Abstrict Blood lancet device (1) for withdrawing blood from a patient for
diagnostic purposes comprises a housing (10), a lancet holder (11)
movable within the housing (10) for retaining a non-rotatable lancet
(4) having a plastic lancet body (31), a lancet needle (33) fixed
in the lancet body (31), a lancet drive (12) to move the lancet
holder in a puncturing and retraction direction, an exchangeable
skin-contact part (5) having an outlet opening (6) for the lancet
(4) and a contact surface (42) for pressing against a patient's
skin. The skin-contact part (5) and lancet (4) form a unitary disposable
item (3) which is intended for once-only use and is intended to
be inserted at an anterior end (2) of the housing (10) in a single
operation only as a unit with the skin-contact part (5) The skin-contact
part (5) and the lancet body (31) are connected to one another through
a first predetermined breaking section (52) to permit the skin-contact
part (5) and the lance body (31) to be separable from one another
following insertion of the disposable item (3). A second breaking
section connects a protective needle cap to the lancet body and
both breaking sections are severed by twisting of the protective
cap.
Claims We claim:
1. Blood lancet device for withdrawing blood for diagnostic purposes,
comprising:
a housing,
a lancet holder, movable within the housing, for holding a lancet,
said lancet being a component of a disposable item which comprises
the lancet with a lancet body made of a plastic material, an exchangeable
skin contact part and a lancet needle fixed in the lancet body,
and which disposable item is intended for once only use and is inserted
at an anterior end of the housing in a single operation,
a lancet drive to drive the puncturing and retraction movement
of the lancet holder with a lancet held therein,
wherein the housing has an anterior end in the puncturing direction,
receiving the exchangeable skin-contact part and the lancet,
said exchangeable skin-contact part having a contact surface for
pressing against the skin when using the blood lancet device and
an outlet opening for the lancet,
wherein said disposable item is configured such that the lancet
can be inserted only together with the skin-contact part, and
wherein the skin-contact part and lancet body are connected to
one another and at the point of connection between the skin-contact
part and the lancet body, a first predetermined breaking section
is provided by means of which the skin-contact part and the lance
body are separable from one another following insertion of the disposable
item.
2. Blood lancet according to claim 1 wherein the lancet has a
tip-protection cap made of a plastic material which is connected
with the lancet body via a second predetermined breaking section,
and
wherein both predetermined breaking sections are separated following
insertion of the disposable item.
3. Blood lancet device according to claim 2 wherein the disposable
item is configured such that the first predetermined breaking section
and the second predetermined breaking section are separable in a
single operation.
4. Blood lancet device according to claim 3 wherein, after insertion
of the disposable item, the lancet holder holds the lancet non-rotatably
and a rotation-limiting stop for the skin-contact part is provided
at the anterior end of the housing, and wherein both predetermined
breaking sections are separable by rotation of the tip-protection
cap relative to the lancet and the skin-contact part.
5. Blood lancet device according to claim 2 wherein the tip-protection
cap is connected with the skin-contact part at an edge of the outlet
opening, and
wherein the first predetermined breaking section is provided at
this connection.
6. Blood lancet device according to claim 5 wherein the skin-contact
part is disposed in front of the lancet body in the puncturing direction,
and the tip-protection cap extends through the outlet opening of
the skin-contact part.
7. The blood lancet device according to claim 2 wherein separation
of the breaking sections allows for removal of the tip-protection
cap while at the same time allows for retention of the skin-contact
part in the housing.
8. The blood lancet device according to claim 7 wherein the separation
of the breaking sections causes removal of a central portion of
the skin-contact part to provide a clear passageway through the
outlet opening for passage of a sharp end portion of the needle
during the puncturing operation.
9. Blood lancet device according to claim 1 wherein the skin-contact
part is configured ring-shaped.
10. Blood lancet device according to claim 1 wherein the lancet
drive has a tension spring and means for ensuring that repeated
tensioning of the lancet drive is permitted only after removal of
a lancet, which during the preceding puncturing and retraction movement
was located in the lancet holder.
11. The blood lancet device of claim 1 wherein the lancet body
is of such shape that it cannot be removed from the housing without
removal of the skin contact part from the housing.
12. A disposable blood lancet device for insertion into a lancet
driver for use in withdrawing blood for diagnostic purposes,
said disposable lancet device comprising a lancet body made of
a plastic material, an exchangeable skin contact part and a lancet
needle fixed in the lancet body,
the exchangeable skin-contact part being attached to the lancet
body, said exchangeable skin-contact part having a contact surface
for pressing against the skin when using the disposable blood lancet
device,
wherein the disposable lancet device is intended for once-only
use and can be inserted into an anterior end of a lancet driver
in a single handling operation,
wherein the skin-contact part and lancet body are connected to
one another by a first predetermined breaking section by means of
which the skin-contact part and the lancet body are separable from
one another following insertion of the disposable item.
13. The disposable blood lancet device according to claim 12 having
a tip-protection cap made of a plastic material which is connected
with the lancet body via a second predetermined breaking section,
and
wherein both predetermined breaking sections are configured for
separation following insertion of the disposable lancet device into
the lancet driver.
14. The disposable blood lancet device according to claim 13 which
is configured such that the first predetermined breaking section
and the second predetermined breaking section are separable in a
single operation.
15. The disposable blood lancet device according to claim 14 wherein
both predetermined breaking sections are separable by rotation of
the tip-protection cap relative to the lancet body.
16. The disposable blood lancet device according to claim 12 having
a tip-protection cap that is connected with the skin-contact part,
and
wherein the first predetermined breaking section is provided at
this connection.
17. The disposable lancet device according to claim 6 wherein the
first predetermined breaking section is provided between the tip-protection
cap and the skin contact part.
18. The disposable blood lancet device according to claim 12 wherein
the skin-contact part is configured ring-shaped surrounding an outlet
opening for said needle.
19. The disposable blood lancet device according to claim 18 wherein
the skin-contact part is disposed in front of the lancet body in
the puncturing direction, and the tip-protection cap extends in
front of the skin-contact part and through the outlet opening of
the skin-contact part.
20. The disposal blood lancet device of claim 12 wherein the lancet
needle has a sharp point and is fixed in the lancet body with its
sharp point positioned posterior to the skin-contact part and wherein
separation of the skin-contact part from the lancet body provides
an opening through the skin-contact part for movement of the needle
point therethrough during a skin puncturing operation.
21. A method for puncturing the skin of a patient for withdrawing
blood for diagnostic purposes utilizing a lancet driver for driving
a tip of a needle of a disposable lancet device into the patients
skin comprising;
inserting a disposable lancet device comprising a lancet body a
lancet needle fixed in the lancet body, and an exchangeable skin-contact
part as a unit into an anterior end of a housing of the lancet driver
with the lancet body and needle being located within said housing
of the said lancet drive and with a surface of the skin-contact
part extending outwardly of the lancet driver housing,
breaking a breaking section connecting the lancet body and the
skin-contact part to disconnect the skin-contact part form the lancet
body without removing the skin-contact part from being held by the
housing,
placing the outward surface of the skin-contact part against the
skin of the patient without removing the skin contact part from
being held by the housing;
actuating the lancet driver to cause the lancet body to move toward
the anterior end of the lancet driver housing and relative to the
skin-contact part wherein a tip of the needle fixed in the lancet
body passes through the skin-contact part and into the patients
skin.
22. The puncturing method of claim 21 wherein the disposable lancet
device inserted into the housing of the lancet driver is provided
with a needle tip protecting cap that covers the tip of the needle
and is unitary with the disposable lancet device, and wherein the
needle tip protecting cap is removed and separated from the disposable
lancet device prior to the placement of the outward surface of the
skin-contact part against the skin of the patient.
23. The puncturing method of claim 22 wherein the breaking of the
breaking section connecting the skin-contact part from the lancet
body occurs simultaneously with the separation of the needle tip
protector cap.
24. The puncturing method of claim 23 wherein the needle tip protector
is separated from the skin-contact part by rotation of the needle
tip protector relative to the skin-contact part.
25. The puncturing method of claim 24 wherein the holding of the
disposable lancet by the driver housing after insertion prevents
rotation of the skin-contact part and the lancet body without preventing
rotation of the needle tip protector.
26. The puncturing method of claim 21 wherein the lancet body is
expelled from the housing after puncturing and wherein during this
expulsion the lancet body abuts the skin-contact part and also causes
the skin-contact part to be expelled from the housing.
Description The invention relates to a blood lancet device for withdrawing
blood for diagnostic purposes, comprising a housing, a lancet holder,
movable within the housing, for holding a lancet which comprises
a lancet body made of a plastic material and a needle fixed in the
lancet body, and a lancet drive to drive the puncturing and retraction
movement of the lancet holder with a lancet held therein, the housing
having, at its anterior end in the puncturing direction, an exchangeable
skin-contact part with an outlet opening for the lancet, said skin-contact
part being provided with a contact surface for pressing against
the skin when using the blood lancet device. The skin-contact part
and lancet form components of a disposable item which is intended
for once-only use and can be inserted at the anterior end of the
housing in a single handling operation, said disposable item being
designed in such a way that the lancet can be inserted into the
housing only together with the skin-contact part.
In various diseases it is necessary to test human blood for specific
blood values. To this end it is often sufficient to withdraw from
the body only a small quantity of blood in the form of a blood droplet
by producing a small puncture wound. An especially important example
is diabetes, in which the blood must be tested at regular intervals
for its glucose content.
The puncture wound is commonly produced using blood lancet devices
comprising a puncturing instrument and exchangeable lancets which
are mutually adapted. The puncturing instrument contains the lancet
holder into which one lancet at a time can be exchangeably inserted.
During the puncturing operation the lancet holder with the lancet
is moved rapidly in the puncturing direction until the tip of the
lancet emerges from the outlet opening of the skin-contact part
and produces a small puncture wound in the body part against which
the skin-contact part is pressed. The lancet holder with the lancet
is then retracted counter to the puncturing direction. An example
of a lancet device of this type is described in U.S. Pat. No. 4442836.
Hereinafter, the end of the puncturing instrument bearing the outlet
opening will be called the anterior end, and the opposite end will
be called the posterior end.
To avoid infection, a new lancet must be used for each puncturing
operation. The instrument described in the above mentioned U.S.
Pat. No. is therefore designed in such a way that the used lancet
is automatically ejected from the instrument following each puncturing
operation, when said instrument is retensioned.
However, a risk of infection may originate not only from the lancet
itself, but also from the contact surface of the puncturing instrument
pressed against the skin. This applies particularly within the hospital
sector and in medical practices in which the same blood-sampling
instrument is used for different patients. Here, on account of the
possible transfer of pathogens contained in the patients' blood,
there is a high risk of infection with, for example, AIDS or hepatitis-B
viruses.
In order to exclude the risk of infection via the skin-contact
surface, in a known instrument of the kind described in the preamble
a special skin-contact part is envisaged which is exchanged together
with the lancet. With this arrangement, the lancet and the skin-contact
part are two separate parts which are assembled to form a unit which
can be applied at the lower end of the puncturing instrument and
is intended for once-only use. Such a unit composed of a lancet
and a skin-contact part which is intended for once-only use is here
called a disposable item.
In the known blood lancet device, the skin-contact part is designed
as a longitudinal sleeve whose length is almost a third of the overall
length of the blood lancet device (when it is in the "usable
state", i.e. ready for use) and completely surrounds its lower
end. The lancet sits in the sleeve as a separate component, being
held anteriorly by elastic plastic strips, which drive the retraction
movement following the puncture. This instrument is tensioned by
manually pushing back the lancet holder which, in the usable state,
is covered by the sleeve-type skin-contact part. Following the puncture,
the instrument can therefore be retensioned only if the skin-contact
part is first removed. Although this ensures that the disposable
item consisting of the skin-contact part and the lancet must be
removed before the device is tensioned or reused, following removal
of the disposable item and retensioning of the blood lancet device
it does not reliably prevent the same disposable item from being
re-inserted into the housing and re-used. Accidental or deliberate
re-use of the disposable item (on account of ignorance of the associated
risks) therefore cannot be excluded.
An object of the invention is therefore to reliably prevent re-use
of all parts of a blood lancet device which may come into contact
with the patient's blood.
In a blood lancet device of the type described in the preamble
this is achieved according to the invention in that, in the disposable
item, the skin-contact part and the lancet body are firmly connected
to one another and at the point of connection between the skin-contact
part and the lancet body a first predetermined breaking section
is envisaged by means of which the skin-contact part and the lancet
body are separable from one another following insertion of the disposable
item.
It is characteristic of the invention that, when being inserted
into the puncturing instrument, the disposable item is in an insertion
state in which the skin-contact part is (directly or indirectly)
firmly connected with the lancet body. This insertion state is maintained
until either the skin-contact part or the lancet or both are in
their end position (position for use) within the blood lancet device.
In the insertion state, the blood lancet device is not usable, because
the lancet body is firmly connected with the skin-contact part.
By severance at the predetermined breaking section, the disposable
item is transformed from the insertion state into a usable state
in which the lancet body, and therefore the lancet, is free, so
that the puncturing and retraction movement for the production of
a puncture wound is possible. The skin-contact part and the lancet
are designed in such a way that, in the usable state following severance
at the predetermined breaking section, it is practically impossible
to insert them into the puncturing instrument (although it may be
possible with the aid of supplementary tools such as, for example,
tweezers). In particular, the skin-contact part is so small that
it can in practice be attached only in conjunction with the disposable
item at the anterior end of the blood lancet device. Re-use both
of used lancets and of used skin-contact parts following severance
at the predetermined breaking section is thereby excluded in practice.
The tip of the lancet is commonly protected with a tip-protection
cap, which is connected with the lancet body via a predetermined
breaking section and is removed before the lancet is used. A tip-protection
cap of this type is also preferably envisaged in the case of the
invention, the predetermined breaking section between the tip-protection
cap and the lancet body being a second predetermined breaking section
(supplementary to the first predetermined breaking section at the
point of connection between the skin-contact part and the lancet
body). In this embodiment, the disposable item is preferably designed
in such a way that the first and second predetermined breaking sections
can be severed in a single handling operation (preferably simultaneously).
This simplifies handling in that the disposable item can be transformed
from the insertion state into the usable state with a single movement
of the hand.
The predetermined breaking section may be created using methods
familiar to a person skilled in the art. Generally it is a web or
strip of material which is mechanically weaker than the rest of
the disposable. Thereby the component of the disposable (lancet
body, skin body part and, where applicable, tip-protection cap)
separate selectively at the predetermined breaking section when
the disposable is put under mechanical stress such as by rotating
the parts relative to each other about their longitudinal axis.
The disposable item as a whole is preferably--with the exception
of the metallic lancet needle--a plastic injection moulding. With
this arrangement, the lancet body, the skin-contact part and, where
applicable, the tip-protection cap can be manufactured in a single
operation by the plastic injection-moulding method, the needle being
located in the longitudinal axis of the plastic part. With the use
of this method, predetermined breaking sections may simply take
the form of easily severable thin spots or webs of the injection-moulded
plastic material.
The connection between the skin-contact part and the lancet body
need not necessarily be direct. In an especially preferred embodiment,
the skin-contact part is connected to the lancet body only indirectly,
via the tip-protection cap, the first predetermined breaking section
being located at the point of connection between the skin-contact
part and the tip-protection cap (at the edge of the outlet opening
provided in the skin-contact part), while the second predetermined
breaking section is, as usual, created between the tip-protection
cap and the lancet body.
A disposable item according to the invention is inexpensive to
manufacture. With manufacture as a plastic injection moulding, the
manufacturing costs scarcely differ from those of lancets commonly
used in blood lancet devices. A low purchase price is an additional
incentive to avoid the reuse of used disposable items. With the
invention the tip-protection cap is used for handling the disposable
item. Therefore the skin-contact part can be very small, preferably
essentially as an annual plate. This compares favourably with the
prior art where a big sleeve is required for handling purposes.
In addition to a substantial reduction of manufacturing costs, the
design of the skin-contact part as a relatively small component
also results in a small overall size of the disposable item and
therefore small packaging volume.
In order to make sure that the device can only be operated in a
defined sequence of steps the lancet drive in a preferred embodiment
has means for ensuring that repeated tensioning of the lancet drive
is possible only after removal of the lancet, which during the prior
puncturing and retraction movement was located in the lancet mounting.
Various possibilities for performing this function are known. In
U.S. Pat. No. 4442836 mentioned above, for example, the lancet
mounting is provided with a lever arm which, during the tensioning
process, abuts against a fixed projection and thereby automatically
ejects the lancet. In this arrangement, therefore, tensioning of
the lancet device is possible only when the used lancet is simultaneously
ejected. The instrument with the sleeve-type skin-contact part,
also mentioned above, has a re-tensioning lock such that the lancet
holder can be pushed back only when empty. Another, especially preferred
embodiment is described in greater detail below in the description
of an exemplifying embodiment of the invention.
An embodiment of this type is especially advantageous because,
in addition to safeguarding against re-use of a skin-contact part
and/or a lancet which has been used and removed from the instrument
("re-use lock"), it ensures that the lancet which is still
in the instrument cannot be used a second time. This provides virtually
complete protection against risks of infection due to mis-use of
the blood lancet device.
The invention is illustrated in greater detail below using an exemplifying
embodiment schematically represented in the following figures:
FIG. 1 A sectional view of a blood lancet device along its longitudinal
axis;
FIG. 2 A partially cutaway side view of a disposable item;
FIG. 3 A sectional view along line III--III in FIG. 2;
FIG. 4 A sectional view along line IV--IV in FIG. 2;
FIG. 5 A sectional view along line V--V in FIG. 1;
FIG. 6 A sectional view along line VI--VI in FIG. 1.
FIG. 1 shows a blood lancet device 1 according to the invention
with a disposable item 3 inserted at its anterior end 2. The disposable
item 3 comprises a lancet 4 a skin-contact part 5 and a tip-protection
cap 7. In FIG. 1 it is represented in its usable state, lancet 4
sitting in a lancet holder 11 and skin-contact part 5 being attached
to an adjusting cap 9 of the housing 10 in such a way that it closes
its anterior opening 8 apart from an outlet opening 6 for the lancet.
The tip-protection cap 7 is removed in the usable state, and for
this reason it is represented as a dashed line in FIG. 1.
In the embodiment shown, the puncturing and retraction movement
of the lancet holder 11 and the lancet 4 located therein is guided
by a driver cam 15 which is formed by a groove-shaped recess in
the circular casing surface 14 of the lancet holder 11. With the
driver cam 15 there engages a driver pin 16 of a drive sleeve 17
enclosing the lancet holder 11 in this region. The drive sleeve
17 extends within the housing 10 almost as far as the (in the puncturing
direction) posterior end of the blood lancet device 1. A spirally
wound coiled spring 18 within the drive sleeve 17 which drives
the drive sleeve 17 is also located here. Through the coiled spring
18 runs an ejector 20 which with its anterior end 20a engages with
the lancet holder 11 and which has an operating button 21 disposed
at its posterior end. The drive sleeve 17 is in operative connection
with an intermediate ring 25 which is permanently secured with
a tensioning ring 24 on to which the adjusting cap 9 can be screwed.
For tensioning of the blood lancet device 1 the housing 10 is
held by its upper sleeve part 22 and the tensioning ring 24 with
the intermediate ring 25 and hence the drive sleeve 17 is rotated
to the right (when viewed counter to the puncturing direction).
This movement is conveyed via the drive sleeve 17 to the coiled
spring 18. At the end of the tensioning movement an arresting device,
not shown, stops the drive sleeve, causing the coiled spring 18
to remain in the tensioned state. A return spring 27 rotates the
intermediate ring 25 with the tensioning ring 24 through a left-hand
movement relative to the drive sleeve 17 into its initial state.
The lancet drive, which in its entirety is given the number 12
is essentially formed by the coiled spring 18 the drive sleeve
17 the driver pin 16 the driver cam 15 and the ejector 20 which
simultaneously provides a torsion protection means. If the lancet
drive is released by a disengaging element 28 the drive sleeve
17 and the driver pin 16 disposed thereon make a left-hand rotation
(when viewed counter to the puncturing direction). With this arrangement,
driver pin 16 travels along the driver cam 15 as a result of which
the lancet holder 11 and the lancet 4 located therein execute the
puncturing and retraction movement.
More precise details concerning the lancet drive used in this exemplifying
embodiment may be found in German published patent application 42
12 315.
In FIG. 2 the disposable item 3 is represented in its insertion
state prior to the separation of its components, the lancet 4 skin-contact
part 5 and tip-protection cap 7. The lancet 4 has a lancet body
31 made of a plastic material, in which a metallic lancet needle
33 extends along its longitudinal axis 32 which is represented
as a dashed line. Both ends of the lancet needle 33 project out
of the lancet body 31. The anterior end of the lancet needle 33
in the puncturing direction is formed as a sharp point 34 while
the posterior end has a stop surface 35. By contrast with otherwise
commonly used lancets the stop surface, which is used for positioning
of the lancet 4 within the lancet holder 11 is provided at the
lancet needle 33 and not the lancet body. In this way, exactly
reproducible puncturing depths can be achieved in the course of
successive punctures with different lancets, especially when small
puncture depths are used. More precise details concerning this aspect
can similarly be found in German patent application 42 12 315. In
the lancet described here, the lancet body has four uniform webs
36 extending along its entire length, disposed at 90.degree. intervals
about the longitudinal axis 32 so that in cross-section they form
a cross (FIG. 4). An intermediate body 38 with inclined contact-pressure
surfaces 39 is located between the webs in the vicinity of the posterior
end of the lancet body 31.
The skin-contact part 5 essentially comprises a disc-like ring-shaped
part 41 and, moulded on to it, two hook-like engaging elements 44
which are used for attachment to the adjusting cap 9. The anterior
surface of the skin-contact part 5 forms the contact surface 42
with which the blood lancet device 1 is pressed against the skin.
The distance between the engaging elements 44 which are bent like
hooks away from the longitudinal axis 32 is greater than the diameter
of the front face 45 of the lancet body 31. The outlet opening 6
for the lancet tip 34 is located in the centre of the ring-shaped
part 41 (represented in FIG. 1 in the usable state).
As previously mentioned, the skin-contact part must for various
reasons be as small as possible. The diameter is at most as large
as the diameter of the anterior end 2 of the blood lancet device
1. The dimension in the direction of the longitudinal axis 32 including
the attachment elements, is less than 1 cm, preferably less than
5 mm. The corresponding dimension of the part of the skin-contact
part which in the insertion state is accessible from the outside
should be considerably smaller, to make separate insertion of the
skin-contact part 5 impossible in practice. In the exemplifying
embodiment represented, the skin-contact part 5 projects beyond
the anterior end 2 of the blood lancet device 1 only by the length
D shown in FIG. 2. This dimension should generally be less than
2 mm. In the preferred embodiment, it is less than 1 mm.
As can be seen in FIG. 5 the adjusting cap 9 has means of attachment
54 for the exchangeable attachment of the skin-contact part 5. In
the embodiment represented, the attachment functions as a type of
bayonet fastening. Along a circumferential line of the opening 8
of the adjusting cap 9 there extend four shoulders 55. Behind each
shoulder 55 a web 56 serving as a rotation-limiting stop 58 is
centrally disposed. A guide recess 57 is located between each pair
of shoulders 55.
FIG. 2 shows that the tip-protection cap 7 extends through the
outlet opening 6 with a shaft 47 and, in the section in front of
the outlet opening 6 has a gripping zone 49 for handling the disposable
item 3. The diameter of the opening 6 should be smaller than 3.5
mm and preferably measure about 2 to 2.8 mm.
The tip-protection cap 7 is connected with the skin-contact part
5 by means of four webs 50 evenly distributed around the boundary
surface of the outlet opening 6 (FIG. 3). The webs 50 are designed
in such a way that they break when the tip-protection cap 7 is rotated,
and thus form the first predetermined breaking section 52. The connection
between the tip-protection cap 7 and the lancet body 31 is formed
by a thin-walled surrounding web 51 between the front face 45 of
the lancet body 31 and the shaft 47 of the tip-protection cap 7.
This web 51 forms the second predetermined breaking section 53.
To accommodate the lancet 4 the lancet holder 11 represented in
FIG. 1 has an accommodating recess which in cross-section is essentially
square. The square recess is adapted to the webs 36 (FIG. 4) of
the lancet body 31 in such a way that the lancet body 31 can be
introduced into the lancet holder 11 in four different positions,
each turned through 90.degree. about the longitudinal axis 32. The
skin-contact part 5 with the engaging elements 44 can also be introduced
into the guide recesses 57 (FIG. 5) of the adjusting cap 9 in these
four positions. Two lugs 61 provided with sloping edges 60 project
into the accommodating recess of the lancet holder 11 said lugs
each being located on elastically deflectable tensioning tongues
62. In addition, when viewed counter to the puncturing direction
a stop element 63 is provided at the rear end of the accomodating
recess running transversely to the puncturing direction.
To insert the disposable item 3 the lancet 4 is introduced against
the pressure of the tensioning tongues 62 into the lancet holder
11 with the lancet drive 12 tensioned. Thereby the ejector 20 is
pushed backwards. At the same time, the lugs 61 slide on the intermediate
bodies 38 of the lancet body 31 said intermediate bodies being
adjacent each lug. Towards the end of the insertion movement, the
two lugs 61 reach the contact-pressure surface 39 with their sloping
edge 60 as a result of which the disposable item 3 is drawn into
the lancet holder 11. The insertion movement is completed when the
contact-pressure surface 35 touches the stop web 63. Simultaneously,
the two engaging elements 44 are introduced into the adjusting cap
9 via two of the recesses 57 so that the hook-like ends 44a of
the two engaging elements 44 are located at roughly the same longitudinal
position as the stop webs 56.
In this position the disposable item 3 is inserted into the blood
lancet device 1. In general, insertion of the disposable item is
considered "complete" for the purpose of the invention
when at least one of the two main components of the disposable item,
namely the lancet 4 and the skin-contact part 5 has reached its
end position in the direction of the puncturing movement. In the
embodiment represented this is the lancet 4 which is located in
the lancet holder 11 in its operating position.
Since in the insertion state the predetermined breaking sections
are still intact, the blood lancet device 1 is not yet usable. In
order to convert it into the usable state, the second predetermined
breaking section between the lancet body 31 and the tip-protection
cap 7 must first be severed by left-hand or right-hand rotation
of the tip-protection cap 7. By further rotation of the tip-protection
cap 7 in the same direction as before, the engaging elements 44
impinge against the corresponding stop webs 56. In this position
the ends 44a of the engaging elements 44 each engage with a shoulder
55. Due to this engagement and by abutment of the conical circumferential
surface 46 of the ring-shaped part 41 against a congruent surface
of the adjusting cap 9 a reliable axial and radial positioning
of the skin-contact part 5 is ensured. Continuation of the rotary
movement of the tip-protection cap 7 causes the four webs 50 to
break, thereby severing the first predetermined breaking section
52.
The two predetermined breaking sections have thus been severed
in a single handling operation, namely rotation of the tip-protection
cap 7 as a result of which the blood lancet device 1 has been transformed
from the insertion state into the usable state. In the separated
state, the individual elements of the disposable item 3 cannot be
re-inserted (or only with the aid of a tool and with considerable
effort, which precludes accidental mis-use).
In the preferred embodiment described, means 64 (FIG. 1) are provided
by which it is ensured that repeated tensioning of the lancet drive
is possible only after removal of the lancet which during the prior
puncturing and retraction movement is located in the lancet mounting.
These means are described below.
On its casing surface, the ejector 20 is provided with an ejection-protection
lug 65 which in the puncturing direction slopes upwards in a ramp-like
fashion. Further forwards and offset relative to the ejection-protection
lug 65 on the circumference, the ejector 20 also has a pin 66 (FIG.
1 and FIG. 6). In front of the pin 66 and offset relative to it
and to the ejection-protection lug 65 on the circumference of the
ejector 20 there is a pushback protection lug 67 on the casing
surface of the ejector 20 which slopes upwards in a ramp-like fashion
counter to the puncturing direction. The anterior end 20a of the
ejector 20 is designed in the form of a fork in such a way as to
be axially movable within the lancet holder 11 in the region of
the stop element 63.
FIG. 1 shows that the drive sleeve 17 in the vicinity of its posterior
end has a first elastic locking tongue 70 which follows an initially
axially parallel course and is then bent slightly inwards, and which
projects into the drive sleeve 17. Further forwards in the puncturing
direction, the drive sleeve 17 has a second elastic locking tongue
71 which follows an arc-shaped course roughly along a circum-ferential
line. The free end of the second elastic locking tongue 71 is provided
with a lug 72 which projects into the interior of the drive sleeve
17 said lug being offset relative to the first locking tongue 70
(FIG. 6) on the circumference. In front of the second locking tongue
71 another axially directed third elastic locking tongue 73 is
present on the drive sleeve 17. This is positioned on the internal
surface of the drive sleeve and forms a deflectable ramp which slopes
upwards in the puncturing direction.
The drive sleeve 17 is now co-ordinated with the ejector 20 in
such a way that, during a puncturing and retraction movement of
the lancet 4 the pin 66 of the ejector 20 and the second locking
tongue 71 as shown in FIG. 1 and FIG. 6 are located at the same
height. This movement of the lancet 4 is effected by a left-hand
rotation of the drive sleeve 17 (as represented in FIG. 6). With
this arrangement, the lug 72 of the second locking tongue 71 moves
over the pin 66 and engages behind it.
Because the ejector 20 is protected against rotary movements, the
right-hand rotation of the drive sleeve 17 which is necessary for
tensioning, is not possible. The disposable item 3 must therefore
first be ejected in its individual parts by operating the ejector
20. The fork-like anterior end 20a of the ejector 20 here pushes
the lancet 4 out of the lancet holder 11 via axial longitudinal
displacement of lancet 4. The lancet body 31 in turn pushes with
its front face 45 on the ring-shaped part 41 between the engaging
elements 44. As a result, the hook-like ends of the engaging elements
44 move over the shoulders 55. The skin-contact part 5 and lancet
4 are then ejected.
Due to this axial displacement of the ejector 20 the pin 66 now
releases the second locking tongue 71. Right-hand rotation of the
drive sleeve 17 and hence tensioning of the blood lancet device
1 is now possible. However, during the ejection movement of the
ejector 20 the pushback protection lug 67 has also moved over the
third locking tongue 73 and engaged behind it. Pushing back the
ejector 20 which is necessary for insertion of a disposable item
3 is therefore impossible. The blood lancet device 1 must of necessity
first be tensioned by right-hand rotation of the drive sleeve 17.
The pushback protection lug 67 is thereby also rotated relative
to the locking tongue 73 and thus released.
The next step is the introduction of the disposable item 3 as
a result of which the ejector 20 is pushed back by pressing the
lancet body 31 against the anterior end of the ejector 20. During
this procedure, the ejection-protection lug 65 moves away under
the first locking tongue 70 due to deflection of the latter. The
ejection-protection lug 65 at the same time engages with the locking
tongue 70 as soon as the disposable item has reached its insertion
state in the blood lancet device 1. Engagement of the locking tongue
70 with the ejection-protection lug 65 prevents (for example unintentional)
ejection of the disposable item 3 before it has been transformed
into the usable state and the lancet has executed the puncturing
and retraction movement.
Overall, this results in fully constrained guidance of the operating
steps for tensioning, insertion of the disposable item, severance
of the predetermined breaking sections, triggering of the puncturing
process, and ejection of the lancet. |