US2631511A - Control for rapid film processing - Google Patents

Description

March 17, 1953 TUTTLE CONTROL FOR RAPID FILM PROCESSING Filed June 26, 1948 R O T T A INVENTOR E l. T T w W m. WWW .L C

Patented Mar. 17, 1953 coNTaoL FOR RAPID FILM PROCESSING Clifton M. Tuttle, Halesite, N. assignor to Kenyon Instrument Company, Inc., Huntington, N. Y.

Application June 26, 1948, Serial No. 35,493

Claims.

This invention has to do with apparatus for rapidly processing photographic film which has been exposed. It is an improvement upon apparatus which was developed for rapid processing of photographs of the cathode-ray tube face of a radar system. This apparatus for radar use, including a camera, a processing unit and a pro jector, came to be known as P 1 and is de-' scribed in the Journal of the Franklin Institute, vol. 242, No. 3, September 1946, at pages 203 et seq.

In P 1, a strip of film is pulled intermittently along a track within a light-tight housing past a station where the image is produced and where the exposed film is processed, and thence past a station outside the housing where the image is projected, one image being formed and processed while the one previously formed and processed is being projected. The film has its emulsion side uppermost and the exposure is made through the film base by focusing the tube face, located below, through an aperture in the track. The processing cycle may be as short as five seconds.

This rapid action is accomplished by delivering hot chemicals in sequence to an open plastic cup in the form of two concentric cylinders arranged to drop onto the film at the processing station so that the film forms the bottom of the cup and a seal is effected by the lip or rim of the outer cylinder. After each hot chemical (e. g., the developer, fixer or wash) has been delivered to the space within the inner cylinder and has had its eifect on the emulsion, suction is applied at the space between the cylinders to remove the chemical and to draw air rapidly over the film surface to dry it; whereupon through action of the controlling cams the delivery of the next chem-ical to the cup is initiated. The whole operation, including film movement and delivery and exhaust of the chemicals and drying air, is controlled by a bank of switches operated by a bank of cams on a single shaft which makes one full turn in the total cycle of about seconds.

The present improvement deals with the control of the supply of processing fluids to the processing unit. It is not limited to use in the P 1 system or to systems of the same purpose, but may be used in various systems and for various purposes where processing fluids are delivered in sequence to a processing unit. 7

The combination of this invention preferably employs a processing unit having certain new features which are the subject of Clifton M. Tuttle et 21., Patent No. 2,582,182, granted January 8, 1952, for improvements in- Apparatusfor Rapid Processing of Film. The same preferred formof processing unit is described here to illustrate that part of the combination, along with the associated parts which complete the control system. The whole is described with reference to the annexed drawing in which the system is shown diagrammatically with the processing unit in vertical section.

The basic idea of control is to project a light beam through the film undergoing processing, the processing apparatus having transparent parts in the path of the beam to permit this; and to use the variations in light value caused by the changes in opacity of the film at different stages of processing to give changes in the output of a photocell activated by the light beam. Properly amplified, the increases and decreases in photocell output are then used to efiect the action of a solenoid which controls the rotation of a shaft carrying cams which operate the valves controlling the supply of processing fluids. In this way, at least some of the valve operations can be controlled to deliver different processing fluids at the proper time in the processing cycle. It is within the broad concept to use the photocell output to control the action of other means than the cam unit for actuating the valves by which the processing fiuids are delivered in predetermined sequence.

For example, the latent image formed upon exposure of a film is translucent. When the film frame comes to the processing station in that condition it passes a definite and considerable amount of light to the photocell. The cell output under this condition may be caused to initiate the opening of a valve to supply developer to the processing unit. The action of the developer causes the film to become more opaque and to reduce the light Value at the cell. The reduction at full development reduces the cell output to a value which may be used to cause the closing of the developer supply valve and the opening of the valve controlling the supply of fixer. The fixing solution checks development and, by dissolving the unchanged silver salts in the emulsion, increases the translucency of the film. This increases the light value at the cell to a degree su'fii'cient to give an increased cell output which may be utilized to cause closing of the valve in the supply of fixing solution and opening of a' valve'controuihg" the supply of all to dry the film. The termination of the drying an the initiation of the pull-down may then be eifected by other means, manual or automatic.

v A preferred form of the invention is described below with reference to the annexed drawings, inwhich' r Fig. 1 is a view in vertical section through the processing unit proper, with a diagrammatic showing of a light-sensitive control for automatically delivering processing fluids to the unit.

Figs. 2 and 3 are, respectively, a plan and an elevatlonal view of one of the components of the processing unit.

I first describe the processing unit which I prefer to use and which has the features that lend it to use in a control system of this new type.

The film It is preferably, but not necessarily, in a horizontal plane at the processing station. In the example shown, the film is at rest at the station; but the only essential is that it be at rest relaive to the processing unit. Here the film is shown with the emulsion face at the lower side. The film is moved intermittently by any suitable means to bring successive frames to the processing station.

At this station is a fixed backing support for the film in the form of a disc I! of transparent plastic mounted in a fixed metal ring I? located above the film track and close to the film. This backer presents a fiat surface to the film at one side so that the film can be held fiat against it during the processing.

Below the film is the unit which during the processing forms a chamber that is closed except for the inlet and outlet through which the processing fluids pass under pressure. This unit provides for a continuous fiow of each processing fluid in a confined thin stream across the emulsion face of the film. It also includes means for bringing the parts which form this confined flow passage into working relation with the film, involving a peripheral sealing engagement between the film and the movable member which in conjunction with the film defines the fiow space.

This lower unit consists of two main structural parts, an outer fixed element i5 and an inner movable element I6 sliding in the fixed part so that it can be brought into and out of enagement with the film. The movable element l6 comprises the parts which define the flow passage for the processing fluids. The processing unit shown here also includes pneumatic means for moving the element I6 into and out of its engagement with the film, certain parts of the fixed and movable elements being so shaped and related that they form two separate piston and cylinder units, one for advancing the inner element it under air pressure and the other for retracting it by a suction action. Because of these piston and cylinder features, which preferably are cylindrical, both parts of the processing unit are of cylindrical shape generally; but it will be evident that this shape is not necessary.

- Considering the fixed element l5 specifically, it has a main body part M of hollow cylindrical shape with an inwardly projecting integral ring I! giving a smaller internal diameter at the lower part. It has a bottom closure l8 in the form of a transparent disc of plastic material which fits within the central bore [9 and has a fiange held in a recess 2| by a threaded retaining ring 22.

The upper and wider part of the central bore of this fixed element I5 receives the main cylindrical part of the movable element, while the smaller bore alforded by the ring ll receives the depending skirt part 26 of the movable element. Packing rings 21 and 28 seal the joints between the interfitting parts which provide the two piston and cylinder units for actuating the movable element [6.

At one side of the fixed element l5, near its bottom, is a nipple 3t threaded into a tap in the cylinder wall. This is for connection to a compressed air line 3|. From this nipple a passage 32 leads through the wall of the fixed element I5 to the central bore l9 at a point just above the bottom closure l8, thereby admitting air to the space 33 within the depending skirt 26 of the movable element. Because there is a partition 45 (described below) across the interior of the movable member, forming with the skirt 25 a piston sliding in the cylinder formed by the inward ring E1, the compressed air admitted through passage 32 to the interior space 33 acts on this piston to cause the movable element to move upward toward the film.

At the other side of the fixed element 15 is another nipple 36 similarly threaded into a tap in the wall and giving connection to a vacuum line 31. A passage 38 in the wall of the fixed element leads upward from this tap through the ring I! to the annular space 39 beneath the main body 25 of the movable element and between the outer wall of the skirt 25 and the inner wall of the fixed element l5. Thus the suction action serves to retract the movable element It by its action in this annular piston and cylinder unit formed by these coacting parts.

Near its upper end the movable element l6 has two nipples 46, 4| threaded into taps extending through the wall of the main body part 25 at opposite sides. These furnish respectively the connections to the supply line 42 and the exhaust line 43 for the processing fiuids, so that fiow can be established through the interior chamber 44 in the movable element. This chamber A l has a bottom closure formed by the transverse partition 45 which is a disc of transparent plastic held in a recess 46 at the lower part of the main body of the movable element by the threaded skirt 26 already mentioned. This bottom closure 45, together with the cylindrical main body part 25, form a cup shaped part the peripheral rim of which engages the film around the area to be processed to form a fluid tight joint, thereby forming the main closure for the processing chamber.

Integral with this partition 15 is a block 56 of transparent plastic which is of smaller lateral size than the interior chamber M. This block 5i) serves as a filler to reduce the free space within the cup shaped part of the movable element, and also serves to further define the fiow path for fluids passing from the inlet to the outlet. It extends upward to a plane just short of the plane of the upper rim 55 of the movable element Hi. When the movable element is brought into sealing engagement with the film at the peripheral rim 55, the top face 56 of the filler block 5i! is slightly spaced below the emulsion face of the film, and so defines with it a shallow flow passage across the film face.

The upper rim 55 of the outer cylinder part 25 of the movable element I6 is tapered to give a narrow surface engaging the film. This gives an effective seal.

To confine the fiow of processin fiuids to the shallow passage at the film face, between the film and the top surface of the filler block 50, there are vertical fins El and 58 at the sides of the filler block 50 midway between the inlet and outlet. These extend into contact with the inner wall of the bore in the movable element and pre-' vent flow around the side of the filler block while providing some free space in the regions of the inlet and outlet connections to give easy flow to the shallow flow passage across the processing area.

It will be understood that the thin stream flow passage across the film face may be obtained by other forms of construction. This use of an otherwise large chamber with a filler block is, however, a good way of providing wall area sufficient for good inlet and outlet fittings while still obtaining the thin stream flow across the film face, which is a desirable feature.

It will be noted from the above that all of the tranverse parts above and below the film are transparent, that is, the backer disc I 0 above the film, the filler member 50 and central partition 45 of the movable element It, and the end closure 18 of the stationary element 15. This permits light from a source 59 below the unit to pass through the entire unit, including the thin stream of processing fluid directly under the film, and the film itself to the extent permitted by the film. An optically selective filter 60 may be interposed between the light source and the processing unit to transmit only the desired visible but photographically non-actinic light. If the light source is incorporated in the processing unit above its bottom closure, the latter of course may be opaque.

The photocell and associated control system are shown schematically since they may be incorporated in a wide variety of housing structures and I claim no present novelty in that respect.

The photocell 62 is located above the backing plate H in the path of the light from the source 59 which is projected through the translucent parts of the processing unit. The cell has one terminal grounded at 63 and its other terminal is connected to the grid 64 of a triode 65 forming part of an electronic control circuit including triode 66, battery 61, and a solenoid 68 which operates an escapement on a one-turn clutch 69 in the driving connection between a constant speed motor and a cam shaft H. Whenever the solenoid is energized by a pulse from the electronic circuit, it causes the clutch 69 to couple motor 10 and shaft H for one complete revolution of the motor shaft, which corresponds to a fraction of a revolution of shaft H. A cam 12 on the latter shaft controls a valve 12 for admitting compressed air from a source 12 to the line 3| which leads to the central bore IQ of the processing unit. The supply of developer fluid, fixer solution and drying fluid is controlled by cams I3, 14 and 15, respectively, which operate valves 13 14 and 15 in the respective supply lines 13*, 14 and 75 leading to a manifold 76 which is connected to pipe 42. A fifth cam 11 controls a switch 18 connected to an electric motor 19 for winding a reel in a housing 80, so as to advance successive frames of the film to the processing unit.

The electronic circuit is so designed that (1) triode 65 is normally non-conducting but becomes conducting when the output of photocell 62 drops below a certain value owing to reduction of the light received from source 59, and (2) triode 66 will pass an electrical pulse by which solenoid 68 is energized when triode 65 becomes conducting and also when it reverts to its non-conducting state. The electronic circuit for producing these pulses is not new in itself, although this application of it in combination with a photocell and actuating device is believed to be new. Its details therefore need but summary statement.

As illustrated, the electronic valve 66 is con- 6. nected in the plate circuit of triode 65 through a resistance-capacitance network including a capacitor 82 connected between the plate of triode 65 and the grid of triode 66, resistors 83 and 8 3 connected between the filament of triode BB and a point between capacitor 82 and triode 65, and a ground connection 35 between the two resistors. The plate of triode 65 is connected by wire 86 to one terminal of solenoid 68, the other terminal of which is connected by wire 81 to one side of battery 67. The other side of the battery is connected through resistor 88 to the grid 64.

In operation, an exposed film frame having the latent image is drawn into the processing position between the block 5! and the part II, this action being effected by momentary closing of contacts 78 to energize motor 19. Then the cam shaft 1! is turned (as by manually operating the clutch 59) so that cam 72 raises the valve 12* from its seat, allowing compressed air from source 72 to pass through pipe 3| into space 19 in the processing unit. As a result, the movable element [6 is brought into sealing engagement with the film at the rim 55. The shaft is then rotated another fraction of a revolution (as by manually operating clutch 69) to cause cam 13 to open valve "a3 the valve 12 being held open. Photographic developer fiuid then passes under pressure from source 13 through manifold 16 and pipe 32 and flows across the film surface and out the waste pipe 13. As the image develops, it becomes more opaque and eventually reaches a state of opacity such that the light on hotocell 82 is reduced to the point where triode 65 becomes conducting. A pulse is thus originated in the electronic circuit, momentarily energizing solenoid 63 and causing shaft 7| to rotate sufliciently to close valve 13 and open valve 14*. This results in cutting off the supply of developer and starting the supply of fixer from source 14 The fixing solution checks the development of the image as soon as it reaches the film in the processing unit, and acts to dissolve the unchanged silver halide salts in the film emulsion. This increases the transparency of the film to the point where the photocell current increases to the cut-01f point of triode 65, whereby a second pulse is transmitted to solenoid 68. The cam shaft then rotates to close valve M and cut off the supply of fixer, and to open valve I5 so as to admit drying air from the source 15*. The air flows through the processing unit in contact with the film surface, and when the latter is dried the cam shaft is again rotated (as by manual operation of clutch 69) to close valves 15 and 12 When valve l2 closes, it uncovers a vent 12, through which the compressed air in line 3| escapes, thereby allowing the vacuum in line 31 to lower the movable element l 6 from the film surface. Switch 78 is then closed again to draw a new film frame into the processing unit, and the processing cycle is repeated.

If desired, a timing mechanism may be arranged to operate the clutch 69 from the time when the drying valve '15 is opened until the developer valve 13 is opened. The timer may be set mto operation by opening of valve 15 whereby the apparatus is fully automatic.

It will be understood that the sequence cycle described above is merely a typical operation and Enay be modified to accommodate desired condiions.

I claim: 1. Apparatus for rapid processing of exposed photographic film, comprising a member preaearsn senting a fiat supporting surface to the film on one side and a member engageable with the opposite side of the film to hold the film against said surface during processing, said members also forming a chamber with inlet and outlet whereby processing fluids may be passed across the face of the film to be processed, said supporting and movable members having transparent parts forming a light path in register with a substantial part of the area of film to be processed, means for delivering said fluids sequentially to said inlet, including valve mechanism and a power source for operating said mechanism step-by-step through a predetermined cycle, to direct the flow of said fluids in predetermined sequence, a light source for transmitting light through the film by way of said light path, and a light sensitive device arranged to receive light transmitted through the film, actuating means operable by said device upon decrease in the amount of light transmitted by the film, actuating means operable by said device upon increase in the amount of said transmitted light, and an operative connection between the actuating means and said power source, whereby the actuating means operates the valve mechanism step-by-step through the power source to cut on" the supply of one of the fluids to the film and initiate the supply of another fiuid to the film upon said decrease in the amount of transmitted light, and to cut off the supply of said last fluid to the film upon said increase in the amount of transmitted light.

2. Apparatus in accordance with claim 1 in which said light sensitive device is a photoelectric cell and in which said actuating means operable thereby comprises an electronic circuit including a triode so arranged as to become conducting when the output of said cell exceeds a predetermined value, and a second triode so arranged as to apply an impulse to said operative connection when said first triode becomes conducting or changes to a non-conducting state upon reduction of cell output.

3. Apparatus according to claim 1, comprising also separate sources of the processing fluids including a source of developer solution, and a valve operable independently of the light-sensitive device for supplying said solution to the chamber, said fluid sources including a source of fixer solution and a source of drying fluid, said valve mechanism being operable from said device to cut off the supply of developer solution and initiate the supply of fixer solution when the photographic film image attains a predetermined opacity under the action of the developer solution, and to cut-off the supply of fixer solution and initiate the supply of drying fiuid when the film attains a predetermined transparency under the action of the fixer solution.

4. In apparatus for rapid processing of exposed photographic film, in which the film is contacted successively with developer and fixer fiuids operable to vary the light-transmitting capacity of the film during the processing, the improvement which comprises valve mechanism for delivering the fluids one by one to the film to make the successive contacts of the film with said fluids, means for directing light of predetermined intensity upon the film during each of said contacts, a light-sensitive device positioned to receive light transmitted by the film from the light-directing means during each of said contacts, and an operative connection between the light-sensitive device and said valve mechanism for controlling the duration of the respective contacts in accordance with variations in the intensity of light received by said device, said operative connection including means operable by said device upon decrease in the amount of light transmitted by the film to said device, to actuate the valve mechanism for cutting off the supply of developer fluid to the film and initiating the supply of fixer fiuid to the film, and means responsive to increase in the amount of said transmitted light for actuating the valve mechanism to cut off the supply of said fixer fiuid to the film.

5. The improvement according to claim 4, in which said connection includes means for operating said mechanism to terminate the developer contact and initiate the fixer contact when the intensity of light upon said device decreases to a predetermined value, and to terminate the fixer contact when said intensity increases to a predetermined value.

CLIFTON M. TUTTLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,895,760 Hunt Jan. 31, 1933 1,959,233 Franke May 15, 1934 2,221,055 Lundegardh Nov. 12, 1940 2,262,573 Bender Nov. 11, 1941 FOREIGN PATENTS Number Country Date 512,969 Great Britain Sept. 29, 1939

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