Patent Publication Number: US-6705780-B2

Title: Processor

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a U.S. original patent application which claims priority on Great Britain patent application No. 0120189.6 filed Aug. 20, 2001. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to an apparatus for processing photosensitive material, in particular it relates to the insertion and removal of the photosensitive material from the apparatus. 
     BACKGROUND OF THE INVENTION 
     In many processors it is necessary to pull the film out of the film cassette or a loading station prior to the film being fed into processing tanks. To prevent damage to the film it is usual to manually attach a leader card to the leading edge of the film. The pulling and guiding forces as the film passes through the processor are then applied to the leader card instead of to the film itself. These leader cards are normally made of a robust flexible plastics material. As they are used they become damaged and therefore they need to be inspected before they can be re used. It is therefore not possible to use these leader cards in kiosk type processors where there is no operator and where the films are automatically withdrawn and fed into the processor. It is also not possible to use these leader cards in processors such as that disclosed in U.S. patent application Ser. No. 09/920,495, now U.S. Pat. No. 6,505,979, where the film is fed around a narrow path by drive rollers. 
     To overcome the above mentioned problems, and to provide a positive drive to load and unload the film from a processor a sprocket wheel system has been devised. 
     SUMMARY OF THE INVENTION 
     According to the present invention there is provided an apparatus for processing photosensitive material comprising a rotatable outer drum and an inner sprocket wheel independently rotatable from the outer drum, the inner wheel being provided with at least two sets of sprocket teeth for engagement with a strip of material to be processed, two pairs of drive rollers being located around the outer periphery of the drum. 
     Preferably one set of teeth are spring loaded. 
     The processor provides a positive drive system for loading and unloading the film. The film is held in position throughout the process and is therefore less likely to be damaged. The film is held in both dry and wet conditions. The pitch of the film does not have to be totally accurate to load into the processor. This allows for variances in the pitch due to film swell or manufacture. During processing there is no relative movement between the outer drum and the inner sprocket wheel. Thus there is no sticking or jamming. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
     FIG. 1 is a schematic view of a processor according to the invention in the loading position; 
     FIG. 2 shows the processor when it is fully loaded; 
     FIG. 3 shows the processor in the unloading position; 
     FIG. 4 shows the processor at the start of the unload position; 
     FIG. 5 is a schematic view of the drive arrangement for the processor; 
     FIG. 6 is a schematic view of the clutch; 
     FIGS. 7A and 7B show the film that may be used in the invention; 
     FIGS. 8A and 8B are schematic views of the wall of the processor; 
     FIG. 9 is a schematic view of the locking mechanism for the processor; and 
     FIG. 10 is a schematic view of the door closing mechanism. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows the processor in the loading position. 
     The processor  1  comprises an outer drum  2  and an inner sprocket wheel  4 . A narrow gap  3  is defined between the outer drum  2  and the inner sprocket wheel  4 . The gap can be up to approximately 3 mm wide to give good results. The inner sprocket wheel  4  can be rotated independently of the outer drum  2 . Sensors  30  and  32  are located on the inner wheel  4  and outer drum  2  respectively for determining the correct location thereof during loading and unloading. The sprocket wheel  4  may be made of any suitable material which is dimensionally stable. The outer drum  2  may be made of metal and/or plastics material. 
     The inner wheel  4  is provided with at least two sets of sprocket teeth around the outer periphery thereof. A first set of teeth  6  engage one end of a length of film  18  when the film is loaded into the processor. A second set of teeth  8  engage the other end of the length of film  18  when the film is loaded into the processor. The teeth may be made of a plastics material such as NORYL, ™. This is an example only of the material which may be used and the invention is not limited to such material. The front end of the first set of teeth  6  is provided with a stop member  10 . A spring  26  is provided behind the first set of teeth. A feed slot  28  is provided through the wall of the outer drum  2  to enable passage of the strip of film into the processor  1 . The feed slot  28  may be closed by a door  12 . The door is made of any suitable flexible material, such as rubber. 
     Two pairs of drive rollers  16 ,  24  are located outside of the processor  1 . The pairs of drive rollers are located at different positions around the circumference of the processor. Drive rollers  16  drive the strip of film  18  into the processor. A knife  14  is provided adjacent the drive rollers  16  on the side nearer to the processor. On the other side of the drive rollers  16  there is provided a sensor  22 . Sensor  22  detects the presence of the film. Drive rollers  28  are utilised to remove the strip of film  18  out of the processor. 
     FIG. 5 shows the drive arrangement for the processor. 
     The outer drum  2  is connected to gear wheel  44  via drive shaft  56 . Drive shaft  56  runs in ball race bearings  52 . The inner sprocket wheel  4  is connected to gear wheel  42  via drive shaft  54 . The drive motor  40  is physically connected to the gear wheel  42 . Gears  42  and  44  are spur gears. A pinion  46  is mounted for engagement with both gear wheels  42  and  44 . The position of the pinion relative to the gears  42  and  44  is controlled by a solenoid  48  and spring  50 . Sensors  38  are provided at periphery of both gear wheels  42  and  44 . A locking member  36  is located adjacent the outer drum  2 . 
     When film  18  from a film cassette  20  is to be loaded into the processor  1  for processing the outer drum  2  is locked into a stationary position. The feed slot  28  is in alignment with the drive rollers  16  in this position. Correct alignment can be sensed by sensor  38 . It is also possible to have a sensor for detecting the correct unload position. Such a sensor is not shown in the drawings. The inner sprocket wheel  4  remains rotatable. 
     Sensor  22  detects the presence of the film  18 . The drive rollers  16  are started on detection of the film. The rollers are activated for a predetermined set period of time during which the film is loaded into the processor. The door  12  in the processor wall is opened and the strip of film  18  to be processed is fed into the processor  1  via the feed slot  28 . The film  18  is driven into the processor by the drive rollers  16 . The inner wheel  4  is positioned within the outer drum  2  such that the first set of teeth  6  lies just below the entrance of the feed slot into the interior of the processor  1 . As the leading end of the film  18  reaches the end of the feed slot  28  it passes over the first set of sprocket teeth  6  and hits the stop member  10 . The inner sprocket wheel  4  starts to rotate in a counter clockwise direction. As the inner wheel  4  rotates the perforations in the film  18  become engaged with the first set of sprocket teeth  6 . The inner wheel  4  rotates and takes the film with it. When almost all of the film is within the processor the knife  14  cuts the film to detach it from the film cassette  20 . The inner wheel  4  continues to rotate until almost all the length of film  18  is within the gap  3  defined between the inner wheel and the outer drum. The trailing end of the film becomes engaged with the second set of sprocket teeth  8 . A short length of film  18  remains in the feeding slot  28 . The door  12  is then closed and the outer drum  2  is unlocked from its stationary position. Processing of the film then takes place. Full details of the processing can be found in co-pending U.S. patent application Ser. No. 09/920,495, the contents of which are herein incorporated by reference. 
     During processing the inner sprocket wheel  4  and the outer drum  2  rotate together. As the processing comes to an end the processor is stopped in a position such that the feed slot  28  is in alignment with the second pair of drive rollers  24 . The outer drum  2  is again locked into a stationary position. The door  12  is opened and the inner wheel  4  is rotated. This time the inner wheel is rotated in a clockwise direction. The rotation of the inner wheel drives out the film until it reaches the drive rollers  24 . The drive rollers  24  rotate at a speed which matches that of the rotation of the inner wheel  4 . This enables the film to remain taut. As the inner wheel rotates all the teeth of the first set of sprocket teeth and the second set of sprocket teeth become disengaged from the film  18 . As the film leaves the processing drum it may then be fed into the next stage of the process. This could be a dryer. 
     The spring  26  located at the rear of the first set of sprocket teeth  6  allows the teeth to engage properly with various pitches of film  18 . The pitch may vary due to different types of film and also be dependent on whether the film is wet or dry, hot or cold. The film may vary by up to 0.4% in length during processing. 
     When both the inner sprocket wheel and the outer drum are rotating together the pinion  46  engages both gear wheel  42  and gear wheel  44 . To lock the outer drum  2  in position a locking member  36  is engaged therewith. The drum is locked in a known position such that the feed slot will be aligned with either the drive rollers  16  or the drive rollers  24 . When the inner wheel is to be rotated for either loading or unloading of the film the solenoid  48  is energised. As the solenoid  48  is energised the pinion  46  is withdrawn from full engagement with both gear wheels. The gear teeth on the pinion  46  are shaved on the length of the pinion engaging with gear wheel  44 . This means that when the solenoid  48  is energised the pinion can be withdrawn such that it is no longer in engagement with gear wheel  44  but is still just engaged with gear wheel  42 . A close up view of this is shown in FIG.  6 . When the solenoid is de-energised the spring  48  pushes the pinion  46  back up towards the gears  42  and  44 . If the teeth on gear wheel  44  are not in line with the teeth on the pinion  46  the pinion will not engage correctly with the gear wheel  44 . The teeth will crown. In this instance the gear wheel  42  is briefly rotated a few degrees in either direction by the drive motor  40 . The pinion  46  is thus shuffled by the gear wheel  42  until the teeth properly engage with the teeth of gear wheel  44 . Both gear wheels  42  and  44  are then fully engaged. 
     A major advantage of having the pinion spring-loaded is that should the either the inner sprocket wheel or the outer drum get jammed in any way, for any reason, the pinion  46  will ‘jump’ out of engagement with the gear wheels. This prevents damage to both the film and the processor. It also provides an audible warning that the drums have jammed due to the noise of the teeth of the pinion jumping. 
     FIGS. 7A and 7B show a typical end of film strip for both 35 mm film and 26 mm APS film. Before processing can take place the tongue  58  must be cut off to enable the strip of film to be fed into the processor. The cut may be made anywhere, preferably not through perforations  60  since this does not give a good strong straight edge. Preferably the cut is made just to either side of a perforation and either side of a picture. It is possible to cut chamfered corners if required to stop the corner of the film catching and jamming in the processor. 
     The teeth of the sprocket wheel  4  are only 1.5 mm to 2 mm in height. Thus it would be quite easy for the film  18  to jump out of engagement with the teeth or not engage at all. To avoid this problem a groove  62  is provided in the inner circumferential wall of the outer drum  2 . The top of the sprocket teeth run through this groove  62 . This is illustrated in FIGS. 8A and 8B. The feeding slot  28  runs into the groove  62 . The top of the teeth are approximately 2 mm wide. The perforations in the film  18  are approximately 3 mm wide. This provides enough clearance for the film to easily engage with the teeth. The shape of the teeth may be profiled for easier engagement. The teeth are narrower than the width of the sprocket wheel  4 . 
     The film is engaged on one side only. The outer drum  2  has a further groove  64  located in the inner side wall thereof. The other side of the film  18  runs in this groove  64 . The groove may be chamfered to reduce friction and damage to the film. The chamfer will be in the region of 2°. 
     FIG. 9 illustrates the locking mechanism for locking the outer drum in position for loading and unloading of the processor. 
     The locking mechanism comprises a wedge shaped member  68 , operated by means of a solenoid, not shown, a pivot  66  and two receiving members  70 , one for locking the drum in the loading position and one for locking the drum in the unloading position. The members  70  are fixed to the outer wall of the outer drum  2  and have a V shaped slot  72 . This mechanism accurately locates the drum  2  in the correct location for loading and unloading. 
     To activate the locking mechanism the solenoid is energised. The movement of the solenoid pushes the wedge shaped member  68 , via pivot  66 , down into engagement with the member  70 . Any slight misalignment of the processor with the locking mechanism can be coped with due to the wedged shape of member  68  and the V shape of the member  70 . This V shape also allows the member  68  to cam out of the member  70  should the outer drum  2  be accidentally moved by the inner sprocket wheel  4 . Any damage to the sprocket wheel, film or outer drum can thereby be prevented. 
     FIG. 10 illustrates the door closing mechanism of the processor. 
     The door closing mechanism comprises an arm  74 , operated by means of a solenoid, not shown, a pivot  76 , a rack  78 , gear  80  and door member  82 . The rack  78  and gear  80  are located on the processor. There are two arms  74  and pivots  76 , located adjacent the processor, one for closing the door at the loading position of the processor  1  and one for opening the door at the unloading position of the processor. 
     The door closing mechanism works in a similar fashion to the locking mechanism described above. When the door is to be opened the solenoid is energised. The movement of the solenoid pushes down the arm  74 , via pivot  76 , down into contact with rack  78 . As the rack is pushed down the gear  80  rotates. The rotation of the gear  80  in turn rotates the door member  82 . The door member  82  is rotated to an open position to allow passage of the film  18 . 
     If the solenoid is not energised the door will close. The solenoid is spring loaded so that the arm  74  is withdrawn out of contact with the rack  78  when it is not energised. The rack  78  is also provided with a spring  84 . If the arm  74  is not pushing down on the rack, due to the solenoid being switched off, the spring  84  will push the rack  78  upwards. The gear  80  will thus rotate in the opposite direction to when the rack is pushed downwards and the door member  82  will be rotated to a closed position. 
     It will be understood by those skilled in the art that it is not essential that a solenoid be used in the mechanisms described above. Any prime mover can be used. 
     The invention has been described with respect to the processing of film material. However the invention may be used with other material, such as paper. 
     The invention has been described in detail with reference to preferred embodiments thereof. It will be understood by those skilled in the art that variations and modifications can be effected within the scope of the invention. 
     Parts List 
       1 . Processor 
       2 . Outer drum 
       3 . Gap 
       4 . Inner sprocket wheel 
       6 . set of teeth 
       8 . set of teeth 
       10 . stop member 
       12 . door 
       14 . knife 
       16 . drive rollers 
       18 . film 
       20 . film cassette 
       22 . sensor 
       24 . drive rollers 
       26 . spring 
       28 . feed slot 
       30 . sensor 
       32 . sensor 
       36 . locking member 
       38 . sensor 
       40 . drive motor 
       42 . gear wheel 
       44 . gear wheel 
       46 . pinion 
       48 . solenoid 
       50 . spring 
       52 . bearings 
       54 . shaft 
       56 . shaft 
       58 . tongue 
       60 . perforations 
       62 . groove 
       64 . groove 
       66 . pivot 
       68 . wedge shaped member 
       70 . receiving member 
       72 . slot 
       74 . arm 
       76 . pivot 
       78 . rack 
       80 . gear 
       82 . door member 
       84 . spring