals that represent various intensities of light and thus densities of the data on the applicable medium.

#The data medium 102 is first located in a position 102′ to be digitized. The digitizer 100 may include a transport control system (not shown) to accept the data medium 102 and drive it to the position 102′ to be scanned. Alternatively, the digitizer 100 may be a flat bed type scanner where a user would position the data medium 102 in position 102′ and the illuminator 101 and light sensitive element 106 would move relative to the data medium 102 while in position 102′.

#The data medium 102 may be any type of medium, e.g., transparent media or reflective media. For example, a transparent media may include an X-ray film used in medical applications. The digitizer 100 is illustrated as a digitizer for digitizing transparent media since the illuminator 101 is positioned above the object plane. However, a digitizer for digitizing reflective media may also be utilized where the illuminator would be positioned below the object plane.