Test tube screw cap and cap gripper assembly with magnet

Abstract

Herein are detailed a cap driver (1) for a test tube screw cap (2), a test tube screw cap, and an assembly thereof, wherein the connection between cap driver and the screw cap is formed by a magnetic link.

Description

[0001] TITLE OF INVENTION

[0002] TEST TUBE SCREW CAP AND CAP GRIPPER ASSEMBLY WITH MAGNET

[0003] TECHNICAL FIELD

[0004] The present invention relates to improvements to test tube screw caps and cap grippers in the field of automatic capping and de-capping of test tube screw caps for improving automation thereof .

[0005] BACKGROUND

[0006] In the field of automatic capping and de-capping of test tube screw caps there are suggested improvements to the connecting process of test tube screw cap and cap gripper by incorporating a magnet in one of either and incorporating an iron or steel core or a complementary ordered magnet in the other, whereby improvements to the connectivity of test tube screw cap and cap driver are obtained and connection wear is minimi zed .

[0007] In automated capping and de-capping of screw threaded caps on test tube containers or bottles , wherein either, or both, of the test tube and the cap are made from plastics , it is a repeated problem to control the torque , which is applied to the screw cap during a capping operation such that the screw thread is not compromised by the forces exerted on the screw thread by cap and test tube during the capping and de-capping operations , while at the same time ascertaining that the cap after capping is suf ficiently tightened .

[0008] Also , since most test tubes are high volume non-reusable laboratory commodities and accordingly are industrially made in large quantities at high tolerance and low cost , typically by molding from low-cost plastic compositions .

[0009] However, standardi zation within the field of test tubes and within the field of standardi zed racks for holding standardi zed test tubes has signi ficantly advanced the use of automated capper-decapper devices in the laboratory . Today, the dominating standard for racks for biological and microbiological test tubes are the so-called SBS format racks in accordance with ANS I standard ANS I SLAS x-2004 , wherein x = 1 , 2 , . . 6 . Such SBS racks may contain, for example 96 test tubes in an array of 8 by 12 apertures designed to hold the tubes securely, but also arrays of 4x6 , 8x6 are in common use . The advantage for automation is that the test tube positions are predetermined by the standard and automation equipment can rely on these predetermined positions within manufacturing tolerance .

[0010] The present invention, while discussing general solutions to the problem of connecting cap drivers and test tube screw caps , in particular relates to the technical field of automated capping and de-capping of screw cap standard type test tubes for storing on a standardi zed test tube rack, such as e . g . , an SBS format test tube rack . Accordingly, in all embodiments of the present invention, screw caps for SBS- compliant test tubes are at the particular focus of the present invention .

[0011] While the advances to standardi zation have facilitated automation, the produced low-cost test tubes are often ill suited for repeated automated capping and de-capping without the test tube parts failing or breaking . However, multiple capping and de-capping operations are often necessary for completing complicated laboratory procedures without risking sample contamination between handling stations , leaving the test tubes formally single use , but not the screw cap parts , e . g . , the opposing screw threads on the test tube and the screw cap, or surfaces on the screw cap experiencing holding and / or ej ection wear originating with the automated capper- decapper device available in a given laboratory .

[0012] Contrary to this , the parts of the capper-decapper device in contact with the test tube screw caps , particularly cap gripper or screw cap ej ector means ( ej ector plates or ej ector pins ) are designed for reuse and consequently, while often manufactured from plastics , but sometimes also from metal such as aluminum or steel , are manufactured to last . This leads to a material strength mismatch between screw cap and cap driver and additional wear to the screw cap therefrom . E . g . , cap drivers in the art rely on being able to form a tight connection by friction to the screw caps for rotating the screw caps during capping or de-capping while at the same time holding the disconnected screw caps during removal of the test tubes from the capper-decapper device , pending subsequent screw cap ej ection from the cap grippers . To this end screw caps compliant with various laboratory standards have designated contact zones for cap gripper and screw caps . However, soft plastics screw cap having been treated to this contact with a harder material a number of times are known to fail , resulting in dropped screw caps or faulty reattached screw caps , thereby becoming a source for experiment failure . And the tight connection relies on correct alignment of screw cap and cap driver for being reali zed, which poses additional requirements on the construction of the capper- decapper devices known in the art . Accordingly, test tube screw cap failure has become a problem that cannot be overlooked in automated test tube screw cap capping and de-capping and the present invention is directed towards providing at least partial solutions for overcoming screw cap failure during automated test tube screw cap capping or de-capping in accordance with the herein detailed aspects and embodiments of the present invention .

[0013] To this purpose , the present inventors suggest decoupling the attachment of the cap gripper to the test tube screw cap from the coupling of the cap gripper to the same test tube screw cap for rotation of the screw cap . In the present disclosure this is done by providing a magnetic coupling pair between the screw cap and the cap gripper, as illustrated in the Figures in the form of a steel or iron core embedded in the screw caps and a magnet arranged in the cap gripper for engaging the aforesaid steel or iron core creating a magnetic coupling between the aforesaid screw cap and cap gripper when these are in contact . Thereby the magnetic link between screw cap and cap gripper holds the screw cap until ej ected, and the cap gripper no longer needs to rely on a close fit to the screw cap for holding the same screw cap during a capping or a de-capping operation .

[0014] In the art , solutions involving magnets and test tubes have been proposed for di f ferent purposes than herein discussed, e . g . , in US 5 , 027 , 966 disclosing storage containers with magnetic handling means , or in US 2011 / 0239791 where magnets in test tube caps are disclosed for cap retrieval in otherwise inaccessible locations , such as test tube caps dropped into liquid nitrogen, which become retrievable using common magnet sticks for collecting magnets from reaction beakers . This solution solves further problems of signi ficant importance in the art . E . g . , in a test tube rack where all test tubes to be tested ( e . g . , in high throughput screenings , where typically the maximum of 96 test tubes in an SBS-rack) are in need of simultaneous capping or de-capping, the problem the necessary for to create frictional connectivity is increased at least by the number of additional test tubes , but in fact increased signi ficantly more . The underlying reason being that the cap drivers must be designed for catching all test tube screw caps compliant with a given standard test tube screw cap speci fication, however acceptable si ze variation within between screw caps inside the speci fication forces the cap grippers in the art to be designed larger than needed on average in order to catch all screw caps in a test tube rack . And with larger si zes come increased requirements on the capper-decapper device holding the cap grippers to provide a compression force high enough to for all cap grippers into a holding contact with the screw caps , a force which is larger than the force average to be expected, making existing capper-decapper devices larger and bulkier for tabletop use than necessary . With the solutions detailed herein below, this problem has been overcome , as the cap drivers of the invention can now hold caps , even where there is no frictional contact , thus relaxing materials requirements on the capper-decapper devices and allowing these to be constructed with lowered footprints and space requirements ( always a scarcity in a laboratory) than conventional capper-decapper devices of the art .

[0015] SUMMARY OF THE INVENTION

[0016] In accordance with the invention, the above challenges can be overcome by the herein detailed aspects and embodiments of the present invention . In a first aspect and embodiment of the present invention (c.f. Figure 1) there is herein detailed a cap driver (1) for a test tube screw cap (2) , the cap driver (1) comprising a screw cap connection element (11) arranged for connecting along a common connection axis (51) to a complementary cap driver connection element (21) comprised on a test tube screw cap (2) , and sharing after connection at least one contact region (52a, 52b) permitting a rotation of the cap driver (1) to be transferred to a rotation of the screw cap (2) ; the cap driver (1) further comprising at least one ferromagnetic cap driver element (3) held by the cap driver (1) to expose at least a part (31) of the ferromagnetic cap driver element (3) in parallel to the common connection axis (51) away from the cap driver (1) in a direction towards a connected screw cap ( 2 ) .

[0017] In a second aspect (c.f. Figure 1) there is herein detailed a test tube screw cap (2) comprising a cap driver connection element (21) arranged for connecting along a common connection axis (51) to a complementary screw cap connection element (11) comprised on a cap driver (1) for a test tube screw cap (2) , and sharing after connection at least one contact region (52a, 52b) permitting a rotation of the cap driver (1) to be transferred to a rotation of the screw cap (2) ; the test tube screw cap (2) further comprising at least one ferromagnetic screw cap element (4) held by the test tube screw cap (2) to expose at least a part (41) of the ferromagnetic screw cap element (4) in parallel to the common connection axis (51) away from the test tube screw cap (2) in a direction towards a connected cap driver (1) . In a third aspect (c.f. Figure IB) , there is herein detailed an assembly (5) comprising a cap driver (1) according to the first aspect and embodiments thereof and a test tube screw cap (2) according to the second aspect and embodiments thereof; wherein the cap driver (1) and the test tube screw cap (2) are connected to each other via the complementary respective screw cap connection element (11) and cap driver connection element (21) such that the cap driver (1) and test tube screw cap (2) after connection share at least one contact region (52a, 52b) permitting a rotation of the cap driver (1) to be transferred to a rotation of the screw cap (2) ; wherein the cap driver (1) and the test tube screw cap (2) are respectively attached to each other via magnetic force between the ferromagnetic cap driver element (3) and the ferromagnetic screw cap element (4) ; and wherein at least one of the ferromagnetic cap driver element (3) and / or the ferromagnetic screw cap element (4) is a magnet.

[0018] BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1: Exemplary embodiment of a cap-driver screw cap assembly of the invention.

[0020] Figure 2: Exemplary embodiment of a cap-driver screw cap assembly of the invention.

[0021] It is to be understood, that the embodiments shown in the figures are for illustration of the present invention and cannot be construed as being limiting on the present invention. Unless otherwise indicated, the drawings are intended to be read (e.g., cross-hatching, arrangement of parts, proportion, degree, etc.) together with the specification, and are to be considered a portion of the entire written description of this disclosure. DETAILED DESCRIPTION

[0022] In Figure 1 there is depicted an exemplary cap driver (1) , an exemplary screw cap (2) and an exemplary assembly (5) of a cap driver (1) and a screw cap (2) in accordance with the general concept of the present disclosure.

[0023] In the art, the cap driver (1) comprises a screw cap attachment element (11) complementary to a cap driver attachment element (21) comprised in the screw cap (2) . However, in the present invention, the cap driver and screw cap no longer need to attach via their complementary attachment elements (11,21) but rather merely have to connect through complementary connection elements (11,21) to form at least one connection region (52a, 52b) suitable for transferring a rotation of the cap driver (1) into a rotation of the screw cap (2) , since in the invention connection and attachment of the two parts (1,2) have been decoupled such that attachment of the parts (1,2) now is mediated by magnetic force.

[0024] In the shown embodiment of Figure 1, the screw cap attachment element (11) is a tap, and the cap driver attachment element (21) is a receptacle for the tap, which (when the two parts are aligned along a common connection axis (51) ) , permit the tap to be received in the receptacle. The shown arrangement is merely for illustrative purposes and other attachment arrangements between cap driver and screw cap are well known in the art .

[0025] However, the solutions presented herein are independent of how cap driver (1) and screw cap (2) engage to form a connection for permitting a rotation of the cap driver (1) to be transferred to the screw cap (2) during any of a capping or a de-capping procedure of the screw cap (2) relative to the test tube to which it is intended for use. Consequently, the present disclosure details the present invention exemplary to the relative setup presented in Figure 1, wherein the cap driver (2) comprises a tap (11) for being received in an opposing receptacle (21) comprised in the screw cap (2) when tap (11) and receptacle (21) are aligned along a common connection axis (51) (grab-inside connection) , however the invention is equally useful when the screw cap forms the tap and the cap driver the receptacle (grab-around connection) .

[0026] When assembled (5) , the cap driver (1) and the screw cap (2) of the invention share at least one contact region (52) permitting the transfer of rotation from the cap driver (2) to the screw cap (2) . In the shown example two shared contact regions (52a, 52b) are present.

[0027] In the prior art assemblies of cap driver and screw cap, the contact regions are in fact overlap regions serving to maintain frictional connection between the cap driver and the screw cap such that the cap driver can hold a screw cap that has been detached from a test tube against gravity. An in high throughput automated procedures, statistical size variation in the screw caps and cap drivers cause regular dropping of held screw caps.

[0028] To minimize this and for properly connecting the at least one overlap region of the cap driver and the screw cap, it requires precise alignment of cap driver and screw cap during attachment of the cap driver to the screw cap. However, lab test tubes are seldom loaded into test tube racks with precision. Accordingly, in order to compensate for this lack of loading precision, additional functionalities are required to be comprised in the capper-decapper device, to which the cap driver is attached, to ascertain that cap drivers can align to all test tubes held in a test tube rack irrespective of the loading position of the test tube and consequently of the attached screw caps.

[0029] It is a benefit of the present invention that the at least one contact region (52) between cap driver (1) and screw cap (2) when assembled (5) is not required to be an overlap region but can merely be a contact region. However, the present invention is suitable also for conventional overlap region (52) test tube-cap gripper arrangements in the art and can be implemented into existing products with a minimum of modifications to existing equipment. However, following the present instructions, the problem of material wear to the at least one overlap region is at least strongly reduced, in fact often eliminated.

[0030] Accordingly, in a first aspect and embodiment of the present invention (c.f. Figure 1) there is herein detailed a cap driver (1) for a test tube screw cap (2) , the cap driver (1) comprising a screw cap connection element (11) arranged for connecting along a common connection axis (51) to a complementary cap driver connection element (21) comprised on a test tube screw cap (2) , and sharing after connection at least one contact region (52a, 52b) permitting a rotation of the cap driver (1) to be transferred to a rotation of the screw cap (2) ; the cap driver (1) further comprising at least one ferromagnetic cap driver element (3) held by the cap driver (1) to expose at least a part (31) of the ferromagnetic cap driver element (3) in parallel to the common connection axis (51) away from the cap driver (1) in a direction towards a connected screw cap (2) . In a second aspect and first embodiment thereof (c.f. Figure 1) there is herein detailed a test tube screw cap (2) comprising a cap driver connection element (21) arranged for connecting along a common connection axis (51) to a complementary screw cap connection element (11) comprised on a cap driver (1) for a test tube screw cap (2) , and sharing after connection at least one contact region (52a, 52b) permitting a rotation of the cap driver (1) to be transferred to a rotation of the screw cap (2) ; the test tube screw cap (2) further comprising at least one ferromagnetic screw cap element (4) held by the test tube screw cap (2) to expose at least a part (41) of the ferromagnetic screw cap element (4) in parallel to the common connection axis (51) away from the test tube screw cap (2) in a direction towards a connected cap driver ( 1 ) .

[0031] In a third aspect and first embodiment thereof (c.f. Figure IB) , there is herein detailed an assembly (5) comprising a cap driver (1) according to the first aspect and embodiments thereof and a test tube screw cap (2) according to the second aspect and embodiments thereof; wherein the cap driver (1) and the test tube screw cap (2) are connected to each other via the complementary respective screw cap connection element (11) and cap driver connection element (21) such that the cap driver (1) and test tube screw cap (2) after connection share at least one contact region (52a, 52b) permitting a rotation of the cap driver (1) to be transferred to a rotation of the screw cap (2) ; wherein the cap driver (1) and the test tube screw cap (2) are respectively attached to each other via magnetic force between the ferromagnetic cap driver element (3) and the ferromagnetic screw cap element (4) ; and wherein at least one of the ferromagnetic cap driver element (3) and / or the ferromagnetic screw cap element (4) is a magnet (3,4) . In a fourth aspect and first embodiment thereof, there is detailed a capper-decapper device comprising at least one cap driver (1) according to the first aspect and any embodiment thereof.

[0032] In a fifth aspect and first embodiment thereof, there is detailed an exchangeable cap-driver cartridge holding at least one cap driver (1) according to the first aspect and any embodiment thereof for use with a capper-decapper device in accordance with the fourth aspect and all embodiments thereof .

[0033] In a sixth aspect and first embodiment thereof, there is detailed a test tube for a screw cap comprising a test tube screw cap (2) in accordance with the second aspect and any embodiments thereof.

[0034] In a seventh aspect and first embodiment thereof, there is detailed a test tube rack comprising a test tube in accordance with the sixth aspect and any embodiments thereof. In an embodiment thereof, the test tube rack is an SBS- compliant test tube rack.

[0035] As discussed in relation to the assembly (5) of cap driver (1) and screw cap (2) , at least one of the ferromagnetic cap driver element (3) and / or the ferromagnetic screw cap element (4) must be a magnet. The other ferromagnetic element (3,4) can be any suitable magnet or magnetizable element, such as an iron core or in some cases an iron alloy, e.g., a magnetizable steel, or an iron alloy with cobalt and / or nickel for enhancing the magnetizability of the magnetizable ferromagnetic element (3,4) . Normally in the invention, it will always be the cap driver element (3) that constitutes the magnet, since this part will be reused as part of the cap driver (1) , whereas the test tube with the screw cap (2) is a laboratory dispensable, wherefore the additional cost of using a magnet in the screw cap (2) generally will not be merited. Further, since correct alignment of the magnet for optimal overlap of the magnetic fields is important, it is easier to align the magnet in the cap driver, e.g., by embedding the magnet (3) into a designated groove (12) at the tip of the cap driver (1) .

[0036] Rather, the ferromagnetic screw cap element (4) in almost all embodiments of the invention, that will see production and marketing will be a magnetizable ferromagnetic element such as an iron core or in some cases an iron alloy, e.g., a magnetizable steel, or an iron alloy with cobalt and / or nickel for enhancing the magnetizability of the magnetizable ferromagnetic element (3,4) . Contrary to this, due to the reusability of the cap driver (1) , the use of e.g., relatively expensive neodymium-based magnets can in some situations be merited and therefore, in the context of the present invention constitutes a preferred embodiment of the magnet (3) when comprised in the cap driver (1) .

[0037] In one preferred embodiment, the at least one magnet (3,4) can be an electromagnet. Again, due to the reusability of the cap driver (1) , it is preferable to magnetize the ferromagnetic cap driver element (3) , but due to the symmetry of the connection between the cap driver (1) and the screw cap (2) it is again not mandatory.

[0038] In a particularly preferred embodiment of the present invention (c.f. Figure 2) , the ferromagnetic screw cap element (4) is an iron or iron-alloy ball (such as magnetizable steel) , which are available in the market at a current prize suitable for inclusion in a cheap, mass- produced dispensable item, such as a laboratory test tube. The advantage of using a ball- or sphere-shaped item as the ferromagnetic screw cap element (4) over other shapes are several, noticeable that the ball-shape minimizes requirements on alignment of the ferromagnetic screw cap element (4) vis-a-vis the ferromagnetic cap driver element (3) and that further it is simple and well-known in the art of plastics molding to embed a metal sphere in the surface of a thermomolded plastics object at a predetermined position .

[0039] However, a ball- or sphere-shaped item as the ferromagnetic screw cap element (4) has additional benefits, when the ferromagnetic cap driver element (3) is a ring magnet (3) aligned perpendicular to the common axis of alignment (51) as the ball- or sphere-shaped ferromagnetic screw cap element (4) now can enter the open interior of the ring magnet (3) for improved overlap of the magnetic field of the ring magnet (3) with the ball- or sphere-shaped ferromagnetic screw cap element (4) . Additionally, when ejection of the screw cap (2) from the cap gripper (1) in a capper-decapper device is by use of an ejection pin, it is necessary to use a ringshaped ferromagnetic cap driver element (3) , such as a ringmagnet (3) , aligned perpendicular to the common axis of alignment (51) in order to allow passage of the ejector pin to the screw cap (2) .

[0040] A further benefit of using a ferromagnetic screw cap element (4) in relation to capper-decapper devices utilizing ejector pins is that the ejector pin now will encounter a hard metal object on the screw cap rather than softer plastics, which incidentally eliminates a problem of prior art ejector pin capper-decapper devices , wherein the force needed to ej ect the screw cap from the cap driver in some instances could cause the ej ector pin to penetrate the screw cap at the contact point with the ej ector pin (particularly, i f the screw cap had been ej ected a few times prior to failure of the part ) , but the present invention eliminates thi s problem in addition to the further benefits detailed herein .

[0041] CLOS ING COMMENTS

[0042] Although the present invention has been described in detail for purpose of illustration, it is understood that such detail is solely for that purpose , and variations can be made therein by those skilled in the art in practicing the claimed subj ect matter, from a study of the drawings , the disclosure , and the appended claims .

[0043] The term " comprising" as used in the claims does not exclude other elements or steps . The indefinite article "a" or "an" as used in the claims does not exclude a plurality . A single processor or other unit may ful fill the functions of several means recited in the claims . A reference sign used in a claim shall not be construed as limiting the scope .

Claims

CLAIMS1. A cap driver (1) for a test tube screw cap (2) , the cap driver (1) comprising a screw cap connection element (11) arranged for connecting along a common connection axis (51) to a complementary cap driver connection element (21) comprised on a test tube screw cap (2) , and sharing after connection at least one contact region (52a, 52b) permitting a rotation of the cap driver (1) to be transferred to a rotation of the screw cap (2) ; the cap driver (1) further comprising at least one ferromagnetic cap driver element (3) held by the cap driver (1) to expose at least a part (31) of the ferromagnetic cap driver element (3) in parallel to the common connection axis (51) away from the cap driver (1) in a direction towards a connected screw cap (2) .

2. A cap driver (1) for a test tube screw cap (2) in accordance with claim 1, wherein the ferromagnetic cap driver element (3) is a magnet, preferably a ring magnet.

3. A cap driver (1) for a test tube screw cap (2) in accordance with claim 1 or claim 2, wherein the ferromagnetic cap driver element (3) is an electromagnet.

4. A test tube screw cap (2) comprising a cap driver connection element (21) arranged for connecting along a common connection axis (51) to a complementary screw cap connection element (11) comprised on a cap driver (1) for a test tube screw cap (2) , and sharing after connection at least one contact region (52a, 52b) permitting a rotation of the cap driver (1) to be transferred to a rotation of the screw cap (2) ; the test tube screw cap (2) further comprising at least one ferromagnetic screw cap element (4) held by the test tubescrew cap (2) to expose at least a part (41) of the ferromagnetic screw cap element (4) in parallel to the common connection axis (51) away from the test tube screw cap (2) in a direction towards a connected cap driver (1) •5. A test tube screw cap (2) according to claim 4, wherein the ferromagnetic screw cap element (4) is ball- or sphere- shaped .

6. An assembly (5) comprising a cap driver (1) according to claim 1 to claim 3 and a test tube screw cap (2) according to claim 4 or claim 5; wherein the cap driver (1) and the test tube screw cap (2) are connected to each other via the complementary respective screw cap connection element (11) and cap driver connection element (21) such that the cap driver (1) and test tube screw cap (2) after connection share at least one contact region (52a, 52b) permitting a rotation of the cap driver (1) to be transferred to a rotation of the screw cap (2) ; wherein the cap driver (1) and the test tube screw cap (2) are respectively attached to each other via magnetic force between the ferromagnetic cap driver element (3) and the ferromagnetic screw cap element (4) ; and wherein at least one of the ferromagnetic cap driver element (3) and / or the ferromagnetic screw cap element (4) is a magnet.

7. A capper-decapper device comprising at least one cap driver (1) according to any of the claims 1 to 3.

8. An exchangeable cap-driver cartridge holding at least one cap driver (1) according to any of the claims 1 to 3 for use with a capper-decapper device according to claim 7.

9. A test tube for a screw cap comprising a test tube screw cap (2) according to either claim 4 or claim 5.

10. A test tube rack comprising a test tube according to claim 9, preferably an SBS-compliant test tube rack.

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