Abstract:
A lancing device includes a main body having a drive spring, hammer, trigger mechanism and a lancet holder  22 . A lancet  34  may be pushed to engage in snap fit with forwardly extending arms  28  of the lancet holder. Whilst free to move axially, the lancet  36  is held against rotation and, following use, is released from the lancet holder by rotating the lancet holder to disengage the lancet from the forwardly extending arms  28  thus freeing the lancet.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to lancing devices and in particular, but not exclusively, to such lancing devices for use with a replaceable lancet. 
     2. Description of the Related Art 
     There is a need for lancing devices in which a disposable lancet is introduced into the device and released therefrom with the minimum of handling. 
     SUMMARY OF THE INVENTION 
     Accordingly, in one aspect, this invention provides a lancing device comprising a housing, a lancet holder within the housing for receiving in use a replaceable elongate lancet introduced into said housing, a drive actuable to drive said lancet momentarily to project a tip from the housing, a lancet release element for effecting relative angular movement of said lancet holder and said lancet generally about the longitudinal axis of the lancet from a position in which said lancet is retained by said holder and a position in which said lancet is released from said retention. 
     Although we do not exclude the possibility of the lancet being rotatable about its longitudinal axis, it is preferred for said lancet holder to be rotatable with respect to said housing. 
     Where said lancet has a main body portion of non-circular cross-section, said housing preferably has a non-circular cross-section passage of similar shape through which said lancet is introduced into said housing. 
     Advantageously, said lancet holder is adapted to receive said lancet in snap engagement when the latter is pushed into said device. 
     Preferably said lancet holder is slideably and non-rotatably engaged with said lancet release, said release element being rotatably disposed within the housing and having an externally accessible portion. 
     Said drive mechanism conveniently includes a hammer moveable to a cocked position within said housing, with said lancet release element preferably being adapted to latch said hammer in its cocked position. 
     In one arrangement the device includes a rotatable nose portion having an aperture through which said lancet projects when fired, said nose portion being threadedly engaged with the forward end of said housing to allow the penetration depth of said lancet tip to be pre-set. Said nose portion may have a generally cylindrical rearward skirt having abutments disposed to face complementary abutments on or associated with said housing, said skirt portion being resiliently deformable between a position in which said abutments engage to prevent or resist rotary movement of said nose portion, and a position in which said abutment means move away from each other to allow rotation. 
     In another arrangement, the device includes a nose portion assembly mounted on the forward end of said housing, said nose portion assembly comprising a non-rotatable nose portion element slideably and non-rotatably mounted on the forward end of said housing, the nose portion being captive on a rotary collar which is threadedly engaged with the forward end portion of the housing to allow the penetration depth of the lancing device to be pre-set. 
     In another aspect this invention provides a lancing device comprising a housing for receiving in use a replaceable lancet introduced into said housing, drive means actuable to drive said lancet momentarily to project its tip from the housing, and a nose portion having an aperture through which said lancet projects when fired, said nose portion being threadedly engaged with the forward end of said housing to allow the penetration depth of said lancet tip to be pre-set, said nose portion being resiliently deformable between a position in which it is locked against rotation and a position in which it is free to rotate. 
     In yet another aspect this invention provides a lancing device comprising a housing for receiving in use a replaceable lancet introduced into said housing, drive means actuable to drive said lancet momentarily to project its tip from the housing, and a nose portion assembly mounted on the forward end of said housing, said nose portion assembly comprising a nose portion element slideably and non-rotatably mounted on the forward end of said housing, the nose portion being captive on a rotary collar which is threadedly engaged with the forward end portion of the housing to allow the penetration depth of the lancing device to be pre-set. 
     Whilst the invention has been described above, it extends to any inventive combination or sub-combination of the features set out above or in the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       Two embodiments of the invention will be described by way of example only, reference being made to the accompanying drawings, in which: 
         FIG. 1  is a general perspective view of a first embodiment of lancing device in accordance with this invention; 
         FIG. 2  is a view similar to  FIG. 1  but with part of the casing removed, showing the device with a lancet loaded and the hammer cocked; 
         FIG. 3  is a view similar to  FIG. 1  but showing the nose piece removed forwardly for introduction/disposal of a lancet; 
         FIG. 4  is a view similar to  FIG. 2  with the hammer in a cocked position but showing the lancet holder rotated to release a lancet; 
         FIG. 5  is a view similar to  FIG. 4  but showing the lancet exiting the housing; 
         FIG. 6  is a view showing a new lancet pushed into engagement with the lancet holder with the hammer cocked; 
         FIG. 7  is an exploded view of the first embodiment of lancing device; 
         FIG. 8  is a longitudinal sectional view through the first embodiment of lancing device loaded with a lancet and with the hammer cocked; 
         FIG. 9  is a top plan view of the first embodiment of lancing device; 
         FIG. 10  is a perspective view of a second embodiment of lancing device in accordance with this invention with a modified depth adjustment mechanism which allows the lancet to be loaded without removing the nose portion of the device, and with the lancet about to be inserted into the device; 
         FIG. 11  is a view similar to  FIG. 10  but showing the lancet cap being twisted off; 
         FIG. 12  is a view of the second embodiment of lancing device with the forward part thereof in section to illustrate the depth adjustment mechanism; 
         FIG. 13  is a full side section view of the second embodiment of lancing device; 
         FIG. 14  is an exploded, detailed view of the depth adjustment device of the second embodiment; 
         FIG. 15  is a longitudinal cross-sectional view of the second embodiment, and 
         FIG. 16  is a top plan view of the second embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring initially to the first embodiment shown in  FIGS. 1 to 9 , this comprises forward and rearward housing parts,  10 ,  12  with a rotary nose portion  14  captive on the forward housing part  10 , for penetration depth adjustment. The device is designed to receive a removable lancet (shown in later Figures) which is introduced through the front end of the device and releasably retained therein. Once loaded with a lancet, the device is cocked using a cocking slider  16 , fired using a firing button  18 , and the lancet then released using a lancet release lever  20 . 
     Referring now more particularly to  FIGS. 2 and 4  to  8 , the forward housing  10  slideably receives a lancet holder  22  which has a cylindrical rear portion  24  to the forward end of which is a circumferential guide flange  26 , and extending forwardly are two resiliently deformable arms  28  terminating forwardly in inwardly directed barbs  30 . The lancet holder  22  is urged rearwardly by means of a compression spring  32  acting between the guide flange  26  and a rearwardly facing shoulder in the forward housing part  10 . The resiliently deformable arms  28  with their inwardly directed barbs  30  are designed to receive in one way snap engagement the rear end of a lancet  34 . The lancet has a main body portion having a central cylindrical stem  36  and diametrically opposed flanges  38 . The flanges are chamfered at the rear end to assist engagement and snapping past the resilient barbs  30 , and then cut away at  40  to form a latch recess for the inwardly directed barbs. The lancet holder  22  includes a thrust surface  41  against which the rear end of the lancet rests. The cylindrical portion  24  includes two diametrically opposed lugs  42  which fit into respective slots  44  formed in a cylindrical shell portion  46  forming part of the lancet release lever  20 . The lancet release lever  20  has protruding flaps  48  which protrude through diametrically opposed slots  50  formed between the forward and rearward housing parts. The lancet release lever  20  is biased in the clockwise direction when viewed from the front by means of a torsion spring  52  engaged at its forward end with the cylindrical shell  46  and at its rearward end on a seat within the rearward housing part  12 . The cylindrical portion  24  of the lancet release lever  20  steps in rearwardly to provide an inner cylindrical portion  54 , which defines a cylindrical latching surface  56 . 
     A hammer  58  is slideably received in the inner cylindrical portion  54  and urged forwardly by a drive spring  59  acting between the hammer and a rear end of the rearward housing part. The hammer is provided with a forwardly extending resiliently deformable arm  60  having a barb  62  on it for cooperating with the latching surface  56  on the cylindrical portion  54  to latch the hammer in a cocked position. Surrounding the aft end of the hammer is a cylindrical cocking shell  64  having two inwardly directed lugs  66  which project to either side of a longitudinal ventral rib  68  on the hammer  58 . At its rearward end the hammer is provided with a rear end disc  70 . The cocking slider  16  is connected to the cocking sleeve  64  by a snap fit through a slider slot  72 . The slider is biased forwardly by a compression spring  74 . 
     At its front end, the forward housing part has an aperture  74  designed to receive the cross-section of the lancet  34 , thus comprising a circular centre with diametrically opposed grooves. The aperture  74  is at the front end of a guide passage  76  of constant cross-section which provides support for the lancet during loading, firing and unloading. 
     The forward portion of the forward housing part is externally threaded at  78  and, rearwardly thereof on a stepped outwardly portion is a series of locking splines  80 . The nose portion  14  has an internal threaded region  81  so that it can be screwed onto the front of the forwarding housing part. The nose portion has a rearward cylindrical skirt  82  designed to fit with clearance over the corresponding surface of the forward housing portion. The skirt has two longitudinal ribs  84  which cooperate with the splines  80 , to restrict or prevent rotation of the nose portion when relaxed. At 90° around the circumference of the skirt  82  are two pressure pads  86 . The nose portion is designed relative to the forward housing part so that, on pressing the pressure pads  86  towards each other, the locking ribs  84  are lifted away from engagement with the splines so that the nose portion can be rotated to adjust the axial position of its foremost portion and thus the penetration depth. The nose portion  14  has a central, circular aperture through which the tip of the lancet  34  projects momentarily when fired. 
     In use, assuming the device already contains a used lancet, the nose portion  14  is unscrewed from the front end of the device and the lancet release lever  20  twisted by pressing one of the flaps  48 . The lancet is held against rotation by engagement with the passage  76  and so the barbed resilient arms  28  are twisted out of engagement with the lancet so the lancet is released and can be dropped into a suitable disposal container (see  FIGS. 4 and 5 ). The lancet release lever  48  is then allowed to return to its original position and a fresh lancet introduced into the device through the passage  76  so that it snaps into engagement with the resilient barbed arms of the lancet holder as seen in  FIG. 6 . The cap  88  of the lancet is then twisted off to uncover the tip, the tip still being safely within the device. The nose portion  14  is screwed on and the appropriate penetration depth set using the marker  90  and indicia  92 . The device is cocked by sliding the cocking slider  16  rearwardly which pulls the hammer  58  backwards until the barb  62  latches against the latching surface  56  on the inner cylindrical portion  54 . The user then offers the device up to their skin and presses the firing button  18  which pushes the barbed arm  60  inwards to unlatch it from the latching surface  56  so the hammer shoots forwardly and impacts the rear of the lancet holder  22  to drive the lancet holder and the lancet forwardly to project the lancet tip through the end of the housing and to rebound back into the housing. 
     Referring now to the second embodiment, in this arrangement the design of the nose portion has been changed so that it is not necessary to remove the nose portion in order to introduce a lancet into the device. Apart from the redesign of the nose portion, the construction and operation of the second embodiment is identical to that of the first and will not be described again. Referring in particular to  FIG. 14 , in this arrangement, the forward housing part  10  is provided with an external thread  94 , and a forward extension of the front portion is provided with two diametrically opposed anti-rotation splines  96 . The forward nose piece  98  is designed to slide onto the forward portion of the housing and has grooves  100  which slide over the splines  96  to prevent rotation. Captively mounted in a scalloped groove  102  is a nose collar  104  having an internal thread which is engageable with thread  94  on the housing. The collar  104  is formed with a resiliently mounted pip  105  which engages the scalloped region in the groove  102  on the nose piece  98  to provide a click detent action. When assembled, the nose piece  98  is held against rotation and turning the collar  104  adjusts the axial position of the nose piece  98 . The collar has a marker  106  which indicates the penetration setting using indicia  108  on the forward housing. In use, a lancet can be introduced into the device before or after the depth setting has been adjusted.