The present invention relates to a method of and apparatus for removing or applying a lid from or to a container, and also relates to removing a lid and subsequently replacing the lid.

The invention is concerned in particular, but not exclusively, with the removal and replacement of a flexible lid of an open topped flexible container for use in micropropagation of plants. Such containers and lids need to be sterile, and there is a common requirement to open and close such containers in sterile conditions. The containers are normally intended to be disposable after use, and are relatively insubstantial structures, subject to flexing and bending.

Micropropagation of plants involves the use of the techniques of plant tissue culture and the application of these techniques to the propagation of plants. At its simplest, micropropagation consists initially of excising small pieces of actively growing tissue, normally shoot tips from an adult plant. Then, under sterile conditions, the pieces of tissue are transferred to a nutrient medium which supports plant growth. Dependent upon the species, the ingredients in the medium are chosen to encourage a particular form of plant growth, e.g. extension of a single shoot or development of a cluster of shoots. After a suitable period of growth the plantlets are cut into smaller pieces for regrowth in accordance with the preferred dissection strategy for the particular plant form. This stage, the multiplication stage, is repeated several times before a batch of plantlets is grown into viable plants. This final stage is that a batch of plantlets must be weaned from the axenic conditions in which they have existed within the laboratory, into viable,

rooted plants capable of survival in conventional horticultural or agricultural environments.

The growth of plants in this way from tissue culture (micropropagation) is a technique which can produce large numbers of genetically identical plants, perhaps possessing a desirable quality such as disease resistance, in a short time. The tasks of dissecting and transplanting such plants are labour intensive and repetitive, and the gains in speed, sterility and labour costs which could be achieved by the use of robots make automation an attractive prospect for the fast-expanding micropropagation industry.

The techniques used at present are labour-intensive and one operation which is repeated frequently is the opening and closing of a container intended to contain a nutrient medium in the base of the container, in the form of a gel, and to contain growing plantlets in an upper portion of the container. The standard container for plantlets is usually similar to a margarine tub, and the lids are removed and replaced manually by operators wearing gloves and handling the tubs in a sterile environment.

One particular problem in micropropagation is contamination of the plant material. This can arise either from contamination of the initial batch of multiplying cultures or by contamination during multiplication. In present commercial practice a rule of thumb is that tools which contact the plant material in one growing box are sterilised before use with the next box of plants. In the commonly used 80mm diameter margarine tub there may be as few as four cultures yielding a total of twelve sub¬ cultures to transfer to fresh media. This example would be extreme, but serves to illustrate the importance of securing sterilisation routines which can be effected with

minimum interruption to output. Hence, any automatic or semi-automatic robotic system for handling containers must be simple and easy to maintain sterile, and to resterilise as necessary after use.

Another particular problem is that the containers are particularly subject to flexing and bending, when empty, or partially filled with nutrient medium, to a height which is a small proportion of the overall height of the container. In particular, it is found to be more difficult to handle such containers when partly full to a low proportion of the volume of the container, than is the case with either a completely full container, or a completely empty container. The production of a robotic system for handling sterilised, partly filled open topped containers, is rendered difficult by the flexible nature of the walls, and the lid for the open topped container. In producing an automatic or semi¬ automatic robotic apparatus, it is not sufficient merely to reproduce the manipulations carried out by the human operator. Rather it is necessary to produce apparatus which is simple, reliable, and easy to sterilise, but which is capable of handling the particularly awkward articles constituted by the sterilised, partly filled, containers used in micropropagation.

According to the present invention in a first aspect there is provided a method of removing or applying a lid from or to a container, comprising: engaging the container; positioning a pressure member below or above, respectively, a lip of a lid of an open topped container; producing relative movement of the pressure member upwardly or downwardly, respectively, relative to the container to break or to effect, respectively, a coupling between the lid and the container at a portion of the periphery of the lid; and producing relative movement between the pressure member and the container in a direction transverse to the

direction of the first relative movement, along the periphery of the lid, to break or to effect, respectively, the coupling between the lid and the container along the periphery of the lid.

Preferably, the engaging step comprises engaging the main body of the container, and the step of producing relative movement of the pressure member to break or to effect a coupling, is carried out by applying a force between the pressure member and the main body of the container. When the method comprises a method of applying a lid to a container, preferably the method includes engaging the container by supporting the base of the container and effecting the said coupling between the lid and the container by applying a downward force to the pressure member acting between the pressure member and the base of the container. When the method comprises a method of removing a lid from a container, preferably the method includes engaging the container by securing the base of the container, and breaking the said coupling between the lid and the container by applying an upward force to the pressure member acting between the pressure member and the base of the container.

In all cases it is preferred that the said relative movement of the pressure member upwardly or downwardly comprises a movement substantially vertically upwardly or downwardl .

It is to be appreciated that where terms are used which relate to the vertical and horizontal, for example references to movement upwardly and downwardly, these terms are intended to relate to the normal orientation of the open topped container, that is to say with the open top at a higher level than the bottom of the container. Thus it is within the scope of the invention for the lid of the

container to be removed, or applied, when the container is in an orientation other than normal, for example with the open top of the container facing downwardly, or the open top of the container facing at any angle between vertically upwards and vertically downwards. In such cases the terms upwardly and downwardly apply relative to the normal orientation of the container and not necessarily to the actual vertical and horizontal. For example if the container is inverted during operation of the invention, the lid will be removed by relative movement of a pressure member downwardly relative to the container, and the lid will be applied by relative of a pressure member upwardly relative to the container.

Similarly it is to be appreciated that the relative movements specified may be achieved either by holding the container, and/or the lid, stationary, and by moving the pressure member relative thereto, or by maintaining the pressure member stationary, and by moving the container and/or lid relative to the pressure member.

The invention has particular application in a method of removing a lid from a container, and subsequently reapplying the lid to the container. Thus in this aspect there may be provided in accordance with the invention a method of removing and subsequently reapplying a lid of a container, comprising: engaging the container; positioning a pressure member below a lip of a lid of an open topped container; producing relative movement of the pressure member upwardly relative to the container to break a coupling between the lid and the container at a portion of the periphery of the lid; producing relative movement between the pressure member and the lid in a direction transverse to the direction of the first relative movement, along the periphery of the lid, to break the coupling between the lid and the container along the periphery of

the lid; effecting an operation utilising the container and/or the lid; positioning the lid in register with the open top of the container; positioning a pressure member over the lip of the lid; producing relative movement of the pressure member downwardly relative to the container to effect a coupling of the lid and the container at a portion of the periphery of the lid; and producing relative movement between the pressure member and the container in a direction transverse to the direction of the first relative movement of the pressure member, along the periphery of the lid, to apply the coupling between the lid and the container along the periphery of the lid.

The operation which utilises the container and/or the lid when the two have been separated may for example be the filling or emptying of the container, or may merely consist of leaving the container in an open state for a period of time, for example during the growth of plantlets in micropropagation. However the most common operation at this stage, will arise when the container has been opened when it is already partly filled with nutrient medium for micro plants, and the operation consists of inserting micro plants into the nutrient medium in the container. After the insertion of the plants, the lid is then replaced on the container.

Where features of the invention have been set out hereinbefore, or hereinafter, in connection with a method, the same features may be provided in apparatus embodying the invention, and vice versa.

In particular, there may be provided in accordance with another aspect of the invention, apparatus for removing a lid from a container, comprising: a pressure member; means for engaging the container; mounting means for positioning the pressure member adjacent the container

beneath an outwardly projecting lip of a lid closing an open top of the container; primary drive means for producing relative movement of the pressure member upwardly relative to the container to lift the lip free from the container at a portion of the periphery of the lid; and secondary drive means for producing relative movement between the pressure member and the container in a direction transverse to the direction of the first relative movement, along the periphery of the lid to lift the lip free from the container along the periphery of the lid.

Preferably, the means for engaging the container comprises means for securing the base of the container and the primary drive means is arranged to apply an upward force to the pressure member acting between the pressure member and the base of the container. Preferably the primary drive means is arranged to produce a movement of the pressure member substantially vertically upwardly.

In another aspect of the invention there may be provided apparatus for applying a lid to a container comprising: means for engaging the container; positioning means for positioning a lid in register with an open top of the container; a pressure member; mounting means for positioning the pressure member adjacent the periphery of the lid and over a lip of the lid; primary drive means for producing relative movement of the pressure member downwardly relative to the container to press the lid onto the container at a portion of the periphery of the lid; and secondary drive means for producing relative movement between the pressure member and the container in a direction transverse to the direction of the first relative movement, along the periphery of the lid to press the lid on to the container along the periphery of the lid. Preferably the means for engaging the container comprises means for supporting the base of the container, and the primary drive means is arranged to apply a downward force

to the pressure member acting between the pressure member and the means for supporting the base of the container. Preferably primary drive means is arranged to produce a movement of the pressure member substantially vertically downwardly.

Finally, there may be provided in accordance with the invention in another aspect apparatus for removing and subsequently replacing a lid of a container, comprising: means for engaging the container; a first pressure member for effecting removal of the lid; a second pressure member for effecting replacement of the lid; first mounting means for positioning the first pressure member adjacent the container beneath an outwardly projecting lip of a lid closing an open top of the container; second mounting means for positioning the second pressure member adjacent the periphery of the lid and over the lip of the lid; positioning means for positioning the lid in register with the open top of the container during replacement of the lid; primary drive means for producing during removal of the lid relative movement of the first pressure member upwardly relative to the container to lift the lip free from the container at a portion of the periphery of the lid, and for producing during replacement of the lid relative movement of the second pressure member downwardly relative to the container to press the lid onto the container at a portion of the periphery of the lid; and secondary drive means for producing during removal of the lid relative movement between the first pressure member and the container in a direction transverse to the direction of the first relative movement thereof, along the periphery of the lid to lift the lip free from the container along the periphery of the lid, and for producing during replacement of the lid relative movement between the second pressure member and the lid in a direction transverse to the direction of the first relative movement thereof, along the

periphery of the lid to press the lid onto the container along the periphery of the lid. Preferably the means for engaging the container comprises means for engaging the main body of the container and the primary drive means is arranged to apply a force to the pressure member acting between the pressure member and the main body of the container.

The invention has particular application where the apparatus defines a first work station at which the lid is to be removed and replaced, and a second work station at which a further operation is to be performed, and the apparatus includes transfer means for producing relative movement between the container and the first work station, for effecting movement of the container to the second work station and subsequent return of the container to the first work station at a position which reinstates the container to its previous position in register with the lid which has been removed.

Conveniently the primary drive means comprises a first primary drive means for producing during removal of the lid the required relative movement of the first pressure member relative to the container, and second primary drive means for producing during replacement of the lid the required relative movement of the second pressure member downwardly relative to the container. Conveniently the first and secondary primary drive means may each comprise a pneumatic ram for moving the relevant pressure member.

It is particularly preferred that the or each pressure member comprises a cantilevered pressure member positioned with the distal end of the pressure member facing inwardly towards a work station for the container in operation. Preferably there are provided two or more pressure members spaced from each other around the periphery of the work

station, most preferably there being provided two pressure members positioned opposite each other on opposite sides of the work station for the container. This allows a balanced application of pressure, either upward or downward to the lid during removal or replacement of the lid.

Conveniently, a particularly compact arrangement can be produced, in which there are provided upper and lower pressure members to effect the closing and opening of the lid respectively, the upper and lower pressure members being spaced apart when free of operation by an amount sufficient for an outwardly extending lip of a container to project between the upper and lower pressure members. Conveniently the upper and lower pressure members are provided one above the other in substantially the same vertical plane.

In accordance with another particularly preferred feature, the or each pressure member comprises a roller mounted to give rolling contact of the roller with the lip of the container during operation. It is found that particularly reliable operation can be achieved by opening the lid by raising a cantilevered roller under a lip of the lid to break a seal between the lip and the container, and that the break in the seal can then be extended around the periphery of the container by rolling movement of the roller along the underside of the lip around the periphery of the container. Correspondingly the application of the lid can be achieved by pressing a roller down on the lip, from above, and then rolling the roller around the periphery of the lid, on top of the lip.

Where the container has a circular cross section, it is particularly preferred that the secondary drive means comprises means for rotating the container about an axis coaxial with the axis of the container. A single secondary

drive means may be used for rotating the container during opening and closing of the lid relative to the container. In other arrangements, for example with a container having an approximately rectangular cross-section the second relative movement of the or each pressure member relative to the container can be achieved by a combination of linear movement along the sides of the container and rotary movement at the edges of the container.

Conveniently the said means for engaging the container comprises means for gripping the container by applying suction thereto. Similarly, the positioning means for positioning the lid may conveniently include means for gripping the lid by applying suction thereto.

As has been mentioned, the invention finds particular application where the apparatus is adapted to operate in a sterilised environment for opening and/or closing a sterilised lid of a sterilised open topped container, for example for operation during micropropagation of plants. The invention is particularly applicable where the method includes effecting the aforesaid steps to a lid and container when the container is partly filled with a gel or other soft solid material or thick flowable material. The method may include a step of at least partly filling the container with a gel or other soft solid material or thick flowable material.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:-

Figure 1 is a perspective view of apparatus embodying the invention for removing and subsequently replacing a lid of a container, shown at a first stage before removal of the lid;

Figure la is a side view, partly in section, of the central components of the apparatus of Figure 1, taken in the direction indicated at A;

Figure lb is a side view, partly in section, of components of the apparatus of Figure 1, positioned to the left of the Figure and taken in the direction indicated at B in Figure 1;

Figure 2 is a perspective view of the apparatus of

Figure 1 at a stage at the beginning of the removal of the lid;

Figure 3 is a perspective view of the apparatus of the preceding figures shown at a stage where the lid has been removed from the container; and

Figure 4 is a perspective view of the apparatus of the preceding figures at a stage when the lid is being replaced on the container.

Referring to Figure 1, there is shown apparatus embodying the invention for opening and closing a container for containing plantlets during micropropagation.

A stacking assembly 11 contains a stack of containers

12 each having a removable lid 13 and each containing in the base of the container a quantity of nutrient material 14 for growing plantlets, for example a gel of agar containing various nutrients for the plantlets. Each lid

13 has an outwardly projecting lip 10 which extends over and around the upper edge of the side wall of the container 12. The lip 10 is arranged to snap onto the upper edge of the container 12, in a generally known manner which is commonly found in containers such as margarine tubs. The

gel 14 extends to a depth of approximately one fifth of the height of the container.

The stacking assembly 11 is mounted on a main frame 15, which carries a carriage 16 moveable along rails 17 driven by a stepper motor 18 engaging a rack 19. In a step of the sequence before that shown in Figure 1, the carriage 16 is positioned under the stacking assembly 11, and a container 12 is dropped onto the carriage 16. The carriage 16 is then moved to the main work station as shown in Figure 1. The container 12 is securely held on the carriage 16 by a suction cup 20.

The main frame 15 has side plates 21 and 22, an overhead cross member 23, and projecting brackets 23A. A number of main components of the apparatus are suspended from the side plates 21 and 22, the cross member 23 and the- brackets 23A, as will be described in more details with reference to Figures la, lb and lc. These components are two lower rollers 24 and 25, each constituting a first pressure member for effecting removal of the lid 13 of the container 12; two upper rollers 26 and 27, each constituting a second pressure member for effecting replacement of the lid; two lower spring biased rams 28 and 29, each constituting a primary drive means for producing removal of the lid; and two upper rams 30 and 31, each constituting primary drive means for producing closure of the lid on the container. The cross member 23 also supports a further pneumatic ram 32, coupled to a suction cup 33 positioned centrally over the lid 13, constituting positioning means for positioning the lid during removal and replacement of the lid. Within the carriage 16 is a further stepper motor (not shown in Figure 1, but shown diagrammatically at 34 in Figure la). The stepper motor 34, and associated gearing, constitutes secondary drive means for producing rotation of the container 12 during removal, and replacement, of the lid.

There will now be described in more detail, the components of the apparatus, particularly with reference to Figures la, and lb, in addition to Figure 1.

Referring to Figure la, the suction cup 20 is mounted on a rotatable shaft 35 mounted in a bearing 36 and rotatable by gears 37 and 38 by the stepper motor 34. Suction is applied to the suction cup 20 from a suction pipe 39 leading through bores 40 and 41 in the bearing housing 36 and the shaft 35, respectively. The upper suction cup 33 is suspended from a rod 42 moveable vertically upwardly and downwardly by the ram 32 relative to the cross member 23, and is supplied with suction by suction pipe 43.

Referring to Figures la and lb, the upper rollers 26 and 27 are mounted respectively on pivot arms 44 and 45, and the lower rollers 24 and 25 are mounted respectively on pivot arms 46 and 47. The pivot arms 44 and 46 are mounted on the side plate 21 by pivot pins 48 and 49 respectively. The pivot arms 45 and 47 are correspondingly mounted on side plates 22 by pivot pins 50 and 51, shown in Figure 1. As shown in Figure lb, the pivot arm 44 is pivoted at one end at the pivot 48, and is biassed upwardly by a tension spring 52 secured to the side plate 21. The lower pivot arm 46 is pivoted at the pivot pin 49 at a point intermediate its length, and is pivoted downwardly by a tension spring 53, also secured to the side plate 21. The upper ram 30 has a piston extension 54 which bears on the distal end of the pivot arm 44, and is arranged to move the roller 26 downwardly upon application of pressurised air to the ram 30 along an air line 55. The lower pivoted arm 46 can be moved upwardly by downward movement of a piston extension 56 of the lower ram 28, bearing upon the end of the pivot arm 46 remote from the roller 24. The piston extension 56 is moved downwardly by application of air to

the ram 28 along air line 56. Release of air pressure in the lines 55 and 56, causes the rollers 26 and 24 to return to the rest positions shown in Figure lb, under the influence of the bias springs 52 and 53 respectively. Corresponding components are mounted on the side plate 22.

There will now be described the manner of operation of the apparatus. Starting from the stage shown in Figure 1, the suction cup 33 is lowered onto the lid 13 of the container 12 at the main work station, by the effect of air pressure at the ram 32. Suction is applied at the suction line 43 to the cup 33 which is securely fastened thereby to the lid 13. Next, the lower rollers 24 and 25 are raised by application of pressurised air to the rams 28 and 29 so that the rollers contact the underside of the outwardly projecting lip 10 of the lid 13. The upwardly rising rollers 24 and 25 break the seal between the lip 10 and the container 12, at two portions of the periphery of the lid 13, which are diametrically opposed across the lid. This stage is shown in Figure 2.

The next stage is that the container 12 is rotated, in a clockwise direction seen from above, by the stepper motor 34. The container is rotated by 360°; i.e. one complete revolution, with the result that the seal between the lip and the container is broken around the entire periphery of the container, and the lid comes free from the container.

The air pressure in the ram 32 is then released, and the suction cup 33 rises through operation of an internal bias spring in the ram 32, to lift the lid 13 free of the container. Next, the rollers 24 and 25 are raised by releasing the pressure in rams 28 and 29, and the carriage 16 is then moved to the left in Figures 1 and la to carry the opened container away from the work station, to reach the stage shown in Figure 3.

There will next be performed at a second work station an operation on the open container, which is not shown or described in detail, and which consists of planting plants into the container, as shown in Figure 3. After this operation, the carriage 16 is returned to the main work station and the stages of replacing the lid commence. Firstly, the piston 32 is activated so that the cup 33 carries the lid 13 downwardly onto the container 12. Next, the rams 30 and 31 are activated to carry the rollers 26 and 27 downwardly onto the top of the lip 10, to reach the stage shown in Figure 4. At this stage the lid 13 is coupled to the container 12, by the lip 10 being pushed onto the top of the container 12, at two diametrically opposed portions of the periphery of the container 12. The last stage, which follows that of Figure 4, is that the container 12 is rotated in a clockwise direction by 720°; i.e two complete revolutions, by the stepper motor 34. The effect of this is that the rollers 26 and 27 press the lip 10 over the top of the edge of the container 12, around the entire periphery of the container 12. The suction cup 33 is then released from the lid by release of the vacuum applied thereto, and the cup 33 is raised by the ram 32. Rollers 26 and 27 are then raised by release of pressure in rams 30 and 31. This brings the container to the same stage as was shown in Figure 1, except that of course the plants have been planted within the container. In typical subsequent steps, the carriage 16 will carry the filled container to a further work station, from which the container can be transferred to a growth area to allow growth of the plants.

Although theoretically the lid could be removed or resealed by rotation of only half a turn, or say by a few degrees more than 180°, (because of the presence of rollers on each side of the container), in practice, it is found that best results are obtained by an amount of rotation,

for lid removal, of 360°, and an amount of rotation, for lid resealing, of 720°, i.e. one or two complete revolutions respectively. Although it may be possible to remove the lid by rotating a few degrees more than 180°, if the container is not placed precisely on the centre of the lower suction cup 20, the lid and container will be misaligned, and the rollers may not operate completely throughout half a revolution. For example a 2mm radial misalignment would give 4mm misalignment after rotation through 180° which may make the rollers ineffective if only half a revolution is used. With regard to resealing, it is found that a lid will usually reseal satisfactorily following a single revolution, but it is preferred that two complete revolutions are used to ensure that the lid is fully sealed.

It is be appreciated that the stepper motor 18, carriage 16, rails 17, and rack 19, (which constitute a transfer means for moving the container) are arranged to give a precise movement of the container from the position below the suction cup 33 (which constitutes a first work station) to a further position, not shown, which constitutes a second work station, and precise return of the container to the first work station at a position which reinstates the container to its previous position in register with the lid which has been removed.

In the method previously described, the operation carried out at the second work station (not shown) consists of planting plants into the container. In another arrangement, the containers may be empty upon removal of the lid, and at the second work station agar gel may be dispensed into the empty container, and then plants added to the agar. However, in preferred arrangements the agar gel will already have been inserted into the containers, before they are stacked with lids in the stacker 11. Thus

in an overall method using the apparatus shown in Figure 1, a previous step which will have been carried out is the filling of agar gel into the containers. Conveniently this is carried out by arranging a nested stack of empty containers, which have been sterilised by irradiation when nested together. The containers are then separated and agar is inserted into each open topped container individually. After partial filling with agar, a lid is added to the container from a nested stack of lids which have been similarly irradiated when nested, for sterilisation. The completed, closed, sterilised containers, which are partially filled with agar gel, are then stacked in the manner shown in Figure 1, and can be transferred when required into the the stacker 11, to be opened and planted and resealed.

A further example of a step which can be carried out at the second work station is that the containers may each already contain plantlets growing in agar geJ . In such a case, after removal of a lid at the first work station, the container may be moved to the second work station, where further nutrient in the form a liquid may then be added to the gel. The lid may then be replaced as has been described.

As has been set out hereinbefore, the entire operation will normally be carried out, in micropropagation, within a sterile environment, with the apparatus operating on sterilised containers and lids. The plantlets will be planted in the agar in the opened containers by robotic end effectors (not shown) which will grasp plant and release the plantlets, all within the sterilised environment.