Abstract:
A low cost, automated film processing system which can replace existing hand dipping development of films, but which is also later expandable in field, to accommodate additional features, should an upgrade to those features be desired. In the preferred embodiment, the design utilizes deep tanks, as defined in the specification, to enable the chemicals to be utilized over an extended period of time. The chemistry utilized in the processor operates at room temperature.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     NONE 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable 
     BACKGROUND OF THE INVENTION 
     This invention relates generally to film processing, and more particularly, to a low-cost system for developing x-ray films on a semi automated basis. While the invention is described in particular reference to its use for x-ray film development, those skilled in the art will recognize the wider applicability from the principals disclosed hereinafter. 
     Table-top automatic x-ray film processors often are used in individual offices of dentists, doctors and chiropractors, for example, to develop films taken of patients under treatment. Conversely, floor-standing automatic x-ray film processors are normally used in hospitals, where higher-volume film processing is required. In general, a body of art has developed around automatic film processors that utilize heated liquid chemicals in order to develop the film. As used herein, heated liquid chemicals refer to developer solutions, for example, which are specifically formulated for use in automatic x-ray film processors and which are normally utilized within a temperature range of 89 to 96 degrees Fahrenheit. These automatic x-ray film processors require heaters for the developer chemistry and often include automatic replenishment systems, recirculation systems and process control systems to bring developer chemistry to operating temperature, and maintain temperatures at specific levels, within a narrow range, over long time periods. Because the developer chemistry must be heated to a relatively high temperature, there is a considerable warm-up period required before the processor may be utilized to develop films. 
     Existing tabletop automatic film processors generally require 15 amp electrical service (10 amps at minimum) to operate their heaters and associated equipment, and generally require permanent plumbing connections for proper operation. Existing tabletop processors generally incorporate a “shallow tank” design, to minimize manufacturing costs, and accordingly, generally require recirculation and replenishment systems, because of the limited liquid volume in each tank. For the purpose of this specification, “shallow tank” refers to tanks, which when filled with liquid to operating levels while containing a transport rack, generally contain liquid with a depth of four (4) inches or less and generally having liquid volumes of one (1) gallon or less per tank. 
     Because of the costs associated with meeting these various operating requirements, and because of the costs of purchasing, installing and maintaining tabletop automatic film processors, many potential customers have been unable to justify the cost of purchasing such tabletop automatic film processors, particularly if their daily film usage is low. Consequently, these potential customers have continued to utilize hand tanks (trays) and manual hand dipping and air-drying in order to obtain dry, fully developed films. While “hand-tank” development produces acceptable films, the use of open chemical tanks or trays in a medical or medical-like environment is undesirable. In addition, there is no convenient way for an operator to tell when the chemicals in use should be replenished or replaced. 
     We have devised a low-cost, automated film processing system which can economically replace the existing hand-dipping development of films, but which is also later expandable in field, to accommodate additional features, should the owner wish to upgrade the capabilities of the processor. 
     BRIEF SUMMARY OF THE INVENTION 
     One of the objects of this invention is to provide a low-cost automated tabletop film processor. 
     Another object of this invention is to provide a low-cost, automated table-top film processor having an enclosure and internal structures which are designed to accommodate the in-field installation of upgradeable features for the system easily, at any later date. 
     Another object of this invention is to provide a low-cost, automated, easily-upgradeable-in-field tabletop film processor, which provides for the development of x-ray film at room temperatures, without heated chemistry or a heated dryer. 
     Another object of this invention is to provide a low-cost, automated, easily-upgradeable-in-field table-top film developer system which does not require heated chemicals nor a heated dryer nor recirculation mechanisms nor automated replenishment systems nor external plumbing for operation, but which is capable of easy in the field upgrading to include one or more of the above features. 
     Other objects will be apparent to those skilled in the art in light of the following description and accompanying drawings. 
     In accordance with this invention, a low-cost table-top x-ray film processor capable of being easily-upgradeable in the field at a later date, by incorporating internal component placement at predetermined locations within the processor is provided. In the preferred embodiment a first tank for containing developer solution, a second tank for containing a fixer solution, and a third tank for containing wash water are used. Preferably, each of the tanks is substantially deeper than normally required for film processing. The chemistry employed in the embodiment illustrated is chosen so as to enable the processor to operate for long periods at room temperature. A dryer section incorporating air blowers but with no air-heating or film-heating elements also is provided. A transport rack drive system for advancing film through the first, second and third tanks and thru the dryer section is operated by a variable speed motor operably connected to the transport rack drive system. Motor speed adjustments adjust the time required to process film through the tanks and dryer, and provides compensation for degradation of the chemical composition of the fixer and developer solutions, variations in ambient room temperature, and; differing density requirements for film processing. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is a view in perspective of one illustrative embodiment of processor of the present invention; 
     FIG. 2 is a front interior view, with a lower front panel removed, showing the dryer blower, terminal block and selected connections for the processor of the present invention; 
     FIG. 3 is a drive-side interior view, with the drive-side cover panel removed, illustrating the side-wall of the solution tanks, the transport rack drive gears, the variable speed motor and the dryer blowers utilized in conjunction with the processor of the present invention; 
     FIG. 4 is an enlarged drive-side interior view, partly broken away, illustrating the variable-speed motor and motor controller. 
     FIG. 5 is a non-drive-side interior view, partly broken away, illustrating the drain system for emptying the developer, fixer and rinse-water wash tanks of the present invention; 
     FIG. 6 is a rear elevation view, showing the location of the input power cord for the processor, and a removable conventional drain hose connection, operable with an internal drain system of the present invention; 
     FIG. 7 is a top perspective interior view, partly broken away, with the top cover removed, showing the developer, fixer, wash and dryer transport racks of the present invention; 
     FIG. 8 is a diagrammatic view showing the film path of the system through the developer, fixer, wash and dryer sections of the device; and 
     FIG. 9 is a chart illustrating operation of the processor of the present invention with room temperature chemistry associated with the developer and fixer tanks. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following detailed description illustrates the invention by way of example and not by way of limitation. This description will clearly enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what is presently believed to be the best way of carrying out the invention. 
     Referring now to FIG. 1, reference number  100  refers to one illustrative embodiment of film processor of the present invention. The film processor  100  has an enclosure  102 , which, in the embodiment illustrated, includes a top cover  1 , a lower-front panel  2 , and upper front panel  3 , a back panel  4 , side panels  5  and  6 , and a film feed cover  7 . Those skilled in the art will recognize that the back  4  and front panels  2  and  3  also are sidewalls for the purposes of this specification. Other embodiments of our invention may employ alternative arrangements for the enclosure  102  design. The upper front panel  3  of the processor  100  has a main power switch  8  and a variable speed control dial  9  mounted to it. The power switch  8  is interposed in a power cord  115  so as to be operatively connected between one side of the electrical line carried by the cord  115  and a terminal board  103 . The power switch  8  selectively applies electrical power to the terminal board  103  (FIG.  2 ). The top cover  1  has a film entrance receptacle  10  formed near the rear of the top cover  1 , under the film feed cover  7 , and developed film exits the processor  100 , in a downward direction, immediately behind the bottom of lower front panel  2 , at a film exit  11 . 
     Referring now to FIG. 8, a diagrammatic view of the operation of the processor  100  shown in FIG. 1 is illustrated. As indicated, film is inserted along an entrance  10  and proceeds through a short developer transport rack  12 , which is immersed in a deep developer tank  47 , then through a short fixer transport rack  13 , which is immersed in a deep fixer tank  46 , then through a short rinse water wash transport rack  14 , which is immersed in a deep wash tank  45 . Upon exiting the short rinse wash transport rack  14 , the film is transported by a long dryer transport rack  15  through a dryer plenum  19 , after which film then exists the processor  100  at film exit  11 . While the general description of film movement just described is conventional, the use of deep tanks with short racks is an important feature of the invention, as later described in detail. It is here noted that the term deep tank refers to tanks having a fluid depth of at least seven (7) inches with of fluid volume capacity of at least two gallons. 
     In the embodiment of the present invention, a motor  30  (shown in FIG. 4) has an output side connected to a belt  40 . The belt  40  powers a worm gear drive rod  41 . The rod  41  is mounted for rotation along support blocks  112 . The rod  41  in turn powers four drive helical worm gears  21 ,  22 ,  23  and  24  of each of four transport racks  12 ,  13 ,  14  and  15  respectively, as is best shown in FIGS. 3 and 7. 
     Referring now to FIG. 4, a motor speed control  42  is operably connected to the variable processing speed control dial  9  on the upper front panel  3  of the processor shown in FIG. 1, and to the motor  30  through the terminal board  103 . Referring to FIG. 5, a drain manifold  50  is operably connected to a developer tank drain connection  32 , and the water tank drain connections  33  and  34 . Each of the connections  32 ,  33  and  34  have manual stand-pipe drain tubes associated with them, which are opened to drain their respective tanks for purposes later described. The drain manifold has an output side  51 . The output side  51  may be connected to a conventional hose, for example, when draining of the tanks is desired. No hose or other plumbing connections are required for operation of the processor shown in FIG. 1, but chemical fixer in fixer tank  46  must normally be drained via a manual standpipe drain tube, to a dedicated hose  109  from fixer tank connection  35  to a segregated container outside of the processor, for silver recovery and environmentally-approved disposal. 
     The processor  100 , as shown in FIG. 3, also includes a pair of dryer blowers  60  and  61 , which are positioned to direct air through the drying plenum  19  of the processor. Because the present invention operates at room temperature, thereby not requiring heating elements, the unit does not use electrical power when film is not being transported through the travel path. Additionally, there is no wait time for the developer solution to reach operating temperature after the processor has been turned on. Further, the use of short racks in deep tanks containing unheated chemistries eliminates the need for recirculation and replenishment systems, because: (a) the use and storage of chemistry at room temperature greatly minimizes evaporation, oxidation and degradation of the chemistry, thereby greatly extending its productive life, and (b) deep tanks hold 2 to 3 times more chemistry per tank than shallow tank processors, thereby allowing extended life, i.e., 2 to 3 weeks of operation without needing replenishment, and; (c) the short rack system allows contaminants and spent emulsion to sink to the bottom of their respective deep tanks, away from the racks and rollers. Because of the settling, operation of the racks and rollers provides circulation of clean chemistry and clean rinse water during the developing process. Finally, none of the complex electrical or electronic circuitry needed to monitor and control heating elements is required, since no heaters are utilized. Without the use of heaters, the development process takes a slightly longer time and, therefore, throughput is reduced. However, the benefits of a less expensive, more efficient processor clearly outweigh the slightly increased development time for low volume applications. 
     EXAMPLE 
     As indicated, the processor  100  has no chemical heating elements, no microprocessor, no feed switch, no lamps, no floaters, no buzzer, no fixer/developer tank recirculation, no replenishment, no water solenoid and no dryer heat. The only electrical components in this machine are the two dryer plenum blowers and the variable speed drive motor. The drive motor and two dryer plenum blowers are connected to a terminal strip that is energized by a conventional main power switch via a 15-amp fuse block, although actual power draw, with full tanks and while developing film, is less than 4 amps, thereby permitting the processor  100  to be utilized when only 10 amp power sources or less are available. Moreover, the processor  100  is only run while developing film. There is standby mode. 
     The processor  100  of the present invention was placed in a user location. The developer and fixer tanks were filled with pre-mixed developer and fixer into the respective first and second tanks  47  and  46 . The third tank  45  was filled with plain tap water. The variable processing speed control dial  9  was set at the fastest setting, which generates a film throughput time of 3 minutes and 43 seconds. This processing speed was kept constant over the entire duration of the test. 
     Diagnostic Imagining, Image Plus Green 14X17 x-ray film was used throughout the example. This film was exposed using a General Electric Mobile 90-II x-ray unit. The x-ray unit was set at 15 MA adjusted for 50 k-V peak, with a {fraction (4/10)} second exposure time. The x-ray tube head was adjusted to 25 inches over the table using the flexible steel scale on the side of the tube head. The x-ray subject was a circuit board. 
     Each working day during the test period, three films were exposed and developed in the processor  100 . Each film was dated and numbered for that date. After the films were processed, the developer temperature was measured using a thermometer, and recorded on the film. 
     A Sakura PDA-85 densitometer was used to measure film density (contrast) on each piece of film exposed during the test. A total of 29 films were processed for the example. Throughout the duration of example, the films developed clearly and legibly. Although there was no dryer heat, film was found to be dry when exiting the processor. The data recorded during testing is shown in the table below and in the graph of FIG.  9 . Since there is no control over developer temperature, density can be increased, if necessary, by increasing the film processing time. Of course, density can also be improved by adding fresh chemical and changing wash water. 
     Although the films developed clearly and with good contrast throughout the duration of the test, density (contrast) readings gradually degraded over time as the chemicals weakened and the wash water became polluted. It was noted that density rebounded after the machine was allowed to sit over night or over a weekend, but declined as each film was processed. This effect probably resulted when weak chemical settled to the bottom of the tank during long periods of inactivity. 
     
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
               
               
                 FIG. 9 Data 
               
             
          
           
               
                   
                   
                 Developer 
                   
                   
               
               
                 Shot 
                   
                 Temp 
                   
                   
               
               
                 No. 
                 Day 
                 (Deg F.) 
                 Densitometer 
                 Comments 
               
               
                   
               
             
          
           
               
                 1 
                 1 
                 77 
                 1.02 
                 Processing speed set 
               
               
                 2 
                 1 
                 77 
                 0.74 
                 at 3 minutes, 43 seconds 
               
               
                 3 
                 1 
                 77 
                 0.87 
               
               
                 4 
                 5 
                 79 
                 0.84 
               
               
                 5 
                 5 
                 79 
                 0.95 
               
               
                 6 
                 5 
                 79 
                 0.92 
               
               
                 7 
                 6 
                 81 
                 0.66 
               
               
                 8 
                 6 
                 81 
                 0.82 
               
               
                 9 
                 6 
                 81 
                 0.79 
               
               
                 10 
                 7 
                 80 
                 0.80 
               
               
                 11 
                 7 
                 80 
                 0.69 
               
               
                 12 
                 7 
                 80 
                 0.75 
               
               
                 13 
                 11 
                 81 
                 0.90 
               
               
                 14 
                 11 
                 81 
                 0.70 
               
               
                 15 
                 11 
                 81 
                 0.64 
               
               
                 16 
                 12 
                 79 
                 0.84 
                 Morning 
               
               
                 17 
                 12 
                 79 
                 0.80 
               
               
                 18 
                 12 
                 79 
                 0.78 
               
               
                 19 
                 12 
                 81 
                 0.70 
                 Afternoon 
               
               
                 20 
                 12 
                 81 
                 0.66 
               
               
                 21 
                 12 
                 81 
                 0.58 
               
               
                 22 
                 13 
                 81 
                 0.66 
               
               
                 23 
                 13 
                 81 
                 0.69 
               
               
                 24 
                 13 
                 81 
                 0.61 
               
               
                 25 
                 15 
                 80 
                 0.66 
                 0.3 gallons of fixer added 
               
               
                 26 
                 15 
                 80 
                 0.64 
               
               
                 27 
                 15 
                 80 
                 0.61 
               
               
                 28 
                 20 
                 78 
                 0.74 
                 #1 was thrown out- 
               
               
                 29 
                 20 
                 78 
                 0.68 
                 two films stuck together 
               
               
                   
               
             
          
         
       
     
     While the specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention, and the scope of protection is only limited by the scope of the accompanying claims. As indicated, the enclosure  120  design may vary in other embodiments of the invention. An important feature of the enclosure  120  and processes it contains is that the processor  100  is easily upgradeable in the field, after installation and use. Thus, if a user requires faster film throughput, a heater can be easily installed in the developer tank to heat the developer chemistry, and/or a pair of heaters can be easily-installed in the dryer plenum to dry film quicker, and/or deeper racks may be used, to provide more time in developer. Likewise, the unit may be upgraded with virtually all other features of more conventional fully automatic processor units. To accomplish these modifications, the enclosure  102  and/or the terminal board  103 , for example, may have predrilled openings from in them as shown, for example by the reference number  99  in FIG. 3, where electrical connections for the additional heaters may be made. Further, the terminal board  103  may be pre wired, as shown at  10 , to ease such installation. In addition, the racks are easily removed and replaced without requiring special knowledge or ability. These variations are merely illustrative.