US 3554107 A
Description (OCR text may contain errors)
United States Patent  Inventors Joseph V. McCarthy Ncedham; Francois R. Gruber, Wilmington, Mass.  Appl. No. 633,151  Filed Apr. 24, 1967  Patented Jan. 12, 1971  Assignee ltek Corporation Lexington, Mass. a corporation of Delaware [54 PHOTOGRAPHIC FILM PROCESSOR 20 Claims, 11 Drawing Figs.
 US. 95/89, 1181101,]18/414  Int.Cl G03d 3/06  Field of Search 95/89Misc, 89Lam, 94Misc; l Iii/410,413,414, 101, 8
 References Cited UNITED STATES PATENTS 1,845,296 2/ 1932 Langsner'. 95/94 2,330,834 10/1943 Meyer et a1. 118/ 101 2,464,771 3/1949 Van Guelpen. 1 18/ 1 01 2,778,734 1] 1957 Fairbank 95/89UX Primary Examiner-John M. Horan Assistant ExaminerFred L. Braun Attorneysl-lorner 0. Blair, Robert L. Nathans and Lester Grodberg ABSTRACT: A photographic film processor utilizing viscous monobath techniques. The film is fed into the processor and a controlled layer of viscous processing agent is deposited on the film by an applicator. Both the thickness and temperature of the viscous layer applied to the film are controlled. The film is then routed through a torturous path in the processor for a sufficient amount of time to enable processing to occur. The viscous processing agent is then wiped off the film by a plurality of obliquely positioned bladesadjacent to the film path. The film then runs through a dryer into a viewing station and then onto a takeup reel. The diameter of the film on the takeup reel 1 is monitored and controls the flow of the viscous processing agent from its storage reservoir to the applicator.
PATENTED JAN 1 2 M SHEET 1 BF 4 INVENTORS.
JOSEP-l V. McCARTHY FRANCOIS R. GRUBER II VI\ ATTORNEYS PATENTED JAN 1 219m SHEET 2 OF 4 FIGQZ INVENTORS. JOSEPH V. McCARTHY FRANCOIS R. GRUBER FIG. 5
ATTORNEYS PATENTED JAN 1 21971 SHEET 3 BF 4 OPTICAL SENSOR SENSOR REFERENCE FIL DIFF. AMP
SERVO MOTOR FIG.
VARIABLE TRANSFORMER INVE NTOR-S. JOSEPH V. Mc CARTHY FRANCOIS R. GRUBER MMVWMIJM ATTORNEYS PATENTEU JAHIEIBH 3554.107
SHEET u 0F 4 "'imuu INVENTORS. JOSEP cCARTHY FRANC GRUBER ATTORNEYS BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention'relates to the processing of photographic film. More particularly, it relates to compact, photographic film processing apparatus employing a viscous developing medium.
2. Description of the Prior Art Conventional photographic processing which employs separate liquid baths for the various steps of developing stopping, fixing and washing is beginning to yield to the socalled viscous processing techniques. While at present viscous techniques have attained only limited use in silver halide film processing, they have become a smallbut important part of the photographic system. Beginning with the application of viscousprocessing in the Polaroid system of photography, usage of such techniques is spreading so rapidly that some projections indicate that 50 percent of the black and white 16 and 35 mm. movie processing machines will utilize viscous monobath techniques by 1971. A monobath is a film processing solution which contains all the ingredients for properly timed sequential developing and fixing of the image on an exposed photographic emulsion. The monobath is generally thickened by the addition of some water soluble viscosity inducing agent such as carboxymethylcellulose.
Conventional wet photographic film processing techniques do have certain distinct advantages. Among these is the fact that wet techniques enable the processing of large batches of film all at one time. It is also generally thought to be true that wet-processing.v techniques can achieve better image resolution, especially with fine grain films which are characterized by thicker emulsion coatings. Wet techniques do, however, suffer from several seriousdrawbacks. They require constant agitation during processing and close temperature control. Then too, the equipment for large scale wet processing involves extensive plumbing and fiuid handling equipment for control and delivery of the required chemicals.
Viscous, or dry processing, requires no agitation and no replenishment of chemicals." It also affords uniformity of processing and rapid dry-to-dry developing time. Viscous processing apparatus is simpler to manufacture and maintain and, when used with somefilms, provides good microimage contrast and improved image structure.
Perhaps the most outstanding feature of viscous processing, though, is the extremely rapid time that it makes possible between initial processing and the moment at which the image may be viewed. This has made viscous processing highly desirable for such applications as photoreconnaissance.
One technique of viscous film processing is disclosed in U.S. Pat. No. 2,948,209 to Neidle et al. Here a monobath is applied to a moving film strip. A transparentplastic cover strip is then applied over the monobath to seal in the monobath so that the image may be viewed as soon as possible. In this system the monobath is apparently neither removed nor dried but remains encapsulated between the film base and plastic cover sheet. This arrangement, however, is likely to cause image distortion because of possible air entrapment between the film and transparent cover sheet and because of distortions in the cover sheet itself.
Another approach to viscous processing is illustrated in U.S. Pat. No. 3,282,695 to Narodny. Here the chemicals for developing and fixing the photographic emulsion are placed on a carrier sheet and applied under pressure to the photographic film. When the film is developed, the carrier is stripped off, presumably taking the developing chemicals with it. The two major disadvantages inherent in this process are first, that the pressure required to achieve good contact between the developing chemicals and the emulsion may damage the image if particulate contaminants are present in either the emulsion or the developing chemicals and second, that stripping ofi the carrier may not remove all of the developing chemicals.
Another approach that has been proposed, involves the addition of constituents to the monobath which will cause it to harden once the film emulsion has been developed and fixed. While only partial success has been achieved up to this point, any layer of material left on the film emulsion, even if hardened successfully, is likely to detract from image clarity.
The invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts which will be exemplified in the constructions hereinafter set forth.
SUMMARY OF THE INVENTION Briefly, our photographic film processor combines a unique wiping unit, for removing viscous monobath from developed film, together with a film conveying system and a viscous monobath dispensing system. In one form, our wiping unit includes a plurality of flexible blades atan angle other than with respect to the axis of the film. This positively shears off substantially all of the monobath present on the film surface, thus enabling rapid drying of the processed film and almost instantaneous image viewing. This method of monobath removal is clearly superior to the prior practice of stripping it off with a backing sheet to which the monobath preferentially adheres. As pointed out above the stripping process can damage the film emulsion and image quality by pressing particulate matter and other contaminants into the emulsion,.
whereas inour apparatus, contaminants remain suspended in the monobath where they are sheared off together with the monobath without at any time applying pressure to the emulsion. Since the monobath acts as a lubricant there is little likelihood that our wiping unit will damage the film emulsion.
In another aspect of ourinvention, we employ an improved metering unit for applying a viscous monobath onto the advancing film. One form of our metering unit utilizes temperature control of the doctor blade, which governs the temperature and thickness of the monobath coating spread onto the film. This in turn controls the developing reaction rate as well as the viscosity of the monobath and hence its rate of flow. Alternatively, we use a metering rod in place of the doctor blade. The metering rod is mounted to rotate eccentrically about its longitudinal axis, so as to adjust thespacing between the rod and the advancing film surface. With this arrangement close control of the amount of monobath deposited on the film is possible.
Further improvement in this concept results from the application of a helical winding of wire to the metering rod. Such a winding imparts numerous fine undulations to the surface of the dispensed monobath, but these undulations are so slight that they tend to be self-leveling. The principal advantage of this technique is that it permits particulate matter to become oriented and pass through the minute grooves between adjacent turns of wire on the rod. Such particles would otherwise tend to get lodged under a conventional doctor blade and scratch the film emulsion as it passes through.
Our photographic film processor is also well-suited for automatic control of monobath viscosity by utilizing an optical sensor to monitor the density of the processed film image. By comparing the density of the processed film image with a reference density, we generate an electric signal proportional to the density difference between the film image and the reference. This signal is then fed back to a current source for a heater in the metering device which determines the thickness of the monobath coating. The heater current is then varied in accordance with the image density difference. In this way the temperature and viscosity of the applied monobath are controlled in response to the quality of the processed image. Since an increase in temperature of the monobath increases density of the developed film, image control of the monobath temperature is a principal factor in controlling image density.
Yet another feature of our processor is that the viscous monobath is dispensed continuously from its source in response to the quantity of the film already processed. in particular, it is made responsive to the increase in diameter of a film takeup reel as the film is processed. This assures complete utilization of the available monobath as well as a continuous supply.
BRIEF DESCRIPTION OF THE DRAWING For a fuller understanding of the nature of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:
FIG. 1 is a plan view, partly in section, of one embodiment of the photographic film processor of our invention;
FIG. 2 is an elevational view, partly in section, of a portion of the film processor;
FIG. 3 is an elevational section of our film guide assembly taken along the line III-Ill in FIG. 1;
FIG. 4 is an elevational view of the wiping blade assembly taken along the line lV-IV in FIG. 1;
FIG. 5 is a plan view of an alternative monobath dispensing arrangement;
FIG. 6 is a perspective view, partly in section, of a disposable monobath feed apparatus;
FIG. 7 is an elevational view, broken away and partly in section, of an improved metering apparatus,
FIG. 7A is an enlarged elevational view of a portion of the apparatus of FIG. 7;
FIG. 8 is an elevational view, partly in section of another metering apparatus embodiment; I
FIG. 9 is a perspective view of an additional metering apparatus embodiment; and p Y FIG. 10 is a schematic diagram of a system for controlling the monobath temperature in response to processed image density.
DESCRIPTION OF THE PREFERRED EMBODIMENTS A typical embodiment of our photographic film processor is illustrated in FIG. 1. Here a roll of film is housed in a cassette 14. The cassette 14 may be secured to the housing 16 of the processor, as shown, or the construction of the processor may be arranged to carry the film roll 12 inside the housing 16.
The film 18 is drawn from the roll 12 and is initially threaded through the processor using a leader. The film leader is then threaded through the processor and onto a takeup reel 20. The takeup reel 20 is driven automatically or by a hand crank (not shown) in synchronism with the film driving sprocket 22.
Processing of the film l8 commences as it passes through a metering unit 24 which controls the volume of viscous monobath dispensed onto the advancing film 18. The metering unit 24 includes an inlet port 26, a chamber 28, for accumulating monobath and applying it to the film surface, and a doctor blade 30 for controlling the thickness of monobath applied to the surface of the film 18. The space between the edge of the doctor blade 30 and the film 18 is adjusted by means of screws 32, which when tight, secure the doctor blade 30, but when loosened permit movement of the doctor blade in a plane perpendicular to the film surface.
As the film 18 exits from the metering unit 24 it is conveyed through a series of guides 34. The guides 34 are so constructed that the film 18 is supported at its edges. This enables the film to be advanced without disturbing the monobath coating which is preferably applied only to the area containing the film image. So that the monobath may have adequate time to react fully with the film emulsion the film path is lengthened by a number of film direction reversing idler rolls 36 which likewise contact the film 18 only at its edge.
Shortly after the developing reaction is complete and the image is fixed, the film 18 moves past a wiping unit 38. The film 18 is maintained in intimate contact with the wiping unit 38 by means of a pressure plate 40 and a spring bias 42. Because of the lubricating effect of the monobath, only slight pressure of the film 18 against the wiping unit 38 is required.
This arrangement of wiping unit 38 and pressure plate 40 removes substantially all the monobath from the surface of the film 18.
After removal of the monobath, the film is dried by a drier 44. Heater Heated air from the drier 44 is ducted to both sides of the film 18 so that the film 13 is conveyed on an air bearing through the drier stage.
The dried film may then be viewed through a viewer 46 while it is illuminated by a lamp 48. As pointedout above, the film I8 is advanced by means of the sprocket 22 onto the takeup reel 20.
An arm 50 rides on the film [8 as it is wound onto the takeup reel 20. As the diameter of wound film I8 on the takeup reel 20 increases, the arm 50 rotates counterclockwise about the pivot point 52. Secured at a fixed angle to the arm 50 for simultaneous rotation about the pivot point 52 is another arm 54. The arm 54 is pivotally connected to an elongated member 56 and exerts a substantially vertical force on the elongated member 56 as it rotates counterclockwise with the arm 50, as viewed in FIG. 1.
The elongated member 56 carries a pawl 58 which oscillates in a slot 60 as the elongated member 56 moves in response to changes in diameter of the film 18 on the takeup reel 20.
Riding on the pawl 58 is a spur 62 secured to a crescent member 64 for rotation about the pivot point 66.
a As the crescent member 64 is urged into clockwise rotation by upward movement of the member 56, it exerts a compressive force on the bellows 68. The monobath which is contained in the bellows 68 is thus expelled, by compression of the bellows 68, out through the tube 70 into the inlet port26 of the metering means 24.
FIG. 2 illustrates more clearly the construction of the drier 44. The drier includes a blower 72 and a duct 74. The duct is divided into arms 76 and 77 which apply the warm air simultaneously to both sides of the film l8 suspending the film on an air bearing as it traverses the drier 44.
FIG. 3 illustrates in cross section the construction of the guides 34. The film l8 rests on the shoulders 78. The shoulders 78 serve the dual purpose of restraining the film 18 against lateral movement and suspending the film on its edges to prevent damage to the film image.
The wiping unit 38 is more clearly illustrated in the plan view of FIG. 4. Here a plurality of blades 79 are shown. The blades 79 are disposed at an angle other than with respect to the axis of the film. This arrangement serves to shear off substantially all the monobath on the film surface and channels it off in one direction only where it may be readily collected. The squeegee effect thus provided, minimizes the amount of drying which will be required and reduces the likelihood of damage to the film surface by particulate contaminants in the monobath.
An alternative method of dispensing the monobath is illustrated in FIG. 5. Here the source of monobath is an aerosol can 80 which is held in place by a clamp 82. The can nozzle is opened as soon as a small amount of the leader is wound up on the takeup reel 20. As in the FIG. 1 embodiment, the elongated member 84 of FIG. 5 moves vertically. Since the member 84 is pinned to the arm 86, vertical movement of the member 84 imparts a counterclockwise motion to the arm 86. The arm 86 is fixedly secured to the arm 88 for rotation about the pivot 90. Counterclockwise movement of the arm 88 then imparts an axial force to the rod 92 which is secured to the arm 88 by means of a washer 94 and cotter pin 96.
The rod 92 also provides an axial force on the right angle member 98 by means of spring 100. Axial movement of the rod 92 exerts a force on the spring 100 by compressing the spring with the washer 102 which is restrained from movement by the cotter pin 104.
The right angle member 98 acts through a Pitman arm-type linkage upon an eccentric member 106 that depresses the aerosol nozzle valve 108. This starts the flow of monobath which continues as long as there is film on the takeup reel and monobath in the can 80. Any additional movement of the rod accompanies change of the source of monobath, can be vexatious. To simplify this cleanup operation a disposable feeder 110 is secured to the tube 70 as illustrated in FIG. 6. The feeder 110 is formed with an elongated hollow chamber 112 which is supplied with monobath from the tube 70 through the inlet port 114. The monobath is then expelled through a slotlike exit passage 1 16 at a point adjacent the doctor blade 1 17. With this arrangement, cleanup is greatly simplified since the inlet tube 70 and disposable feeder 110 are removed together with the source of monobath. In this way, substitution of a new such unit may be accomplished with little or no cleanup at all, except for removal of the small amount of monobath adhering to the edge of the doctor blade.
FIGS. 7-9 illustrated various improvements in the metering unit for controlling the thickness of the layer of dispensed monobath. In FIG. 7, for example, a metering unit 118 includes an inlet port 120 through which the monobath enters and contacts the film 18. The thickness of the monobath coating is controlled by means of a rod 122 which is mounted at point 124 for eccentric rotation about its longitudinal axis. The two extreme positions of the rod 122 are shown first by the solid line and then by the dashed line in FIG. 7A. A resilient sealing member 126 is in contact with the portion of the rod opposite the film to prevent leakage of the monobath past the rod by any means other than by flowing out on the film surface. Eccentric mounting of the rod provides a very fine adjustment of the spacing between the rod 122 and the film 18 by rotation of the rod 122. This means of adjustment is simpler and more refined than loosening the screws 32 to move the doctor blade 30 as illustrated in FIG. 1.
Another variation of the arrangement in FIG. 7 is illustrated, in FIG. 8 which is identical with FIG. 7 except that an elliptical rod 128 is used in place of the eccentrically mounted round rod 122 in FIG. 7.
FIG. 9 shows in perspective a further improvement in the monobath metering unit 118 which employs a metering bar 130 helically wound with wire. This improvement may be utilized with either the eccentrically mounted rod or the elliptical rod, as illustrated in the drawings. The helical wire wrapping on the rod member 130 serves a two-fold purpose. First, it provides a fluted lateral profile to the dispensed monobath as it flows past the wire onto the film. This minimizes the likelihood of an entrapment of particulate matter between the rod 130 and the advancing film 18 which could scratch the film emulsion. Second, if insulated resistance wire is used, it may be heated by passing an electrical current through it. This may be used to control the viscosity and temperature of the monobath as it is spread on the film.
The combination in FIGS. 7, 8 and 9 of the cover plate 132 to limit vertical movement of the film and the shoulder 133 to limit lateral movement of the film maintains the film 18 in constant contact with the metering unit 118 so that the monobath does not exude out around the edges of the film where it can gum up the guides 34 and the idler rolls 36.
Another feature of our photographic film processor is that automatic image density control is readily achievable. A typical system for image density control is illustrated in FIG. 10. Here, the film 18 is conveyed past a light bulb 134 which shines through the film 18 into an optical sensor 136. The light bulb also illuminated illuminates a reference sensor 138. Both the optical sensor 136 and reference sensor 138 produce electrical signals in response to light from the bulb 134. A variable resistance 139 is used to adjust the output signal of the optical sensor 136, so that it equals that of the reference sensor 138 when the proper film density exists. When film is present, the outputs of the optical sensor 136 and reference sensor 138 are applied to a differential amplifier 140. Here-the signals are compared and an output from the differential amplifier 140, equal to the difference between the signals from the optical sensor 136 and reference sensor 138, is applied to the servomotor 142. The servomotor 142 is mechanically linked to and drives an adjustable transformer 143 with an output that provides the desired amount of current to the heater 144 on the doctor blade to control properly the temperature of the monobath.
In another variation, a variable speed electric drive is used to power the film advance mechanism. The electric drive speed is then controlled by the output of the transformer 143. In this way the film image density is monitored to assure that there is always enough monobath spread on the film to develop fully the image, and that the film speed is as great as it can be while allowing sufficient time for the image to be developed and fixed before the monobath is removed.
In still another variation of the proposed control system, the reference sensor 138 is made a part of the optical sensor and is arranged to monitor the light passing through a carefully exposed reference line on the film edge. By comparing the density of the properly exposed line on the film edge with the density of the developed image, a signal is generated which is indicative of the degree to which the film image is developed so that corrections in the temperature of dispensed monobath or film speed are made if necessary.
Various monobath materials are commercially available. One formulation which works well with our processor is as follows:
55 Additional water to bring total volume up to 1,000 ml.
Film processing apparatus of the type illustrated in FIG. 1 has been built to a size approximating 14 inches by 20 inches. Using new monobath materials now in the final stages of development processing speeds of 5 feet per minute are obtainable. It is believed that film speeds even higher than this will be obtainable as monobath formulations improve.
While in the ordinary course of events drying the film before takeup is anticipated, certain applications make this unacceptable. In enclosed spacecraft or oceanographic vessels the moisture and malodorous gasses passed out by the drier may make drying unacceptable. In such cases the image may be viewed while not fully dried and the film in a partially dried condition is then wound on the takeup spool. In most cases this will not damage the image. On the other hand, however, if the larger size of the unit is not a problem, drying may be achieved in a closed vehicle by pumping the exhaust air through a bed of silica gel and activated charcoal or other We claim: l. A photographic film processor comprising: a. means for conveying film through the processor;
b. reservoir means for storing a supply of viscous processing agent;
c. means for dispensing a layer of said viscous processing agent of a predetermined thickness onto the film to enable processing of the films, and
d. monitoring means responsive to the amount of film that has been processed to control delivery of said processing agent from said reservoir means to said dispensing means.
2. Apparatus as set forth in claim 1 wherein said reservoir means includes an aerosol container.
3. Apparatus as set forthin claim 1 wherein said [@5505 means includes a collapsible container which expels said viscous processing agent as it collapses.
4. Apparatus as set forth in claim 3 wherein said collapsible container and said dispensing means are selectively disposable to facilitate cleaning and processing agent replenishment of the processor.
5. Apparatus as set forth in claim 1 wherein said processor includes a takeup reel to wind the film on after it has been processed and said monitoring means monitors the diameter of film wound upon said takeup reel.
6. Apparatus as set forth in claim 5 wherein said reservoir means includes a collapsible container which expels said viscous processing agent as it collapses, and said monitoring means includes a linkage means which monitors the diameter of film wound on said takeup reel and exerts a force on said' collapsible container to control th expulsion of viscous processing agent from said collapsible container.
7. Photographic film processing apparatus comprising:
a. means for conveying film through the apparatus;
b. reservoir means for storing a supply of viscous processing agent;
c. means for dispensing a layer of said viscous processing agent of a predetermined thickness onto a selected portion of the film to enable processing of the film; and
d. wiping means, including at least one blade disposed at an oblique angle relative to the path of the conveyed film, for removing said processing agent from the film after film processing has occurred.
8. Apparatus as set forth in claim 7 wherein said wiping means includes a plurality of blades disposed successively along the path of the conveyed film, each blade being disposed at an oblique angle relative to the path of the conveyed film to enable the successive removal of said viscous processing agent from the film.
9. Apparatus as set forth in claim 7 wherein said dispensing means includes a doctor blade disposed across the width of the film to control the thickness of processing agent dispensed on the film.
10. Apparatus as set forth in claim 9 wherein said dispensing means includes a dispensing member having an elongated slotted exit passage to discharge the processing agent onto the film, the slotted exit passage being disposed across the width of the film and in front of said doctor blade.
11. Apparatus as set forth in claim 10 wherein said reservoir means includes a collapsible container which expels said viscous processing agent as it collapses.
12. Apparatus as set forth in claim 11 wherein said collapsible container and said dispensing means are selectively disposable to facilitate cleaning and processing agent replenishment of the processor.
13. Apparatus as set forth in claim 12 wherein said processor includes: a takeup reel to wind the film on after it has been processed; and said dispensing means includes means for sensing the diameter of film wound upon said takeup reel and for controlling the delivery of viscous processing agent from said collapsible container in accordance with the sensed diameter.
14. Apparatus as set forth in claim 13 wherein said sensing means includes a linkage means which senses the diameter of the film wound on said takeup reel and exerts a force on said collapsible container to control the expulsion of viscous processing agent from said collapsible container.
15. Apparatus as set forth in claim 7 wherein said dispensing means includes a metering rod disposed across'the width of 17. Apparatus as set forth in claim 16 wherein said helically wrapped wire is connected to an electric source to provide a heater means for regulating the density of the developed film image.
18. Apparatus as set forth in claim 7 wherein said dispensing means includes a heater means for regulating the density of I the developed film image.
19. In a processor for photographic film including film advancing means and means for dispensing a viscous processing agent onto the advancing film, the improvement comprising metering means for controlling the volume of said viscous agent dispensed onto said advancing film, said metering meansincluding a rod member transverse to the axis of said film, said rod member being helically wrapped with a wire to control the thickness of the dispensed processing agent while providing a fluted later lateral profile to the dispensed processing agent thereby minimizing the likelihood likelihood of entrapment of particulate matter between said rod member and the advancing film which could scratch the film emulsion, said rod member further having a heating means for regulating the density of the developed film image, said heating means including electric means for passing an electric current through said wire to generate heat, and thereby control the density of the processed film.
20. Photographic film processing apparatus comprising:
a. means for conveying film through said apparatus;
b. means for dispensing a viscous monobath onto said film;
c. means for controlling the thickness of the monobath layer on said film, said thickness control means including:
1. an electrical heating element to control the temperature of said dispensed monobath;
d. means for removing the monobath layer after the film developing and fixing reaction has occurred;
e. means for sensing the density of the processed film image;
f. means for comparing the density of said processed film image with a reference density;
g. means for generating an electrical signal proportional to the difference between the sensed density and the reference density; and
h. means for applying said signal to a current source for said heating element thereby enabling the temperature of said