Device having a tool holder, a tool and a balance

The invention relates to a device that comprises a tool holder that can be adjusted in an x-axis, a y-axis which is perpendicular thereto, and a z-axis that is perpendicular both to the x-axis and the y-axis and that can be pivoted about the z-axis. A dispense head for solid material is mounted on the tool holder as the tool. Two scales are disposed on the dispense head for solid material, said scales weighing the material which is or is to be delivered by the dispense head for solid material. The inventive design with two scales directly mounted on the dispense head for solid material allows for weighing of the material without the dispense head for solid material or the material having to be placed on separate scales.

BACKGROUND OF THE INVENTION

The invention relates to a device having a tool holder, which can be displaced in an x direction and a z direction which is perpendicular to the x direction, and a tool in the form of a metering head, which is secured to the tool holder. A further aspect of the invention relates to weighing out a desired quantity of substance using a device of this type.

Devices of this type are used, inter alia, for automatically metering substances into a plurality of reaction vessels or test tubes which are arranged, for example, next to one another.

In a device which is known as Caco-2 Assay produced by Mettler Toledo Bohdan, Greifensee, Switzerland, there are two tool holders with different tools. The tool holders can be displaced in a horizontal x direction, a horizontal y direction which is perpendicular to the x direction, and a vertical z direction which is perpendicular to the x and y directions, and in this way can serve reaction vessels arranged next to one another under the control of software. One of the tools is designed for metering liquid as a metering head in the form of a four-needle head with four parallel hollow needles which can be spread apart. The other tool is a gripper for handling substance plates which have a multiplicity of recesses for holding substance. To weigh matter which can be handled by the device, there is a balance, on which, by way of example, a corresponding substance plate or a test tube is placed.

Although the two fixedly installed tools do make it possible to handle liquids and solids, they do not, for example, allow a solid to be metered directly into a reaction vessel. Moreover, there are two tool holders which have to be able to move independently of one another, in which context it must be ensured that they do not collide with one another. Finally, accurate weighing out of a defined quantity of substance is relatively complex.

DE 40 02 255 A1 has disclosed a fixedly mounted device for metering liquids by dispensing them from at least one metering valve connected to a liquid reservoir, which device has a main balance on which a vessel for holding liquid can be positioned. This main balance has a wide weighing range of, for example, several tons and therefore a relatively low accuracy of, for example, ±100 g. Between the metering valve and the liquid reservoir there is a buffer vessel, the weight of which can be determined by means of a precision balance and which can be sealed off with respect to the liquid reservoir in order to dispense small quantities of liquid from the metering valve. The precision balance can be used to determine the weight of the buffer vessel and the liquid which is present therein, according to the disclosure with an accuracy of, for example, ±0.1 g, and from this determination to determine the quantity of liquid which has been dispensed. The accuracy of the weight of the quantity of liquid dispensed is limited firstly by the fact that the buffer vessel is connected to the storage reservoir and the metering valve via flexible lines, which has an adverse effect on the measurement, and secondly by the fact that the liquid is not dispensed directly from the buffer vessel, but rather firstly passes via a line to the metering valve and is only dispensed by the latter. Moreover, the complex structure with storage vessel, buffer vessel and metering valve, which are connected via lines, in practice prevents the metering device from being of mobile design or being fitted to a robot arm or a linear axis system.

In view of the drawbacks of the devices of the prior art which have been described above, the invention is based on the object of providing a device which is intended to allow simplified weighing out of a desired quantity of substance.

SUMMARY OF THE INVENTION

The essence of the invention consists in the fact that, in a device having a tool holder, which can be displaced in an x direction and a z direction which is perpendicular to the x direction, and a tool in the form of a metering head, which is secured to the tool holder, a balance, by means of which substance or capsules which has/have been taken up or dispensed or is/are to be dispensed by the tool can be weighed, is arranged on the tool or on the tool holder.

The fact that a balance is arranged directly on the tool or on the tool holder allows a substance which has been taken up or dispensed or is to be dispensed, a substance capsule or another object to be weighed without the substance, the substance capsule or the other object or the tool for this purpose having to be placed onto a separate balance. This significantly simplifies the weighing operation and also means that the weighing is virtually location-independent within the range of action of the device and can even take place where, for technical reasons, it is difficult or impossible to position a balance, for example beneath a shaken reaction vessel.

The balance used may, for example, be a balance having at least a weighing range from 0 to 2 kg and an accuracy of 0.1 g. Balances of this type are available, for example, from Sartorius AG, 37070 Göttingen, Germany. However, it is preferable to use a more accurate balance with an accuracy of 0.1 mg.

Preferably, the substance or capsule(s) can be dispensed or taken up by a metering means which is also weighed by the balance. As a result, any substance which has remained attached to the metering means is always weighed as well and is not recorded as already having been metered in.

Advantageously, the metering head carries all the substance which is to be dispensed with it. Consequently, it does not have to be supplied, for example via flexible hoses, which would have an adverse effect on the weighing accuracy.

In an advantageous exemplary embodiment, the balance is arranged on the tool, and the tool can be detached from and refitted to the tool holder without screws having to be undone.

Preferably, the metering means is arranged on the balance in such a way that the metering means can be detached from and refitted to the balance without screws having to be undone, in particular by being lifted off and put back on. As a result, it is easy to use different types of metering means in order, for example, to meter liquids or solid substances in succession. The handling of the metering means may take place manually or automatically.

Advantageously, the metering means has a metering unit, which comprises a storage vessel, and a drive unit, it being possible for the metering unit to be removed from and refitted to the drive unit without screws having to be undone, in particular by being lifted off and put back on. As a result, it is possible to prepare different substances in a plurality of metering units and then to meter them successively using the same drive unit. The metering units can be handled manually or automatically.

In a variant embodiment which is advantageous for certain tools, the balance bears a vessel for temporarily holding substance which is to be dispensed, which vessel can be completely emptied, the vessel preferably being the concave part of a spoon which can be tilted in order to be completely emptied. This allows substance which is to be dispensed to be weighed accurately in a vessel, which then, depending on the results, is either emptied completely at the metering location, for example into a reaction vessel, i.e. the substance is definitively discharged, or is filled further or, in particular if an excessive quantity of substance has been measured, is emptied at a location other than the metering location and is then refilled.

Advantageously, in addition to the first balance arranged on the tool or on the tool holder, the device according to the invention also has a second balance, the second balance preferably bearing the vessel for temporarily holding substance which is to be dispensed and being used to measure the weight of substance to be dispensed which is being temporarily held, while the first balance can be used also to measure the weight of substance which has not yet been dispensed to the vessel for temporarily holding substance which is to be dispensed. This allows more accurate weight measurement, in particular of substance which is to be dispensed, with the aid of checking measurements carried out by the second balance.

In a preferred exemplary embodiment, the tool holder can rotate about the z direction. This in particular allows the tool to rotate through, for example, 90°, i.e. allows, by way of example, a multi-needle head having a plurality of hollow needles arranged next to one another to be used to meter substances, which may differ according to the hollow needle used, to vessels belonging to a matrix in rows, then allows the multi-needle head to be rotated through 90° and substances, which once again may differ according to the hollow needle used, to be metered to the vessels of the matrix in columns. It is thus possible for a different combination of substances to be metered to each vessel of the matrix in a simple way. Moreover, the rotation allows reaction vessels, starting-material bottles, etc. to be arranged over an area and not just on a straight line.

Preferably, the tool holder can additionally be displaced in a y direction, which is perpendicular to the x direction and the z direction. This enables reaction vessels, starting-material bottles, etc. to be arranged over a larger area.

In an advantageous variant embodiment, the tool is secured to the tool holder by means of magnets, in which case it is preferable, where there are two permanent magnets which attract one another, for one of the two permanent magnets to be arranged on the tool holder and the other of the two permanent magnets to be arranged on the tool, and for it to be possible for the action of the attraction between the two permanent magnets to be cancelled out by means of at least one electromagnet. Connecting tool and tool holder by means of magnets allows automatic securing of the tool to the tool holder, for example by the tool holder being guided over the tool and then lowered onto it or the tool holder being moved laterally onto the tool. Detaching the tool from the tool holder by activating the at least one electromagnet by means of current pulses also contributes to enabling the tool change to take place automatically.

In alternative advantageous variant embodiments, the tool is secured to the tool holder by screw connection, by means of a bayonet connection or by means of a clamping connection, etc. Although these methods of securing are normally more complex to implement, they are relatively simple to automate, in particular if the tool holder can be rotated about the z direction.

Preferably, the tool is a screw metering head, which comprises a screw which can rotate forward and backward about the z direction in a tube which is at least partially open at its lower end and which can be used to take up and dispense substance. A screw metering head of this type can be used for targeted removal of pulverulent or liquid substance from a storage vessel and also for targeted dispensing of this substance.

Advantageously, the lower open end of the tube can be closed off by a diaphragm provided with holes, and there is preferably a ram, which runs on the screw and presses substance through the diaphragm as the screw rotates when substance is being dispensed, arranged in the tube. The use of a diaphragm leads to more uniform dispensing of substance, since the substance is forced uniformly through the holes in the diaphragm. This in turn has the advantage that metering can be carried out more accurately.

Preferably, at the diaphragm there is a stripper which periodically strips off any substance adhering to the diaphragm. This allows more accurate metering.

Advantageously, the tool is a capsule-transporting head, by means of which a capsule can be picked up and released, preferably by suction. A tool of this type makes it possible to transport substances in capsules or similar containers.

Preferably, the tool is a matrix-capsule-transporting head, by means of which capsules which are arranged in the manner of a matrix can be picked up, preferably by suction, and the capsules can be released individually, together or in groups. The matrix-capsule-transporting head also makes it possible to transport substances in capsules, it being possible for a large number of capsules which are arranged in matrix form to be handled at the same time.

Advantageously, the tool is a capsule-handling head, by means of which at least one capsule can be picked up, which capsule can be opened in the tool, preferably by means of a hollow needle, and in which tool the contents of the capsule can preferably be mixed with another substance, in particular a solvent. The mixing can be effected, for example, by adding solvent to the capsule, sucking up substance and solvent from the capsule and returning the material which has been sucked up into the capsule. Alternatively, the hollow needle can also be used to suck substance out of the capsule and dispense it again at another location. The capsule-handling head according to the invention makes it possible to prepare even more successfully for chemical reactions outside a reaction vessel.

In a preferred variant embodiment, the tool is a matrix-capsule-handling head, by means of which a plurality of capsules which are arranged in the form of a matrix can be picked up, which capsules can be opened in the tool, preferably using hollow needles, and in which tool the contents of one capsule can preferably in each case be mixed with another substance, in particular a solvent. The mixing can be effected, for example, by adding solvent to the capsule, sucking up substance and solvent from the capsule and returning the material which has been sucked up into the capsule. Alternatively, the hollow needle can also be used to suck substance out of the capsule and dispense it again at another location. The matrix-capsule-handling head also makes it possible to handle substances in capsules and to prepare for chemical reactions, it being possible for a multiplicity of capsules which are arranged in the form of a matrix to be picked up and processed simultaneously.

In another preferred variant embodiment, the tool is a capsule-dispensing head, in which a multiplicity of capsules are stored and can be dispensed individually, together or in groups, it preferably being possible for the capsules to be opened in the capsule-dispensing head, and it even more preferably being possible for the contents of the capsules to be mixed with another substance, in particular a solvent, in the capsule-dispensing head. The capsule-dispensing head according to the invention makes it possible to prepare for chemical reactions largely outside a reaction vessel and means that the appropriate capsules or the contents thereof simply have to be added to the reaction vessel in order to carry out these chemical reactions.

Advantageously, the tool is a needle head with a hollow needle, a multi-needle head with a plurality of hollow needles, which can preferably be displaced individually in the z direction and/or the distance between which can preferably be adjusted, or a solids-metering head.

Advantageously, the tool is a combination head having at least two identical or different tool parts, one of the tool parts preferably being a needle head, multi-needle head, capsule-transporting head, matrix-capsule-transporting head, capsule-handling head, matrix-capsule-handling head, capsule-dispensing head, screw metering head or solids-metering head. This allows a plurality of method steps to be carried out in succession or simultaneously using a single tool.

Advantageously, the device according to the invention has a camera, which is preferably arranged on the tool holder and which can be used to film an area below the tool holder, as well as a control computer having an image-processing unit, which evaluates images which have been filmed by the camera, it being possible for the displacement of the tool holder and, if necessary, a change of tool to be controlled preferably on the basis of the evaluation result.

In an advantageous variant embodiment, the device according to the invention has an infrared analysis unit, which is preferably arranged on the tool holder and has an infrared transmitter, by means of which infrared waves can be radiated into an area below the tool holder, and an infrared sensor, which can be used to measure reflected infrared waves, as well as a control computer having a measured-value-processing unit, which evaluates the reflected infrared waves measured by the infrared sensor, it preferably being possible for the displacement of the tool holder and, if necessary, a change of tool and/or the quantity of substance to be metered to be controlled on the basis of the evaluation result. The precise way in which an infrared analysis unit of this type functions is described, for example, in U.S. Pat. No. 6,031,233, which is hereby specifically incorporated by reference in the present description.

The camera or the infrared analysis unit, together with the control computer, allows the device to operate completely automatically without an operator having to evaluate the substance or capsule to be handled and then actively control the displacement of the tool holder and/or any change of tool which may be required.

In an advantageous variant embodiment, the device according to the invention comprises a further tool holder for attachment of a further tool which can be displaced in an x direction and in a z direction which is perpendicular to the x direction, it preferably additionally being able to rotate about the z direction and/or to be displaced in a y direction which is perpendicular to the x direction and to the z direction. The second tool holder may be designed and controlled in the same way as the first. With two or even more tool holders with tools attached to them, it is possible to multiply the speed of the device; at the control, it must be ensured that the various tool holders and tools do not impede one another.

A method according to the invention for weighing out a desired quantity of substance using a device having a tool holder, which can be displaced in an x direction and a z direction which is perpendicular to the x direction, and a tool in the form of a metering head, which is secured to the tool holder, and a balance arranged on the tool or on the tool holder, by means of which substance which has been taken up by the tool can be weighed, is characterized by the steps thata) substance is taken up by the tool;b) the substance is weighed;c) the difference between the weighed value obtained and the desired set value is calculated; andd) if the difference lies outside the range of a desired level of accuracy, the tool is used to discharge substance or take up additional substance depending on this difference;
steps b) to d) being repeated until the difference is equal to zero within the range of a desired level of accuracy.

A similar method according to the invention for dispensing a desired quantity of substance using a device having a tool holder, which can be displaced in an x direction and a z direction which is perpendicular to the x direction, and a tool in the form of a metering head, which is secured to the tool holder, and a balance which is arranged on the tool or on the tool holder and can be used to weigh substance which is to be dispensed from the tool, the balance bearing a vessel for temporarily holding substance which is to be dispensed, which can be completely emptied, is characterized by the steps thata) a quantity of substance is placed into the vessel for temporarily holding substance which is to be dispensed;b) the substance in the vessel is weighed;c) the difference between the weighed value obtained and the desired set value is calculated; andd) if the difference lies outside the range of a desired level of accuracy, additional substance is added to the vessel or the vessel is at least partially emptied at a location other than an intended metering location and then substance is added to it again, depending on this difference;
steps b) to d) being repeated until the difference is equal to zero within the range of a desired level of accuracy, after which the substance which is present in the vessel is dispensed by the vessel being completely emptied.

A further similar method according to the invention for selecting a capsule with a desired quantity of substance using a device having a tool holder, which can be displaced in an x direction and a z direction which is perpendicular to the x direction, and a tool in the form of a metering head, which is secured to the tool holder, and a balance which is arranged on the tool or on the tool holder and can be used to weigh capsules which have been picked up by the tool, is characterized by the steps thata) the tool is used to pick up a capsule containing substance;b) the capsule with substance is weighed;c) the difference between the weighed value obtained and the desired set value is calculated; andd) if the difference lies outside the range of a desired level of accuracy, the capsule is released again from the tool and a new capsule containing substance is picked up;
steps b) to d) being repeated until the difference is equal to zero within the range of a desired level of accuracy.

These three weighing methods which operate in accordance with the test principle make it easy to weigh out a desired quantity of substance or a desired object with the desired level of accuracy at any desired location within the area of action of the device. Moreover, for example when substance is being dispensed into, for example, a reaction vessel, a test tube, a substance plate, etc., it is possible for the weight of the quantity of substance which has effectively been dispensed to be measured again. This has two important advantages: 1) Monitoring and more accurate determination of the effective value. 2) If, for example, small quantities of substance remain attached to the tool, this is determined and can be corrected, for example by vibration or topping up the metering.

DESCRIPTION OF PREFERRED EMBODIMENTS

A linear axis system for holding and displacing a tool holder1comprises two guide rails6,61, which run parallel to one another in the y direction and are anchored in a fixed position in a manner which is not illustrated. The first ends of the two guide rails6,61are connected by a rotary rod7, which can be rotated by means of a stepper motor71. An upper running rail5is secured to the two guide rails6,61in such a manner that it can be displaced in the y direction. The upper running rail5is fixedly connected to a lower running rail51by means of two end plates52,53. As a result of the rotary rod7being rotated by means of the stepper motor71, in each case one toothed belt in the interior of the guide rails6,61is driven, causing the running rails5,51to be displaced in the y direction. In the present context, the term displacement in the y direction is to be understood as meaning both a displacement in the +y direction and in the −y direction (the opposite direction).

A carriage4is secured to the two running rails5,51in such a manner that it can be moved in the x direction. In the present context, the term movement in the x direction is once again to be understood as meaning both a movement in the +x direction and in the −x direction (the opposite direction). The carriage4is driven by a stepper motor54via a toothed belt arranged in the hollow upper guide rail5.

A tool rod3is secured to the carriage4in such a manner that it can move in the z direction. In the present context, the term movement in the z direction is once again to be understood as meaning both a movement in the +z direction and in the −z direction (the opposite direction). In order for the tool rod3to be displaced, a stepper motor31is attached to it via a hollow plate32, and a toothed belt is arranged in the hollow plate32and the tool rod3.

At the lower end of the tool rod3there is a rotary drive2, to which the tool holder1is secured. The tool holder1can be rotated both ways about the z direction, as indicated by the arrow c, with the aid of a rotary motor21. In order to secure a tool, the tool holder1substantially consists of a permanent magnet, in which an electromagnet is arranged.

A camera10, which is directed downward in the z direction and can be used to film an area below the tool holder1, is attached to the tool holder1. The images which are filmed by the camera10are transmitted via a data line to an image-processing unit of a control computer11, which evaluates these images. The control computer11can then control the displacement of the tool holder1in the x, y, z and c directions by means of the motors54,71,31and21and the selection, securing or release of a tool on the basis of the evaluation results.

The following consideration applies to the whole of the remainder of the description. If a figure includes reference symbols which are provided for the purpose of clarity of the drawing but these reference symbols are not mentioned in the immediately associated text of the description, or vice versa, reference is made to the corresponding explanations given in preceding descriptions of figures.

In this case, a needle head100is removably secured as the tool to the holder1by means of a permanent magnet101. The permanent magnet101of the needle head100and the permanent magnet of the tool holder1attract one another, so that when the needle head100is removed it can be secured to the tool holder1by being placed onto the latter, an operation which can be performed automatically, i.e. the needle head100does not have to be attached to the tool holder1manually. The needle head100is detached from the tool holder1by means of the electromagnet which is arranged in the tool holder1, cannot be seen and, when it receives a current pulse, cancels out the action of the attraction between the permanent magnet101of the needle head100and the permanent magnet of the tool holder1.

A linear drive103is attached to the permanent magnet101via a plate102. A hollow needle105is secured to the outer cylinder of the linear drive103by means of two holding parts104, which are provided with continuous receiving holes for the hollow needle105. With the aid of the linear drive103, the hollow needle105can be displaced in the z direction.

A hollow needle105of this type can be used, for example, to meter or remove liquid substances into or from reaction vessels. In particular, for this purpose a suction and/or blowing means can be connected to the top end of the hollow needle105.

Unlike inFIG. 1, a balance9, which can be used to measure the total weight of the tool holder1, the needle head100and the substance which is present in the hollow needle105, is additionally arranged on the tool holder1below the rotary drive2. If the weight of the tool holder1and the needle head100is subtracted from this total weight, the result is the weight of the substance which is present in the hollow needle105. The weight of substance which has been taken up or dispensed can be determined by differential measurements.

The tool is in this case formed by a needle head120with four hollow needles125, which can be individually displaced in the z direction and the distance between which can be adjusted from a minimum distance aminto a maximum distance amax, the distance between each pair of adjacent hollow needles125always being identical. To this end, the hollow needles125are each secured to the outer cylinder of a linear drive123by means of two holding parts124which are provided with continuous hollow-needle receiving holes. The linear drives123which can be used to displace the hollow needles125individually in the z direction are for their part in each case attached to an associated plate122. The four plates122are arranged movably in two grooves in a permanent magnet121, the drive for this purpose being effected by means of two spindles which are driven by a motor and are located inside the permanent magnet121. The needle head120, as described in connection withFIG. 2, is connected to the tool holder1via the permanent magnet121. Once again, the needle head120is detached from the tool holder1by means of the electromagnet (not visible) arranged in the tool holder1.

A needle head120of this type can be used, for example, to meter liquid to or remove liquid from a plurality of reaction vessels simultaneously. In particular, suction and/or blowing devices can be connected to the top end of the hollow needles125for this purpose.

Unlike inFIG. 1, a balance9, which can be used to measure the total weight of the tool holder1, the needle head120and the substance which is present in the hollow needles125, is additionally arranged on the tool holder1below the rotary drive2. If the weight of the tool holder1and of the needle head120is subtracted from this total weight, the result is the weight of the substances which are present in the hollow needles125. The weight of substances which have been taken up or dispensed can be determined by means of differential measurements.

The tool is in this case formed by a capsule-transporting head140, by means of which a tightly closed capsule150, which is in the form of a small tube and contains a pulverulent substance151, can be picked up by suction. The capsule-transporting head140comprises a permanent magnet141, by means of which, as described in a corresponding way in connection withFIG. 2, it is connected to the tool holder1. It can be released by means of the electromagnet arranged in the tool holder1. A suction tube143having a capsule-holding end piece144is attached to the permanent magnet141via a balance145and an intermediate part142. A reduced pressure can be generated in the suction tube143by means of a conventional suction means (not shown).

To pick up a capsule150, the capsule-transporting head140is moved such that the capsule-holding end piece144is above the top end of the capsule150, and then the capsule150is picked up as a result of a reduced pressure being generated in the suction tube143, as illustrated inFIG. 6. Then, the capsule150is transported by the linear axis system to the intended location, inFIG. 7a reaction vessel171arranged in a matrix170, where it is released into the reaction vessel171as a result of the reduced pressure in the suction tube143being eliminated.

The balance145can be used to measure the total weight of the intermediate part142, the suction tube143with the capsule-holding end piece144and the capsule150filled with substance151which it has picked up. If the weight of the intermediate part142and the suction tube143with the capsule-holding end piece144are subtracted from this total weight, the result is the weight of the capsule150filled with substance151. The weight of the substance151in the capsule150can be determined by differential measurements using an empty capsule150.

The tool is in this case formed by a matrix-capsule-transporting head160which comprises a permanent magnet161, by means of which, as has been described in a corresponding way in connection withFIG. 2, it is connected to the tool holder1. It is released by means of the electromagnet arranged in the tool holder1. Sixteen suction tubes163, which are arranged in the form of a matrix and each have a capsule-holding end piece164, are attached to the permanent magnet161via a balance165and a suction-tube plate162. A reduced pressure can be generated in the suction tubes163via the suction-tube plate162by means of a conventional suction means (not shown).

To pick up capsules150, the matrix-capsule-transporting head160is moved such that the capsule-holding end pieces164are above the top ends of the capsules150, and then the capsules150are picked up as a result of a reduced pressure being generated in the suction tubes163. Then, the capsules150are transported by the linear axis system to the intended location, in this case reaction vessels171arranged in a matrix170, where the capsules150are dispensed into the reaction vessels171as a result of the reduced pressure in the suction tubes163being eliminated.

The balance165can be used to measure the total weight of the suction tube plate162, the suction tubes163with the capsule-holding end piece164and the capsules150filled with substances which they have picked up. If the weight of the suction tube plate162and the suction tubes163with the capsule-holding end pieces164is subtracted from this total weight, the result is the weight of the capsules150filled with substances. The weight of the substances in the capsules150can be determined by differential measurements using empty capsules150.

In this case, the tool is formed by a capsule-handling head220, which comprises a cylindrical housing221which is divided into two compartments223and224by a partition222and is closed off at the top by an end wall227. At the open end of the bottom compartment223, in the cylindrical housing221, there is an air-filled sleeve225, for example made from rubber, which in the unladen state as shown inFIG. 9has an internal diameter dmin. In the upper compartment224there is a plunger226, to which a plunger rod228, which projects out through the end wall227and is provided at its top end with an outer push-button229, is attached. Between the plunger226and the cylindrical housing221and between the plunger rod228and the end wall227there is in each case an annular seal230,231. Between the plunger226and the partition222there is a coil spring232, which in the unladen state holds the plunger226in the position shown inFIG. 9. Between the plunger226and the end wall227there is an air-filled space233, which is in communication with the interior of the sleeve225via an air line234.

In addition, the capsule-handling head220comprises a hollow needle235, to which an inner push-button236is attached. The inner push-button236is mounted movably in a recess237in the outer push-button229, a coil spring238being arranged in the recess237below the inner push-button236, which coil spring238, in the unladen state, holds the inner push-button236and the hollow needle235in the position shown inFIG. 9. The hollow needle235passes through the plunger rod228, the plunger226and the partition222. It is in communication with the internally hollow inner push-button236, which can be fed, for example, with a solvent or another liquid via a feed line239.

FIG. 10shows the capsule-handling head220after it has picked up a capsule150, an operation which can be effected by placing the capsule-handling head220onto the capsule150. The capsule150is held by the sleeve225, which now has an internal diameter d which corresponds to the external diameter of the capsule150and is greater than the internal diameter dminin the stress-free state.

FIG. 10also illustrates that the capsule-handling head220comprises a balance241and a permanent magnet240, via which, as described in a corresponding way in connection withFIG. 2, it is connected to the tool holder1. The capsule-handling head220is detached from the tool holder1by means of the electromagnet arranged in the tool holder1. Moreover, the figure diagrammatically indicates that the inner push-button236can be actuated by a rotary lever242and the outer push-button229can be actuated by a rotary lever244, the two rotary levers242,244being articulatedly mounted on a rod243, which is secured to the balance241by means of a bearing part245, in such a manner that they can rotate in the direction indicated by the arrows. The drives for the two rotary levers242,244, which are controlled by the control computer, are not shown.FIGS. 9,11and12do not show the permanent magnet240, the balance241, the two rotary levers242,244, the rod243, the bearing part245and the tool holder1, for reasons of clarity.

The balance241can be used to measure the total weight of the capsule150which has been picked up by the capsule-handling head220and is filled with substance and of the capsule-handling head220with the exception of the permanent magnet240and the balance241itself. If the weight of the capsule-handling head220with the exception of the permanent magnet240and the balance241is subtracted from this total weight, the result is the weight of the capsule150filled with substance. The weight of the substance in the capsule150can be determined by differential measurements using an empty capsule150.

The coil spring238is compressed as a result of the inner push-button236being pushed downward, and as a result the hollow needle235is forced into the capsule150, as illustrated inFIG. 11. As a result, the capsule150is opened and it can be supplied, via the hollow needle235, with a substance from the inner push-button236, which is fed via the feed line239. Alternatively, the feed line239could also be connected directly to the hollow needle235. The substance supplied, in particular a solvent, can be mixed with the substance which is already present in the capsule150, for example by the capsule-handling head220being shaken. If a sufficiently long hollow needle is used, the mixing could also be effected by the substances which are present in the capsule150being sucked up and discharged again a number of times.

If pressure is no longer being exerted on the inner push-button236, the coil spring238forces it back upward into the starting position.

In order for the capsule150to be released, the outer push-button229is pressed downward, as illustrated inFIG. 12. In the process, the plunger rod228and the plunger226are moved downward so as to compress the coil spring232, with the result that the size of the space233between the plunger226and the end wall227is increased greatly and a reduced pressure is generated therein. This reduced pressure causes air to be extracted from the interior of the sleeve225via the air line234, with the result that the internal diameter of the sleeve225is increased to a maximum value dmax, which is greater than the external diameter of the capsule150, so that the capsule150is no longer held by the sleeve225and drops downward under the force of gravity.

If pressure is no longer being exerted on the outer push-button239, the coil spring232forces it back upward into the starting position shown inFIG. 9.

The tool is in this case formed by a matrix-capsule-handling head250, which comprises a holding plate255which is removably connected to the tool holder1by means of a permanent magnet, in a manner which is not illustrated. The matrix-capsule-handling head250is detached from the tool holder1by means of the electromagnet which is arranged in the tool holder1and the power supply line8of which can be seen. Two rods252,253, which are fixedly connected to the holding plate255, extend upward in the z direction, i.e. vertically, from two diagonally opposite corner regions of the holding plate255. A release plate254, which can be displaced in the z direction and is guided by the rods252,253in two diagonally opposite corner regions, is arranged above the holding plate255. A trigger plate251located above the release plate254can likewise be displaced in the z direction and is guided by the two rods252,253. The vertical displacement of the release plate254and of the trigger plate251is effected by two motors (not shown), although in principle it could also be brought about manually.

Sixteen capsule-handling elements256are secured in the holding plate255. The capsule-handling elements256, which are only diagrammatically depicted in this figure, apart from the connecting part241and the permanent magnet240, are constructed in substantially the same way as the capsule-handling heads220shown inFIGS. 9 to 12and each comprise, in addition to a cylindrical housing221, an outer push-button229and an inner push-button236. The inner push-buttons236with the hollow needles attached to them can be actuated jointly as a result of the trigger plate251being lowered. The joint actuation of, the outer push-buttons229is effected as a result of the release plate254being lowered. The matrix-capsule-handling head250can be used to take hold of sixteen capsules150arranged in a matrix149together, to open each of them by means of a hollow needle235and if appropriate to mix the substances contained therein with other substances and release them again.

Unlike inFIG. 1, a balance9, which can be used to measure the total weight of the tool holder1, the matrix-capsule-handling head250and the capsules150, which have been picked up by it and are filled with substances, is additionally arranged on the tool holder1beneath the rotary drive2. If the weight of the tool holder1and of the matrix-capsule-handling head250is subtracted from this total weight, the result is the weight of the capsules150filled with substances. The weight of the substances in the capsules150can be determined by means of differential measurements using empty capsules.

The tool is in this case a first exemplary embodiment of a capsule-dispensing head280, which comprises a balance296and a permanent magnet295, by means of which, as has been described in a corresponding way in connection withFIG. 2, it is connected to the tool holder1. The removal of the capsule-dispensing head280from the tool holder1is effected by means of the electromagnet arranged in the tool holder1.

The capsule-dispensing head280comprises a substantially cylindrical housing281, the lower part of which narrows to form a neck282and in which a large number of capsules150, which each contain a substance151, are stored. One of the capsules150is held by an air-filled sleeve283, which is arranged in the neck282and is made, for example, from rubber. In a separate cylinder284there is a plunger285, to which a plunger rod286, which projects out through an end wall287of the cylinder284and is provided at its top end with a push-button288, is attached. Between the plunger285and the cylinder284and between the plunger rod286and the end wall287there is in each case an annular seal289,290. Between the plunger285and the base291of the cylinder284there is a coil spring292, which in the stress-free state holds the plunger285in the position illustrated. Between the plunger285and the end wall287there is an air-filled space293, which is in communication with the interior of the sleeve283via an air line294.

In order for the capsule150which is being held by the sleeve283to be released, the push-button288is pressed downward. In the process, the plunger rod286and the plunger285are moved downward so as to compress the coil spring292, with the result that the size of the space293between the plunger285and the end wall287is increased greatly and a reduced pressure is generated therein. This reduced pressure causes air to be extracted from the interior of the sleeve283via the air line294, with the result that the internal diameter of the sleeve283is increased to a value which is greater than the external diameter of the capsule150, so that the capsule150is no longer held by the sleeve283and drops downward under the force of gravity. At the same time, a second capsule150moves up to take the place of the first capsule150, it being important for the pressure on the push-button288to be released again sufficiently quickly, so that the coil spring292moves the plunger285back upward into the starting position, the size of the space293is reduced again and air is fed back to the sleeve283via the air line294sufficiently quickly for the capsule150to be gripped by the sleeve283.

Moreover, the figure diagrammatically indicates that the push-button288can be actuated by a rotary lever297, the rotary lever297being articulatedly mounted on a rod298in such a manner that it can rotate in the direction of the arrow, this rod in turn being secured to the balance296by means of a bearing part299. The drive of the rotary lever297, which is controlled by the control computer, is not illustrated.

The balance296can be used to measure the total weight of the capsules150which are present in the capsule-dispensing head280and are filled with substances and of the capsule-dispensing head280, with the exception of the permanent magnet295and the balance296itself. The weight of a capsule150filled with substance can be measured by measuring the weight difference before and after a capsule150has been dispensed. The weight of the substance in the capsule150can be determined by differential measurements using an empty capsule150.

The tool is in this case a second exemplary embodiment of a capsule-dispensing head300, which comprises a balance318and a permanent magnet317, by means of which, as has been described in a corresponding way in connection withFIG. 2, it is connected to the tool holder1. The removal of the capsule-dispensing head300from the tool holder1is effected by means of the electromagnet arranged in the tool holder1.

The capsule-dispensing head300comprises a substantially cylindrical housing301, which in its lower part narrows to form a neck302and in which a multiplicity of capsules150, which each contain a substance151, are stored. One of the capsules150is held by an air-filled sleeve303, which is arranged in the neck302and is made, for example, from rubber, while the other capsules150are arranged in the cylindrical housing301in a chamber part315which can rotate in the manner of a revolver as indicated by arrow E. In a separate cylinder304there is a plunger305, to which a plunger rod306, which projects out through an end wall307of the cylinder304and is provided at its top end with a push-button308, is attached. Between the plunger305and the cylinder304and between the plunger rod306and the end wall307there is in each case an annular seal309,310. Between the plunger305and the base311of the cylinder304there is a coil spring312, which in the stress-free state holds the plunger305in the position illustrated. Between the plunger305and the end wall307there is an air-filled space313, which is in communication with the interior of the sleeve303via an air line314.

In addition, the capsule-dispensing head300comprises a hollow needle316, which passes through the push-button308, the plunger rod306, the plunger305and the base311. As a result of the hollow needle316being forced downward, the capsule150which is located above the capsule which is held by the sleeve303can be punctured. If necessary, another substance, in particular a solvent, can be fed to the open capsule150via the hollow needle316.

In order for the capsule150which is being held by the sleeve303to be released, the push-button308is pushed downward. In the process, the plunger rod306and the plunger305are moved downward so as to compress the coil spring312, with the result that the size of the space313between the plunger305and the end wall307is increased greatly and a reduced pressure is generated therein. This reduced pressure causes air to be extracted from the interior of the sleeve303via the air line314, with the result that the internal diameter of the sleeve303is increased to a value which is greater than the external diameter of the capsule150, so that the capsule150is no longer held by the sleeve303and drops downward under the force of gravity. At the same time, the capsule located above this capsule150drops into the position which was occupied by the capsule150which has been released, it being important for the pressure on the push-button308to be released again sufficiently quickly, so that the coil spring312moves the plunger305back upward into the starting position, the size of the space313is reduced again and air is fed back to the sleeve303via the air line314sufficiently quickly for the next capsule150to be gripped by the sleeve303. Then, the chamber part315is rotated one step onward, so that a new capsule150moves into the position directly above the neck302. The rotation of the chamber part315may be effected externally, for example by hand, or may be triggered by the actuation of the push-button308. For this purpose, if necessary the cylindrical housing301has access openings.

Moreover, the figure diagrammatically indicates that the hollow needle316can be actuated by a rotary lever319and the push-button308can be actuated by a rotary lever322, the two rotary levers319,322being articulatedly mounted on a rod321, which is secured to the balance318by means of a bearing part323, in such a manner that they can rotate in the direction indicated by the arrows. The drives of the two rotary levers319,322, which are controlled by the control computer, are not shown.

A cuboidal housing, in which the capsules150are arranged in a plate which can be moved in the x direction and in the y direction, may also be provided instead of the cylindrical housing301and the chamber part315which can rotate in the manner of a revolver.

The balance318can be used to measure the total weight of the capsules150which are filled with substance and are present in the capsule-dispensing head300and of the capsule-dispensing head300with the exception of the permanent magnet317and the balance318itself. The weight of a capsule150filled with substance can be measured by measuring the weight difference before and after a capsule150has been dispensed. The weight of the substance in the capsule150can be determined by differential measurements using an empty capsule150.

The tool is in this case formed by a screw metering head320, which comprises a permanent magnet321, by means of which, as has been described in a corresponding way in connection withFIG. 2, it is connected to the tool holder1. The removal of the screw metering head320from the tool holder1is effected by means of the electromagnet arranged in the tool holder1.

A motor part326is attached to the permanent magnet321by means of a balance333and a connecting part322, and an open tube323, in which a screw324, which can rotate forward and backward about the z direction as indicated by arrow F, with screw shaft325is mounted at its bottom end. The screw324is anchored by means of the screw shaft325in such a manner that it can be rotated by a motor arranged in the motor part326and is stable in the z direction. Rotation of the screw324results in a ram327which runs on the screw moving up or down. The lower, open end of the tube323can be closed off by means of a diaphragm328which is provided with holes329and is secured to two pivot arms330,331which are mounted pivotably in a suspension332on the motor part326. InFIG. 16, the diaphragm328has been removed from the open end of the tube323and can be moved into the closed position illustrated inFIG. 17by being pivoted in the direction indicated by arrow I.

To take up substance, the open end of the tube323is moved onto the substance with the diaphragm328in its pivoted-away position. Rotation of the screw324in the direction which moves the ram327upward causes substance to be carried upward directly by the screw324.

To dispense substance, the diaphragm328is pivoted under the screw324to cover the open end of the tube323. Then, the screw324is rotated in the direction which moves the ram327downward, with the result that substance is forced out downward through the holes329in the diaphragm328on the one hand directly by the screw324and on the other hand by means of the ram327. A stripper334, in the shape of a U-shaped wire, part of which bears against the underside of the diaphragm328, is, like the two pivot arms330,331, mounted pivotably on the suspension332. Pivoting the stripper334in the direction indicated by the arrow K ensures that any substance which has remained attached to the bottom of the diaphragm328is periodically stripped off, allowing more accurate metering.

The diaphragm328is responsible for continuous delivery of substance, but in principle metering is also possible without a diaphragm328.

The balance333can be used to measure the total weight of the substance which has been taken up by the screw324and of the screw metering head320with the exception of the permanent magnet321and the balance333itself. If the weight of the screw metering head320with the exception of the permanent magnet321and the balance333itself is subtracted from this total weight, the result is the weight of the substance which has been taken up. The weight of substance which has been additionally taken up or dispensed can be determined by differential measurements.

The tool is in this case formed by a solids-metering head350, which comprises a permanent magnet351, by means of which, as has been described correspondingly in connection withFIG. 2, it is connected to the tool holder1. The removal of the solids-metering head350from the tool holder1is effected by means of the electromagnet arranged in the tool holder1.

On the permanent magnet351there is a bearing part352, on which a carriage353is mounted in such a manner that it can move in the z direction. A holding plate354has been pushed laterally into the carriage353and has attached to it a metering housing355, the internal diameter of which decreases in steps toward the bottom and which has an intermediate base371with a conical metering opening which tapers upward. The holding plate354with the metering housing355can be detached from the carriage353by means of a horizontal movement involving little force.

A rotating metering shaft357, which drives a stripper356and can be displaced in the z direction, runs in the z direction centrally through the metering housing355and the conical metering opening in the intermediate base371. At the lower end of the metering shaft357there is a closure cone372which tapers upward and partially or completely closes off the conical metering opening in the intermediate base371depending on the z position, substance which flows downward when the metering opening is partially open being fed to the stripper356.

The rotating metering shaft357is fixedly connected to a co-rotating bearing part368, projects from below into a shaft359driven by a motor360and is rotated with the shaft359. A rotating stripper358which is arranged in the upper part of the metering housing355runs through the bearing part368and likewise projects into the shaft359from below. The stripper358can move in the z direction in the bearing part368and is driven, together with the metering shaft357, by the shaft359.

The displacement of the metering shaft357in the z direction is brought about by two electromagnets362and363, which are mounted on the holding plate354and bear a cover plate366via two support parts364,365. The cover plate366is connected to the bearing part368fixedly in the z direction, a ball bearing361enabling the bearing part368to rotate on the rotationally fixed cover plate366. On activation, the electromagnets362,363generate a force in the z direction and raise or lower the cover plate366and as a result the bearing part368and the metering shaft357.

The motor360and the electromagnets362,363are controlled by a control part367, which is arranged laterally on the bearing part352and to which the motor360is secured.

Moreover, a balance369with a minimum weighing range from 0 to 2 kg and an accuracy of 0.1 g, which is in contact with the carriage353via a pin370, is attached to the bearing part352. Balances of this type are commercially available, for example from Sartorius AG, 37070 Göttingen, Germany. However, it is preferable to use a more accurate balance with an accuracy of 0.1 mg.

If substance which is stored in the metering housing355is dispensed via the conical metering opening in the intermediate base371, the weight load applied to the carriage353is reduced and the carriage353is pulled downward less strongly, a fact which is measured by the balance369via the pin370.

A second balance374is secured to the control part367by means of a connecting part373. The balance374bears, via a rotary axle376extending in the z direction, a tiltable spoon375, the concave part of which is located vertically below the metering housing355.

Substance which has been dispensed by the metering housing355firstly drops into the concave part of the spoon375, so that its weight can be measured there by means of the balance374. If the measured weight corresponds to a quantity of substance which, by way of example, is to be metered to a reaction vessel, the substance is added to the reaction vessel as a result of the spoon375being tilted through 180° as indicated by arrow G. If the weight corresponds to a quantity of substance which is smaller than the quantity desired, either first of all the quantity of substance which is present is added to the reaction vessel as a result of the spoon375being tilted, and then the spoon375is rotated back into the receiving position and the differential quantity which is still missing is weighed out in a second step, and finally this quantity is added to the reaction vessel, once again as a result of the spoon375being tilted, or, as an alternative, more substance is fed direct to the concave part of the spoon375until the desired quantity is reached. On the other hand, if the measured weight corresponds to a quantity of substance which is greater than the desired quantity, either the concave part is, as a result of rotation of the rotary axle376and therefore of the spoon375attached to it in the direction of arrow H, rotated away, emptied, rotated back under the metering housing355and refilled with substance, or, as an alternative, the entire solids-metering head350is displaced over the tool holder1, the concave part is emptied, is guided back under the metering housing355as a result of displacement of the solids-metering head350and is refilled with substance.

The balances369and374can in each case either be used on their own or together in order to check one another, the balance374having the advantage of measuring a smaller total weight. In principle, however, it would also be possible for the rotary axle376to be mounted directly on the connecting part373and for it, together with the spoon375, to be controlled purely on the basis of the measurement results from the balance369.

As an alternative to the spoon375, by way of example a vessel, e.g. a funnel, which has a closable opening at the bottom, is also conceivable.

A solids-metering head of this type, but without magnet coupling to the tool holder1, without spoon375and without balances369and374arranged directly on the solids-metering head, is marketed by Auto Dose SA, CH-1228 Plan-les-Ouates.

In this exemplary embodiment, the tool is formed by a screw metering head420, which can be connected to a tool holder401, which is secured to the rotary drive2, by means of a bayonet connection. The bayonet connection comprises, on the tool holder side, an annular connecting part411with a connecting bolt412and, on the tool side, an annular connecting part421with a recess422for receiving the connecting bolt412. Moreover, on the tool side there is a mandrel424which is intended to engage in the annular connecting part411and stabilizes the bayonet connection.

Via eight contact locations413, which are distributed over the outer circumference, on the annular connecting part411on the tool holder side and eight contact locations423, which are distributed over the inner circumference, on the annular connecting part421on the tool side, the screw metering head420can be supplied with power via the annular connecting part411and data communication can take place. For its part, the annular connecting part411is connected via a cable414to the fixed part of the device.

The screw metering head420comprises a weighing unit with a housing425, in which the control electronics426and a balance427are arranged. It is preferable to use a balance with an accuracy of 0.1 mg. As can be seen fromFIG. 20, a bearing part428of the balance427projects out of the housing425. A metering unit430rests on the bearing part428via a drive unit440and in this way is weighed, together with the drive unit440, by the balance427.

To increase the weighing accuracy, a second balance, which measures the influence of any vibrations, which is then subtracted from the measurement result of the balance427, can be used in addition to the balance427.

A filling connection piece450is held removably beneath the metering unit430by a holder451which is fixedly connected to the housing425. The filling connection piece450does not touch the metering unit430and therefore does not have any adverse effect on the weighing operation. The fact that it is separate from the metering unit430means that the balance427is subjected to load from a lower weight, with the result that the weighing accuracy is increased. Moreover, the metering unit430and the filling connection piece450can be removed and stored separately from the drive unit440and the holder451, respectively.

Alternatively, it would also be possible to use a filling connection piece which is connected to the metering unit430, which would have the advantage that any residual substance which has remained in the filling connection piece would also be weighed.

The structure of the metering unit430can be seen fromFIGS. 21 and 22. The metering unit430comprises a storage vessel431, an extruder432having a screw part4322and a web part4321, a metering funnel433and a cover434which is provided with toothing. The screw part4322tapers from the top downward, i.e. away from the web part4321, with the result that when pulverulent substance is being metered, this substance does not clump together as it passes through the metering funnel433. The toothed cover434has an internal screw thread and is screwed onto a screw thread4311of the storage vessel431, the extruder432being clamped between cover434and storage vessel431. The clamping is effected by means of the web part4321, from which, moreover, strippers, which are not shown inFIG. 2, preferably extend toward the screw part4322. The metering funnel433is held rotatably between cover434and extruder432and has lugs4331which, when the metering unit430is inserted in the drive unit440, engage in recesses4411of a metering-unit receiving part441of the drive unit440.

The drive unit440also comprises a motor442which is secured to a printed-circuit board443provided with control electronics and actuates a transmission gearwheel444. The transmission gearwheel444engages through a gap in the metering-unit receiving part441in the toothed cover434of the metering unit430and rotates the toothed cover434together with the storage vessel431and the extruder432, while the metering funnel433is held in a fixed position by the lugs4331engaging in the recesses4411. The resultant relative movement between metering funnel433and extruder432causes substance to be conveyed out of the storage vessel431through the metering funnel433into the filling connection piece450.

The motor442is fed by two storage batteries445and446, which, by way of example, can be recharged by the charging means429which is shown inFIG. 19and is attached to the housing425. The charging device429is designed as a switch and is only in contact with the storage batteries445,446while they are being charged. During the weighing operation, the charging means429does not touch the storage batteries445,446, so that the weighing operation is not adversely affected.

Alternatively, the charging of the storage batteries445,446could also take place in a separate charging station which is separate from the screw metering head420, in which case the drive unit440, to this end, would simply have to be lifted off the bearing part428of the balance427and transported to the charging station.

The motor442is controlled by means of the printed-circuit board443, which for its part receives control signals from the control electronics426arranged in the weighing unit. The transmission of signals from the weighing unit to the printed-circuit board443is effected by means of light through an opening4251, which can be seen inFIG. 20, in the housing425, so that mechanical contact between weighing unit and drive unit440is avoided and the weighing operation is not adversely affected.

The screw metering head420can be modified in various ways. In particular, by way of example, the storage vessel431can be fixed in such a way that it does not also rotate during the metering operation. In this case, it is also preferable for a driver to extend into the storage vessel431from the rotating extruder432.

The metering may generally take place continuously, but periodic additions of substance and a weighing operation between the individual addition operations are also possible. Moreover, it is conceivable for the storage vessel431to be shaken during the metering operation, so that the pulverulent substance contained therein is loosened.

It is possible to execute further design variations on the devices according to the invention which have been described above. Express mention should also be made of the following at this point:In all the exemplary embodiments described, the balance or balances may be provided either on the tool or on the tool holder1. Arranging the balance on the tool holder1has the advantage that, in the event of a tool change, there is no need for each tool to have a balance. However, this solution means that the weight of the entire tool is always measured as well. By contrast, arranging the balance on the tool has the advantage that in each case a lower overall weight is measured. This tends to make the measurements more accurate.The connection between tool holder1and tool may also be formed in a different way than with magnets or bayonet connections. By way of example, screw connections or clamping connections are conceivable. However, it should be possible for the connection to be produced and released again automatically, i.e. not by hand.In addition to the tools described, it is also possible to use further tools which are equipped with a connection point to the tool holder and possibly a balance.