Abstract:
A transport device for X-ray cassettes, each having a phosphor sheet stimulable by X-rays, is provided in a cassette processing apparatus ( 100 ), which is of simple physical construction and allows rapid and reliable processing of X-ray cassettes of different formats in a space-saving and user-friendly fashion. The apparatus has a plurality of transporters ( 11, 12, 21, 22 ) which are arranged in a horizontal plane (E) and are spaced apart from one another in the transport direction (T) and also perpendicular thereto. A conveying mechanism ( 30 ) which, in the area of the spacings (A 1 , A 2 , A 3 ) between the transport means, can be conveyed vertically in and out as far as the plane (E) in such a way that lowering effects a transfer of an X-ray cassette into a cassette receiving device ( 50 ), and raising effects a transfer out of the receiving device ( 50 ). The receiving device ( 50 ) can be pivoted from the vertical into a horizontal transport direction, for direct loading of an X-ray cassette into the loading slot of a reading unit suitable for the phosphor sheet.

Description:
FIELD OF THE INVENTION 
     The invention relates to a transport device for X-ray cassettes, each having a phosphor sheet stimulable by X-rays, in a cassette processing apparatus, comprising a first and a second conveying means configured as a cassette loading and unloading device, by which a plurality of vertically positioned X-ray cassettes of different formats can be guided to and away from a reading and erasing unit suitable for the phosphor sheet and provided with a horizontal loading slot. 
     BACKGROUND OF THE INVENTION 
     German Patent DE 37 18 131 C2 discloses a device for the transport of film sheets, the device having a transport table over which film sheets output from a cassette loading and unloading apparatus are transported to a developing apparatus. The transport table is selectably adaptable to different loading and unloading slots of the attached apparatuses. This device is suitable, however, only for straight-line transport from the cassette loading and unloading apparatus to the developing apparatus, for which purpose the apparatuses are to be arranged in a line one behind another. It is disadvantageous that this arrangement requires a long positioning depth or length for the entire assemblage of apparatuses. In addition, the loading and unloading points of the apparatuses are arranged on sides which face away and are remote from one another. 
     A modification of a transport device which is improved over the aforesaid device is disclosed by German Patent DE 44 17 050 A1, in which the films are transportable, by means of a transport carriage provided with several conveyor belts, to the loading and unloading slots which are arranged at different heights from one another. 
     European Patent Application EP 0 309 874 B1 discloses a handling apparatus for X-ray film cassettes with a phosphor-coated foil as a recording material. The cassettes to be processed do not need to be individually loaded into the handling apparatus, but can be loaded automatically from a cassette stack into the apparatus. For this purpose, appropriately configured cassette stack holders for the cassettes being loaded or unloaded are used, which are each arranged in front of a vertically extending cassette loading and unloading slot of the processing apparatus. In this context, transport of the cassettes from the loading slot—via apparatuses, for example, for detecting the cassette format, reading out patient data, laser-scanning the latent image on the phosphor-coated foil, etc.—to the unloading slot takes place in essentially straight-line fashion through the apparatus. This transport system also requires that the handling apparatus be long, and therefore occupies a large volume. 
     A reading unit for X-ray cassettes having a phosphor-coated foil as recording material (Scanner for PSL Radiography) is described by European Patent Application EP 0 747 752 A1. In this, a cassette is transported from a cassette stack, by means of correspondingly configured elements, via an elongated transport belt to a scanner. 
     U.S. Pat. No. 5,493,128 discloses a receiving device for X-ray cassettes in a handling apparatus (autoloader) suitable for the transport of vertically positioned cassettes of different formats with no need for additional pallets. This device substantially has a part, configured as a separating mechanism, with a number of slots into which the cassettes are loaded. By means of a part which can be lifted and lowered vertically and moved horizontally forward in steps, and which has a number of slots that corresponds to the number of slots in the separating mechanism, the cassettes are transported to a transfer device which transfers them into the reading and erasing unit. 
     This transport device is, however, of complex physical construction and, because of the large number of moving parts whose movements must be precisely adjusted to one another, is also susceptible to malfunctions. 
     SUMMARY OF THE INVENTION 
     It is the object of the invention to create a transport device in a processing apparatus for X-ray cassettes which is of simple physical construction and allows rapid and reliable processing of X-ray cassettes of different formats in a space-saving and user-friendly fashion. 
     The transport device according to the invention comprises a plurality of transport means which are arranged in a horizontal plane and are spaced apart from one another in the transport direction and also perpendicular thereto, as well as conveying means which, in the area of the spacings between the transport means, can be conveyed vertically in and out as far as the plane in such a way that lowering effects a transfer of an X-ray cassette into a cassette receiving device, and raising effects a transfer out of the device. Means are also provided for pivoting the receiving device from the vertical into a horizontal transport direction, for direct loading of an X-ray cassette into the loading slot of a reading unit. 
     The particular advantageous result of an arrangement of this kind is that X-ray cassettes of different formats can be transferred in a space-saving manner from a vertical transport position into a horizontal one. Furthermore, no additional means, such as adapters or the like, are needed for the transport device in order to be able to receive and deposit cassettes of different formats. 
     The invention, and its objects and advantages, will become more apparent in the detailed description of the preferred embodiments presented below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic drawing showing a known processing apparatus for X-ray cassettes, with conveying means configured as a cassette loading and unloading device; 
     FIG. 2 is a perspective view of the transport device for X-ray cassettes according to the invention; 
     FIG. 3 is a perspective detailed view of the various transport and conveying means, without the pivoting device; 
     FIG. 4 is a side view of the entire transport device in the state prior to transfer of an X-ray cassette into the holding means of the pivoting device; 
     FIG. 5 is a side view of the transport device as shown in FIG. 4, in the state after transfer of an X-ray cassette into the holding means of the pivoting device; 
     FIG. 6 is a perspective view of the pivoting device with the cassette receiving device in the vertical state according to FIG. 5; and 
     FIG. 7 is the pivoting device with the cassette receiving device in the horizontal state for transfer into a reading unit (not depicted). 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The transport device according to the invention is utilized in a processing apparatus  100  for X-ray cassettes, an autoloader known per se and depicted in FIG.  1 . The autoloader substantially comprises two conveying means  10  and  20  configured as cassette loading and unloading devices, an electronic control unit (not depicted), a reading unit (scanner) and erasing unit for the phosphor sheet (not depicted) in housing part  110 , and further transport means for transporting and handling the X-ray cassettes between the aforesaid units. The reading unit and the scanner contained therein have already been described in detail in one of U.S. Pat. Nos. 4,743,758; 5,105,079; 5,107,116; and 5,151,592, so that additional explanation may be dispensed with. The transport means for transporting the X-ray cassettes between the reading and erasing units are also sufficiently disclosed in U.S. Pat. No. 5,330,309 and, in particular with reference to FIG. 3, in U.S. Pat. No. 5,493,128, so that they do not require further explanation. X-ray cassettes  1  of different formats, but preferably of the formats 18×24 cm, 24×30 cm, 35×43 cm, and 35×35 cm, with the same X-ray cassette thickness in each case, are in particular transportable by means of the transport device. 
     As depicted in FIGS. 2 and 3, conveying means  10  and  20  arranged on a carrier plate  2  have at least three endless transport belts  11  to  13  and  21  to  23 , which lie horizontally in a plane E and are separated by a spacing A 3  in the transport direction T of the X-ray cassettes, and also by spacings A 1  and A 2  perpendicular thereto. Spacing A 3  is selected such that it slightly exceeds the thickness of an X-ray cassette. A further cassette holding element  40 , configured as an endless transport belt  41 , runs parallel to the rear longitudinal edge of transport belts  11  and  21  in a vertical plane. Transport belt  41  is arranged, by means of support elements  42 , at a height H from horizontally extending transport belts  11  and  21  such that an X-ray cassette of even the smallest format can still be reliably seized and transported by transport belt  41 . For vertically arresting and transporting the X-ray cassettes on cassette loading device  10 , only the respective transport belts  11  and  41  have knob-shaped elements  15  and  45  which are spaced apart from one another and arranged on the transport belts. The X-ray cassettes can be deposited in a vertical position into receptacles  14  and  44  formed thereby. The drive shafts  16  and  26  of the transport belts of conveying means  10  and  20  are driven by means of a stepping motor  3  via a toothed belt  4 , as are also the front and rear drive shafts  46  and  47  of transport belt  41  via bevel gears  17  and  18 , as visible in FIG.  5 . In a further embodiment of the invention, the aforesaid transport belts can also be driven by respective separate stepping motors which are then operated by the electronic control unit. In both embodiments, however, all transport belts  11  to  13 ,  21  to  23 , and  41  are each driven synchronously, so that no slippage occurs between the individual transport belts. 
     A conveying mechanism  30  which comprises three conveyor belts  31  to  33  spaced apart perpendicular to the transport direction T and arranged on a carrier  37 , is movable vertically, as depicted by arrow P 1  in FIGS. 4 and 5, by means of a chain  38  driven by a motor  38   b.  Carrier plate  2  has, at spacings A 1  to A 3 , respective openings S 1  to S 3  through which conveyor belts  31 ,  32 , and  33  of conveying mechanism  30  can be introduced as far as plane E. The contact length of conveyor belts  31  to  33  is selected such that spacing A 3  is definitely overlapped. Transfer of an X-ray cassette from conveying means  10  to conveying mechanism  30 , and from conveying mechanism  30  to conveying means  20  configured as the cassette unloading device, can thus be accomplished without difficulty. A counterweight  38   a  is provided in order to minimize the energy expenditure for moving the entire conveying mechanism  30  up and down, with carrier  37  of conveying mechanism  30  being guided by means of two guide rods  39 . Synchronous driving of conveyor belts  31  to  33  is guaranteed by means of a stepping motor  37   a  which drives a drive shaft  36 . As already mentioned, all the aforesaid transport and conveyor belts  11  to  13 ,  21  to  23 , and  31  to  33  are driven in synchrony by means of an electronic control unit (not depicted), known per se, of motors  3  and  37   a.    
     As is apparent from FIGS. 4 to  6 , a cassette receiving device  50  is coupled via joining elements  61  to a pivoting table  60 , the cassette receiving device  50  substantially comprising three U-shaped carrier elements  55 ,  56 , and  57  which are spaced apart from one another. Loading slot  51  resulting from the U-shaped configuration serves to receive an X-ray cassette  1  which is prevented from falling out to the side by delimiting panels  52 . The spacings between carrier elements  55  to  57  are adapted to the width and spacings of the respective conveyor belts  31  to  33 , so that conveying mechanism  30  can easily be transferred out of plane E (FIG. 4) into the state as depicted in FIG.  5 . Arranged in the bottom of loading slot  51  are a transport roller  53  that can be driven by a motor  5453 , and a switching roller  58 , on which X-ray cassette  1  is supported. The switching roller serves as a signal generator for the control unit, indicating whether an X-ray cassette has been loaded into the loading slot. To ensure that an X-ray cassette is reliably transferred into loading slot  51  (FIGS. 4 and 5) when conveying mechanism  30  is lowered vertically, the spacing from the top edge of carrier elements  55  to  57  to the bottom edge of carrier plate  2  (FIG. 4) is selected such that X-ray cassette  1  is either still supported on carrier plate  2  or already supported on carrier elements  55  to  57 , without having the pivoting movement of the pivoting table, depicted by arrow P 2  in FIG. 5, impeded by carrier plate  2 . 
     An optoelectronic sensor  5  mounted on cassette holding element  40  above opening S 3  (A 3 ) by means of a holding member  43  determines on the one hand whether an X-ray cassette is located in a position for transfer from conveying means  10  into conveying mechanism  30 , and whether it has been properly conveyed into loading slot  51 . Optical scanning is accomplished in the manner depicted with dashed lines in FIG.  5 . Sensor  5  is formed by IR transmission and reception elements known per se, which are controlled by means of the electronic control unit (not depicted). 
     As already mentioned, the cassette receiving device  50  is coupled via joining elements  61  to pivoting table  60 . To compensate for the weight of cassette receiving device  50 , a counterweight  62  is attached to the extension of joining elements  61  constituted by carrier arms  62   a  and  62   b,  as is evident from FIG.  6 . Pivoting table  60  is pivoted from the vertical into the horizontal position (arrow PF 2 ) by means of fulcrum  63 , which is also supported on the housing of processing apparatus  100  (not depicted). A crank rod  65  which is joined via the center of rotation  66   a  to a further crank rod  66  coupled to a drive motor  67 , engages on a shaft  64  which is arranged alongside the fulcrum at a spacing of 1:2 of the crank length and offset upward at a 45-degree angle. The result of this configuration is that with a 180-degree motor rotation or crank rotation of crank rod  66 , for example from the position corresponding to FIGS. 6 to  7 , cassette receiving device  50  can be pivoted 90 degrees with minimal energy expenditure. 
     Also mounted on the housing of processing apparatus  100  is a conveying means  6  with which an X-ray cassette  1  located in loading slot  51  can be transported in the direction TL to the reading unit. The X-ray cassette is seized by means of a transport roller  7  which is driven by a stepping motor  8  and is displaceable along a guide rail  9  by means of a motor-driven belt drive (not depicted), and conveyed by the two driven transport rollers  53  and  7  in the direction TL toward the reading unit, until it is seized by further transport rollers of the reading unit. 
     With cassette processing apparatus  100  in its initial state, conveying mechanism  30  which is not loaded with an X-ray cassette, is located in plane E, as depicted in FIG.  4 . X-ray cassettes  1  with the aforesaid different formats can now be loaded into conveying means  10 , configured as the cassette loading device, in any order and in vertical alignment into receptacles  14  and  44  of transport belts  11  and  41 . Up to fifteen X-ray cassettes can be delivered to the cassette loading device in accordance with the preferred length of the transport belts. After actuation of the start button on the electronic control unit (not depicted), optoelectronic sensor  5  determines whether an X-ray cassette  1  is in a position for transfer to conveying mechanism  30 . If not, stepping motors  3  and  37   a  advance transport belts  11  to  13 ,  21  to  23 ,  31  to  33 , and  41  into that position. If so, a further advancing movement aligns X-ray cassette  1  in the center of conveying mechanism  30  and thus also exactly in A 3 . The stepping motors for the transport belts thereafter remain shut down. Conveying mechanism  30  is lowered by means of stepping motor  37   a  out of plane E, such that the X-ray cassette is introduced into loading slot  51  of cassette receiving device  50 . Switching roller  58  in the bottom of loading slot  51  is actuated by the weight of the X-ray cassette, and the switching signal generated thereby causes the electronic control unit to actuate motor  67 . Pivoting table  60  is thus transferred by crank rods  66  and  67  from a vertical into a horizontal position, actuating a contact switch (not depicted). The triggering of the contact switch causes transport roller  7  to move along guide rail  9  until it comes into non-positive contact with the lateral edge of the X-ray cassette, adjusted by a friction clutch. Transport to the reading unit for the phosphor-coated recording sheet is then accomplished by means of transport rollers  53  and  7 . After the sheet has been read (scanned) and the latent image has then been erased, as recited initially by the U.S. patent documents, the procedure described occurs in reverse order: the X-ray cassette is reintroduced into loading slot  51  by means of transport rollers  53  and  7 ; pivoting table  60  is pivoted out of the horizontal into the vertical position; the X-ray cassette is transferred by means of conveying mechanism  30  out of loading slot  51  into plane E; and stepping motors  3  and  37   a  are activated so that the processed X-ray cassette  1  is transported onto transport belts  21  to  23  of the cassette unloading device. All the X-ray cassettes deposited in cassette loading device  10  are processed in the manner indicated above, the number of cassette deposition spaces in the cassette loading and unloading device being identical. X-ray cassettes not removed from the cassette unloading device are safely received by a tray (not depicted) arranged at the end of transport belts  21  to  23 . 
     The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.