GB2154905A - Photographic colour print processing equipment - Google Patents

Abstract

An automatic photographic colour print processor designed for amateur use to eliminate the wastage of chemicals inherent with most existing designs, but giving all the advantages of unattended processing and the ability to change the process at will, even between prints. The principle is to release pre-measured quantities of processing solutions in a pre-arranged sequence from containers into a modified conventional processing unit, draining each solution from the processing unit, and optionally segregating it for re-use, before the next solution is dispensed, the whole operation being under the control of a timer/controller which enables each part of the process sequence to be determined and time in advance. In one form the containers 1 are tipped over in sequence by means of cams 7 driven through a common shaft 5 by a solenoid 6 so as to discharge their contents into a common outlet 3. <IMAGE>

Description

SPECIFICATION Improvements to photographic colour print processing equipment The commercial processing of colour prints from negatives is well established using sophisticated automatic continuous-web exposing and chemical processing equipment. Such equipment is very expensive and requires large throughput to justify its use. On a smaller scale, equipment is available which will process exposed sheets of paper by carrying them through tanks of solutions on rollers, belts or in frames. These are economic only when several hundred prints have to be made during the active life of the chemical solutions and are suitable for the small scale "custom" commercial processor, particularly for making colour prints from diapositive slides.

Nothing exists between such equipment and the manual processing used by amateurs in which prints are developed in light-tight drums or dishes by pouring in and emptying appropriate solutions in sequence and agitating for set times. In some equipment the agitation is performed mechanically and there is automatic temperature control, but all require the almost continuous attendance of the operator to change the solutions at appropriate times and generally supervise the process.

The processing a single print may require 10-20 minutes of such attention and is tedious, error-prone and inefficient.

The present invention describes means whereby the advantages of automatic processing may be made available to the amateur photographer who wishes to make a few prints at a time and may not use the equipment again, possibly for several weeks or months, without wasting chemicals and in a fully automatic manner, enabling him to devote his attention to other matters such as the selection and exposure of the next print or batch of prints whilst the previous batch is being processed.

Because of the high cost and short active life of chemicals for colour processing and the random nature of amateur processing, which makes it impracticable to predict usage in advance, an automatic processor for the amateur should use a "one shot" system, whereby each print or group of prints forming a batch should use only the minimum amount of each solution necessary for the chemical reactions and which should then be discarded.

In certain processes it is possible to achieve further economy by recovering each solution separately and reusing part of it mixed with fresh solution to make up the quantities for the next batch. This is known as the partial replenishment technique.

The most usual way for the amateur to process prints is curled on the inside surface of a light-tight cylindrical drum which has a removable end cap, or caps with light traps which enable solutions to be poured in and emptied out, normally with the axis vertical.

After adding the solution the drum is rotated with its axis horizontal so that the solution travels in a wave repeatedly over the surface of the print until the reaction has taken place when it is emptied, and rinsed if necessary, and the subsequent solution added and the procedure repeated.

More recently a fact well known to those skilled in the photographic art has been rediscovered, namely that a print may be processed with the absolute minimum amount of solution if it is flat and horizontal on the smooth surface of a dish which is lightly agitated, preferably with an orbital movement, so that the solution maintains a thin continuous film over the sensitive surface of the paper. Modern resin coated or plastic film bases will lie perfectly flat, especially when wet, thus facilitating this action. Two examples of this technique have recently appeared on the U.K. market, the Paterson Orbital Colour Print Processor which is available with manual or motorised agitation and the Agnekolor "Colour Wedge" Processor, of U.S. origin, which has only manual agitation.

Both are essentially light-tight dishes fitted with light traps to enable solutions to be poured in and emptied out, into which the exposed print to be processed is placed in darkness, all subsequent operations being carried out manually in a lighted room.

It is the object of this invention to provide additional means not now available whereby such a dish-type processor forms the basis of a fully automatic processing system which carries out the desired process or processes from start to finish without human intervention. The system to be described is also applicable to a drum processor with simple modification.

By way of example, the following is a description of the invention applied to a Paterson Orbital Colour Print Processor (POCPP) as described in British Patent Application No.

The additional equipment consists of: (1) The dispensing unit which usually rests on top of the POCPP dish, hereinafter called the dish, and which dispenses the solutions into the dish in sequence.

(2) A drain system which allows each solution to be emptied before the next is dispensed and which, if required, collects the used solutions in separate containers to enable re-use.

(3) The timer/controller which sequences and controls the various operations necessary at adjustable preset intervals.

The dispensing unit now to be described utilises the colour-coded measuring cups or containers for solutions sold with the POCPP which determines the size and general configuration of the unit, but this convenience should not be construed as limiting the scope of the invention. In the initially preferred arrangement, Fig. 1, the plastic cups 1 are each supported in a compartment with its base resting on a member 2 displaced from the line of action of the centre of gravity so that in the absence of other restraint it tends to tip over and deposit its contents. Further support/restraint is provided to the upper rim of the cup by the three sides of the compartment, two of which just clear the rim diameter, and by a movable release mechanism which in its normal position completes the support system.If the support of the release mechanism is withdrawn the cup will tip over pivoting on its base support 2 with its rim travelling in the clearance space until it comes to rest with its previously horizontal rim now approximately vertical, its contents being discharged into another container 4 of which the interconnected compartments form part which drains through an aperture 3 into the dish inlet as in Fig. 1 or alternatively discharging directly into the circular inlet 9 of the dish if the compartment is arranged as part of a group around the inlet as in Fig. 2 in which the radial lugs 11 prevent the cups from moving too far forward when released and interfering with one another.

It is desirable to consider the cup and its support and release mechanism as a dosing unit which can be duplicated in various convenient configurations depending on the precise application and the number of processing stages required to form the dispensing unit.

Depending on such configuration, the release mechanisms may be combined or, in the case of a circular or carousel configuration, a single release mechanism used which is brought into conjunction with each unit in turn. The type of cup or container used will have considerable influence on the design of the support and release system and if the container is specially designed for the application, improvements can be made to size, simplicity, elegance and efficiency of the unit, particularly by the use of partially-captive containers.

Whatever method is used to support and release the container must be kinematically sound to give foolproof and predictable operation, constraining the container to fall in a manner and position which will not interfere with the correct operation of subsequent containers. To achieve this, by way of example, the existing cup-shaped containers may be supported and released in the following ways: (a) Resting the base on a support off-centre and restraining the rim by means of three edges, or the equivalent, plus a fourth edge which is the release mechanism. Withdrawal of the release mechanism produces a completely defined movement, as used in Figs. 1 and 2.

(b) Resting the rim on three points and withdrawing one, the support unit being desired so that the base of the cup strikes a part of the support unit during its fall which is off centre and is tipped in the desired direction.

(c) Resting the base of the cup on a hinged tilting tray with or without additional side restraint and guidance for the rim. Tilting the tray beyond the angle where the centre of gravity lies outside the base will cause the cup to fall and deposit its contents.

(d) Nesting the container in a gimbal which can be rotated through 90' to empty it.

(e) A combination of these.

The use of the existing cup limits the number of processing stages to about four in the case of the simple linear arrangement, or four to six for the circular configuration (six if a funnel is used to increase the effective diameter of the dish inlet). Up to eight could be provided by mirror-imaging the linear arrangement with two cam shafts geared to a single actuator or the equivalent. Alternatively, by redesigning the containers in a square-section format, more stages can be accommodated compactly with the same overall dimensions in the arrangements described. An example of a specially designed partially-captive container and its support and release mechanism is shown in Fig. 3. This gives a simplification of the support system, and saving in material and size. As an example, the overall size of the four-in-line dispensing unit shown in Fig.

1 may be reduced, for the same container contents, from 285X 110 mmto 190 X 80 mm.

The please mechanism may take a variety of forms depending on the geometrical arrangement of the compartments. Independent solenoid-operated latches could be used for any arrangement but, in general, it will be cheaper to use a single actuator operating a sequential release mechanism since there is normally no need to vary the sequence. A simple and highly reliable arrangement makes use of a rotary stepping solenoid of the type used to drive wafer switches. If the compartments are arranged in line a simple camshaft 5 driven by the rotary solenoid 6 is all that is necessary with the cam surfaces forming the latches directly as shown in Fig. 1. All the cams may be the same shape, but are disposed on the camshaft at suitable angles to release the containers in sequence. For a circular arrangement of container compartments a single crescent-shaped cam 10 may be used, as shown in Fig. 2, or alternatively a cam driving a series of spring-loaded plungers or the equivalent. Inclusion of switch wafers 1 2 in the arrangement enables feedback position signalling and/or sequence-time switching and means to return the camshaft to the starting position to be provided. The stepping solenoid, 6 in Fig. 1, may be replaced by a miniature geared motor 1 3 connected so as to drive the switch, and hence the cam(s), to the next position as used in the arrangement of Figs. 2 and 4, or any other device which can provide the desired movement.

An alternative form of release mechanism is shown in Fig. 3a where the specially designed containers may be provided with tabs 1 projecting above rim level. These tabs are engaged by a member 2 shown here in its linear form which is provided with openings 3 so positioned as to release the series of tabs sequentially as the member is moved axially.

Operation can be by means of a solenoid and ratchet or other means such as a geared motor and rack. Positional feedback for the timer/controller is obtained from a linear or rotary switch element with suitably positioned contacts. The rectangular containers in Fig. 3a are provided with shaped slots 4 on opposite sides which engage with a series of co-linear hinge pins 5 supported on brackets 6. When a container has been placed on the hinge pins and the member 2 moved to the release position the container falls over as depicted in Fig. 3b discharging its contents but remaining captive by the shaped hinge slot when in the horizontal position.

Another solution-dispensing device departing from the principle of separable containers may be constructed by way of example as in Fig. 4. The four containers usually necessary are formed as a single plastic moulding 14 preferably in transparent material with graduated volume markings on each section, around a central tube 15, each container section connecting with the tube by a port 1 6 at the base so that its contents can empty through the port. A rotating selector valve is formed by another tube 1 7 whose external diameter is a close fit in the central tube at the bottom and which is provided with an aperture corresponding with the aforementioned ports, and by being rotated will uncover each port in turn, allowing the contents of the containers to be emptied in turn.Alternatively, a cylindrical plug with an axial slot in its circumference of width such that it can be rotated to uncover each port in turn can be used. The valve is rotated from the top by means of an extension.

It is of paramount importance that such a valve must be absolutely leak proof under the conditions in which it is used because otherwise cross-contamination could occur which can be deleterious to the photographic process. Normally some contamination of subsequent stages by the chemicals of previous stages is acceptable and inevitable, but reverse contamination, like fixer in the developer, can be disastrous. It is one of the features of the separable container principle described heretofore that this can not occur and to match this advantage the performance of the selector valve must be perfect and completely reliable. In the type of rotary valve described this can be achieved by close manufacturing tolerances and the correct choice of materials and by sizing the valve with adequate overlaps between stages particularly in the fully-closed starting position.A preferred method which has been found to be completely effective is to make the rotating ported tube from an elastomer such that it forms a tight seal in the fixed tube and accommodates its shape to cover any slight imperfections in the inner surface of the fixed tube. This elastomeric tube 1 7 with port 18 can be attached, for example, by adhesive to an actuating rod or tube 21 which is provided at its upper end with means for retaining it in the container tube in the correct position so that the ports are in conjunction in the axial direction and for coupling it to the actuator in a unique position so that commanded movements relate to the correct part of the cycle.

Such a valve is preferably actuated by a small geared motor, preferably detachable to enable the container to be washed easily, which is arranged to index in the described example at 45 and/or 90" intervals opening and closing each port in turn under the control of the timer/controller. A retaining pin 1 9 fitting in a blind hole 20 drilled radially in the top end of the rotating member in Fig. 4 can provide both locating functions in conjunction with a slotted cap 22 attached to the actuator shaft which fits over the rotating member as a coupling.

In the case of the POCPP the solutiondispensing device just described can be made to fit directly into the circular light-trapped solution inlet and forms a compact low-cost and elegant addition to the existing processing unit.

None of the currently available dish or drum processors has provision for drainage other than by manually lifting into a near-vertical position and emptying through a light-trapped opening involving a major change in the attitude of the dish or drum and, therefore, unsuitable for automatic operation. A lighttight valve must therefore be provided at a position on the dish or drum through which the contents can be drained rapidly under the control of the timer. It is important that this valve stays effectively closed under the conditions of agitation to which the dish or drum may be subjected during processing and opens only at the end of a cycle when commanded to do so.It should also be simple, reliable, easily cleaned, should not trap solution and be unaffected by corrosive processing solutions, small and easily attached to or incorporated into the dish or drum and the operating means must be either unaffected by washing or detachable or external. This list disqualifies most commercially available components and invites novel design.

The problem of drainage in this application is unusual because the average solution depth if it were uniformly distributed over the sur face of the print is only about 1 millimetre.

Even when collected into one corner or an edge of the dish the head available to provide drainage pressure is very small. The scavenging opening, therefore, should be as large as practicable and shaped so as to minimise surface tension and discourage meniscus formation which would impede rapid clearance of the last few drops. At the same time, the design must prevent light entering the dish.

Since the fluid pressure is negligible the design tendency should be towards a relatively large aperture with closing means exerting relatively light pressure. In fact, it is not necessary to effect a complete physical closure, merely to raise the effective height of the outlet above that of the internal fluid level which can be done by a sluice or a short flexible outlet which can be raised and lowered, or deformed to provide the same effect.

In the case of the drum application described in conjunction with Fig. 9 it is sufficient to provide a permanently open light-trapped aperture at a height just above the normal solution level, and this simplification could apply to a dish processor with a shape and agitation cycle designed to keep the solution spread evenly over the surface and allowing the level to build up at the aperture only when drainage is required by stopping the agitation cycle in a suitably tilted position.

If solution recovery is not required, a single receptacle placed under the drain valve is sufficient to collect used solutions for subsequent disposal. The segregation and retrieval of used solutions is best achieved by draining into colour-coded containers similar to those used for the fresh solutions. This requires means for bringing the appropriate container into conjunction with the drain before it discharges used solution under the control of the timer/controller. The optimum means will depend on the type and geometry of the dish or drum processor used. A universal method would be to keep the drain outlet stationary and to move the containers under it as needed, most conveniently on a turret or turntable actuated under the control of the timer/controller.

Because it will be usual for the processor to be used in the darkroom whilst the photographer is carrying out other work, it may be considered sufficient to provide an audible warning signal signifying that a solution has just been emptied and the container should be changed. As long as this is done before the next solution is to be emptied (usually several minutes) his response to the warning signal which is provided by the timer/controller may be at his leisure.

If solution recovery is required, a particularly elegant and economical processor design results from combining the solution delivery and retrieval systems at different levels on the same turret or carousel. This configuration enables a large number of processing stages to be accommodated in a compact structure and would enable more than one complete sequence to be prepared at one loading. Temperature control of the solutions, if this is needed, is also simplified by the close conjunction of the containers. Although any of the dosing units described previously may be employed, a circular version of the captive container arrangement of Fig. 3 is particularly suitable.The rectangular dispensing containers are arranged in a circle on the upper level, each supported by two hinge pins in rectangular compartments formed by radial projections from a central cylindrical moulding flanged out at the base to form a tray on which the solution recovery containers sit, each in radial conjunction with its corresponding dispensing container. This carousel or turret rotates around a central fixed base-and-column support which contains an indexing motor drive actuated from the timer/controller. Affixed to the top of the stationary column is a cap with a vertical flanged edge containing a single aperture slot. This flanged cap performs the release function, engaging the tabs at the tops of the containers and releasing them sequentially as they move round past the fixed aperture slot.The operation can be visualised by imagining the linear arrangement of Fig. 3a bent round in a circle, the shape of the brackets 6 being changed to support hinge pins in the correct positions relative to the containers. The actuating channel member 2 is then conveniently replaced by a flanged cap with a single aperture as described above.

Depending on the precise application, the whole structure can be sized so that the dispensing containers discharge, for example, directly into the inlet of the POCPP whilst its drain discharges into the solution recovery containers, or, with appropriate changes, to service a processing drum.

There are two generic types of electricallycontrolled drain valve: those which require a continuous electrical signal to hold them in the open (or closed) position, and those which are opened or closed by a pulse of current. A third class of non-electrically operated valve may be derived from some of the examples to be described by bringing the valve into conjunction with magnets or mechanical actuators such as pins at appropriate times by mutual movement which forms part of the cycle of agitation of the processor. The first type will normally use a conventional actuator such as a linear or rotary solenoid to move the valve mechanism and hold it in the open position for sufficient time until emptying is complete.

The second type can use a latching or indexing actuator in the same way, but the principle lends itself to novel arrangements which are simple and effective. The valve shown in Fig. 5a consists of a springy plastic leaf 1 on which is mounted (preferably by encapsulation as shown in 2) a small thin magnet 3 magnetised in the direction of movement. This requires the use of a very high-coercivity permanent magnetic material such as the recently available rare-earth cobalt magnets. The flexible leaf effectively covers an aperture 4 in the dish through which the contents can empty. A small piece of magnetic material 5 (e.g. a wire ring surrounding a circular hole) is imbedded in the seating so that the magnet is normally attracted to it and keeps the leaf closely in contact with the surface thus closing the hole and preventing draining.In order to exclude light from the dish, the leaf is made of lightproof material and the assembly is enclosed by a thin rigid non-magnetic cover 8 spaced a few millimetres from the leaf to allow it to open sufficiently, but shaped to provide a light trap although allowing liquid to pass through at 6.

A preferred construction, Fig. 5b, is to make the valve mechanism as a self-contained unit in the form of a shallow moulded box-like structure comprising 7 and 8 embodying the aperture and magnetic seating on its rear surface to the inside of which the leaf is attached. The front surface embodies a means such as a dovetail, or a dowelled magnetic catch to locate and retain the detachable actuator 9 which is removed when the processor is being cleaned. This valve mechanism can be permanently attached to the side of the processor with adhesive with its aperture covering a suitable drain hole drilled in the processor dish. As stated, a magnetic actuator can be attached to this cover when the system is in use and detached when the processor is being washed. The simplest actuator is an electromagnet consisting of a coil 10 with an iron core 11 positioned over the magnet on the leaf.The flux necessary to displace the leaf magnet from its seating in the closed position is not sustainable for more than a few seconds because the electro-magnet will overheat. The flux is, therefore, provided by a current pulse preferably from a charged capacitor in a direction to attract the leaf magnet which then stays in the open position by attraction to the electromagnet core even when there is no electromagnetic flux. To restore the leaf to the closed position the current pulse in the electromagnet is reversed, repelling the leaf magnet which then adheres to its ferromagnetic seat in the closed position.

Depending on the distance which it is necessary to move the leaf or other member simple electromagnetic operation may or may not be practical. When the operating distance or the force required is too large for direct electromagnetic operation another novel method may be used. Very high spatial magnetic flux densities may be obtained from compact permanent magnets of the rare-earth cobalt variety which exceed those practicable from electromagnets other than superconducting types. If such a magnet is used to provide the flux and its position or attitude is modified by external means such as a linear or rotary solenoid or the equivalent then an amplification effect is introduced which renders several constructions practicable which would otherwise not be.

In the case of the leaf valve previously described, simple movement of the actuating permanent magnet at right angles to the direction of opening of the leaf will attract or release the leaf magnet. If the actuating magnet is made as a horseshoe or if its magnetic axis lies parallel to its direction of motion, then attraction and repulsion of the leaf magnet can be obtained at the extremes of movement making the valve action more positive and removing the need for a ferromagnetic seat to keep the valve closed. A more simple and elegant construction is shown in Fig. 6. A short cylindrical axially-magnetised magnet 1 2 is pivoted about an axis at right angles to its magnetic axis and surrounded by a coil 1 3 sufficiently large to allow 1 2 free rotation on its pivots.The coil can be made in two sections to allow the pivot to pass through and be supported. A piece of ferromagnetic material 14 is positioned above the coil approximately on its magnetic axis at a distance such that the rotation of magnet 1 2 has two stable positions with either pole opposite 1 4.

These stable positions can be reversed by means of a current pulse in a suitable direction in coil 1 3. If this assembly is used instead of the simple electromagnet in the foregoing Fig. 5b then enhanced performance can be obtained over longer distances with the advantage of positive repulsion between the magnets 12 and 3 in the closed position.

An alternative type of drain valve using a permanent magnetic actuator is shown in Fig.

7. A ball 1 5 made of magnetic material, e.g.

magnetic stainless steel or normal ball-bearing steel covered, if necessary, with an anti-corrosion coating such as polytetrafluorethylene, is contained in a slightly tapered conical tube 1 6 made of plastic or other non-magnetic material which can be integral with the processor moulding. If the tube is approximately vertical and has an internal diameter at the bottom slightly less than the ball, the ball will seal the tube under gravity. If now magnet 1 7 is moved close to the wall of the tube at a position above the centre of the ball, the ball will adopt a stable position opposite the magnet leaving clearance 1 8 with the tube through which drainage can take place.The magnet can be brought into position by any suitable actuator or by allowing the processor to move so that. conjunction with a fixed magnet occurs. Similarly, in the third class previously referred to, the ball-and-cone valve just described could be opened by bringing it down over a vertical pin mounted, for example, in the centre of the container(s) used to collect the used solutions, displacing the ball mechanically instead of magnetically.

Another suitable drain valve is shown in Fig. 8 which uses a solenoid to move a plug covering an aperture in the dish. Like the preceding valves in Fig. 5 this is conveniently made as a unit for attachment to the dish and comprises a light-excluding housing 1 9 which is attached by means of adhesive to the dish 24 so that its drain aperture covers a suitable hole drilled in the dish. A solenoid body 20 with a bayonet mounting 25 which enables it to be attached and detached easily for cleaning is fitted to the housing and carries a plunger 21 spring-loaded by spring 22 so that in the un-energised state the sealing plug 23 is held tightly against the drain aperture.A suitable construction for this plug comprises a soft elastomer disc 27 backed by a disc-andpin component turned or moulded from a material such as nylon or polypropylene with the pin waisted as shown at 26 to make the plug self-aligning. When the solenoid is energised the plug is pulled clear of the aperture permitting drainage to occur. The seal 28 prevents solutions entering the solenoid.

With all the valve arrangements described the dish requires to be placed in an optimum draining position as the valve is opened. The POCPP can be drained effectively from one corner or from the centre of a long side as the base is curved in one plane. Whichever position is chosen the dish must be stopped with the drain point in its lowest position when it is required to be drained. With the POCPP this can most conveniently be done by preventing the dish from precessing (rotating with respect to its base) and switching off the orbiting motor at the point in the orbit which corresponds to the lowest position of the drain.

Because the orbiting design involves a sliding frictional effect which causes the precession any attempt to link the dish and its base together rigidly interferes with the smooth orbiting movement and makes it jerky. The precession can be prevented by means of a light spring or a rubber band stretched between two adjacent corners of a long edge of the dish with the centre point anchored to the base. This does not interfere with the desired orbital movement but provides a centering force to overcome the tendency to precess.

This method, although effective, is inconvenient because it must be attached and detached every time the dish is placed on or removed from the base. A more convenient arrangement, which is similarly effective, is to provide a cantilever spring formed from a piece of spring wire fixed to the outer edge of the base and aligned radially inwards. This spring stands proud of the curved base conforming to its curvature and engages in a slot made in the bearing support ring of the dish providing a gentle restraining force at the extremities of the slot and preventing precession. The motor can be stopped in the exact position necessary for draining by mounting a microswitch inside the base operated by an adjustable cam which fits over or, alternatively, made part of the plastic drive member so that it is opened at a point in each revolution corresponding to the correct draining position.The microswitch is fitted in series with the motor, but is bypassed for normal orbiting. When the timer/controller demands drainage the by-pass switch is opened and the orbiting motor is stopped by the microswitch opening within the next revolution of the drive member. The drive member is currently provided with two apertures which can engage the drive pin on the underside of the dish. One of these must be closed off to prevent ambiguity of the draining position.

Although the foregoing description has been mainly in relation to dish processors, the same techniques are applicable to drum processors. The dispensing units, drain valves and timer/control unit can be either identical or adapted with little change. Fig. 9 shows a drum with a modified end cap which enables it to be adapted to automatic operation. The drum is normally sitting horizontally on a motorised cradle which enables it to be rotated for agitation and it can be stopped in a predetermined position to fill or empty by the action of the cam detent 1 on the microswitch 2 in the same way as described for the POCPP. A dispenser 3 of the general type of Fig. 1 or Fig. 4 supplies solutions through a funnel and/or a tube or guide to the inlet 4.

Alternatively, a flexible inlet tube can be coupled to a short length of tube 5 which is loosely captive by means of flanges 6 in the centre of the end cap and forms a rotating light-trapped bearing which allows the solution to enter the drum without a discontinuity.

Polytetrafluorethylene is a suitable low-friction material for this component.

A type of drain valve is selected which can be mechanically or magnetically actuated by an actuator fixed to the cradle or, alternatively, drainage is most simply effected by placing a light-trapped drain aperture 7 on the bottom of the end cap slightly higher than the solution level in the drum. Drainage can be effected by tilting the drum by a few degrees by raising its opposite end when stopped in the drain position so that solution collects and drains freely through the aperture. A solenoidoperated mechanism supporting rollers 8 closer together is a convenient way of accomplishing the tilt.

The timer/controller is a unit which is electrically connected to the various actuators/motors which move the release mechanisms, valves and agitation mechanism and coordinates these functions in the correct sequence and for preselected times. It also indicates the position in the overall cycle which has been reached and provides visual and/or audible warning of the end of the cycle and, if required, the completion of intermediate stages.

It will normally be an electronic unit which can be simple or sophisticated but will follow well-known design principles utilising standard components and needs no further treatment here. A sequence diagram of its essential functions is shown in Fig. 10.

IMPROVEMENTS TO PHOTOGRAPHIC COL- OUR PRINT PROCESSING EQUIPMENT DRAWINGS Figure 1 Linear arrangement of cups. Sheet 1/7 Figure 2 Circular arrangement of cups.

Sheet 2/7 Figure 3 Rectangular captive containers and latch mechanism. Sheet 3/7 Figure 4 Compact dispenser. Sheet 4/7 Figure 5 Leaf valve and actuator. Sheet 5/7 Figure 6 Flipping magnet. Sheet 5/7 Figure 7 Ball/cone valve. Sheet 5/7 Figure 8 Solenoid valve. Sheet 5/7 Figure 9 Arrangement for drum processor.

Sheet 6/7 Figure 10 Typical control sequence diagram. Sheet 7/7

Claims (15)

1. An automatic photographic print processor which utilises premeasured amounts of processing solutions held in containers, the contents of each of which can be emptied as needed into a processing unit containing the print(s) after the preceding solution has been emptied, the whole sequence including any auxiliary actions such as agitation and solution retrieval being under the control of a timer/controller which carries out the operations in a prearranged sequence and for preset times.

2. An automatic photographic print processor as claimed in Claim 1 in which the solution containers are separate and the contents of each discharged as needed by changing the attitude of the said container so that its contents empty into the required place.

3. An automatic photographic print processor as claimed in Claim 1 in which the solution containers are arranged in a cluster around a central valve mechanism which can empty each one as needed through an aperture.

4. An automatic photographic print processor as claimed in Claim 1 in which the dispensing containers are arranged on a turret at a level which allows their contents to be emptied into the processing unit in sequence by rotating the turret whilst, at the same time, solution retrieval containers arranged in conjunction at a lower level are brought into position in relation to the drain of the processing unit so that the used solutions are separately collected.

5. An automatic photographic print processor as claimed in Claim 1 in which the dispensing containers are made in such a way that the support and release mechanisms form part(s) of the container.

6. An automatic photographic print processor as claimed in Claims 1 and 5, in which the support system of the dispensing container enables the container to be removed for cleaning and filling but renders it captive during and after the discharge of its contents.

7. An automatic photographic print processor as claimed in Claim 1 in which the release mechanism for the containers is by means of a cam or cams, or the equivalent, moved by an actuator under the control of the timer/controller.

8. An automatic photographic print processor as claimed in Claims 1 and 4, in which the release mechanism for the containers is by means of a gap in a fixed retaining ring, a container being released as it or a member thereof passes the gap during the indexing movement.

9. An automatic photographic print processor as claimed in Claim 1 which incorporates a drain valve consisting of a flexible leaf arranged to cover and uncover an aperture through which the solutions may empty, the leaf being moved by any suitable electric or mechanical actuator.

10. A leaf valve as in Claim 9 which is biassed to a closed position by magnetic attraction.

11. A leaf valve as in Claim 10 which is opened and closed by an electromagnet in which a pulse of current in the appropriate direction attracts, moves and retains a permanent magnet attached to the leaf holding the leaf open whilst a pulse of current in the opposite direction repels the permanent magnet and closes the leaf valve.

1 2. A magnetic actuator to replace the stationary electromagnet in Claim 11 which consists of a permanent magnet moved into position by an electro-mechanical or mechanical actuator such as a solenoid the extremes of movement being chosen to attract, release or repel the permanent magnet attached to the leaf.

1 3. An electromagnetic actuator consisting of a permanent magnet pivoted inside a coil or coils on an axis at right angles to its magnetic axis, the magnet being stabilised in two or more stable positions which can then be interchanged by pulses of current in the coil or coils in appropriate directions, so producing an external field which can be changed in direction and maintained without external power.

1 4. A fluid valve consisting of a thin wall tapered tube inside which a magnetic ball is fitted of such a diameter that it can close the tube if held in that position by gravity or spring pressure, the valve being opened by moving a permanent magnet close to the outside of the tube at a position of larger diameter, attracting the ball and moving it to produce an opening.

15. A valve as described in Claim 14 in which the actuating magnet is of the type described in Claim 1 3.