Abstract:
The invention comprises a printer that has a conveyor ( 200 ) for holding photosensitive media, a lens positioned adjacent the conveyor, and an optical combiner ( 120 ) positioned with respect to the lens so as to direct light through the lens to the photosensitive media. The invention includes an optical printer ( 100 ) positioned to direct an optical exposure to the optical combiner, and a digital printer ( 110 ) positioned to direct a digital exposure ( 630 ) to the optical combiner. A controller is connected to the optical printer and the digital printer, and the optical printer and the digital printer are controlled by the controller so as to direct both the optical exposure and the digital exposure simultaneously to the optical combiner, which, in turn, passes the combined digital exposure through the lens to the photosensitive media.

Description:
FIELD OF THE INVENTION  
         [0001]    The invention relates to the field of printing on photosensitive paper and more particularly to a system of printing an optical exposure and a digital exposure on the photosensitive paper.  
         BACKGROUND OF THE INVENTION  
         [0002]    Developed film and digital images can be transferred to photographic paper in a number of different ways. For example, as described in U.S. Pat. No. 5,652,661 (incorporated herein by reference) an optical printer can transfer the developed film image onto the photographic paper. The optical printer typically includes a light source, focusing lens and development station. The film is illuminated by the light source and the image is transferred through the focusing lens to the photographic paper. Alternatively, the developed film image can be scanned into a processing unit and converted into a digital image. Scanned and digital film images and images obtained with digital equipment are generally printed with a digital printer.  
           [0003]    Digital printers generally include light sources (color filtered incandescent lights, colored lasers, light emitting diodes (LEDs), etc.) that are selectively exposed on the photographic paper using a spatial light modulator such as a digital micromirror device (DMD) as discussed in U.S. Pat. No. 5,061,049 (incorporated herein by reference) or liquid crystal device (LCD). As with the optical system, the images produced are focused through a lens onto the photographic paper.  
           [0004]    Some photographic systems combine digital printers with optical printers (see, for example, U.S. Pat. Nos. 6,025,904; 5,734,461; and 5,652,661, all of which are incorporated herein by reference). However, such systems separate the operation of the optical printer from the digital printer. This makes the printing process slower (because multiple operations must be performed on each photographic image) and makes the printing apparatus larger and more complicated (because multiple stations must be included within the printing apparatus). In addition, the particular methods of printing such as optical printing with a lamp house, and digital printing with laser based illumination require careful balancing of exposure times in order to avoid reciprocity failure at the media.  
           [0005]    Scan based digital engines such as a laser marking engine, or linear CRT require the scanning apparatus be incorporated in the paper path. It is not always trivial to combine an area optical printer with a linear digital printer. Finally, the inclusion of a LCD based digital writer can be considerably more cost effective, particularly if the digital writer is not required to either print the entire image, or print at the same resolution.  
         SUMMARY OF THE INVENTION  
         [0006]    In view of the foregoing, the present invention has been created to provide a system that simultaneously performs optical and digital printing. More specifically, the present invention comprises a printer that has a conveyor for holding photosensitive media, a lens positioned adjacent the conveyor, and an optical combiner positioned with respect to the lens so as to direct light through the lens to the photosensitive media. The present invention includes an optical printer positioned to direct an optical exposure to the optical combiner, and a digital printer positioned to direct a digital exposure to the optical combiner. A controller is connected to the optical printer and the digital printer and the optical printer and the digital printer are controlled by the controller so as to direct both the optical exposure and the digital exposure simultaneously to the optical combiner, which, in turn, passes the combined digital exposure through the lens to the photosensitive media.  
           [0007]    The optical printer can include an optical printer light source and the digital printer can include a separate digital printer light source. Alternatively, a common light source can be positioned with respect to the optical printer and the digital printer so as to provide light to both the optical printer and the digital printer. In such a situation, a beam splitter is positioned adjacent the common light source. The beam splitter can be adapted to variably divide light from the common light source between the optical printer and the digital printer so as to supply different amounts of light to the optical printer and the digital printer and satisfy the different illumination requirements of the optical printer and the digital printer. Also, the digital printer can include a spatial light modulator used to restrict the digital exposure to a limited region of the photosensitive media.  
           [0008]    The present invention also provides a method of exposing a photosensitive media. This method positions the photosensitive media adjacent to a lens, positions an optical printer to transmit an optical exposure through the lens, positions a digital printer to transmit a digital exposure through the lens, and controls the optical printer and the digital printer to simultaneously transmit the optical exposure and the digital exposure through the lens to the photosensitive media.  
           [0009]    The present invention produces a number of advantages when compared to conventional digital/optical printing systems. One advantage is that the invention simultaneously exposes the photosensitive material using the digital and optical printers. Also, the size of the composite system can be reduced through the use of a single light source. The use of a spatial light modulator (SLM) based digital engine eliminates the need for spinning polygons that laser systems employ. As SLM&#39;s are becoming readily available due to the proliferation in the projection industry, the net cost of this design is significantly less. With the use of multiple light sources as is described in certain embodiments, the color gamut is extended.  
           [0010]    The uses of this system are many. First, text can be added to an optical print. The result could be greeting cards, business cards, brochures or any other printing product. In addition, a separate digital section to a printer may be particularly useful in motion picture film applications. For instance, many copies of a film may be made for distribution. While copies may be made conventionally, it is useful to be able to add the subtitles independently in whatever language is required. Also, adding copyright insignia&#39;s or “hidden” information can prevent piracy and copyright infringement. Finally, the digital channel can be used to correct imperfections in the original film images. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a schematic diagram illustrating an optical adder combining the output from a digital printer and an optical printer.  
         [0012]    [0012]FIG. 2 is a schematic diagram of a conveyor system sequentially exposing a photosensitive material with an optical exposure and digital exposure.  
         [0013]    [0013]FIG. 3 is a schematic diagram of an optical printer and a digital printer aimed at a single location.  
         [0014]    [0014]FIG. 4 is a schematic diagram of an optical printer.  
         [0015]    [0015]FIGS. 5A and 5B are schematic diagrams of digital printers.  
         [0016]    [0016]FIG. 6 is a schematic diagram of a printing apparatus according to the present invention.  
         [0017]    [0017]FIG. 7 is a schematic diagram of a printing apparatus according to the present invention.  
         [0018]    [0018]FIG. 8 is a schematic diagram of a printing apparatus according to the present invention.  
         [0019]    [0019]FIG. 9 is a schematic diagram illustrating the use of digital printing in a portion of an image.  
         [0020]    [0020]FIG. 10 is a schematic diagram illustrating the use of digital printing in a portion of an image. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]    The present invention combines digital and optical printers into a single printer and simultaneously prints optically and digitally. In one example, the present invention combines a digital printer with a traditional film printer that illuminates film with a white light lamp source. The generated image is then passed through a projection lens to a media plane. In the digital leg, a transmissive spatial light modulator (SLM) display is illuminated with a lamp and filter wheel, LEDs, or lasers. The image is then relayed through the combiner to a print lens. In the case of an LCD display, the illumination needs to be polarized and the output analyzed.  
         [0022]    It is important to recognize the purpose of the digital printer. If the intention is to create additional image data of some complexity, care must be taken with optical design. Specifically, the illumination assembly of the transmissive LCD should be telecentric in nature and extremely uniform. This then forces the print lens to be telecentric. Additionally, uniform optics such as integrating bars or lenslet arrays may be employed. If the image data projected by the LCD is not complex (i.e., a simple trademark insignia) the optical relay mechanism need not be telecentric. Furthermore, if the added digital data is monochromatic, the illumination source need not be broadband. If it is polychromatic, either a white light source with filters need be employed, or LEDs sequentially illuminated in a single LCD system are used.  
         [0023]    At this point it is necessary to discuss the utilization of a LCD in a digital printer. LCDs are designed to present an image viewable by the eye. The eye&#39;s response to image data is quite different than photographic media response. Thus, with the present invention, the LCD or spatial light modulator is adjusted to operate in the dynamic range as well as the spectral range of the media. This may require adjusting the address voltage to determine a contrast as defined by the media. Additional address voltages, and drive conditions can be adjusted to deliver a response curve, or gamma curve, suitable to the media. Finally, address conditions, such as voltage can determine optimal response with respect to illumination wavelength. In the case of color sequential printing, the applied voltage may be cycled as a function of color.  
         [0024]    Illumination time, and power are a function of the required exposure of the media. In as much as the image is a single composite image, the required exposure between the optical and digital engines is balanced with the invention. For example, if a region of the print is expected to have a density of 1.4, the optical engine may furnish 1.0, and the digital engine furnishes 0.4. Alternatively, each leg of the printer can illuminate a different area and be responsible for all the required density. In the case of digitally adding subtitles or information at max density, balance is not as critical, as one can simply give a max or over exposure to a region.  
         [0025]    Another feature of the present invention relates to the use of alternate illumination such as infrared (IR) illumination. By illuminating the SLM with IR and then projecting the resultant image onto the media, one can incorporate “hidden” data, or trademark symbols to help prevent infringement.  
         [0026]    [0026]FIG. 1 illustrates one embodiment of the present invention that includes an optical printer  100  and a digital printer  110 . The optical exposure output from the optical printer  100  is combined with the digital exposure output from the digital printer  110  by an optical adder or a beam splitter/recombiner  120 . These combined exposures are then simultaneously imaged through a print lens  130  onto a photosensitive material  140 .  
         [0027]    [0027]FIG. 2 illustrates a sequential processing apparatus whereby photosensitive material  140  is moved along a conveyor belt  200  and sequentially exposed by the optical printer  100  and the digital printer  110 .  
         [0028]    [0028]FIG. 3 illustrates another embodiment of the present invention where the optical printer  100  and the digital printer  110  are aimed at a single location on the photosensitive material  140 . As with the structure shown in FIG. 1, the structure shown in FIG. 3 allows the optical printer and the digital printer to simultaneously expose the photosensitive material  140 , while the structure in FIG. 2 does not.  
         [0029]    The details of one example of the optical printer  100  are shown in FIG. 4. More specifically, the optical printer  100  includes a light source  400  which can be any conventional source used to eliminate photosensitive material such as shuttered and colored filtered incandescent light sources, different colored laser lights sources, LEDs, infrared sources, etc. The developed film image is represented by item  410 . The optical printer shown in FIG. 4 includes a number of structures that support the developed film image  410  and allow multiple film images to be passed through the optical printer. However, in order to more clearly illustrate the salient features of the present invention, such structures have been intentionally omitted from the drawing. In addition, the optical printer  100  includes some form of shutter or masking plate  415 . The shutter/masking plate  415  controls the size and time of exposure of the optical engine. Alternatively, the light source may be directed modulated to effect shuttering. A focusing lens  420  focuses the exposed image on the photosensitive material  140 .  
         [0030]    [0030]FIG. 5A illustrates one example of the digital printer  110  in greater detail. FIG. 5A illustrates a light source  500 . As discussed above, such a light source can include shuttered (or modulated) and colored filtered incandescent light sources, different colored laser lights sources, LEDs, etc. The spatial light monitor is shown as item  510 .  
         [0031]    Color digital printers can operate in a sequential manner where different colors are illuminated in different exposure steps. Alternatively, the spatial light monitor  510  based system can comprise a color-based unit allowing a single exposure to produce a color image on the photosensitive material  140 . This is achieved either through the incorporation of color filters on the SLM or through the use of a multichannel SLM system.  
         [0032]    A multichannel system may incorporate, for example, a red, green, and blue channel. FIG. 5B illustrates a digital printer that includes such multiple illumination sources  500 , multiple spatial light monitors  510  and multiple shutters  415 . The light output from the different devices is combined using a light adder  520 . In a similar manner to that discussed above, the focusing lens  420  focuses the light output from the adder on to the photosensitive material  140 .  
         [0033]    The optical/digital printer shown in FIG. 1 is shown in a complete system (an enclosed printer device)  60  as item  610  in FIG. 6. The developed film and/or digital image data is input by item  605  into the printer device  60 . The developed optical film is scanned by a scanner  600  which provides a digital representation of the scanned image to the central processing units  615 . Digital data is processed by a central processing unit  615 . The developed optical film is passed from the scanner  600  to the optical/digital printers  610  and then to an output  670  using a conveyor system  635 . Photosensitive paper  625  is provided from a supply  620  and is simultaneously exposed by optical and digital exposures  630  produced by the optical/digital printer  610  (as described above).  
         [0034]    In addition, the system shown in FIG. 6 can be used to make film copies. For example, the supply  620  can contain unexposed movie film  625  that it exposed by the optical/digital printer  610 . A developer/processor  640  processes the photosensitive paper/film  625 . A cutter  650  optionally cuts the photosensitive paper into photographic prints and outputs the developed images through the output  675 .  
         [0035]    [0035]FIG. 7 illustrates in greater detail the components included within the inventive optical/digital printer. In the optical portion of the printer, a lamp  700  is used to provide illumination. The illumination is processed through the filter wheel  701  and the illumination lens  702  prior to passing through the optical image on the film  703 . This image then passes through a relay lens  704  at which point it is combined with the digital image by the recombiner (optical combiner)  720 . The combined optical/digital image is then directed through the print lens  721  and on to the photosensitive media  730 .  
         [0036]    The digital portion of the printer shown in FIG. 7 includes a light source  710  that produces light that is directed through a digital illumination assembly  711 , a polarizer  712 , the spatial light modulator  713 , and an analyzer  714 . As with the optical image, the digital images then passed through a relay lens  704 , at which point it is combined with the optical image by the recombiner  720 . The combined optical/digital image is then directed through the print lens  721  and on to the photosensitive media  730 .  
         [0037]    An alternate embodiment employs the same illumination source for the optical and digital engines. Such a system is shown in FIG. 8. A single light source (which may consist of a lamp and filter wheel, LEDs or lasers)  800  is split into two illumination paths by a beam splitter  801 . Mirrors  802 ,  803  are used to direct the light through each of the optical and digital processing paths. In the case where the SLM is a LCD panel, the beam splitter may be a polarizing beam splitter that sends a preferential polarization state to the modulator in which case the polarizer  712  can be eliminated.  
         [0038]    [0038]FIGS. 9 and 10 illustrate another aspect of the present invention that utilizes a regional area spatial light modulator  900  shown in FIG. 9. In FIG. 9, a region  902  of the spatial light modulator is addressed with “on” pixels. The rest of the device is loaded with data corresponding to “off” pixels (or vice versa). In the image  1000  shown in FIG. 10, only the same region  1004  of the composite image  1002  displays digital data. One advantage of such a system is that the location, content, and extent of the digital data can be adjusted on a frame by frame basis. For example, when printing greeting cards, text can appear in different regions.  
         [0039]    The present invention produces a number of advantages when compared to conventional digital/optical printing systems. One advantage is that the invention simultaneously exposes the photosensitive material using the digital and optical printers. In one embodiment, the digital printing aspect is monochromatic and of a lower resolution than the optical system. This allows the exposure times of the digital to be less than previous embodiments.  
         [0040]    Further, the present invention corrects the optical differences between the digital printing and optical printing systems. For example, in the case where the aspect ratio of the SLM does not match the aspect ratio of the print or of the optical image, anamorphic lenses can be used to resize the image of the SLM to whatever proportion is required. Suppose, a square SLM employed to create a rectangular image within the image plane, cylindrical or anamorphic lenses in the path or as a printing lens could be employed. Alternatively, a portion of the SLM employed that corresponds to the required image size, can be addressed.  
         [0041]    It should be noted that specific examples of optical architecture have shown a transmissive LCD. This system could easily employ a reflective LCD, or DMD with equal ease.  
         [0042]    The proposed structure has many uses and advantages. First of all, the size of the composite system can be reduced through the use of a single light source. Also, the use of an SLM based digital engine eliminates the need for spinning polygons that laser systems employ. Also, the SLM&#39;s are becoming readily available due to the proliferation in the projection industry, the net cost of this design is significantly less. With the use of multiple light sources as is described in certain embodiments, the color gamut is extended.  
         [0043]    The uses of this system are many. First, text can be added to an optical print. The result could be greeting cards, business cards, brochures or any other printing product. In addition, a separate digital section to a printer may be particularly useful in motion picture film applications. For instance, many copies of a film may be made for distribution. While copies may be made conventionally, it is useful to be able to add the subtitles independently in whatever language is required. Also, adding copyright insignia&#39;s or “hidden” information can prevent piracy and copyright infringement (using the infrared exposure embodiment discussed above). Finally, the digital channel can be used to correct imperfections in the original film images.  
         [0044]    The invention has been described in detail with particular reference to certain and preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the scope of the.  
       Parts List  
       [0045]    [0045] 60  Printing device  
         [0046]    [0046] 100  Optical printer  
         [0047]    [0047] 110  Digital printer  
         [0048]    [0048] 120  Optical adder or beam splitter/recombiner  
         [0049]    [0049] 130  Print lens  
         [0050]    [0050] 140  Photosensitive material  
         [0051]    [0051] 200  Conveyor belt  
         [0052]    [0052] 300  Photosensitive media  
         [0053]    [0053] 400  Light source  
         [0054]    [0054] 410  Film image  
         [0055]    [0055] 415  Shutter or masking plate  
         [0056]    [0056] 420  Focusing/imaging lens  
         [0057]    [0057] 500  Multiple illumination sources  
         [0058]    [0058] 510  Spatial light modulator  
         [0059]    [0059] 520  Light adder  
         [0060]    [0060] 600  Scanner  
         [0061]    [0061] 605  Input item  
         [0062]    [0062] 610  Optical/digital printer  
         [0063]    [0063] 615  Central processing unit  
         [0064]    [0064] 620  Supply  
         [0065]    [0065] 625  Paper/film  
         [0066]    [0066] 630  Digital exposures  
         [0067]    [0067] 635  Conveyor system  
         [0068]    [0068] 640  Developer/processor  
         [0069]    [0069] 650  Cutter  
         [0070]    [0070] 670  Output  
         [0071]    [0071] 675  Output  
         [0072]    [0072] 700  Lamp  
         [0073]    [0073] 701  Filter wheel  
         [0074]    [0074] 702  Illumination lens  
         [0075]    [0075] 703  Film  
         [0076]    [0076] 704  Relay lens  
         [0077]    [0077] 710  Light source  
         [0078]    [0078] 711  Illumination assembly  
         [0079]    [0079] 712  polarizer  
         [0080]    [0080] 713  Spatial light modulator  
         [0081]    [0081] 714  Analyzer  
         [0082]    [0082] 720  Recombiner  
         [0083]    [0083] 721  Print lens  
         [0084]    [0084] 730  Photosensitive media  
         [0085]    [0085] 800  Single light source  
         [0086]    [0086] 801  Beam splitter  
         [0087]    [0087] 802  Mirror  
         [0088]    [0088] 803  Mirror  
         [0089]    [0089] 900  Regional area spatial  902  light modulator  
         [0090]    [0090] 902  Region  
         [0091]    [0091] 1000  Image  
         [0092]    [0092] 1002  Composite image  
         [0093]    [0093] 1004  Region