Abstrict Blood lancet system for blood withdrawal for diagnostic purposes
with a housing, a lancet holder movable in the housing for holding
an exchangeable lancet, and a lancet drive for driving the pricking
movement of the lancet holder with the lancet contained herein.
The housing has a cap at the front end in pricking direction which
can be removed in order to remove a used lancet from the lancet
holder. The lancet and the housing cap are coupled, during the attachment
of the housing cap, by a coupling mechanism comprising coupling
elements matched to each other and enabling the extraction of the
lancet from the lancet holder simultaneously with removing the housing
cap.
Claims What is claimed is:
1. Blood lancet system for blood withdrawal for diagnostic purposes,
comprising a lancet and a pricking apparatus with a housing, a lancet
holder movable in the housing for holding an exchangeable lancet,
and a lancet drive for driving a pricking movement of the lancet
on a predetermined pricking path, the housing comprises a cap to
be attached at a forward end thereof in pricking direction, the
cap being removable for removing a used lancet out of the housing,
the lancet and the cap are adapted to be automatically coupled,
during attaching the cap to the housing, by a coupling mechanism
comprising matching coupling elements, thereby enabling the extraction
of the lancet from the lancet holder without additional handling
steps by removing the cap wherein the coupling mechanism comprises
a movable ejector for ejecting the lancet, and a coupling element
of the ejector and a corresponding coupling element of the cap are
adapted to each other such that the cap is coupled to the ejector
during attachment of the cap to the housing and during removal of
the cap.
2. Blood lancet system according to claim 1 wherein at least one
of the coupling elements has a protrusion, which is elastically
biased in a direction transversal to the pricking direction and
which latches during the coupling of the lancet and the cap into
a corresponding recess of the other coupling element.
3. Blood lancet system according to claim 1 wherein the lancet
comprises a lancet body made of plastic, a lancet needle fixed in
the lancet body, and a tip cover element covering the lancet tip,
the tip cover element being connected to the lancet body via a breaking
point such that it can be removed after the insertion of the lancet
into the lancet holder in order to expose the lancet tip protruding
from the lancet body.
4. Blood lancet system according to claim 1 wherein the cap has
a contact surface for contacting the blood lancet apparatus to the
skin, the cap can be fixed to the housing at a defined position
in the pricking direction, and the longitudinal position of the
cap in the pricking direction can be adjusted by an adjustment device
in order to adjust the pricking depth.
5. Blood lancet system according to claim 1 wherein the cap has
a contact surface for contacting the blood lancet apparatus to the
skin, the cap can be fixed to the housing at a defined position
in the pricking direction, and the longitudinal position of the
cap in the pricking direction can be adjusted by an adjustment device
in order to adjust the pricking depth.
6. Blood lancet system for blood withdrawal for diagnostic purposes,
comprising a lancet. a pricking apparatus with a housing, a lancet
holder movable in the housing for holding an exchangeable lancet,
and a lancet drive for driving a pricking movement of the lancet
on a predetermined pricking path, wherein the housing comprises
a cap to be attached at a forward end thereof in pricking direction,
the cap being removable for removing a used lancet out of the housing,
and the lancet and the cap are adapted to be coupled, during attaching
the cap to the housing, by a coupling mechanism comprising matching
zoupling elements, thereby enabling the extraction of the lancet
from the lancet holder by removing the cap, and an ejector which
is movable in the housing in the pricking direction for ejecting
the lancet from the lancet holder, is a component of the coupling
mechanism, and has at a first end thereof a first of the matching
coupling elements and at a second end thereof a lancet contact element
contacting the lancet during the ejection thereof.
7. Blood lancet system according to claim 6 wherein a second of
the matching coupling elements is arranged at the cap.
8. Blood lancet system according to claim 6 wherein the ejector
has an intermediate part guided by a guide element such that it
is movable parallel to the pricking path, the front end of the intermediate
part being connected to the coupling element and the rear end of
the intermediate part being connected to the lancet contact element.
9. Blood lancet system according to claim 8 wherein the movable
intermediate part comprises a sleeve surrounding a lancet which
is inserted in the holder.
10. Blood lancet system according to claim 6 wherein the cap has
a contact surface for contacting the blood lancet apparatus to the
skin, the cap can be fixed to the housing at a defined position
in the pricking direction, and the longitudinal position of the
cap in the pricking direction can be adjusted by an adjustment device
in order to adjust the pricking depth.
11. Blood lancet system according to claim 6 wherein at least
one of the coupling elements has a protrusion which is elastically
biased in a direction transversal to the pricking direction and
which latches during the coupling of the lancet and the cap into
a corresponding recess of the other coupling element.
12. Blood lancet system according to claim 6 wherein the lancet
comprises a lancet body made of plastic, a lancet needle fixed in
the lancet body, and a tip cover element covering the lancet tip,
the tip cover element being connected to the lancet body via a breaking
point such that it can be removed after the insertion of the lancet
into the lancet holder in order to expose the lancet tip protruding
from the lancet body.
13. Blood lancet system according to claim 6 wherein the cap has
a contact surface for contacting the blood lancet apparatus to the
skin, the cap can be fixed to the housing at a defined position
in the pricking direction, and the longitudinal position of the
cap in the pricking direction can be adjusted by an adjustment device
in order to adjust the pricking depth.
14. Blood lancet system for blood withdrawal for diagnostic purposes,
comprising a lancet and a pricking apparatus with a housing, a lancet
holder movable in the housing for holding an exchangeable lancet,
and a lancet drive for driving a pricking movement of the lancet
on a predetermined pricking path, the housing comprising a cap to
be attached at a forward end thereof in pricking direction, the
cap being removable for removing a used lancet out of the housing,
the lancet and the cap being adapted to be automatically coupled,
during attaching the cap to the housing, by a coupling mechanism
comprising matching coupling elements, thereby enabling the extraction
of the lancet from the lancet holder without additional handling
steps by removing the cap, wherein the coupling mechanism comprises
a movable ejector for ejecting the lancet, a coupling element of
the ejector and a corresponding coupling element of the cap are
adapted to each other such that the cap is coupled to the ejector
during attachment of the cap to the housing and during removal of
the cap after the pricking action the lancet is ejected from the
lancet holder in such a manner that the used lancet falls into the
cap or remains unattached in the lower section of the housing, whereby
the used lancet can be disposed without user contact.
15. Blood lancet system according to claim 14 wherein a second
of the matching coupling elements is arranged at the cap.
16. Blood lancet system according to claim 14 wherein the ejector
has an intermediate part guided by a guide element such that it
is movable parallel to the pricking path, the front end of the intermediate
part being connected to the coupling element and the rear end of
the intermediate part being connected to the lancet contact element.
17. Blood lancet system according to claim 16 wherein the movable
intermediate part comprises a sleeve surrounding a lancet which
is inserted in the holder.
18. Blood lancet system according to claim 14 wherein at least
one of the coupling elements has a protrusion which is elastically
biased in a direction transversal to the pricking direction and
which latches during the coupling of the lancet and the cap into
a corresponding recess of the other coupling element.
19. Blood lancet system according to claim 14 wherein the lancet
comprises a lancet body made of plastic, a lancet needle fixed in
the lancet body, and a tip cover element covering the lancet tip,
the tip cover element being connected to the lancet body via a breaking
point such that it can be removed after the insertion of the lancet
into the lancet holder in order to expose the lancet tip protruding
from the lancet body.
20. Blood lancet system according to claim 14 wherein the cap
has a contact surface for contacting the blood lancet apparatus
to the skin, the cap can be fixed to the housing at a defined position
in the pricking direction, and the longitudinal position of the
cap in the pricking direction can be adjusted by an adjustment device
in order to adjust the pricking depth.
Description This invention is concerned with a blood lancet system for blood
withdrawal for diagnostic purposes.
In case of various illnesses it is necessary to investigate the
human blood with respect to a component (analyte) contained therein.
To this end it is oftentimes sufficient to withdraw a small amount
of blood from the body by generating a small prick wound. A particularly
important such case is diabetes mellitus, which requires the blood
to be investigated in regular intervals for its glucose content.
For generating the necessary prick wound, commonly blood lancet
systems are used which comprise a pricking apparatus and replaceable
lancets, adapted to this apparatus. The housing of the pricking
apparatus contains a lancet adapted for holding the lancet in a
replacable manner. During the pricking process, the lancet is driven
by a lancet drive, also integrated in the lancet apparatus, in a
way that the lancet is moved quickly in the pricking direction,
until the lancet tip protrudes from an opening at the front end
of the pricking apparatus, thus generating a small prick wound in
the body part pressed against the front end. Thereafter the lancet
is moved back (against the pricking direction).
When common pricking apparatuses are in their use state, the lancet
holder is covered by a housing cap which forms the front end of
the pricking apparatus housing and has a small opening through which
the lancet tip can protrude during the pricking process. The pricking
opening is surrounded by a contact surface which serves for contacting
the blood lancet apparatus to the body part from which the blood
shall be withdrawn during use of the blood lancet apparatus (usually
the finger tip or the ear lobe).
For avoiding infections, the lancets are disposable elements designed
for a single use. In order to insert a new lancet, the housing cap
covering the lancet holder is removed, and the lancet is inserted
into the lancet holder. The housing cap is also removed for removing
used lancets.
Blood lancet systems are not only used by medical staff, but also,
and to a large extent, by non-experts. This is particularly true
for the therapy control of diabetics. It was determined that serious
damages occurring in conjunction with diabetes (e.g. blindness)
can be dramatically reduced if the glucose concentration of the
diabetic's blood is measured very often (four to five times a day),
adjusting the insulin injections very exactly, using these measurements.
The willingness and the ability of diabetics to check their blood
that often in the scope of home-monitoring highly depends on the
optimal function of the blood lancet system used.
An important part of this function are the handling steps necessary
for the insertion of new and the removal of used lancets. On one
hand, they should be as simple as possible, and on the other hand
there should be maximum safety against injury and infection risks.
At the same time, the cost, in particular with respect to the disposable
material, should be as low as possible.
During the insertion of the lancet, the sharp tip of the lancet
needle is usually covered by a tip cover element made of plastic
and allowing a secure handling of the lancet. Once the lancet is
inserted, the tip cover element must be removed and the housing
cap must be attached. After the pricking process, the housing cap
must be removed, so that the lancet becomes accessible again. Then,
the lancet can be manually removed. The risk of injury at the lancet
tip, however, is very high, in particular taking into account that
a large share of the users is handicapped by high age, bad vision
or trembling hands.
In order to simplify the removal of the used lancet, many apparatuses
are equipped with a manually operated ejection mechanism. For example,
U.S. Pat. No. 5318584 describes a blood lancet system in which
the blood lancet can be ejected from the lancet holder by means
of an ejection rod; the ejection rod is actuated by pressing an
actuation button provided at the rear end of the pricking apparatus.
U.S. Pat. No. 4442836 describes an apparatus having an ejection
mechanism designed in a way that the used lancet is automatically
thrown out when re-cocking the apparatus after each pricking process.
However, such ejection mechanisms require a relatively complicated
and expensive construction. The handling is not as easy as desirable,
taking into account the health state of many users.
EP 0 958 783 A1 describes a blood lancet apparatus which is equipped
with so-called engagement means at the cap, which can be moved by
the user from a first position, not in engagement with the lancets,
into a second position, where they contact the lancet pressing it
against the opposite interior wall of the cap. For actuation of
the engagement means, a button may be provided which protrudes laterally
from the cap. After the pricking process the user must first press
this button, thus clamping the lancet in the cap, then take off
the lancet together with the cap, and finally dispose the lancet.
This requires an additional, difficult handling step, causing a
severe problem for many users.
With the aim to achieve optimal simplicity and operational safety
some known blood lancet systems have the lancet integrated into
the cap, so that the lancet and the housing cap together form a
replaceable, disposable unit. Such designs are described in EP-0595148
A1 and in U.S. Pat. Nos. 4990154 and 5628765. A disadvantage
of this design is the high material consumption, because the entire
disposable design unit, including the housing cap, has to be disposed
after each use. Due to the high cost these systems are only appropriate
for application areas with high safety and hygienic requirements,
in particular for the use in hospitals. In the home-monitoring area,
on one hand safety risks are lower since the blood lancet systems
are always used by the same patient, on the other hand the cost
for the integrated lancet-cap-disposables is not acceptable.
On this basis, the invention addresses the problem to provide a
blood lancet system, in particular for home-monitoring, which allows
a riskless and simple removal of used lancets from the lancet holder
without a need to touch the lancet and with as little expense as
possible.
This problem is solved by a blood lancet system for blood withdrawal
for diagnostic purposes, comprising lancets and a pricking apparatus
with a housing, a lancet holder movable in the housing for holding
an exchangeable lancet, and a lancet drive for driving a pricking
movement of the lancet on a predetermined pricking path, wherein
the housing comprises a cap to be attached at a forward end thereof
in pricking direction, the cap being removable for removing a used
lancet out of the housing, and the lancet and the cap are coupled
to each other, while the cap is attached to the housing, by a coupling
mechanism comprising coupling elements matched to each other, thereby
enabling the extraction of the lancet from the lancet holder simultaneously
with removing the cap.
In contrast to the mentioned lancet-cap-disposables, the lancet
used with the instant invention is a separate element, produced
and distributed independently from the housing cap. It is the only
disposable part. The cap can be used permanently, thus it can be
produced with higher quality. The use is very simple as the pulling-off
of the housing cap and the removal of the used lancet is performed
in a single handling step.
In contrast to the design described in EP 0958783 the invention
does not require any additional handling steps, as the coupling
of the cap with the lancet is performed automatically during the
procedure of the handling steps which are anyway necessary and common.
In the most simple case, the coupling mechanism acts directly between
the housing cap and the lancet. Generally, lancets have a lancet
body made of plastic, surrounding the metal lancet needle. The first
of the matched coupling elements can be provided at this lancet
body. The second coupling element is provided, preferably, directly
at the cap (at its inner wall). For example, the lancet body may
have a groove-type recess running in the direction of its longitudinal
axis, in which a catch may latch in, which latch protrudes from
an elastic tongue fixed at the inside wall of the cap. When the
cap is attached, the protruding catch latches into the groove. The
dimensions of the groove are designed in such a way that the lancet
movement in pricking direction, required for the pricking process,
is possible.
An embodiment in which the coupling mechanism includes an additional
part designated as ejector, is preferred. The ejector is arranged
in the housing in a way that it is movable in the pricking direction.
It is provided with a lancet contact element which contacts the
lancet during the ejection process, thus pressing or pulling it
out of the holder. For this design type, a first of the matched
coupling elements is arranged at the ejector, and, preferably, a
second of the matched coupling elements is arranged at the cap.
The invention is explained in more detail with reference to an
embodiment represented in the figures. The features described there
can be applied single or in combination in order to create preferred
embodiments of the invention.
FIG. 1 shows a perspective exploded view of the front part of a
blood lancet apparatus according to the invention,
FIG. 2 shows a longitudinal section through the blood lancet apparatus
in the state of utilization (lancet inserted, ejector retracted),
FIG. 3 shows a longitudinal section according to FIG. 2 during
the removal of the cap (lancet free, ejector pulled out)
FIG. 4 shows a perspective view of the lancet holder, the lancet
and the ejector in the position according to FIG. 2
FIG. 5 shows a perspective representation according to FIG. 4 without
the lancet holder,
FIG. 6 shows a longitudinal section according to FIG. 2 in reduced
scale in a handling stage just after inserting a new lancet,
FIG. 7 shows a longitudinal section according to FIG. 6 in a handling
stage in which the housing cap is attached,
FIG. 8 shows a longitudinal section according to FIG. 6 in a handling
stage in which the housing cap is removed,
FIG. 9 shows a longitudinal section according to FIG. 8 in a slightly
later handling stage during removing of the housing cap.
The blood lancet system 1 represented in FIGS. 1 to 5 consists
of a pricking apparatus 2 and exchangeable lancets 3 adapted to
be used together with the pricking apparatus 2. The lancets 3 have
a lancet body 4 made of plastic and a needle 5 fixed in the lancet
body 4; the sharp tip 6 of the lancet needle 5 protrudes from the
lancet body in the pricking direction symbolized by the arrow 7.
For the unused lancet 3 represented in FIG. 1 the tip 6 is covered
by a tip cover element 8 which is connected to the lancet body
4 via a breaking point 9 in a way that it can easily be removed
by turning and pulling, thus exposing the tip 6.
In the embodiment shown, the housing 10 of the pricking apparatus
2 is designed with an elongated shape, similar to a pencil (so-called
pencil-design). The longitudinal axis 11 of the pricking apparatus
2 runs in the pricking direction 7.
A lancet holder 12 is located in the housing 10. The lancet 3 is
fixed in the lancet holder 12 by means of an appropriate clamping
device in an exactly reproducible longitudinal position. In the
represented case, the lancet holder 12 has two holder tongues 12a,
precooked radially towards the interior of the holder and engaging
with corresponding recesses 4a of the lancet body 4. Further characteristics
of this fixing design can be taken from U.S. Pat. No. 5318584.
The lancet holder is guided and arranged in a way that it can be
moved forward, with as few vibrations as possible, in pricking direction
7 inside the housing 10 until the lancet tip 6 protrudes from an
opening 13 thereby generating a prick wound in a body part 25 (FIG.
2) touching a contact surface 14 which is ring-shaped and surrounds
the opening 13.
The pricking movement of the lancet holder 12 and a lancet 3 held
thereby is driven by a lancet drive, designated as a whole as 15.
The lancet drive is preferably designed according to the principles
described in U.S. Pat. No. 5318584. This includes use of a cam
control. A control pivot 16 (FIG. 4) is arranged at the lancet holder;
it meshes, acting as operating cam, into a recess of a drive rotor
17 (only partially visible in FIGS. 2 and 3). The drive rotor 12
performs a turn around the longitudinal axis 11 of the housing 10.
The rotation of the drive rotor 17 with the operating cam located
therein, leads to a corresponding longitudinal movement of the control
pivot 16 and thus of the lancet holder 12 in pricking direction
7. Further characteristics of this preferred lancet drive 15 can
be taken from the US patent mentioned before.
The front end, in pricking direction, of the housing 10 is formed
by a cap 20 covering the insertion end designed for inserting the
lancet 3 into the lancet holder 12. The cap 20 is removeably fixed
at the housing 10. To this end different fastening principles can
be used, as long as a precise and reproducible definition of the
longitudinal position of the housing cap 20 with respect to the
lancet holder 12 is provided. For the design shown, a latch fastening
is used, in which a bulge 22 provided at the cap 20 latches into
a corresponding recess 23 of a housing part 24. Instead of such
a latch fastening, a thread fastening can also be used.
In the embodiment shown, the housing part 24 to which the cap 20
is fastened, is adjustable in its longitudinal position in relation
to the rest of the housing 10 and thus in relation to the lancet
holder 12 by means of a thread 26. This allows an adjustment of
the pricking depth. The more the housing part 24 and thus the cap
20 where the contact surface 14 is located, are shifted forwardly,
in pricking direction 7 the smaller becomes the pricking depth,
for a given lowest position of the lancet holder 12 in pricking
direction 7.
A coupling mechanism 28 by which the lancet 3 and the housing
cap 20 are coupled automatically to each other while the housing
cap is attached the housing 10 includes an ejector 30 moveably
arranged in pricking direction 7. It can best be seen in its entirety
in FIG. 5. Generally, the ejector 30 may be formed by any constructive
part comprising in its forwardly located section, with respect to
the pricking direction, a coupling element 34 for coupling to the
housing cap 20 and in its rearwardly located section a lancet contact
element 31 which may contact the lancet 3 in such a way that movement
of the lancet contact element 31 in pricking direction 7 causes
ejection of the lancet 3 from the lancet holder 12. The part of
the ejector 30 between the lancet contact element 31 and the coupling
element 34 is designated intermediate part 33.
In the embodiment shown, the lancet contact element 31 is formed
by two ejector rods 32 pushing against the rear end of the lancet
3. A coupling element 34 of the ejector 30 and a corresponding coupling
element 35 of the housing cap 2 are adapted to each other such that
the cap 20 is coupled to the ejector 30 and thus indirectly to
the lancet 3 during attachment of the housing cap 20 to the housing
10. In the represented case, the ejector-side coupling element 34
is embodied by three segments of a radial collar 37 protruding
radially outwardly from a sleeve 38 surrounding the lancet holder.
The sleeve 38 has recesses in the area of the collar 37 separating
the segments of the radial collar 37 from each other and allowing
an elastic deformation, radially to the inside, of the sleeve 38
in the area of the radial collar 37.
In the embodiments shown, the coupling element 35 provided at the
housing cap 20 is formed by a ring-shaped protrusion 41 located
at the inside wall 40 of the housing, arranged and adapted in such
a manner that during the attachment of the cap 20 the sleeve 38
is slightly compressed in the area of the radial collar 37 and
the radial collar 37 latches, after passing the narrow formed by
the ring-shaped protrusion 41 into a recess 43 which is located
before the ring-shaped protrusion 41 in pricking direction 7.
Numerous variations of the coupling mechanism 28 are possible,
provided that, on one hand, the coupling between the housing cap
20 and the lancet 3 (preferably indirectly via an ejector 30) is
effected during attaching of the housing cap 20 onto the housing
10 (after previously having inserted the lancet 3 as a separate
part into the lancet holder 12), and, on the other hand, the lancet
3 is during the removal of the cap 20 simultaneously pulled out
of the lancet holder 12. The represented coupling principle, in
which at least one of the coupling elements 3435 is biased elastically
in such a manner that it latches into a corresponding recess (here,
the recess 43) of the other coupling element 35 is preferred, because
it allows a particularly simple handling. However, an appropriate
coupling can also be obtained, e.g., by a bayonet joint.
Furthermore, the contact between a lancet contact element 31 provided
at the ejector 30 and the lancet, which is necessary for the removal
of the lancet 3 from the lancet holder 12 must not necessarily
be embodied by a push-out device, which pushes against the lancet
from its rear end, as the ejector rod 32 does. A design which pulls
the lancet 3 out of the lancet holder 12 is also possible in which
case a lancet contact element provided at a correspondingly shaped
ejector may latch into a corresponding recess of the lancet body,
conveniently from the side.
The embodiment shown, in which the intermediate part 33 of the
ejector 30 which joins the ejector-side coupling element 34 with
the lancet contact element 31 is at least partially sleeve-shaped,
is particularly preferred, as the sleeve 38 allows a precise guiding
of the lancet holder 12 contained therein. Other designs are also
possible. For example, the ejector can be formed by two or more
rods arranged preferably rotation-symmetrically in pricking direction.
At the front section of these rods, coupling elements for coupling
to the cap 20 may be provided, and at their rear section, a lancet
contact element 31 may be present.
FIGS. 6 to 9 show, complementary to the FIGS. 2 and 3 some more
handling stages of the blood lancet system 1 according to the invention.
The lancet is gripped at the tip cover element 9 and inserted into
the holder 12 (FIG. 6) with the housing cap 20 removed. Thereafter,
the tip cover element 9 is turned off and the housing cap 20 is
attached, its protrusion 41 pressing against the radial collar 37
of the sleeve 38 thus pushing the ejector 30 backwards, until its
axial backward movement is stopped by a thrust block (FIG. 7).
If the housing cap (20) is further pushed backwards (into the position
represented in FIG. 2), the ring-shaped protrusion 41 comes into
an axial position behind the radial collar 37 so that the coupling
elements 3435 latch into each other.
After the pricking process, which is not different from previously
known blood lancet systems, the housing cap 20 is removed again.
During removal it reaches the position represented in FIG. 8 where
the ring-shaped protrusion 41 is in contact with the radial collar
37. Thus, if the housing cap 20 is moved further in forward direction
(in pricking direction 7), the ejector 30 is moved forward, pushing
by means of its lancet contact element 31 (ejector rod 32) the lancet
3 out of the holder in forward direction. The lancet then falls
into the housing cap 20 or remains unattached in the lower section
of the housing 10. After taking off the housing cap 20 the used
lancet 3 can be disposed into a waste bin without having to touch
it. |