Abstract:
The present invention is a completely portable film dryer. The film is hung in strips within an encircling shroud. A heater assembly positioned at the top of the shroud blows warm air downward over the suspended film strips and out through exhaust vents near the shroud&#39;s bottom. A drip pan at the bottom of the shroud catches any free water drops. The entire unit, with the film placed inside, can be hung from a clothes hanger, shower curtain rod, or other suitable point. Power is provided to the heater assembly via a 110 volt AC plug or a DC adapter (for automotive cigarette lighters and the like). When not in use, the invention collapses to a significantly reduced size so that it can be transported in a suitcase or equipment container.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     Not Applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     MICROFICHE APPENDIX 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention. 
     This invention relates to the field of photographic film processing. More specifically, the invention comprises a portable device for drying strips of photographic film in a controlled, dust-free environment. 
     2. Description of the Related Art. 
     The processing of film by the professional photographer or skilled amateur is often conducted by hand. The exposed film (negatives or slides) is chemically processed (developed) in a variety of solutions. All these solutions leave the film wet. Prior to further use, the film must be dried. The typical method is to cut the roll of film into lengths of two or three feet and hang these lengths up on a suspending line. Unfortunately, the film&#39;s surface is relatively soft when wet and this makes it particularly vulnerable to dust contamination. Accordingly, many processing facilities use a specially-equipped drying room, or semi-permanent fixtures in another type of room This approach uses controlled heat and air circulation. It also employs dust filters to minimize airborne contaminants. 
     While these types of specialized drying methods are effective, they obviously have practical limitations as far as cost and available space. More importantly, however, the professional photographer is often traveling away from a processing facility. He or she is therefore unable to use the specialized drying room or facility, even if such a room or facility is available. The only alternative is to hang the film strips in a conventional room—such as a bathroom. The results of this technique vary. Water remaining on the film for more than a few minutes will often cause streaks and spots. Dust contamination is also difficult to control. Dust particles which become partially embedded in the surface of the film are very difficult to remove without damaging the film itself. Accordingly, the principal drawback of the prior art devices available for film drying is that they are not portable. The prior art devices have additional disadvantages in that they: 
     1. Are expensive; 
     2. Consume significant space; 
     3. Fail to prevent contamination; and 
     4. Allow the formation of streaks and spots. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is a completely portable film dryer. The film is hung in strips within an encircling shroud. A forced air heater assembly positioned at the top of the shroud blows warm air downward over the suspended film strips and out through exhaust vents near the shroud&#39;s bottom. A drip pan at the bottom of the shroud catches any free water drops. The entire unit, with the film placed inside, can be hung from a clothes hanger, shower curtain rod, or other suitable point. Power is provided to the heater assembly via a 110 volt AC plug or a DC adapter (for automotive cigarette lighters and the like). 
     When not in use, the invention collapses to a significantly reduced size so that it can be transported in a suitcase or equipment container. Accordingly, the objects and advantages of the present invention are to provide a portable film dryer which: 
     1. Is inexpensive; 
     2. Is compact; 
     3. Prevents dust contamination; and 
     4. Prevents the formation of streaks or spots on the film during the drying process. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is an isometric view, showing the proposed invention. 
     FIG. 2 is an isometric view, showing the hanging of the film. 
     FIG. 3 is an isometric view, showing the invention in operation. 
     FIG. 4 is an isometric view, showing the internal details of the heater assembly. 
     FIG. 4B is an isometric view, showing the heater assembly from another angle. 
     FIG. 5 is an isometric view, showing the invention in its collapsed state. 
     FIG. 6 is an isometric view, showing an alternate embodiment. 
    
    
     REFERENCE NUMERALS IN THE DRAWINGS 
       10  portable film dryer 
       14  hanging hook 
       18  support cable 
       22  lower film hanger 
       26  drip pan 
       30  access flap 
       34  ambient air 
       38  film strip 
       42  exhaust air 
       46  filter cartridge 
       50  fan 
       54  timer 
       12  heater assembly 
       16  swivel 
       20  upper film hanger 
       24  shroud 
       28  exhaust vent 
       32  snap closure 
       36  heated air 
       40  clip 
       44  top 
       48  body 
       52  power input 
       56  air intake 
       58  alternate drip pan 
       62  weight 
       66  keyhole slot 
       60  throttle vent 
       64  mounting boss 
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows the invention fully assembled. When in use, portable film dryer  10  will commonly be hung vertically from a hanging rod in a closet or a shower curtain rod. Hanging hook  14  is provided for this purpose. Suspended beneath hanging hook  14  is heater assembly  12 . Heater assembly  12  has an upper portion, an outer perimeter, and a lower portion. A plurality of air intakes  56  are formed in its upper portion. The function of heater assembly  12  is to pull in ambient air  34  through air intakes  56 , heat it, and discharge it downward as heated air  36 . The internal details of heater assembly  12  will be explained subsequently. 
     Support cable  18  descends downward from the lower portion of heater assembly  12 . While cable  18  could be a rigid rod, it is preferable to make it a flexible cable so that portable film dryer  10  can be collapsed for storage when not in use. Upper film hanger  20  is hung from support cable  18  at a position beneath heater assembly  12 . Upper film hanger  20  consists of a plurality of horizontally oriented rods radiating outward from support cable  18 , bounded by a surrounding ring to provide stiffness. These radiating rods are used to attach the upper ends of the film strips to be dried, as will be explained subsequently. 
     Lower film hanger  22 , which is positioned further down on support cable  18 , is similar to upper film hanger  20 . Its function is to secure the lower ends of the film strips to be dried. Weight  62  is provided in the middle of lower film hanger  22  to provide downward tension on the film strips when they are hung. Lower film hanger  22  is free to slide up and down support cable  18 . A clamping mechanism capable of fixing it in one position may be provided as well. This allows the device to suspend film strips having different lengths. 
     Drip pan  26  is provided at the bottom extreme of portable film dryer  10 . It is also suspended from support cable  18 . The function of drip pan  26  is to catch any water droplets blown off the hanging film and prevent them from falling to the floor. 
     The reader will observe that heated air  36  will be blown over film strips hanging between upper film hanger  20  and lower film hanger  22 , thereby drying them. However, absent an additional containments device, heated air  36  will deflect outward and fail to reach the lower portions of the hanging film strips. Shroud  24  is provided to concentrate and direct the flow of heated air  36 . Shroud  24  is preferably a flexible material, such as the clear plastic used in shower curtains. It descends downward from the outer perimeter of heater assembly  12 , where it is attached by any conventional means. The reader will observe that shroud  24  has an open lower end. This opening is sealed by drip pan  26 . Again, the attachment between shroud  24  and drip pan  26  can be made by any conventional means. Once shroud  24  and drip pan  26  are in place, heated air  36  can only escape through exhaust vents  28 , which are distributed around the lower end of shroud  24 . By the use of shroud  24  and the positioning of exhaust vents  28 , heated air  36  is forced to flow down the entire length of the hanging film strips, only being allowed to escape at the bottom. 
     It is obviously important to provide the user with access to the interior of shroud  24  so that the user may place and remove the film to be dried. Shroud  24  contains access flap  30  for this purpose. Access flap  30  is shown open in FIG.  1 . In the open position, it allows the user to reach inside to place and remove film. When the user wishes to close access flap  30 , a plurality of snap closures  32  will secure it in place. Those skilled in the art will realize that the perimeter of access flap  30  will leak some heated air  36  unless tightly sealed. In actuality, some leakage is acceptable with minimal compromise of the invention&#39;s function. So long as positive pressure is maintained within shroud  24 , outside dust will not contaminate the drying process. Some leakage is therefore acceptable, as long as it does not significantly redirect the flow of heated air  36 . Those skilled in the art will also realize that air leakage can be substantially eliminated by replacing snap closures  32  with magnetic strips or VELCRO-type fasteners. 
     FIG. 2 shows portable film dryer  10  with access flap  30  in the open position. Film strips  38  have been suspended between upper film hanger  20  and lower film hanger  22  by the use of clips  40 . Clips  40  are commonly plastic-coated spring wire devices. Ordinary wood clothes pins may also be used. The result is that film strips  38  are suspended vertically within shroud  24 . The radiating rods found within the film hangers are long enough to accommodate film of many different widths—such as 35 mm and 120 mm. 
     Upper film hanger  20  holds the weight of film strips  38 . Lower film hanger  22  stabilizes them—through he use of weight  62 —so the blowing air does not move them about. Although only two film strips  38  are shown, those skilled in the art will appreciate that many more film strips  38  can be placed within the device. Both upper film hanger  20  and lower film hanger  22  are free to rotate about support cable  18 . This feature allows the user to rotate the hangers until a position is conveniently located with respect to access flap  30 . 
     FIG. 3 shows portable film dryer  10  with access flap  30  closed and heater assembly  12  in operation. Ambient air  34  is drawn into heater assembly  12  where it is heated and blown out in a downward direction. Exhaust air  42  eventually exits through exhaust vents  28  in shroud  24 . The device typically operates for 10 to 15 minutes in order to completely dry the film contained inside. 
     FIG. 4 shows some internal details of heater assembly  12 . The reader will observe that top  44  detaches from body  48 . Top  44  contains several air intakes  56 , which allow the entry of ambient air when the device is operating. Sandwiched between top  44  and body  48  is filter cartridge  46 . This replaceable unit filters dust from the incoming air before it is heated and blown onto the film. It must be periodically replaced. 
     Hanging hook  14  is attached to top  44  by swivel  16 , which allows hanging hook  14  to fold against top  44  when the invention is stored. Top  14  is removably joined to body  48  by any conventional means, with mating threads being found to be particularly effective. 
     Body  48  contains fan  50 , which moves the air through heater assembly  12  and directs it toward the film. A heating element (not shown) is positioned beneath fan  50 . This heating element is typically an electrical-resistance type. Electrical power is provided to fan  50  and the heating element by power input  52 . Heater assembly  12  can have either an internal or external AC to DC converter/transformer assembly, so that the invention can run on either AC household power or DC power as provided by automotive cigarette lighters and the like. 
     Timer  54  is a user-adjustable knob that allows the user to set how long heater assembly  50  will run. The particular unit employed can be varied between 0 and 30 minutes. No temperature adjustment is shown, as one set temperature works well for all applications. However, it would be a simple matter to provide temperature control means in addition to the timer shown It is also important to provide safety circuitry, which would prevent ground faults. Another sensing circuit which disables the heating element if the fan is not running would also be recommended. 
     FIG. 4B shows body  48  from a different angle. On some occasions a shower curtain or clothes rod will not be available. Mounting boss  64  is provided so that the unit may be mounted directly on a wall. Mounting boss  64  has conventional keyhole slot  66 . The reader will observe that keyhole slot  66  has a large opening and a small slot intersecting the large opening. This allows the user to place keyhole slot  66  over a nail or screw in the wall, thereby mounting the dryer directly on the wall. 
     FIG. 5 shows portable film dryer  10  in a collapsed state suitable for transportation and storage. Shroud  24 , which is a thin and flexible material, is collapsed so that heater assembly  12  rests nearly on top of drip pan  26 . Hanging hook  14  has been folded down against the upper portion of heater assembly  12 . The reader will observe that the resulting unit is very compact and easily stored. A securing strap can be provided to lock the unit in the collapsed state shown. As such a device is well known in the prior art, it has not been illustrated. 
     FIG. 6 shows an alternate embodiment of the invention. Alternate drip pan  58  is substituted for drip pan  26 . Alternate drip pan  58  has a plurality of throttle vents  60 , which correspond to exhaust vents  28  in shroud  24 . Alternate drip pan  58  can be rotated with respect to shroud  24 . This rotation will affect the alignment of throttle vents  60  with exhaust vents  28 . By rotating alternate drip pan  58 , the user can thereby adjust the exhaust area of exhaust vents  28 , thereby regulating the airflow through the device. 
     Accordingly, the reader will appreciate that the proposed invention provides a portable film dryer which: 
     1. Is inexpensive; 
     2. Is compact; 
     3. Prevents dust contamination; and 
     4. Prevents the formation of streaks or spots on the film during the drying process. 
     Although the preceding description contains significant detail, it should not be construed as limiting the scope of the invention but rather as providing illustrations of the preferred embodiment of the invention. As an example, shroud  24  could be made from rigid material which would allow the invention to stand upright on a counter (although reducing the desired goal of compact storage). The cylindrical shape shown could be modified to square or any other desired shape. None of these changes—or other changes of similar scope—would effect the basic nature of the invention disclosed. Thus, the scope of the invention should be fixed by the following claims, rather than by the examples given.