Abstract:
Apparatus for changing the direction of transport of a sheet by about 75° to about 90° comprising: a first flat guide for contacting the leading edge of a sheet transported along a path to change its direction of transport by an acute angle; a second flat or concavely curved guide spaced from the first guide for contacting the leading edge of the sheet to change to direction of transport by an acute angle wherein the change of direction of transport of the sheet by the first and second guides totals about 75° to about 90°, the second concavely curved guide providing accumulation of the proper amount of sheet required to change the direction of transport of the sheet by the about 75° to about 90°.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates in general to transporting film between film supplies, optics and thermal processor assemblies in a medical laser imager.  
       BACKGROUND OF THE INVENTION  
       [0002]     Known medical laser imagers have been designed with one or two film supplies.  
         [0003]     One such imager is designed with a single film supply that utilizes a direct path to feed film from the film cartridge to the optics assembly. Since this machine has just one film supply, a single curved guide can be used to turn the film 90° degrees to re-direct the film towards the optics assembly. Another separate direct path is used to transport the film from the optics assembly to the thermal processor. Another such imager is also designed with a single film supply that utilizes a direct path to feed film from the film cartridge to the optics assembly. Another direct path is used to transport the film from the optics assembly to the thermal processor. A third such imager is designed with two film supplies. The lower film supply feeds film directly from the film cartridge to the optics assembly. The upper film supply feeds film into a transport assembly that feeds the film to the optics assembly. This same transport assembly is also used to feed film from the optics assembly to the processor.  
         [0004]     Therefore, the current state-of-the-art in film transport is the use of separate direct feed paths in single film supply imagers. The two-film supply imager has a separate transport assembly that uses the same feed path to transport film from the upper film cartridge to the optics assembly and from the optics assembly to the thermal processor.  
         [0005]     There is therefore a need for a film transport system for use in a medical laser imager having three film supplies such that any size film can be fed from any one of the three film supplies downwardly to an imaging assembly, and such that any size film can be fed from the imaging assembly up to a thermal processor located above the three film supplies.  
       SUMMARY OF THE INVENTION  
       [0006]     According to the present invention, there is provided a solution to the problems of the prior art.  
         [0007]     According to a feature of the present invention, there is provided an apparatus for changing the direction of transport of a sheet by about 75° to about 90° comprising: 
        a first flat guide for contacting the leading edge of a sheet transported along a path to change its direction of transport by an acute angle;     a second flat or concavely curved guide spaced from said first guide for contacting the leading edge of said sheet to change to direction of transport by an acute angle wherein the change of direction of transport of said sheet by said first and second guides totals about 75° to about 90°, said second concavely curved guide providing accumulation of the proper amount of sheet required to change the direction of transport of said sheet by said about 75° to about 90°.        
 
       ADVANTAGEOUS EFFECT OF THE INVENTION  
       [0010]     The invention has the following advantages.  
         [0011]     1. The film transport invention is a passive system that does not require components, such as film guides, to be moved out of the way for films from the middle or upper film supplies to pass through. A non-passive system with moving guides would significantly increase cost, complicate software development and reduce reliability due to additional moving parts.  
         [0012]     2. The design includes a separate film path from the imaging assembly to the thermal processor to maximize throughput.  
         [0013]     3. Film guides are designed to allow only the leading and trailing edges of the film to contact the guides while turning the film. In addition, guide rollers are designed to support the film during film turning. Both of these design elements prevent film scratching during film transport.  
         [0014]     4. The geometry of the film turn guides are designed to accumulate the proper amount of film required to turn the film the required turn angle prior to entering the final roller. This is a key design feature in turning film through a desired angle. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1A  is a diagrammatic view of a laser imager illustrating the film turning concept with the film pass-through capability from the previous film supply.  
         [0016]      FIG. 1B  is an exploded diagrammatic view of the film turning concept of  FIG. 1A .  
         [0017]      FIG. 2  is an isometric view of the assembled Vertical Transport frame with structural standoffs shown.  
         [0018]      FIG. 3  is an isometric view showing the five unique types of film transport rollers utilized in an embodiment of the present invention.  
         [0019]      FIG. 4  is an isometric view showing the assembly method for the drive and idler rollers.  
         [0020]      FIG. 5  is an elevational view showing the different types of film guides used in an embodiment of the present invention.  
         [0021]      FIG. 6  is an elevational view showing motors, belts and other drive train components of an embodiment of the present invention.  
         [0022]      FIG. 7  is a diagrammatic view of how the different film sizes line up to a segmented roller.  
         [0023]      FIG. 8  is a partial elevational view showing an input roller set with covers that create light tight seal to film supply.  
         [0024]      FIG. 9  is a partial elevational view showing a film contacting initial film guide.  
         [0025]      FIG. 10  is a partial elevational view showing film contacting initial segmented guide roller.  
         [0026]      FIG. 11  is a partial elevational view showing film contacting curved film guide.  
         [0027]      FIGS. 12A and 12B  are partial elevational views showing film contacting secondary solid film roller.  
         [0028]      FIG. 13  is a partial elevational view showing film exiting outlet roller set after 90° film turn.  
         [0029]      FIG. 14  is a partial elevational view showing film passing through lower film guides.  
         [0030]      FIG. 15  is a partial elevational view showing film after final turn towards imaging assembly. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0031]     Referring now to  FIG. 1A , there is shown a laser imager incorporating an embodiment of the present invention. As shown, laser imager  100  includes unexposed film supplies  102 ,  104 ,  106  for storing stacked sheets of unexposed heat processable film, preferably in removable film cartridges. Supplies  102 ,  104 ,  106  can receive film of the same or different sizes. Typically, each supply will receive film of different sizes. Individual sheets of film (such as x-ray film) are fed from one of supplies  102 ,  104 ,  106  to a down film path  108  to laser imaging region  110  where the unexposed film is exposed to an image (x-ray) by means of a (laser scanning assembly shown). The exposed film is transported up film path  112  to processor  113  which includes heated drum  114  and hold down rollers  116 . The heat processed film is then transported to output tray  118  for removal by the user.  
         [0032]     The primary challenge in transporting film from the imaging assembly  110  to the processor  113  is to retain the film as much as possible while still allowing access for film jam removal. A guide with an angled lead-in was developed to guide the film when transporting up to the processor  113 .  
         [0033]     As discussed previously, the challenge in turning the film the required  750  to  900  is to develop a film turning mechanism that includes an open path for film to pass through from the middle and upper film supplies  102 ,  104 . The goal in this design was to develop a passive system that did not require components, such as film guides, to be moved out of the way for films from the middle or upper film supplies to pass through. A non-passive system with moving guides would significantly increase cost, complicate software development and reduce reliability due to additional moving parts. A passive concept consisting of spring-loaded roller sets, drive rollers, and leading/trailing edge film guides was developed to turn the film. According to the invention as shown in  FIG. 1B , an initial leading edge film guide  120  is designed to turn the film approximately 45°. Following this guide is a drive roller  122  that supports the film prior to contacting the secondary film guide  124 . A roller is used to prevent the surface of the film from contacting the film guide. This is done to prevent film scratching. The secondary film guide  124  is designed to turn the film the remaining 30° to 45°.  
         [0034]     Following is a description of the major components that make up the vertical transport assembly  119  including down film path  108  and up film path  112 .  
         [0035]     As shown in  FIG. 2 , the frame  130  is designed with a sheet metal front plate  1  and sheet metal back plate  2  separated and supported by cold rolled steel rod standoffs  3 . This design approach was selected to provide a structurally rigid frame  130  capable of supporting a large number of rollers and guides. A design approach with separate front and back plates  1  and  2  also simplifies individual part shipping and handling due to smaller parts versus a complete welded style frame.  
         [0036]     There are several types of rollers required to transport film through the imager  100 . The five types designed for the vertical transport assembly  119  are described below. These rollers are shown in  FIG. 3 . 
        segmented drive roller  4      solid drive roller with features for film advance knob  5      solid drive roller  6      segmented idler roller  7      solid idler roller  8         
 
         [0042]     The two fundamental types of rollers used in film transport include drive rollers and idler rollers. The assembly of these rollers into the frame is described below and shown in  FIG. 4 .  
         [0043]     A drive roller is placed in precision holes located in the front plate  1  and back plate  2  of the transport frame. A flanged, shielded, extended inner race ball bearing  9  is placed over the ends of the shaft of the drive roller  4 ,  5 ,  6  and inserted in the precision holes in front and back plates  1 ,  2 . The bearing  9  is retained by an e-ring  10  inserted into a groove in the shaft of roller  4 ,  5 ,  6 . The extended inner race bearing  9  was selected to prevent the e-ring  10  from contacting the bearing shield.  
         [0044]     An idler roller  7 ,  8  is placed in the rectangular holes located in the front plate  1  and back plate  2  of the transport frame  130 . A bearing retainer  12  is placed over the ends of the shaft of the idler roller  7 ,  8 . A flanged, shielded, extended inner race ball bearing  11  is placed over the ends of the shaft of the idler roller  7 ,  8 . The bearing retainer  12  and the bearing  9  are retained by an e-ring  10 . An extension spring  13  is wrapped around the bearing retainer  12  and connected to the spring hook features located in front and back plates  1 ,  2 . The bearing retainers  12  slide in the rectangular hole until the idler roller  7 ,  8  contacts the drive roller  4 ,  5 ,  6 .  
         [0045]     A number of different types of film guides are required to transport film through the vertical transport assembly  119 . The types required are listed below and shown in  FIG. 5 . 
        lower down film guide  14      middle curved down film guide  15      upper curved down film guide  16      flat down film guide  17      right down film guide  18      lower up guide assembly  19      up guide assembly  20      sensor up guide assembly  21      flat segmented film guide  22      dual segmented film guide  23         
 
         [0056]     The film transport drive train consists of stepper motors, drive pulleys, belt tensioners and timing belts. These components and their assembly to the vertical transport assembly  119  are described in the following sections and shown in  FIG. 6 .  
         [0057]     A stepper motor  24  is attached to the back plate  2  for the down film transport  108  drive system. A second stepper motor  35  is attached to the back plate for the up film transport  112  drive system.  
         [0058]     For drive trains with more than two pulleys a belt tensioning assembly is required. Two types are used in the vertical transport assembly  119 . A flat tensioning assembly  25  is designed with an idler pulley for the flat side of the timing belt. This type is used in the lower film supply drive train and the top belt in the up film transport drive train. A grooved tensioning assembly  27  is designed with an idler pulley for the grooved side of the timing belt. This type is used in middle and upper film supply drive trains.  
         [0059]     A flat idler  26  consists of a stationary shaft attached to the back plate  2  of the vertical transport assembly  119 . This stationary idler  26  is used in the lower, middle and upper drive trains to create proper belt wrap around the drive pulley  28 .  
         [0060]     A number of timing belts are used in the vertical transport assembly  119  drive train. The six belts used are listed below. 
        lower film supply drive train (includes stepper motor  29 )     middle film supply drive train  30 A     upper film supply drive train  30 B     lower film supply drive train  29  to middle film supply drive train  30 A connection  31 A     middle film supply drive train  30 A to upper film supply drive train  30 B connection belt  31 B     input roller set  70  to roller set  72  connection belt  32      roller set  72  to roller set  74  connection belt  33      roller set  74  to roller set  76  connection belt (includes stepper motor  34 )        
 
         [0069]     A number of drive and idler rollers are segmented to provide a recessed area in the urethane material for film guides. The segments were designed to support the edge of the film for all possible film sizes. Film edge support was considered important due to the planned high-speed film transport.  FIG. 7  shows the leading edge of the film  80 A,  80 B in relation to a segmented lower film transport roller  82 . The possible film leading edge lengths include 35.5 cm, 25.4 cm, and 24 cm. The film edges are shown before  80 A and after  80 B the film is shifted 1.5 cm for film centering in the imaging assembly.  
         [0070]     To transport film, the idler roller must be in contact with the drive roller with a certain amount of contact force. This contact force is created by spring loading the idler roller to the drive roller. A bearing retainer is designed to slide in a rectangular hole in the transport frame. An extension spring is wrapped around the bearing retainer and attached to spring hooks on the transport frame (see  FIG. 4 ).  
         [0071]     The guides utilized in transporting the film from the film supply to the imaging assembly are designed to guide the leading and trailing edges of the film while preventing the film surfaces from contacting the guides. The leading and trailing edge film guide approach is done to prevent scratches on the surface of the film. The guides are also fabricated from polished stainless steel to prevent scratching. Segmented guides are utilized to prevent scratching in the transition from film guide to roller. Without a segmented guide the first few millimeters of the leading edge of the film would be subject to scratching prior to contacting a urethane roller.  
         [0072]     The guides utilized in transporting the film from the imaging assembly to the processor are designed to guide both side of the film as much as possible while leaving some free span areas for film jam access. The free span areas rely on the beam strength of the film to span the open area prior to entering a film guide. The up guides have an angled lead-in to help guide the film following a free span area.  
         [0073]     To minimize torque requirements and the number of idler rollers, a multiple belt approach for the vertical transport assembly is shown in  FIG. 6 . For the down film transport, a single belt is used for the drive train components for each film supply. One belt length is required for the middle and upper film supply drive trains. An additional belt length is required for the lower film supply drive train due to the stepper motor. A third belt length is required to connect the lower film supply drive train to the middle film supply drive train. This same belt is used to connect the middle film supply drive train to the upper film supply drive train. Three additional belt lengths are used for the up film transport drive train.  
         [0074]     The operations that occur as a film passes through the vertical transport assembly  119  are described below. Details on light tight, turning the film 75°-90°, leading and trailing edge guiding, and transporting the film up and down are described.  
         [0075]      FIG. 8  shows an input roller set  200 ,  202  with a piece of film  39  entering a light tight seal which must be provided between the film supplies and the inlet to the vertical transport assembly  119 . This is required to prevent ambient light from reaching an exposed film that is being fed into the processor  113 . To provide this light tight seal a drive roller cover  36  and an idler roller cover  37  were designed to cover the input roller set  200 ,  202 . The goal was to create a circuitous path to prevent light entering the vertical transport area of the machine. This circuitous light path is the gap between the roller and the inside surface of the roller cover. In addition, a film supply gasket  38  is attached to the frame to provide a seal around the inlet to the input roller set.  
         [0076]     The flat down film guide  17  is designed to provide a leading edge guide to start turning the film  39  as the film  39  is fed through the input roller set  200 ,  202 . The film with an initial bend is shown in  FIG. 9 .  
         [0077]     The segmented guide roller  4  is designed to support the film  39  after the leading edge of the film  39  leaves the flat down film guide  17 . Both the flat down film guide  17  and the guide roller  4  are segmented. This allows the segmented tabs on the film guide  17  to be recessed into the corresponding recessed areas in the guide roller  4 . With this designed, the film  39  can transition from the film guide  17  to the roller  4  without any contact between the film guide  17  and the surface of the film  39 . This is done to prevent scratching on the film surface. The segmented guide roller  4  is a driven roller to match the speed of the film  39 . This is done to prevent any scratching of the film  39  that could occur with a non-driven guide roller  4 . The film  39  with an initial bend after the transition to the segmented guide roller is shown in  FIG. 10 .  
         [0078]     The middle curved down film guide  15  is designed to provide the next phase in the process of turning the film  39 . The leading edge contacts the curved guide  15  to continue bending the film  39 . The non-emulsion surface of the film  39  will remain in contact with the segmented guide roller  4 . This phase of turning the film  39  is shown in  FIG. 11 .  
         [0079]     The solid drive roller  6  is designed to provide the next phase in the process of turning the film  39 . As the leading edge of the film  39  slides along the middle curved down film guide  15 , the emulsion side of the film will contact the solid drive roller  6 . As the film  39  continues to be fed into the assembly, the contact with drive roller  6  will overcome the beam strength of the film  39  allowing the continued turning of the film  39 . This solid drive roller  6  is driven to prevent any scratching of the film  39 . This phase of turning the film  39  is shown in  FIGS. 12A and 12B .  
         [0080]     The curved leading edge film guide  15  is designed to provide enough accumulation of film  39  prior to the second roller set  204 ,  206  to result in a total film turn of 90°. If too little film  39  is accumulated prior to the leading edge of the film  39  entering the second roller set  204 ,  206 , the film  39  will not be turned a full 90°. If too much film  39  is accumulated prior to the leading edge of the film  39  centering the second roller set  204 ,  206 , the film  39  will be turned more than 90°. The film  39  exiting the second roller set  204 ,  206  after being turned 90° is shown in  FIG. 13 .  
         [0081]     After the film  39  is turned 90°, it must continue down towards the imaging assembly  110 . As the film  39  exits the second roller set  204 ,  206  the film  39  is unsupported for several inches prior to entering the lower set of film guides  14 ,  18 . The film  39  has sufficient beam strength to span this distance while retaining its direction. This open span is required to provide access for film jam removal. After traveling unsupported for several inches, the film  39  enters the angled lead-in portion  220  of the lower curved down film guide  14  and the right down film guide  18 . If necessary, the angled lead-in portion  220  of these guides  14 ,  18  direct the film  39  between the guides  14 ,  18 . After passing between these two guides  14 ,  18  the leading edge of the film  39  will contact the flat segmented film guide  22 . The film  39  is shown passing through the two film guides  14 ,  18  and contacting the flat segmented film guide  22  in  FIG. 14 .  
         [0082]     The flat segmented film guide  22  is a leading edge film guide designed to turn the film  39  15° from vertical to direct the film  39  towards the Imaging Assembly  110 . After sliding along this film guide  22  the film  39  will enter the final roller set  208 ,  210  prior to entering the imaging assembly  110 . This film guide  22  is located to accumulate the proper amount of film  39  prior to entering the roller set  208 ,  210 . The film  39  is shown in the final roller set  208 ,  210  15° from vertical in  FIG. 15 .  
         [0083]     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 spirit and scope of the invention.  
       Parts List  
       [0084]    
       
          1 front plate  
           2  back plate  
           3  steel rod standoffs  
           4  segmented drive roller  
           5  solid drive roller with features for film advance knob  
           6  solid drive roller  
           7  segmented idler roller  
           8  solid idler roller  
           9  extended inner race bearing  
           10  e-ring  
           12  bearing retainer  
           13  extension spring  
           14  lower down film guide  
           15  middle curved down film guide  
           16  upper curved down film guide  
           17  flat down film guide  
           18  right down film guide  
           19  lower up guide assembly  
           20  up guide assembly  
           21  sensor up guide assembly  
           22  flat segmented film guide  
           23  dual segmented film guide  
           24  stepper motor  
           25  flat tensioning assembly  
           27  grooved tensioning assembly  
           28  drive pulley  
           29  lower film supply drive train  
           30 A middle film supply drive train  
           30 B upper film supply drive train  
           31 A connection  
           31 B connection belt  
           32  connection belt  
           33  connection belt  
           34  stepper motor  
           35  second stepper motor  
           36  drive roller cover  
           37  idler roller cover  
           38  film supply gasket  
           39  film  
           70  input roller set  
           72  roller set  
           74  roller set  
           76  roller set  
           80 A leading film edge  
           80 B shifted film edge  
           82  film transport roller  
           100  laser imager  
           102  unexposed film supplies  
           104  unexposed film supplies  
           106  unexposed film supplies  
           108  film path  
           110  laser imaging region  
           112  film path  
           113  processor  
           114  heated drum  
           116  down rollers  
           118  output tray  
           119  vertical tray assembly  
           120  leading edge film guide  
           122  drive roller  
           124  secondary film guide  
           126  second roller set  
           130  frame  
           200  input roller set  
           202  input roller set  
           204  second roller set  
           206  second roller set  
           208  final roller set  
           210  final roller set  
           220  angled lead-in portion