US3712204A

US3712204A - Device for controlling the regenerating of photographic processing solution

Info

Publication number: US3712204A
Application number: US00193922A
Authority: US
Inventors: M Aelterman
Original assignee: Agfa Gevaert NV
Current assignee: Agfa Gevaert NV
Priority date: 1970-10-30
Filing date: 1971-10-29
Publication date: 1973-01-23
Anticipated expiration: 1990-01-23
Also published as: DE2153826A1; FR2113228A5; GB1327209A; GB1359137A

Abstract

A device for controlling the regeneration of photographic processing compositions. The operation of the device is based on the separation of two electrically conductive rollers from each other as the film passes therebetween. The distance between the rollers causes a corresponding decrease in capacitance of roller electrode portions which in turn causes actuation of the regeneration device for replenishing the processing compositions.

Description

United States Patent 1 m1 3,712,204 Aelterman [4 1 Jan. 23, 1973 DEVICE FOR CONTROLLING THE [56] References Cited REGENERATING OF PHOTOGRAPHIC 1 W PROCESSING SOLUTION UNITED STATES PATENTS 3,334,566 8/1967 Friedel 3,418,9l3 121968 S ..95 94 R [75] Inventor: Marcel Frans Aelterman, Mortsel, nan

Belglum Primary Examiner-Sarnuel S. Matthews [73] Assignee: Agfa-Gevaert N.V., Mortsel, Belgi- Assistant ExaminerRiChard M. Sheer um Att0mey-William J. Daniel [22] Filed: Oct. 29, 1971 ABSTRACT 21 A LN 19 2 1 pp 0 3,9 2 A device for controlling the regeneration of photographic processing compositions. The operation of the device is based on the separation of two electrically [30] Foreign A li ti P i it D t conductive rollers from each other as the film passes therebetween. The distance between the rollers causes Oct. 30, 1970 Great Britain ..5l,788/70 a corresponding decrease in capacitance of roller elec trode portions which in turn causes actuation of the ..95/89 180932961: regeneration device for replenishing the processing [58] Field of Search ..95/89, 94-

4 Claims, 5 Drawing Figures DEVICE FOR CONTROLLING THE REGENERATING OF PI-IOTOGRAPHIC PROCESSING SOLUTION The present invention relates to a device for controlling the regeneration of processing liquid in a photographic film processor.

in the processing of photographic material, it is desirable for the developing solution to be of substantially constant composition otherwise the time for obtaining a standard degree of development will vary. Thus in developing large quantities of light-sensitive photographic material on a continuous processing basis, it is necessary to replenish the developer at substantially the same rate at which the solution is being consumed.

Devices are known for maintaining a photographic processing solution at a predetermined composition in which, at a particular moment, a predetermined amount of replenishing solution is added to a photographic processing bath. The regeneration device is controlled by a mechanical or optical system which is responsive to the amount of film passed through the processing apparatus.

A system for controlling a regeneration device is known from U.S. Pat. specification 3,418,913. The arrangement disclosed in said publication comprises a pair of cooperating rollers, one of which is displaceable with respect to the other. The rollers are biased towards each other and, as a sheet passes between the rollers, the movable roller is slightly displaced from the other. The displacement of the shaft extremity of said roller is used to control a microswitch which, in its turn, controls the regeneration device.

For very thin film sheets or film strips, such as graphic film types the support thickness of which amounts to 0.05 mm, the requirements to be met by the microswitches are very stringent and the device is no longer sufficiently reliable.

It is the object of the present invention to provide a device for controlling the regeneration in a photo graphic processor, which is reliable, and which responds to sheet materials with a very small support thickness, say less than 0.05 mm.

The control device according to the present invention suitable for controlling a device for regenerating the processing liquid in a photographic film processor, comprises opposed rollers having electrically conductive sectional portions which are normally close to each other and form part of an electric control circuit, and between which photographic film to be processed can be passed, and means for causing the regeneration device to function in response to the removal of the sectional portions away from each other.

In the present description the term electrically conductive sectional portions means that only a portion or portions of the length of the rollers may be electrically conductive, but the term also includes rollers the greater part of their length, or even the full length of which, is electrically conductive.

While the above statement broadly defines the present invention, particular embodiments of the invention are mentioned hereinafter.

The control of the regeneration device is based on the interruption of a galvanic circuit. In this arrangement the opposed electrically conductive sectional portions normally contact each other, and the regeneration device functions in response to the interruption of the contact between said opposed rollers.

The control of the regeneration device is based on a change in the electric capacitance between two electrodes. ln such arrangement, the opposed electrically conductive sectional portions normally do not contact each other so as to form a capacitor with a determined capacitance and the regeneration device functions in response to the reduction in capacitance between said opposed sectional portions as a consequence of the increase in mutual distance between the opposed sectional portions at the passage of a photographic film between the roliers.

The regeneration device may operate according to different principles, known in the art. For instance, a pump may be used which pumps liquid from a supply container into the processing tray or tank, the excess of liquid in the tank being discharged, e.g., by an overflow system. The time of operation of the pump determines the quantum of the regeneration liquid. Alternatively, a volumetrical regeneration system may be used. in such system, a small measuring container contains a predetermined quantum of regenerating liquid which is discharged in the processing tank as a predetermined amount of film has been processed. A description of the latter type of regeneration system is disclosed in British Pat. specification 1,045,450, relating to a device for maintaining a photographic processing solution at a predetermined composition.

The invention will be described more in detail by way of example with reference to the accompanying drawings in which:

FIG. 1 represents diagrammatically an embodiment of the invention, and

HO. 2 shows a second embodiment of the invention,

FIGS. 3 and 4 are electric control circuits,

HO. 5 shows a third embodiment ofthe invention.

According to HO. 1 a pair of inlet rollers 10 and ll forms part of an apparatus 20 for processing photographic material. The rollers are made of an electrically conductive material and are arranged in a DC electric circuit in which a relay 14 is connected, the contact 15 of which is normally closed. The roller bearings are electrically insulated from each other and plastic gears (not shown) through which the rollers are driven electrically insulate the rollers from the body of the apparatus. By the numeral 12 a processing tray for the photographic material is indicated whereas the dash and dot line 13 refers to the path followed by the material through the apparatus.

If, for example, a sheet of photographic material is passed between the rollers 10 and ll, then the rollers are separated from each other and the electric contact between the rollers is broken so that the current flow through the relay 14 is interrupted. The contact 15 which was opened during the energizing of the relay, now is closed and an electric A.C.-motor 16 will start. The motor 16 is coupled to a pump 17 which pumps regeneration liquid from a supply container 25 into the processing tray 12. The excess of liquid may be discharged from the tray through a conventional overflow.

FIG. 2 refers to an embodiment of the invention wherein the control of the regeneration device is based on a change in electric capacitance, rather than in electric conductivity as described hereinbefore.

A

transport roller pair

26, 27 of a processing apparatus is only partially shown, and is journalled at either extremity in insulating

plastic journals

28 and 29 which are tensioned towards each other by means of a rubber ring 30 which fits in a corresponding recess in the journals. Both journals may slide in a corresponding vertical slot in the side walls of the processing tank, not shown. The shaft of the lower roller bears a plastic gear 31 made from an electrically insulating wear resistant plastic material, such as Nylon, Delrin (registered trade Marks) or the like, through which it is coupled to the driving mechanism of the apparatus. The upper roller 26 is driven through frictional contact with the lower roller and may be slightly lifted from the lower roller upon passage of a film sheet between the rollers. The rollers comprise a stainless steel shaft which is provided with a resilient covering of low electric conductivity. The rollers furthermore comprise electrically

conductive rings

32 and 33, the diameters of which are slightly smaller than the diameter of the resilient covering of the rollers. The rings may be electrically connected to the corresponding roller shafts, and the extremities of the shafts may be connected through slip rings or the like to an electric control circuit which is responsive to changes in the capacitance formed by the opposed ring electrodes.

The electric circuit may be a simple series A.C. circuit, a decrease in the capacitance between the electrodes resulting in a decrease in the electric current flowing through the circuit. An embodiment of such circuit is shown in FIG. 3, wherein the electrode ring 32 of an upper roller is connected to a source 39 of A.C. voltage, whereas the electrode ring 33 of an opposed lower roller is connected to an operational amplifier 34, the output signal of which is coupled over a capacitor to a clipping circuit comprising two

diodes

36 and 37 connected in anti-parallel. The amplification factor of the amplifier is adjusted by means of a feedback resistor so that an output signal is obtained at terminal 35 if no film is present between the electrodes. As a film is introduced between the rollers, the distance between the electrode rings increases so that the capacitance decreases. The current decreases as a consequence of the increased impedance, and the output signal of the amplifier becomes so small that it is no longer transmitted through the clipping diodes.

A more sensitive response may be obtained by a timed circuit. An embodiment thereof is illustrated diagrammatically in FIG. 4, and comprises an oscillator 40, a timed circuit 41 and a voltage follower 42. The operation of the control device is as follows.

The oscillator 40 generates an electric signal with a determined frequency. The signal is coupled over a capacitor to a circuit 4] which forms a timed circuit together with the capacitance of the

ring'electrodes

32 and 33. The circuit may comprise a parallel LC circuit, a ceramic filter, etc. The electric circuit comprising the circuit 41 and the electrode capacitance may be timed to resonance with the generator 40 for the case no film is present between the

rollers

26, 27. The voltage which is applied to the voltage follower 42 is then maximum, and the output signal at terminal 43 may control a relay which may operate in the same way as relay l4 illustrated in FIG. 1. As a film sheet enters between the re]- lers, the capacitance between the

electrode rings

32 and 33 decreases on account of the increasing distance. The resonance frequency of the circuit 41 no longer corresponds to the frequency of generator 40 so that the output signal at terminal 43 will be smaller and thereby the relay controlling the regeneration device may be de-energized to start thereby the regenerating.

FIG. 5 relates to a third embodiment of the present invention. Two

rollers

45 and 46 are composed of a series of electrically conductive sections 47 which are electrically insulated from each other by insulating disks 48. The conductive rollersections are connected by sliding brushes or contacts 49, each set of two opposed roller sections constituting a separate electric circuit. In the inoperative position, the rollers contact each other and the electric circuits of the different opposed roller sections are closed. In the operative position, the rollers are slightly removed from each other by the film which passes between them, and thereby the electric connections between the opposed roller sections are interrupted. This interruption in the electric circuit may control the regenerating of the processing liquid.

In addition to the mentioned control, it is also possible to make a distinction between the roller sections between which the film sheet is present, and the roller sections which are separated by a layer of air. As a matter of fact, the dielectric constant of a film, c.g., a polyethylene terephthalate film, amounts to about 3.5 and thus there exists an appreciable difference in the capacitance of the roller. sections in the operative position. Each pair of opposed roller sections controlling a separate electric circuit it is possible, e.g., by an arrangement as illustrated in FIG. 4, to detect the number of roller sections between which a film is present. In the mentioned way the regeneration device may be controlled also as a function of the width of a film sheet which is being treated. in a practical embodiment, the time during which the rollers are separated may control the time of operation of a centrifugal regeneration pump, whereas the number of roller sections between which a film is present, may control the position of a metering valve in the conduit from the pump to the processing tank.

In the mentioned way, the regeneration may be made to closely correspond to the actual film surface being processed.

It will be understood that the embodiment illustrated in FIG. 3 functions as well, if one of the two rollers is replaced by an uninterrupted roller which forms a common electrode for the opposed roller electrode sections.

We claim: v

l. A control device for controlling a device (17, 25) for regenerating processing liquid in a photographic film processor, comprising movably mounted superposed rollers (l0, ll 26, 27)"having electrically conductive sectional portions (32, 33) which are normally closely adjacent to each other and form part of an electric control circuit, said superposed rollers forming a nip between which photographic film to be processed is passed, and means for causing the regeneration device to function in response to a change in said electric control circuit caused by the movement of the sectional portions away from each other by passage of photographic film between said rollers.

2. A control device according to claim 1, wherein opposed electrically conductive sectional portions of said superposed rollers normally contact each other, and wherein the regeneration device functions in response to the interruption of the contact between said opposed portions.

3. A control device according to claim 1, wherein opposed electrically conductive sectional portions of said superposed rollers normally do not contact each other so as to form a capacitor with a determined capacitance, and wherein the regeneration device functions in response to the decrease in capacitance between said opposed sectional portions as a consequence of the increase in mutual distance between the opposed sectional portions at the passage of a photographic film between the rollers.

4. A control device according to claim 1, wherein said superposed rollers (45, 46) comprise a plurality of electrically conductive sectional portions (47) which control individual electric circuits, so that the regeneration is a function of the number of sectional roller portions corresponding to the width of the film, thereby to regenerate processing liquid at a rate which is also a function of the width of the film.

Claims

1. A control device for controlling a device (17, 25) for regenerating processing liquid in a photographic film processor, comprising movably mounted superposed rollers (10, 11 - 26, 27) having electrically conductive sectional portions (32, 33) which are normally closely adjacent to each other and form part of an electric control circuit, said superposed rollers forming a nip between which photographic film to be processed is passed, and means for causing the regeneration device to function in response to a change in said electric control circuit caused by the movement of the sectional portions away from each other by passage of photographic film between said rollers.