Abstract:
An imaging apparatus ( 10 ) to image wise expose desired microcapsules ( 38 ) within a photosensitive media ( 44 ) with an image exposure device ( 12 ) to harden the desired microcapsules applying pressure to the exposed photosensitive media rupturing the unexposed microcapsule ( 40 ), releasing the image-forming material ( 48 ) encapsulated within to form an image on the photosensitive media, the exposure device having a molded lenslet array ( 14 ) with a printed lens mask improving channel cross talk, aberrations, and reducing flair.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     Reference is made to commonly-assigned copending U.S. Patent Application Ser. No. (Attorney Docket No. 86088/NAB), filed herewith, entitled METHOD OF REGISTERING A MOLDED LENSLET ARRAY WITH AN ARRAY OF LIGHT EMITTING ELEMENTS, by Kerr et al., the disclosure of which is incorporated herein.  
       FIELD OF THE INVENTION  
       [0002]     The present invention relates in general to the field of image exposure devices and more particularly to a method of masking a molded one-dimensional or two-dimensional lenslet array of an image exposure device to reduce channel cross talk, aberrations, and flair.  
       BACKGROUND OF THE INVENTION  
       [0003]     Image exposure devices having light emitting elements have been used in imaging equipment to expose images on photosensitive media. Such a device is described in U.S. Pat. No. 6,034,712, which uses an array of light emitting light elements disposed within recesses formed in a substrate with a pinhole mask to expose an image on photosensitive media. The photosensitive media may be of the type having a plurality of microcapsules, with an image-forming material encapsulated within the microcapsules.  
         [0004]     To form an image on a photosensitive media having microcapsules, a multiple channel image exposure device may be used to expose desired microcapsules with at least one of the multiple light emitting elements. Image wise exposure by the exposure device hardens the desired microcapsules such that when pressure is applied by means of a microcapsule-rupturing device only the unexposed microcapsules are ruptured. The ruptured microcapsules release an image-forming material encapsulated within to form an image within the photosensitive material. Similar imaging forming equipment is described in U.S. Pat. Nos. 4,440,846 and 4,339,209.  
         [0005]     Image exposure devices having molded lenslets generally have a mask to reduce channel cross talk, aberrations, and flair. Depending on the application, the mask can become very important to the image quality of a completed image. Typically the mask is placed in the light path of the exposure device. Accuracy of the location and features of the mask may be required to be within a few microns to prevent blocking the light source or forming image artifacts in an image formed on the photosensitive media due to the alignment or accuracy of the mask. Alignment can become complicated and expensive as the number of imaging channels increases. Thus, there is a need for improved image quality and lower cost by improving the fabrication and alignment accuracy of a mask used in a multiple channel image exposure device.  
       SUMMARY OF THE INVENTION  
       [0006]     Briefly, according to one aspect of the present invention a method of masking a molded lenslet array having an array of light emitting elements comprises printing a mask on the molded lenslet array to reduce channel cross talk aberrations, or flair in the in the exposure of a photosensitive media.  
         [0007]     In one embodiment, the mask is printed on the input side of the molded lenslet array or the output side of the molded lenslet array, or both input and output sides of the molded lenslet array. In another embodiment, the mask may be printed on the molded lenslet array after the molded lenslet array has been molded or may be applied to the mold during the process of molding the molded lenslet array.  
         [0008]     The present invention is intended to lower the cost while improving the image quality of an imaging apparatus that uses a multiple channel-imaging device to generate an image on or within a photosensitive media. In a preferred embodiment the invention is used with a photosensitive media having a polarity of microcapsules with an image-forming material encapsulated within the microcapsules. With image wise exposed by a multiple channel image exposure device, microcapsules sensitive to certain radiation become hardened to a point that when processed through a microcapsule rupturing device, the exposed microcapsules are not ruptured while the unexposed microcapsules that release the image-forming material encapsulated are ruptured to form an image on or within the photosensitive media.  
         [0009]     The multiple channel image exposure device of the present invention is used to expose the photosensitive media. It utilizes a molded lenslet array aligned to an array of one-dimensional or two-dimensional multiple light emitting elements to form a multiple channel image exposure device. To improve the image quality of the multiple channel image exposure device, a mask is printed onto the surface of the molded lenslet array which lowers the cost of a multiple channel image exposure device by removing the need to accurately align a mask relative to the light source and the molded lenslet array in X-Y and Z directions. The invention allows a mask which can follow the shape of the molded lenslet array and improve the accuracy of the mask both in location and edge definition.  
         [0010]     The invention and its objects and advantages will become more apparent in the detailed description of the preferred embodiment presented below. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     A more complete understanding of the invention and its advantages will become apparent from the detailed description taken in conjunction with the accompanying drawings, wherein examples of the invention are shown, and identical reference numbers have been used, where possible, to designate identical elements that are common to the figures referenced below:  
         [0012]      FIG. 1  is a schematic, cross-sectional view of an imaging apparatus having a multiple channel image exposure device according to the present invention;  
         [0013]      FIG. 2  is a schematic, cross-sectional view of a multiple channel image exposure device of one embodiment according to the present invention;  
         [0014]      FIG. 3  is a schematic, cross-sectional view of a multiple channel image exposure device according to another embodiment of the present invention;  
         [0015]      FIG. 4  is a schematic, cross-sectional view of a multiple channel image exposure device according to yet another one embodiment of the present invention; and  
         [0016]      FIG. 5  is a schematic, cross-sectional view of a mold for multiple channel image exposure device according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]     The present invention will be directed in particular to elements forming part of, or in cooperation more directly with an apparatus in accordance with the present invention. It is to be understood that elements not specifically shown or described may take various forms well known to those skilled in the art.  
         [0018]     Referring now to  FIG. 1 , a schematic, cross-sectional view of an imaging apparatus  10  for exposing a photosensitive media  44  utilizing a multiple channel image exposure device  12  is shown. The multiple channel image exposure device has a molded lenslet array  14  with a printed mask. Photosensitive media  44  is removed from media tray  20  to a preheat station  22 . Once the preheat step is complete the preheated photosensitive media  56  proceeds to the exposure station  24  to be image wise exposed by the multiple channel image exposure device  12 . The exposed photosensitive media  58  is then passed through the microcapsule rupturing device  50  where pressure is applied by rupturing rollers  52 . The developed photosensitive media  60  is then passed to the post-heating section  32  and from there to the exit tray  34  as competed image  62 .  
         [0019]      FIG. 2  shows a schematic cross sectional view of a multiple channel image exposure device  12  shown in  FIG. 1 . Multiple channel image exposure device  12  has a molded lenslet array  14 . An input printed mask  86  and output printed mask  88  are in alignment with an array of light emitting elements  54  that are mounted on silicon pad  28  within light source alignment recesses  42 . Light emitting elements  54  are attached by means of soldering, adhesive bonding, or other methods well known in the art. Light emitting elements may be laser diodes or light emitting diodes (LEDs).  
         [0020]     Registration of the molded lenslet array  14  to the array of light emitting elements  54  is accomplished by registration pins  18  that interface with locating recesses  30 . Registration recesses  30  and light source alignment recesses  42  are etched into silicon pad  28  by a micro-lithographic mask and fabrication process. The micro-lithographic mask and fabrication process form the tapered sidewalls  64  of the registration recesses  30  and light source alignment recesses  42  at an angle between 45 degrees-75 degrees. Both the registration recesses  30  and light source alignment recesses  42  will be formed at the same slope angle and the same depth such that the length of the registration pins  18  and the depth of the registration recesses  30  locate the imaging lenses  16  formed in the molded lenslet array  14  to a predetermined distance in the Z direction from the array of light emitting elements  54 . In the preferred embodiment the molded lenslet array  14  is molded of a polyolefin or other materials well known by someone in the art.  
         [0021]     The photosensitive media  44  is of the type having a plurality of microcapsules  46  with an image-forming material  48  encapsulated within the microcapsules  46 . Image wise exposure of the certain microcapsules  46  in photosensitive media  44  hardens the exposed microcapsules  38  to a point such that when processed through a microcapsule rupturing device  50  that utilizes rupturing roller  52  to generate pressure to rupture unexposed microcapsules  40 , the exposed microcapsules  38  remain unbroken. The unexposed microcapsules  40  release the image-forming material  48  encapsulated within the unexposed microcapsules  40  to form an image within the photosensitive media  44 .  
         [0022]      FIG. 3  shows a schematic cross sectional view of a multiple channel image exposure device  12  shown in  FIG. 1  having a molded lenslet array  14  with an input printed mask  86  printed with an ink or other material to prevent cross talk from one imaging lens  16  to another imaging lens  16 . The mask material is preferably light absorbing material and blocks the wave length required to be absorbed. The material may also be reflective.  
         [0023]      FIG. 4  is a schematic cross sectional view of a multiple channel image exposure device  12  shown in  FIG. 1  having a molded lenslet array  14 . In this embodiment, an output printed mask  88  is printed with an ink or other material to prevent cross talk from one imaging lens  16  to another imaging lens  16  and should be noted that a printed mask may only cover selected surfaces  66  or a portion of a selected surface as needed.  
         [0024]      FIG. 5  shows a schematic cross sectional a view of a mold  92  for molded lenslet array  14 . Ink  90  is on the portions of the mold that form the printed input mask  86  and the printed output mask  88  such that when the molded lenslet array  14  is molded the mask is formed on the molded lenslet array  14 . The printed mask may also be printed on the on the molded lenslet array by making a negative from the molded lenslet array  14 , applying ink to the negative, then printing on the molded lenslet  14 .  
         [0025]     The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the scope of the invention.  
       PARTS LIST  
       [0026]    
       
         
           
               10 . Imaging apparatus  
               12 . Multiple channel image exposure device  
               14 . Molded lenslet array  
               16 . Imaging lens  
               18 . Registration pin  
               20 . Media tray  
               22 . Preheat station  
               24 . Exposure station  
               28 . Silicon pad  
               30 . Registration recess  
               32 . Post-heating station  
               34 . Media exit tray  
               38 . Exposed microcapsule  
               40 . Unexposed microcapsule  
               42 . Light source alignment recess  
               44 . Photosensitive media  
               46 . Microcapsule  
               48 . Image-forming material  
               50 . Microcapsule rupturing device  
               52 . Rupturing roller  
               54 . Array of light emitting elements  
               56 . Pre-heated photosensitive media  
               58 . Exposed photosensitive media  
               60 . Developed photosensitive media  
               62 . Completed image  
               64 . Tapered sidewalls  
               66 . Tapered locating surface  
               86 . Input printed mask  
               88 . Output printed mask  
               90 . Ink  
               92 . Mold