Patent Publication Number: US-2009223419-A1

Title: Plate pallet stock detection

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Reference is made to commonly-assigned copending U.S. patent application Ser. No. ______ (Attorney Docket No. 94853/NAB), filed herewith, entitled PLATE PALLET ALIGNMENT SYSTEM, by Korolik et al., the disclosure of which is incorporated herein. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to an apparatus and methods for detecting the amount of plate stock left in a pallet of printing plates configured to be loaded into a computer-to-plate (CTP) imaging device. 
     BACKGROUND OF THE INVENTION 
     The CTP systems known today provide manual user input into a system controller of information relating to plate amount and plate type, which are loaded into the various plate trays associated with the CTP device. This data is updated further on by the system controller by counting down the number of plates used during the plate imaging process. 
     The present invention provides an automatic technique, which does not require manual entry of plate quantitative data. The present invention detects plates availability and alerts the user when plate replenishment is required. 
     SUMMARY OF THE INVENTION 
     Briefly, according to one aspect of the present invention a plate stock detection apparatus detects plates remaining on a plate pallet on an automatic plate pallet loading system which is configured to load plates into an imaging device. Plate pallet stock detectors measure stock of plates left in the plate pallet and a plate pallet elevation system elevates the plate pallet in response to feedback from the plate pallet stock detectors. 
     These and other objects, features, and advantages of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings wherein there is shown and described an illustrative embodiment of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustrating a plate pallet stock detection system using a light source and detector placed on opposite sides of the pallet; 
         FIG. 2  is a schematic illustrating a plate pallet stock detection system using a light source and detector placed in same side of the pallet and a reflective surface on the opposite side; and 
         FIG. 3  is a schematic illustrating a plate pallet stock detection system using a physical detector. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention describes apparatus and methods for detection of printing plate quantities left in a plate pallet for an automatic pallet loading (APL) device attached to a computer-to-plate (CTP) device. 
     Referring to  FIG. 1 , plate pallet  13 , attached to plate pallet adaptor  11 , is placed on a plate pallet elevation system  12 . The plate pallet elevation system  12  is used to elevate the plate pallet  13 , towards a plate loading system  18 . Encoder  14  detects the elevation level of the plate pallet elevation system  12 . 
     Light source  15  is directed towards light detector  16  via the optical path  17 , in order to detect the existence of a plate ready to be loaded by plate loading system  18 . Another embodiment, shown in  FIG. 2 , comprises light source  15  and light detector  16 , located on one side of the pallet, with the light reflected back via a reflected optical path  22  from a reflective surface  21  located at the opposite side of the pallet. 
     When light is detected by light detector  16 , the plate pallet elevation system  12  raises plate pallet  13 . This process is iterative and is performed until the light detector  16  is not able to detect the light generated by light source  15 . 
     Light source  15  and light detector  16  might be replaced by a physical detector  31 , shown in  FIG. 3 , such as a micro switch, inductive device, or optical device. This will indicate that plate pallet  13  is in the right level where the plate loading system  18  can pick a plate from pallet  13  in order to load it into the imaging device. This method also enables a processor to calculate the number of blank plates left in pallet  13  for further usage. The calculation will be done by knowing the original amount of plates or pallet height in the plate pallets, the elevated height of the plate pallet elevation system  12  derived from encoder  14 , and the original elevator position. A simple calculation will determine the number of blank plates left, and this information will be alerted to the user to the need for a new pallet. 
     The light detector  16 , also helps to avoid a hazardous situation aliasing from elevating plate pallet  13  to an uncontrolled height, possibly damaging the APL and CTP devices. 
     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  
     
         
           11  plate pallet adaptor 
           12  plate pallet elevation system 
           13  plate pallet 
           14  encoder 
           15  light source 
           16  light detector 
           17  optical path 
           18  plate loading system 
           21  reflective surface 
           22  reflected optical path 
           31  physical detector