Apparatus for automatic plug removal and method therefor

An automatic plug removing apparatus has a conveying section and a plug removing section and, while a plurality of containers having test samples therein and sealed with plugs are being conveyed on a batch basis, the plugs are automatically removed from the containers. The plug removing section includes a member for holding a plurality of containers in an immovable state, a member for grasping the plugs provided to the containers and then removing the plugs from the containers, the grasping member being rockable and vertically movable by driving members, and partition plates insertable into gaps between the containers to provide isolated spaces for respective containers and prevent contamination between samples. A suction block may be added to suck the air in the vicinity of upper openings of the containers to eliminate a mist of samples floating thereabout.

BACKGROUND OF THE INVENTION
 The present invention relates to an apparatus for automatically removing
 sealing plugs, stoppers or caps (hereinafter referred to as plugs) from
 drawn blood tubes or test tubes (hereinafter referred to as containers) at
 the time of clinical or laboratory examination and also a method therefor.
 In the field of clinical examination, open drawn blood tubes and vacuum
 drawn blood tubes have been widely used as containers for materials to be
 tested or examined such as blood (hereinafter referred to as samples). A
 sample drawn and collected by a syringe is in general poured into an open
 drawn blood tube and kept therein being closed and sealed with a plug or
 cap. In this case, the tube (the container) does not have to keep the the
 sample in a vacuumed state, and the container and plug are usually made of
 plastic such as polyethylene or the like. A sample that must be kept in a
 vacuumed state is contained in a vacuum tube, and a rubber plug or the
 like is used in order to stably maintain the vacuumed state within the
 tube for a long time.
 In advance of removal of a plug from of a container for analysis, a
 collected sample needs to be put in a centrifuge to separate the
 components thereof. There have been automatic plug removing methods using
 apparatus as well as manual plug removal by a person's hands at work. For
 example, Japanese Laid-Open Patent Publication No.263558/1989 (Tokukaihei
 1-263558) discloses an automatic plug removing apparatus having a cap
 holding down member with a recess. In this apparatus, a cap provided on a
 drawn blood tube is fitted into the recess of the apparatus and the cap
 holding down member is actuated to apply a twist and the like to the cap
 in the recess so as to loosen the seal between the cap and the drawn blood
 tube and then the cap is removed from the tube.
 The centrifuging process and transportation prior to the plug removal
 usually cause samples to adhere to a plug on the container. Such sample
 adhering to the plug might scatter due to a shock at the time of removing
 the plug from the container or might drop down due to swinging, vibration
 or the like at the time of disposal. Such scatter or drops of the sample
 may inadvertently enter other containers and end up with contamination of
 samples in the other containers. As a result, correct analysis for the
 respective samples can not be obtained even if high-accuracy analysis is
 conducted. Such contamination causes a serious error in the results of
 clinical examination and the like, and therefore must be absolutely
 avoided.
 Manual plug removal by a person at work tends to cause injury, infection to
 the person due to the scatter of samples, and contamination of samples in
 other containers.
 In order to avoid scattering and splashing of samples, some of conventional
 automatic plug removing apparatus provide improved arrangements. For
 example, one gives a twist or a circular arc oscillating movement to a
 plug and then removes it from a container with a lighter force, or another
 reduces a plug removing speed just before a plug is removed away from a
 container. There is another apparatus which has a dish for receiving and
 collecting liquid drops from a plug in order to prevent inadvertent sample
 drops at the time of disposing the plug. However, these conventional
 apparatus fail to prevent samples from scattering or splashing completely.
 Especially when a plurality of containers are simultaneously put under the
 plug removing process on a batch basis, complete prevention of
 contamination cannot be obtained by the conventional apparatus.
 SUMMARY OF THE INVENTION
 It is an object of the present invention to provide an apparatus for
 automatically removing plugs from containers without contamination between
 samples in the containers and a method therefor.
 The apparatus of the present invention is an automatic plug removing
 apparatus having a conveying section and a plug removing section, in
 which, while a plurality of containers sealed with plugs are being
 conveyed on a batch basis, the plugs are automatically removed from the
 containers. The plug removing section includes a holding means for holding
 a plurality of containers with plugs in an immovable state, a grasping
 means for grasping the plugs provided to the containers and then removing
 them from the containers, driving means for rocking and vertically moving
 the plug grasping means, and partition plates which are insertable into
 gaps between the plurality of containers. The apparatus may further
 includes an adjusting mechanism for the level of containers so as to allow
 the plug removing process to be done irrespective of the length of the
 containers on the batch. Furthermore, the apparatus may include a suction
 block which is positioned in the vicinity of the upper openings of the
 containers at the time of the plug removing process.
 The method for automatic plug removal during conveyance of the present
 invention includes a prerequisite step of providing a plurality of
 containers sealed with a plurality of plugs on a conveying section on a
 batch basis, a first step of holding the plurality of containers with
 plugs in an immovable state, a second step of grasping the plugs which
 seal the containers, a third step of inserting partition plates into gaps
 between the plurality containers, and a fourth step of loosening the seal
 between the plugs and the containers and then lifting the plugs up to
 remove them from the containers. Here, the second and the third step are
 done in random order after the first and before the fourth step.
 The above and other objects, features and advantages of the present
 invention will become apparent from the following description in
 conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION
 An automatic plug removing apparatus of the present invention includes a
 means for holding a plurality of containers 8 in an immovable state, such
 as a clamp 11; a means for grasping plugs 9 that seal the containers 8,
 such as a plug chuck 14; driving means 16 and 17 for driving the grasping
 means 14; and partition plates 12 that can be removably inserted between
 the plural containers 8. In the automatic plug removing apparatus of the
 present invention, the operation is carried out on a rack basis (batch
 basis) in which a rack receives a plurality of containers 8, and during
 the plug removing process the plural plugs 9 are removed from the
 containers 8 at the same time.
 A flow of processes in which the containers 8 sealed with the plugs 9 are
 sent to a plug removing section 5, the plugs 9 are removed from the
 containers 8, and thus unplugged containers 8 are discharged can be
 understood in FIG. 1. This drawing shows that one rack 2 receives ten
 containers 8, but this is not limitative and any number of containers may
 be received in one rack.
 First, ten containers 8 which have test samples therein and are sealed by
 plugs 9 are placed in a rack 2 and put on a start yard (an upstream
 conveying section) 1. Next, the rack 2 with the containers 8 is conveyed
 on the start yard 1 in an arrow direction (an upward direction in FIG. 1)
 down to an end of the start yard 1. At this end, the rack 2 changes its
 flow direction to a lateral direction indicated by an arrow and reaches to
 the plug removing section 5. After the plugs 9 having been removed from
 the containers 8 at the plug removing section 5, the rack 2 is further
 transported in the lateral direction to a discharging yard (a downstream
 conveying section) 3. The rack 2 again changes its flow direction and
 advances in an arrow direction (an upward direction in FIG. 1). On one
 side of the plug removing section 5 is provided a plug dumping box 4.
 The function of respective members of the apparatus is described in
 accordance with the processing sequence of the containers 8.
 A height measuring device 6 for containers 8 in a rack as shown in FIG. 2
 is provided at the downstream end of the start yard 1. When the rack 2
 reaches the end of the start yard 1, the height measuring device 6 comes
 down and measures the height of the containers 8. After the measurement,
 the rack 2 is forwarded to the plug removing section 5 by a rack
 forwarding mechanism 7. This height measuring device 6 and a height
 adjusting mechanism 10 (described later) collaborate to adjust the level
 of the plugs 9 of the containers 8. And, therefore, even if the length of
 containers 8 is different in each rack 2, as long as the containers in the
 same rack 2 have the same length, the plug removing process can be
 conducted at the plug removing section 5 without any problem.
 FIG. 3 is a front view of the automatic plug removing apparatus in which
 one rack 2 having plugged containers 8 is located at the end of the start
 yard 1, another rack having unplugged containers are on the discharge
 yard, and the plug removing section 5 is empty. FIG. 4 is a side view of
 the automatic plug removing apparatus in which one rack 2 is placed at the
 plug removing section 5, plugs 9 have been removed from containers 8, and
 a liquid drop receiving dish 13 and a plug dumping chute 18 are located
 under the removed plugs 9. Referring to these two drawings, the movement
 of respective members of the apparatus is described.
 The height adjusting mechanism 10 functions in response to data from the
 height measuring device 6. In case a rack 2 having shorter containers 8
 comes in, the height adjusting mechanism 10 raises the rack 2, while in
 case another rack having longer containers 8 comes in, it lowers the rack
 2, and adjusts the height of plugs 9 to a level where a plug chuck
 reliably grasps respective plugs. With this mechanism, the plug chuck 14
 as the plug grasping means may always work at the same level.
 A plurality of containers 8 in a rack 2, the number of which is ten in this
 case, are supported and held immovably at the same time by a clump 11 as
 the container holding means. Next, partition plates 12 advance into
 respective nine gaps between the ten containers 8. These partition plates
 12 isolate the respective containers 8 so as not to cause contamination of
 the samples therein in spite of sample scattering at the time of removal
 of plugs described below.
 The plug removing process is carried out by a rocking motor 16 and a
 vertical motion motor 17. The rocking motor 16 moves a rocking plate 15
 which is provided with the plug chuck 14 and an upper plate 20. The upper
 plate 20 is provided with plug pressing members 23. The vertical motion
 motor 17, which is also connected to the rocking plate 15, raises and
 lowers the plug chuck 14, the upper plate 20 and the plug pressing members
 23 together with the rocking plate 15, and also opens and closes the plug
 chuck 14 provided on the rocking plate 15.
 First, the vertical motion motor 17 actuates the rocking plate 15 to lower
 down to a predetermined level, at this level the plug chuck 14 provided on
 the rocking plate 15 is closed so as to grasp the plural plugs 9 at once.
 The rocking motor 16 subsequently actuates the rocking plate 15 to
 oscillate up and down, thereby allowing the plug chuck 14 attached to the
 rocking plate 15 to oscillate responsively. According to this oscillation,
 the plugs 9, gripped by the plug chuck 14 from opposite sides, slide up
 and down on the inner walls of the containers 8 in opposite directions on
 the opposite sides. And consequently the plugs 9 become out of the sealing
 state in the containers to be loosened. In this state, the vertical motion
 motor 17 actuates the rocking plate 15 and the plug chuck 14 to rise up,
 and the plugs 9 held by the plug chuck 14 are pulled up and removed from
 the containers held by the clamp 11. The movement of the rocking plate 15
 due to the rocking motor 16 while the plug chuck 14 grasps the plugs 9 may
 be set in one direction (i.e. in FIG. 4, the right side of the rocking
 plate 15 is moved only upward or only downward), or may be set in
 repetitious up and down movements. The latter allows easier removal of the
 plugs 9 from the containers 8 and a smaller shock at the time of removal.
 Each plug pressing member 23 is provided to the rocking plate 15 having the
 upper plate 20 therebetween. When the plug chuck 14 grasps the respective
 plugs 9 at their outer circumferential walls, the plug pressing members 23
 press their top faces. Therefore in case rubber plugs, as shown in FIG. 6,
 this results in reducing deformation of the plugs 9 and ensuring reliable
 grasping and holding of the plugs 9. The plug removing apparatus of the
 present invention may also apply to plugs of other material such as
 plastic.
 In this embodiment, a servo motor is used as the vertical motion motor 17,
 the raising speed of plugs 9 is set to be reduced immediately before the
 plug removal (just before the plugs 9 come off the containers 8). With
 this set-up of the mechanism, scattering of samples is reduced to a
 minimum.
 In FIGS. 5 and 6, the plug chuck 14 grasps the plugs 9 and the partition
 plates 12 are inserted into the respective gaps between the containers 8.
 As seen from FIG. 5, each partition plate 12 is located between both
 (upper and lower in the drawing) gripping members of the plug chuck 14,
 and, as seen from FIG. 6, extended to a level higher than the top level of
 the containers 8. With this constitution, the gaps between the plugs 9 of
 the adjacent containers 8 (the gaps in a lateral direction of FIG. 5) are
 separated by partition plates 12 up to a rather high level.
 Therefore, the partition plates provide an isolated space in the vicinity
 of the top opening of each container 8 so that even if scattering of
 samples occurs, it is possible to prevent the scattered samples from
 erroneously entering the adjacent containers, and consequently to prevent
 contamination due to the scatter of the samples.
 In a more preferred embodiment, a suction block 24, shown in FIG. 7, is
 provided in addition to the above-mentioned partition plates 12. The
 suction block 24 has a shape as shown in FIG. 7. The front side which
 faces the containers 8 is provided with recesses 25 at positions
 corresponding to the respective containers 8 and cut-out sections 26 at
 positions corresponding to the respective partition plates 12. Each recess
 25 has a hole in its inward back which is connected to an air hose 27 that
 extends in the longitudinal direction of the suction block 24. Each of the
 cut-out sections 26 of the suction block 24 receives one portion of each
 partition plate 12. Therefore, whether the suction block 24 is used or
 not, the space in the vicinity of the top opening of each container 8 is
 isolated by the partition plates 12 at the time of removal of the plugs
 from the containers 8.
 As shown in FIG. 6, the suction block 24 is placed in the vicinity of the
 top openings of the containers 8. When the plugs 9 have been pulled out
 from the containers 8, the outer air rapidly flows into the containers 8,
 or abruptly mixes with air inside the containers 8. As a result, portions
 of the samples tend to become mist and spread and float in the vicinity of
 the openings of the containers 8. In order to prevent such a mist of the
 samples from contaminating other samples, the first embodiment is provided
 with the partition plates 12 for separating the space between the adjacent
 containers 8. However, there is a possibility that such mist of the
 samples might still cause contamination of the other samples in the
 adjacent containers 8. Here, by sucking air through the recesses 25 of the
 suction block 24 at the time of removing the plugs, the mist of samples
 floating in the air is sucked away so as to completely prevent the
 contamination.
 Referring back to FIG. 4, after the plugs 9 are removed from the containers
 8 held by the clamp 11, the liquid drop receiving dish 13 quickly advances
 between the removed plugs 9 and the containers 8, and receives and
 collects liquid drops from the plugs 9 so as to prevent them from entering
 other containers 8.
 Next, the plug dumpling chute 18 is shifted between the removed plugs 9 and
 the containers 8, and the plug chuck 14 opens and releases the removed
 plugs 9 into the plug dumping chute 18. In order to secure release of the
 removed plugs 9 which might remain sticking to the plug pressing member
 23, a driving mechanism (not shown) may be provided. This mechanism
 actuates the plug pressing members 23 to retract into the upper plate 20
 and lets them release the plugs 9 securely.
 Subsequently the plugs 9 drop into the plug dumping chute 18 and are guided
 to and collected in the plug dumping box 4 shown in FIG. 1. The plug
 dumping chute 18 and the plug dumping box 4 are detachable from the main
 system for easy cleaning, collection of dumped plugs and other maintenance
 purposes.
 Afterwards, the rack carrying the unplugged containers 8 is caught by a
 rack chuck 21 shown in FIG. 3, shifted by a rack drawing member 22 to the
 discharge yard 3 shown in FIG. 1. Such racks are accumulated there and
 conveyed forward in due course. On the other hand, the plug removing
 section 5 receives subsequent racks 2 carrying plugged containers 8 one
 after another, and repeats the same plug removing process.
 During the automatic plug removing process according to the present
 invention, the partition plates 12 are located between the adjacent
 containers so as to separate the space between the top openings of the
 containers and isolate respective separated spaces. This prevents
 contamination of samples in respective containers to be examined and
 therefore correct examination results can be obtained from the
 uncontaminated samples. Moreover, addition of the suction block 24 allows
 to suck and eliminate a mist of samples floating around the openings of
 the containers due to plug removal. This results in complete prevention of
 contamination and more highly reliable examination results can be
 obtained.