Patent Publication Number: US-6217238-B1

Title: Photographic film processor and method of developing film

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     This invention relates generally to photographic film processing, and more particularly to a compact, energy efficient apparatus and a method for processing such film. 
     Processing of film, requires chemically treating the film followed by rinsing and drying. The chemical treatment typically involves the application of a series of specific chemical agents, in a specific order, with the film being exposed to each treating chemical for minimum amounts of time. To obtain this processing, the film being treated is typically passed through a series of treatment tanks and into the dryer area. One such prior art device is disclosed in U.S. Pat. No. 4,613,221 to Takase et al., issued Sep. 23, 1986. 
     But the known prior art devices suffer two principle disadvantages: 1) the exposure requirements of certain treating chemicals, such as the developing solution, require relatively large treatment tanks, and 2) the drying process requires enormous amounts of energy. As a result, the known film processing devices are large and cumbersome, and are also extremely expensive to use due to high energy consumption. The known prior art also either requires the use of custom, proprietary drive belts which are costly to replace, or a multiplicity of gears and drive shafts which undesirably increase maintenance costs. Finally, the known film processing equipment either requires separate additional drive mechanisms or undesirably permits significant amounts of the treating chemicals to be transferred, either by the drive mechanism or the film being processed, to subsequent treatment tanks thereby increasing the consumption of the treating chemicals and causing contamination of the treating chemicals found in subsequent tanks. 
     There is need for a compact and energy efficient apparatus of the present invention, which enables rapid and energy efficient automatic processing of photographic film, as during its exposure to different liquids or solutions, prior to a final drying stage which uses standard drive belts to move the film through the processing equipment and which minimizes cross-tank contamination caused when the film carries treatment chemicals to subsequent treatment tanks. 
     SUMMARY OF THE INVENTION 
     It is a major object of the invention to provide improved energy efficient apparatus and method, meeting the above needs. Basically, the improved apparatus comprises: 
     a) receptacle means having a succession of short, low volume processing tanks containing liquids, 
     b) efficient drive means for advancing the film strip endwise through those tanks and to selected depths in the liquids corresponding to required exposure times of the film to the different solutions, 
     c) precise and efficient heating means for warning solutions to process temperature, 
     d) means for employing waste heat generated by control circuitry, power supply, circulation means, and heating means to supplement the dryer heater in evaporating residual solution from the film strips as they pass through the drying zone, 
     e) control means and power supply to efficiently deliver power to said heating, driving and circulating means. 
     It is another object to provide an apparatus wherein the heating means includes heaters located outside the film processing zones, and a waste heat recovery system having an air flow passage which channels the air heated by waste heat generated by the solution heaters, circulation pumps, control circuitry and power supply toward a film strip drying zone. At least one of the heaters may typically include a heating element exposed to the air flow passage, there being a duct for circulating processing liquid in heat transfer relation with that element, and toward one of the processing zones. Multiple such elements such as electrical coils may be employed for heating processing liquids circulating in heat transfer relation with the respective elements while flowing toward the respective processing zones. 
     A further object is to provide one or more pumps located in series with the duct or ducts, to pump processing liquid for circulation to the receptacle tanks. Such pumps, heating elements and ducts may be compactly located at one side of the receptacle means, the air flow passage being located at that side of the receptacle means, whereby air flowing through the passage contacts the heaters and pumps in series sequence. 
     Yet another object is to provide electrical control circuitry to control pumps, drive system and heaters, such circuitry generating heat, and the air flow passage extending in such proximate relation to that circuitry that generated heat is transferred to air flowing in said passage, toward the drying zone to assist in the film drying process. 
     An additional object is to provide the receptacle means to define a series of tanks to receive film processing liquid, and removable racks received in the tanks, the drive means extending into the racks to drive the film strips downwardly and upwardly in the respective racks. The racks typically have associated rotors and guides to direct a leader card with attached film strips downwardly and upwardly therein. Further, the leader card engaging rotors associated with one rack include lower and upper rotors, with longer racks employing a third mid-way rotor, to direct the leader card sequentially downwardly and upwardly within that rack. Drive may be transmitted to lower rotors from upper rotors utilizing a pulley associated with each rotor, said pulley engaging a timing belt to transmit drive, whereby only one main drive shaft is required per belt. The leader card with attached film strips may be entrained by a sprocket associated with each rotor. In at least one of the racks, the films are directed downwardly and upwardly twice each so that longer exposure to processing fluid will be obtained within a shallower tank. Means are provided to direct said leader card and films from an entrance area to said racks and from said racks to the exit. 
     A further object of the present invention is the reduction of the amount of treating solution which is undesirably carried from one treatment tank to the next. 
     The method of the invention basically includes: 
     a) providing receptacle means having a succession of film processing tanks containing different processing liquids to contact the endwise traveling film strips, 
     b) advancing the film strips endwise through those tanks and to selected depths in the liquids corresponding to required exposure times of the film to the different liquids, 
     c) heating the liquids in different tanks to selected processing temperatures, 
     d) employing waste heat generated in said apparatus to supplement heating means for film drying, 
     e) and a control circuit and power supply which advantageously employ low voltage direct current to unpart power to the heating elements. 
     These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following specification and drawings, in which: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a container or housing for apparatus incorporating the invention; 
     FIG. 2 is a perspective view of a film strip being pulled from a supply cassette, by a leader card that advances through the processing apparatus; 
     FIG. 3 is a schematic side elevation of the processing apparatus, showing a sequence of processing tanks, and the film paths through the successive tanks; 
     FIG. 4 is a top plan view showing the processing tanks, film drive means, and processing liquid replenishment tanks; 
     FIG. 5 is a side elevation taken on lines  5 — 5  of FIG. 4; 
     FIG. 6 is a section taken on lines  6 — 6  of FIG. 4; 
     FIG. 7 is a fragmentary elevation taken on lines  7 — 7  of FIG. 6; 
     FIG. 8 is an enlarged fragmentary section showing the turning advancement path of the film leader card, at the bottom of a processing tank; 
     FIG. 9 is a section taken in plan on lines  9 — 9  of FIG. 8; 
     FIG. 10 is an elevation taken on lines  10 — 10  of FIG. 8; 
     FIG. 11 is a schematic view of the apparatus of the present invention illustrating the waste heat air passage; and 
     FIG. 12 is a schematic view of a rotor assembly which illustrates the squeegee rollers and associated drive apparatus of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     I. General Description 
     FIG. 11 shows, in schematic form, an apparatus for processing and drying an elongated strip  28  of photographic film which has been exposed and requires development. As shown, such apparatus comprises a) receptacle means such as a receptacle  10  having a succession of film processing tanks  11  containing various processing liquids, b) drive means as for example a drive  12  for advancing the film strip  28  endwise through such tanks and to selected depths in the liquids corresponding to required exposure times of the film to the different liquids, c) heating means, as for example one or more heaters  14 , for heating the liquids to selected temperature or temperatures, d) and additional means, such as air flow paths  15 - 18  and heat transfer or drying zone  19 , for air drying the film strip, after it has passed through the liquids in the processing tanks. 
     A housing for the apparatus appears at  20 . The above schematic showing of the invention is considered as one preferred embodiment. 
     II. Detailed Description 
     Extending the description to FIGS. 1-3, the housing  20  includes a front end wall  21  having a loading door  22 , top and bottom walls  23  and  24 , rear end wall  25 , and opposite side walls  26  and  27 . A latch  29  releasably holds the loading door in closed position. 
     The elongated film strip to be processed is shown at  28  in FIG. 2, temporarily attached by removable tape  29   a , to a leader card  30 . The film may be pulled from a storage cassette or cartridge  28   a  in response to endwise advancement of the card  30  through the processing apparatus. The leader card  30  is constructed of a thin flexible material such as a synthetic resin and contains an endwise series sequence of through openings  32 , adapted to mesh with teeth on drive rotors, to be described, to advance the card, that pulls the film strip from the cassette, for processing in the apparatus. The leader card  30  of the preferred embodiment is approximately 9 inches long. Note that the film strip is offset laterally from the longitudinal row of openings  32  (shown in FIG.  10 ). 
     Although this apparatus is not limited to the C- 41  process of development, FIGS. 3 and 4 illustrate this process as one example configuration. In FIGS. 3 and 4, the processing liquid receptacle or tanks  11  are shown sequentially at  11   a - 11   g , and may contain processing liquids, the receptacles identified as follows for the C- 41  example: 
       11   a —color developer 
       11   b —bleach 
       11   c —fixer 
       11   d —fixer 
       11   e —stabilizer 
       11   f —stabilizer 
       11   g —stabilizer 
     The liquids in the successive or different tanks may vary according to the process chosen including, but not limited to the C- 41 , E- 6  and Black and White processes. 
     Drive rotors and guides to advance and guide the leader card and film strips through the successive solutions are identified as follows: 
       31   a —entrance guide roller which directs the card  30  toward the entrance sprocket 
       30   a —entrance sprocket to advance leader card and film from the entrance area toward the processing tanks 
       33 ,  40 ,  42 ,  47 ,  52  &amp;  58   a —upper rotors which directly engage the leader card with sprocket teeth to drive the card downwardly into the processing solutions or drying zone 
       35 ,  38 ,  44 ,  49 ,  54  &amp;  58   b —lower rotors driven by timing belts engaged from upper rotors serve to direct the leader card upwardly. Furrow rollers ( 92 ) on a common shaft with the lower rotors serve to guide the film around the bottom turn guide as it is pulled upwardly by the leader card. 
       31 —crossover rollers guide the film on its upper turn as it is pulled back downwardly by the leader card 
       40 ,  41 ,  46 ,  51 ,  56 ,  58 ,  60  &amp;  62 —crossover guides direct the leader card from upward to downward travel 
       36 —upper turn guide in center of double rack to turn the leader card back downwardly while films are constrained by crossover rollers  31   
       57 ,  59  &amp;  61 —sprockets drive the leader card downwardly around lower furrow rollers and then upwardly towards the crossover guides in the shorter racks which are too small to incorporate both upper and lower rotors. 
     As the above discussion should make clear, the upper turn guide  36  works in conjunction with the upper rotor  33  and  40  and lower rotors  35  and  38  in the first treatment tank to reverse the direction of the filmstrip advance such that the upper rotor  33  advances the leader card  30  and attached film strip downwardly into the film processing liquid within said tank where the lower rotor  35  re-directs the leader card  30  such that it advances upwardly toward the cross-over film guide  36 , the cross-over film guide  36  contacts the leader card and film strip before the leader card and film strip emerge from the film processing liquid in the tank and re-directs the leader card and film strip downwardly toward the second lower rotor assembly  38 , which then re-directs the film strip and advances said film strip upwardly toward the second upper rotor  40  which advances the film strip upwardly, out of the film processing liquid. 
     The leader card and film then pass through drying zone  19 , being guided and driven by rotors  58   a  and  58   b  upwardly and downwardly while exposed to hot drying air. Pinch rollers  63  and  64  drive the leader card and film out of the drying zone to the exit of the apparatus. 
     Upright walls of the succession of separate receptacles or tanks act as a support structure and allow the racks to be removed from the tanks  11  after the top cover  23  is lifted, via a handle or handles  23   a  and the upper crossover guides  32 ,  41 ,  46 ,  51 ,  56 ,  58 ,  60  and  62  are removed. The upper rotors, lower rotors and crossover rollers have their axles carried by racks within the receptacle. See for example axles  65  in FIG. 6 carried by upright walls  81  and  82  of a rack  83  that fits downwardly within receptacle or tank  11   a . Similar racks are employed in the other receptacles or tanks. The racks have wall perforations as at  86  to pass process liquid or drying air into the rack interiors. Upper rotors have axles  66  supported by walls  81  and  82 . 
     The upper rotors typically carry drive teeth  99  at one side, to engage timing belts  100  that entrain similar teeth  101  on the lower rotors for rotating the latter. The upper and lower rotors carry sprocket teeth  102  on the other side to engage the perforations  32  on the leader card  30  to advance the latter. In long racks, a middle rotor ( 35   a ,  38   a  and  58   a ) may be incorporated to engage and direct the leader card before it disengages from the upper or lower rotors. A small tensioning rotor  31   b  may be used to prevent the timing belt  100  from disengaging from the middle rotor. See FIGS. 7-9. 
     The upper rotors also have drive axles as at  69  carrying bevel gears  70  isolated from the interiors of the receptacles. Such gears are simultaneously driven by bevel gears  71  on a common drive shaft  72  rotated by an actuator  73 , see FIG.  4 . FIG. 3 shows the power supply  74  and step-down transformer  75  for the actuator motor, within the housing. 
     FIG. 6 shows upper rotor axles  66  and  69  carried by the rack  83 , to be upwardly removable with the rack from the tank or receptacle. A flange  90  on the rack is supported by the receptacle at  91 . FIG. 8 also shows upwardly concave guide surface  170  helping to turn the leader card and film back upwardly at the bottom of a rack. 
     As best illustrated in FIG. 12, to reduce tank to tank transmission of treatment chemicals, the upper end of each rack includes matching, opposed pairs of squeegee rollers  250  and  251 . These rollers contact the leader card and the film at the top of the rack as the leader card and film exits treatment tank  11   a . The squeegee rollers  250  and  251  rotate in opposite directions through a single-sided drive belt  252  which draws power from the common drive shaft  72 . The frictional contact of the squeegee rollers  250  and  251  on opposite sides of both the leader card  30  and the film strip  28  operates to remove excess treatment chemicals and thereby minimizes liquid loss from the treatment tanks and contamination caused by tank-to-tank transfer of treatment chemicals. Treatment tanks  11   b ,  11   d , and  11   g  may also be outfitted with the squeegee roller system disclosed above. 
     Also provided are heating means for heating the liquids in the receptacles to selected temperature, and additional means for employing heat generated by said heating means for drying the film strip after it has passed through such liquids. The heating means typically includes heaters located outside the processing tanks, and the additional means (for drying film strip  28 ) advantageously includes an air flow passage to conduct flowing air in heat transfer relation with the heaters, pumps and control components and toward a film strip drying zone. 
     Further, the heaters may include electrical heating elements exposed to the air flow passage, with ducts provided for circulating processing solutions in heat transfer relation with the respective heating elements and toward the respective processing tanks, whereby liquid in each processing tank may be kept at its required elevated temperature. 
     In the preferred example shown in FIG. 6, the receptacle  11   a  has a laterally projecting upper portion  11   aa , to which liquid is supplied from the interior of  11   a . Such liquid in  11   aa  then circulates through a filter  110 , and downwardly at  111  to a pump  112 , as for example a centrifugal pump, driven as by a motor  113  in a housing  114 . The liquid then passes through a heat exchanger  115 , i.e. a heater acting to heat the liquid circulated downwardly and laterally at  116  to the lower interior of the receptacle  11   a . Each of the receptacles  11   a - 11   g  as for the C- 41  example may have a similar filter, pump and heater to heat the liquids in the various receptacles to selected processing temperatures controlled at  210 . It will be noted that the heater or heaters  115 , and the pump, are located in an air flow passage or passages, as referred to at  16  and  17  in FIG. 11, and located between the receptacles  11  and the housing side wall  27 . 
     Waste heat generated by the liquids heaters and pumps is transferred to air flowing sidewardly of the receptacles, and within the housing, i.e. within passages  15 - 18 , for use in drying the processed film strip  28 . This heat transfer also serves to cool the pump motors  113  in passages  16  and  17 . An auxiliary air heater  120  may be employed in an adjacent passage  18  as shown in FIGS. 3 and 5. Note that air flowing through passages  16  and  17  contacts the heaters  115  and pumps  114  in series sequence. Electrical control circuitry is located at  210  near the front end of the apparatus, to also transfer generated heat to the flowing air, at or near passage  15  for cooling the controls. Exhaust fans  124   b  and  124   c  are shown in FIG. 3, to draw film drying air through the air passages  15 - 18 , and to exhaust  125 . See also fan  124   a  helping to drive air over the motor  73  and to passages  16  and  17 . If two film strips are attached to the leader card  30 , at laterally opposite sides of the teeth drive card perforations  32 , drying air may circulate between the two spaced film strips, for efficient drying. 
     Although the waste heat shed into the air in the waste heat air channel provides some degree of natural convective air movement, the preferred embodiment of the invention utilizes three fans to improve circulation within the air channel. Specifically, and as shown in FIGS. 3 and 4, a first fan  124   a  is provided in the air channel between the electronic equipment area and the circulation pump and solution heater area so as to draw air from the outside, through the air passages  15  and  16 , in which the electronic equipment placed and into the air channel  17  in which the serial circulation pump and motors,  112  and  113  and solution heater  115  are placed. The waste heat shed by this electronic and mechanical equipment is thereby efficiently transferred to the air in the waste heat air channel and directed towards the drying zone  19 . This circulation is aided by a second fan  124   b  which draws the pre-heated air from air passages  16  and  17 , and circulates it through the dryer heater  120  which is disposed within air channel  18 , to the drying zone  19 . Finally, a third fan  124   c  is used to draw the hot, humid air from the drying zone  19  and vent it to the outside through the exhaust  125 . This use of the recycled waste heat in the drying process increases the energy efficiently of the film processor and dramatically reduces overall energy consumption. 
     FIG. 4 shows process liquid auxiliary supply tanks  130 - 133  located laterally of receptacles  11   a - 11   d , at the opposite side of the latter from the heaters. Liquid is delivered from tanks  130 - 133  to the receptacles  11   a - 11   d  via supply tubes  130   a - 133   a , to make up for any loss of process liquid. FIG. 6 shows pumps as at  136  adjacent the tanks  130 - 133  to deliver supply liquid to the ducts  130   a   14   133   a . Pumps  136  are controlled by control circuitry  210 . 
     Legs  152  hold the bottom wall  24  above a support to allow leveling of the apparatus. 
     While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.