Patent Publication Number: US-6908083-B2

Title: Recording plate or film loading device

Description:
The invention relates to a recording plate or film loading device for use with an image recording scanner. 
   DESCRIPTION OF THE PRIOR ART 
   Modern image recording scanners have been developed which can record images onto a plate or film having dimensions up to 1200×1000 mm. By a recording plate or film we include any conventional imaging media such as photographic film, polyester plate, paper, aluminium plate etc. In some cases, a stack of unexposed plates or film sheets is provided in a cassette from which they are automatically loaded into the image recording scanner such as an internal drum imaging scanner (see for example EP-A-0822454). However, these cassettes are expensive and in many cases users prefer manually to load plates or films. This also has the advantage that successive images can be recorded on different size plates. In typical manual devices, a large, horizontal table is positioned adjacent the image recording scanner. The user places the unexposed film flat on the table and slides it towards an input opening on the scanner where it is picked up by feed rollers and fed into the scanner. A drawback of this is that it requires the user to have significant expertise in being able to orient correctly the film. 
   SUMMARY OF THE INVENTION 
   In accordance with the present invention, a recording plate or film loading device for use with an image recording scanner comprises a platen arranged at an angle to the horizontal and onto which a plate or film is manually placed; a loading mechanism including one or more first pusher members cooperating with the platen to push a plate or film to an output position; and a centering mechanism including a pair of second pusher members movable laterally with respect to the platen to centre a plate or film on the platen. 
   With this invention, we partially automate the manual feeding process by utilizing a special loading device provided with first and second pusher members which enable the plate or film to be correctly centred and then pushed at the correct speed into the image recording scanner. By mounting the platen at an angle to the horizontal, the plate or film will be maintained in contact with the first pusher member(s) under gravity thus ensuring that its position is accurately known. This angling also reduces the overall footprint of the device and reduces dust accumulation. 
   Although the pusher members could be manually operated, preferably the loading mechanism comprises a motor connected to the first pusher member(s) via a rack and pinion, typically mounted on a carriage running on linear tracks. This provides a simple implementation of the loading mechanism although other implementations will be readily envisaged by a person of ordinary skill in the art. For example, if more than one first pusher member is provided, each could be actuated by a respective motor. 
   Conveniently, the or each first pusher member includes a roller to assist lateral movement of the plate or film across the platen by the second pusher members. Thus, the roller would be pivoted to rotate in the lateral direction. Alternatively, the or each first pusher member could comprise a narrow edge across which the plate or film can be moved laterally or a low friction, flat surface. 
   Typically, the centering mechanism comprises a motor connected to the second pusher members via respective rack and pinion connections. As with the loading mechanism, other implementations of the centering mechanism are possible. 
   For semi-automatic implementations of the loading device, conveniently the centering mechanism includes a sensor for sensing engagement between the second pusher members and a plate. The sensor could monitor for the pressure exerted on the second pusher member by the plate in order to detect the presence of the plate but conveniently the sensor comprises an electrical circuit connecting the second pusher members and including a voltage source and current detector. This takes advantage of the fact that the plate will usually be electrically conductive. 
   Preferably, an inductive sensor is mounted to the platen to detect a metal plate on the platen. This provides further information about the presence of a plate. 
   Preferably, the device further comprises a control system for receiving information defining a plate or film size and for controlling the loading mechanism and centering mechanism so that the first and second pusher members take up positions corresponding to the defined size. The advantage of this is that placement of a film or plate of the incorrect size can be prevented since it becomes obvious to the user that the plate or film does not contact the pusher members correctly. 
   Typically, the platen is angled at 70-75°, preferably 71°, to the horizontal. This helps to prevent dust accumulation. 
   In order to prevent further dust accumulation, an air curtain or the like could be provided at the entrance to the image recording scanner. Furthermore, to reduce the risk of scratching of the sensitive surface of the plate or film, the platen may be covered by a suitable non-scratch material such as velvet. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An example of a loading device according to the invention coupled to an internal drum image scanner will now be described with reference to the accompanying drawings, in which: 
       FIG. 1  is a perspective view of the loading device and scanner; 
       FIG. 2  is a front perspective view of the loading device; 
       FIG. 3  is a rear perspective view of the loading device; 
       FIG. 4  is a perspective view of the front of the loading mechanism; and, 
       FIG. 5  is a circuit diagram of the lateral pusher member location detection circuit. 
   

   DESCRIPTION OF THE EMBODIMENTS 
   The apparatus shown in  FIG. 1  comprises an internal drum image scanner  1  of conventional construction (for example as shown in WO-A-99/17535) having a control computer  2  mounted internally for controlling operation of the scanner. The control computer  2  is also connected to an illuminated control panel  3  mounted at the top of the scanner  1  for receiving inputs via a touch screen and displaying information. The scanner  1  has an input slot  4  for receiving individual plates or film sheets to be exposed. 
   A recording plate or film loading device  5  is mounted to the front of the scanner  1  and this is shown in more detail in FIG.  2 . The device  5  comprises a platen  6  mounted at an angle α to the horizontal of 71°. The platen is mounted by means of side plates  7  to a back plate  8  and extends beneath an air curtain  9 . A plate or film sheet exits from behind the air curtain  9  and passes into the slot  4 . 
   The platen  6  has a pair of laterally spaced upwardly extending slots  10 , and a pair of horizontally extending slots  11  towards its upper end. Protruding from each slot  10  is a respective first pusher member constituted by a roller  12 , each roller  12  being mounted on an axle so that it is rotatable in the lateral direction. A pair of metal plates  13  defining second pusher members extends through respective slots  11 . 
   An infrared sensor  15  ( FIG. 3 ) is mounted behind an aperture  14  in the platen. 
   The first pusher members  12  are mounted on a carriage  22  ( FIG. 4 ) which is slidable along a linear track  23 . A stepper motor  16  is coupled to the carriage  22  and is mounted to a rack  17  fixed to a rear surface of the platen  21  (FIG.  3 ), the motor  16  being coupled to the rack  17  via a pinion (not shown). Power to the motor  16  is supplied though a ribbon cable  18  connected to a power source (not shown), the ribbon cable  18  also carrying control instructions from the control computer  2 . When the motor  16  is activated, it rotates the pinion which runs along the rack  17  thus moving the carriage  22 , motor  16  and pusher members  12 . 
   The pusher members  13  are connected to respective racks  19  slidably mounted to the rear surface of the platen  21  and engaging opposite sides of a pinion (not shown) of a stepper motor  20 . The stepper motor  20  is fixed to the platen  21  and connected (by means not shown) to a power supply and the control computer  2 . When the stepper motor  20  is activated, the pusher members  13  will move along the slots  11 . 
   The pusher members  13  are connected into an electrical circuit  30  (FIG.  5 ), the electrical circuit also being coupled to the control computer  2 . The pusher members  13  are connected across an RC circuit  31  whose output is fed to an inverting amplifier  32 . One of the pusher members  13  is connected to a five volt line  33  while the other is connected to a ground line  34 . When no plate is present between the pusher members  13 , the input to the amplifier  32  will be high resulting in a logic low output whereas when the contacts  13  both contact a (electrically conductive) plate, the RC combination will be short circuited and the output from the amplifier  32  will be become high. 
   In use, when an operator wishes to record an image on a recording plate or film, he enters the dimensions of that film/plate via the control panel  3 . Typical film/plate dimensions include a horizontal dimension of between 100 and 1200 mm and a “vertical” dimension of between 100 and 1000 mm. Typical thicknesses range from 0.1 to 0.3 mm. 
   Once the control computer  2  has received the dimensions, it then controls the motors  16 , 20  so as to locate the first and second pusher members  12 , 13  at positions at which they will just engage the sides of the film or plate. 
   The user then places a film or plate onto the platen  6 . This placement will first be detected by the sensor  15  while in addition the circuit  30  containing the pusher members  13  will be completed when the plate/film is centred. All this information is received by the control computer  2  which will determine that a plate has been correctly located on the platen  6 . Of course, for non-conductive media this automatic determination will not be possible unless, for example, an optical sensor has been provided. 
   Once the control computer  2  has ascertained that the correct medium has been placed on the platen  6 , the motor  16  is actuated to move the sheet upwardly along the platen  6  at a speed suitable for it to be picked up by the feed rollers (not shown) of the input scanner  1  from where it is drawn into the scanner. The pusher members  12 , 13  are then returned either to a position previously determined for the next film or plate to be fed or to a default position. In the default position preferably it is not possible to load a film or plate onto the platen.