Patent Publication Number: US-2023144482-A1

Title: Latch mechanism for preventing lancet oscillation in a lancing device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. Non-Provisional patent application Ser. No. 17/741,517 filed May 11, 2022, which is a continuation of U.S. Non-Provisional patent application Ser. No. 17/034,888 filed Sep. 28, 2020, which is a continuation of U.S. Non-Provisional patent application Ser. No. 15/824,443 filed Nov. 28, 2017, now U.S. Pat. No. 10,820,849 issued Nov. 3, 2020, which is a continuation of U.S. Non-Provisional patent application Ser. No. 13/655,168 filed Oct. 18, 2012, now U.S. Pat. No. 9,844,331 issued Dec. 19, 2017, which claims the priority benefit of U.S. Provisional Patent Application Ser. No. 61/570,894 filed Dec. 15, 2011, the entireties of which are hereby incorporated herein by reference for all purposes. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to the field of medical devices, and more particularly to a lancing device for blood sampling and testing with an incorporated mechanism for preventing excess lancet oscillation. 
     BACKGROUND 
     Lancing devices are utilized for penetrating the skin of a human or animal subject at a lancing site to obtain a sample of blood or other body fluid for medical testing, as in blood-typing or blood-glucose testing. Known lancing devices commonly include a housing containing a drive mechanism with a drive spring, a charging mechanism for energizing the spring, and a release mechanism for releasing the drive mechanism to propel a lancet through a lancing stroke. A lancet is propelled by the drive mechanism from a retracted position within the housing to an extended position where a sharp tip portion of the lancet projects from the housing to prick the subject&#39;s skin at a desired lancing site. U.S. Patent App. Pub. No. US2011/0196261 and U.S. Patent App. Pub. No. US2010/0160942 show example lancing devices and are incorporated herein by reference. 
     Many known lancing devices include two springs, a drive spring to drive the lancet along an advancing portion of the lancet stroke toward the lancing site, and a return spring to retract the lancet along a return portion of the lancet stroke back into the housing. Achieving the correct balance of spring forces between the two springs presents design challenges, and incorrect balance can reduce the lancet speed, potentially increasing pain sensation. It has also been discovered that some drive mechanisms can cause or permit the lancet to continue to oscillate after the lancing stroke (one forward and reverse cycle) is completed, possibly pricking the subject&#39;s skin unintentionally a second time or more and resulting in a greater sensation of pain for the patient. Friction between device components and/or energy dissipation from the lancing of the skin serves to dampen lancet oscillation in previously known lancing devices to some extent, but not to an entirely effective extent. 
     Thus it can be seen that needs exist for the reduction or elimination of excess lancet oscillation in a lancing device. It is to the provision of a system and method for preventing excess lancet oscillation in a lancing device meeting these and other needs that the present invention is primarily directed. 
     SUMMARY 
     The present invention relates to systems and methods for preventing excess lancet oscillation in lancing devices. In example embodiments, a latch mechanism allows operation of the drive mechanism to carry out the lancing stroke unimpeded, but after a single penetration of the skin at the lancing site the latch is engaged to reduce or prevent further oscillation of the lancet, to thereby prevent the lancet from contacting the skin a second time. In multi-use designs, the latch mechanism optionally also holds the drive mechanism during ejection of the lancet from the drive mechanism. 
     In one aspect, the present invention relates to a lancing device including a drive mechanism for advancing and retracting a lancet through a lancing stroke, and a latch mechanism for allowing advancement and retraction of the lancet once (through the lancing stroke) but limiting further/excess/secondary oscillation thereof. In one embodiment, the latch mechanism includes a pivotal L-shaped latch member having a leg, a foot extending generally perpendicular to and transversely offset from the leg, and a resilient finger extending generally parallel to and transversely offset from the leg and operably engaged and deflected by a ramp. In another embodiment, the latch mechanism includes a pivotal (rotary) tube/sleeve-shaped latch member with an angled guide surface and with an axially extending tooth having a lancet carrier stop projecting transversely therefrom for operable engagement by a resilient finger. 
     In another aspect, the invention relates to a method of preventing secondary oscillation of a lancet in a lancing device. The method comprises providing a lancing device with a pivotal latch mechanism configured and positioned to permit a first oscillation of the lancet when the latch mechanism is in a non-blocking position, and moving the latch mechanism to a blocking position where subsequent/excess oscillations are prevented. 
     These and other aspects, features, and advantages of the invention will be understood with reference to the drawing figures and detailed description herein, and will be realized by means of the various elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following brief description of the drawings and detailed description of example embodiments are exemplary and explanatory of preferred embodiments of the invention, and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is a side view of a lancing device according to a first example embodiment of the present invention, with a portion of the housing removed to show internal components of the device, showing a latch mechanism for preventing excess lancet oscillation, with the latch in a blocking position. 
         FIG.  1 B  shows the lancing device of  FIG.  1 A  with the drive mechanism being charged and the latch being pivoted toward an intermediate non-blocking position. 
         FIG.  1 C  shows the lancing device of  FIG.  1 B  with the latch in the intermediate non-blocking position. 
         FIG.  1 D  shows the lancing device of  FIG.  1 C  with the lancet traveling along a forward portion of its lancing stroke and the latch pivoted to a press non-blocking position. 
         FIG.  1 E  shows the lancing device of  FIG.  1 D  with the lancet traveling along a rearward return portion of its lancing stroke and the latch retained in the press non-blocking position. 
         FIG.  1 F  shows the lancing device of  FIG.  1 E  with the lancet traveling farther along its rearward return portion of its lancing stroke and the latch pivoted back to the blocking position of  FIG.  1 A . 
         FIG.  2 A  is a front perspective view of the latch member of the latch mechanism of  FIGS.  1 A- 1 F . 
         FIG.  2 B  is a top view of the latch member of the latch mechanism of  FIGS.  1 A- 1 F . 
         FIG.  2 C  is a rear perspective view of the latch member of the latch mechanism of  FIGS.  1 A- 1 F . 
         FIG.  3 A  shows the lancing device of  FIG.  1 A  with the housing entirely removed to show details of internal components of the latch, charge, and drive mechanisms, with the latch mechanism in the blocking position of  FIG.  1 A . 
         FIG.  3 B  is a top view of a portion of the lancing device of  FIG.  1 A  with a top portion of the housing removed to show the internal components, with the latch mechanism in the blocking position of  FIG.  1 A . 
         FIG.  3 C  is a front view of the lancing device of  FIG.  1 A  with a front portion of the housing removed to show the internal components, with the latch mechanism in the blocking position of  FIG.  1 A . 
         FIG.  3 D  is a front perspective view of the latch mechanism in the blocking position of  FIG.  1 A , showing details of a detent ramp of the latch mechanism. 
         FIG.  3 E  is a top view of the latch mechanism of  FIG.  3 D , showing details of the detent ramp of the latch mechanism. 
         FIG.  4    is a rear perspective view of the latch member and the detent ramp with the latch mechanism in the position of  FIG.  1 B . 
         FIG.  5    is a top perspective view of the latch member and the detent ramp with the latch mechanism in the press non-blocking position of  FIGS.  1 D and  1 E . 
         FIG.  6 A  is perspective view of a portion of a latch mechanism according to an alternative embodiment to that shown in  FIGS.  1 A- 5   , with the latch mechanism in the blocking position. 
         FIG.  6 B  shows the latch mechanism portion of  FIG.  6 A  with the latch mechanism in the intermediate non-blocking position. 
         FIG.  7 A  is a front perspective view of a latch member of a latch mechanism of a lancing device according to a second example embodiment of the present invention. 
         FIG.  7 B  is a rear perspective view of the latch member of  FIG.  7 A , showing a torsion spring coupled thereto. 
         FIG.  7 C  is a top view of the latch member of  FIG.  7 A . 
         FIG.  8 A  is a rear perspective view of a spring finger of the latch mechanism of  FIGS.  7 A- 7 C . 
         FIG.  8 B  is a front perspective view of the spring finger of  FIG.  8 A . 
         FIG.  9 A  is a perspective view of the lancing device with the latch mechanism of  FIGS.  7 A- 8 B , with portions removed to show internal components thereof, showing the latch in a blocking position. 
         FIG.  9 B  shows the lancing device of  FIG.  9 A  with the drive mechanism being charged and the latch pivoted to an intermediate non-blocking position. 
         FIG.  9 C  shows the lancing device of  FIG.  9 B  with the lancet traveling along a forward portion of its lancing stroke and the latch pivoted to a press non-blocking position. 
         FIG.  10 A  is a side view of the lancing device in the blocking position of  FIG.  9 A . 
         FIG.  10 B  is a side view of the lancing device in the intermediate non-blocking position of  FIG.  9 B . 
         FIG.  10 C  is a side view of the lancing device in the press non-blocking position of  FIG.  9 C . 
         FIG.  11 A  is a cross-sectional view of the lancing device taken at line  11 A- 11 A of  FIG.  10 A . 
         FIG.  11 B  is a cross-sectional view of the lancing device taken at line  11 B- 11 B of  FIG.  10 B . 
         FIG.  11 C  is a cross-sectional view of the lancing device taken at line  11 C- 11 C of  FIG.  10 C . 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS 
     The present invention may be understood more readily by reference to the following detailed description of the invention taken in connection with the accompanying drawing figures, which form a part of this disclosure. It is to be understood that this invention is not limited to the specific devices, methods, conditions or parameters described and/or shown herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to be limiting of the claimed invention. Any and all patents and other publications identified in this specification are incorporated by reference as though fully set forth herein. 
     Also, as used in the specification including the appended claims, the singular forms “a,” “an,” and “the” include the plural, and reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” or “approximately” one particular value and/or to “about” or “approximately” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. 
     With reference now to the drawing figures, wherein like reference numbers represent corresponding parts throughout the several views,  FIGS.  1 A- 5    show a lancing device  10  according to a first example embodiment of the invention. The lancing device  10  generally includes a drive mechanism  15 , a charging mechanism  30 , a release mechanism  40 , and a housing  12  at least partially enclosing these components. 
     The drive mechanism  15  includes a drive spring  14  and a return spring  16  for driving a lancet carrier  18  through a lancing stroke. In multi-use embodiments such as that depicted, the lancet carrier  18  removably engages a lancet  20  comprising a lancet body with a sharp lancet tip  22  projecting therefrom. The charging mechanism  30  operates to retract the lancet carrier  18  from a neutral or normal position to a retracted or charged position to energize the drive spring  14 , and the release mechanism  40  holds the lancet carrier  18  in the retracted position and upon actuation releases the lancet carrier  18  to initiate the lancing stroke. The charged drive spring  14  propels the lancet carrier  18  and lancet  20  along an advancing/forward portion of the lancing stroke, from the charged position within the housing to an advanced/extended position where at least the sharp lancet tip  22  projects from the housing  12  to penetrate the subject&#39;s skin at a lancing site. The forward portion of the lancing stroke charges the return spring  16 , and the now-charged return spring then returns the lancet carrier  18  and lancet  20  to the neutral/normal position. 
     Optionally, the housing can include an endcap or nose-cone portion  50  that provides for adjustment of the penetration depth of the lancet tip  22 . Removal of the endcap  50  also allows access for removal and replacement of the disposal lancet  20  after use, for example, by actuation of a lancet ejection mechanism  60 , in some multi-use designs. 
     In other embodiments, the lancing device  10  includes other conventional drive mechanisms, charging mechanisms, release mechanisms, and/or depth-adjustment mechanisms. For example, the drive mechanism can include a single spring element for driving and retracting, the charging mechanism can be provided by a twist-to-charge or push-to-charge mechanism, the release mechanism can be provided by a slide or rotary release, and/or the lancing device can include a multi-lancet carrier holding a plurality of lancets for sequential use. 
     In the depicted embodiment, the lancet carrier  18  and the lancet  20  are separates parts, with the lancet being replaceable so that the lancing device  10  can be used multiple times. In disposable embodiments, the lancet carrier/holder and the lancet are a single integral component. And in the depicted embodiment, a spring retainer  80  for the drive spring  14  and/or return spring  16  is mounted onto and travels with the lancet carrier  18 , and is such considered to be a component of the lancet carrier, even though it could additionally or alternatively be considered to be a component of the drive mechanism. As such, reference herein (including the appended claims) to the lancet carrier  18  is intended to also refer to the lancet  20  itself as well as to any component of the drive mechanism  15  or another mechanism of the lancing device  10  that travels with the lancet carrier. 
     The lancing device  10  of the first embodiment further includes a latch mechanism  100  that functions to permit a first oscillation of the lancet carrier  18  and lancet  20  then prevent subsequent (i.e., excess or secondary) oscillations. The term “oscillation” as used herein is defined as the lancet  20  generally moving from a first/retracted position forward to a second/extended position (i.e., where the lancet tip  22  projects out of the housing  12  to contact the lancing site), and rearward back to or at least toward the first/retracted position (i.e., such that the lancet tip is retracted back into the housing). 
       FIGS.  1 A- 1 F  show details and a sequence of operation of the lancing device  10  with the latch mechanism  100 , and  FIGS.  2 A- 5    show components of the latch mechanism in greater detail, with  FIGS.  3 A- 3 E  corresponding to  FIGS.  1 A and  1 F , with  FIG.  4    corresponding to  FIG.  1 B , and  FIG.  5    corresponding to  FIGS.  1 D and  1 E . In typical embodiments such as that depicted, the latch mechanism  100  includes a latch member  102 , a latch-pivoting element  135  of the charging mechanism  30 , a latch-engaging element  181  of the lancet carrier  18 , a spring-biased latch retainer  130  of the latch member or other portion of the lancing device  10 , and a ramp  190  of the housing  12  or other portion of the lancing device. 
     The latch member  102  is pivotally coupled to an element of the lancing device  10 . For example, the latch member  102  can be pivotally coupled to the housing  12  by a pivot pin  107  with an axis transverse to the angular motion of the latch member  102 , as depicted. As used herein, “pivot” (and other terms with that as the root) includes to rotate or otherwise move angularly. 
     The latch member  102  of the depicted embodiment includes a leg  110  and a foot  120  integrally formed with or attached to the leg and extending at an angle from the leg. In the depicted embodiment, for example, the foot  120  includes at least a portion that extends from the leg  110  in a direction Y that is generally perpendicular to the pivot axis and at least a portion that extends laterally from the leg in a direction X that is generally parallel to the pivot axis. More particularly, the depicted latch member  102  is generally L-shaped with the leg  110  having a first end  104  and a second end  105 , and with the foot  120  extending generally perpendicularly and laterally offset from the second end of the leg. The foot  120  includes a charge-pivot face  122  that is engaged by the latch-pivoting element  135  of the charging mechanism  30  during operation, and a drive-stop face  128  that interferes with the latch-engaging element  181  of the drive mechanism  15  during operation to mechanically block excess oscillation. The charge-pivot face  122  and the drive-stop face  128  are formed on the portion of the foot  120  that extends in the X and Y direction from the leg  110  and are oppositely facing away from each other. Typically, the foot  120  includes portions that extend in the opposite of the X and Y directions (that is, across the leg faces referenced as  111  and  116 , respectively, in  FIG.  2 A ) for providing strength and durability. In addition, the foot  120  includes an end face  124 , and a pressing surface  125  typically defined by a corner chamfer extending between the faces  122  and  128  for pressing engagement against the pressed surface  282  of the lancet carrier  18 . 
     In the depicted embodiment, the spring-biased latch retainer  130  is in the form of a resilient finger  130  that is integrally formed with or attached to the leg  110 , the housing  12 , or another element of the lancing device  10 , and that interacts with a rear portion  192  of a ramp  190  (described below). In typical embodiments, the finger  130  extends from, and is generally parallel to and laterally offset from the leg  110  on the opposite side from the foot  120 . In the depicted embodiment, for example, the finger  130  extends from the first end  104  of the leg  110 . The finger  130  includes a contact (e.g., outer) face  132  that engages the ramp  190  when the latch  102  is pivoted through its operating motion. In the depicted embodiment, the finger  130  also includes an opposite (e.g., inner) face  134  that cooperates with a face of the leg  110  to define a slit  136 . The finger  130  is preferably sufficiently thin and resilient to allow a degree of flexure/deflection toward (as permitted by the slit  136 ) and away from the leg  110 . As such, the resilient finger  130  functions as a spring to provide a biasing force against the ramp  190  when the two components are moved into engagement with each other. In other embodiments, instead of the cantilevered finger depicted, the spring-biased latch retainer is in the form of a leaf spring, detent, or other spring-biased element or mechanism. And in yet other embodiments, the position of the finger  130  and the ramp  190  are switched, with the ramp extending outwardly from the latch member  102  and the finger extending inwardly from the housing  12 . 
     The leg  110  includes a drive-pivot face  111  that is engaged by the latch-engaging element  181  of the drive mechanism  15  during operation. The drive-pivot face  111  of the leg  110  is laterally offset from and angled relative to the charge-pivot face  122  of the foot  120 , as discussed above. In addition, the pivotal mounting, and thus the pivot point  107 , of the latch member  102  is at the leg  110 . In the depicted embodiment, the leg  110  includes a mounting hole  114  for receiving the pivot pin  107  to attach the latch member  102  to the lancing device  10  and allow the latch member to rotate about an axis A (see  FIG.  3 E ) generally perpendicular to the advancement and retraction motion of the lancet carrier  18 . In other embodiments, the pivot pin extends from the latch member and is rotationally received in a mounting hole in the housing  12  or other element of the lancing device  10 . 
     The latch-pivoting element  135  of the charging mechanism  30  faces generally rearward and moves axially rearward when the charging actuator  31  is actuated to charge the drive mechanism  15 . In the depicted embodiment, for example, the charging mechanism  30  includes an internal member (e.g., the generally wedge-shaped member  37  depicted) extending from the charging actuator  31  and having a surface defining a charging element  33  that engages the drive mechanism  15  to charge the drive spring  14  and also having a surface defining the latch-pivoting element  135 . So when the charging actuator  31  is axially retracted, the latch-pivoting element  135  is also axially retracted into contact with the charge-pivot face  122  of the foot  120  to pivot the latch member  102  in a first/rearward direction from a blocking position to an intermediate non-blocking position. The latch-pivoting element  135  is typically ramped, for example it can have an arcuate shape as depicted. Additionally or alternatively, the charge-pivot face  122  of the foot  120  can be ramped, for example arcuate, to induce the latch-pivoting function. 
     The latch-engaging element  181  of the lancet carrier  18  faces generally forward and moves axially forward with the lancet  20  when the drive mechanism is released/actuated to drive the lancet through the lancing stroke. For example, the drive spring  14  and/or return spring  16  can be held on the lancet carrier  18  by a spring retainer  80  that is mechanically connected to the lancet carrier, with the spring retainer defining the latch-engaging element  181  (see  FIG.  3 A ). In the depicted embodiment, the spring retainer  80  has a forward-facing surface defining the latch-engaging element  181  (and also defining a surface that is engaged by the charging element  33  to charge the drive spring  14 ). And a pressed surface  182  of the lancet carrier  18  can be formed for example by a bottom surface of the spring retainer  80 . In other embodiments, the latch-engaging element is in the form of a tab or other projection that extends from or attaches to the spring retainer or another element of the drive mechanism. In any event, when the release mechanism  40  is actuated (e.g., by depressing the release actuator  41 ), the lancet carrier  18  is released so it can be propelled by the drive spring  14  through the forward portion of the lancing stroke and at the same time the latch-engaging element  181  is propelled into contact with the drive-pivot face  111  of the leg  110  to pivot the latch member  102  in a second/forward direction from the intermediate non-blocking position back toward the blocking position. 
     The ramp  190  extends inwardly from the housing  12  or other portion of the device  10 . The ramp  190  has a front ramped portion  191  that is engaged by the deflected resilient finger (or another type of spring-biased latch retainer)  130  when the drive mechanism  15  propels the lancet carrier  18  through the drive/forward portion of the lancing stroke to cooperatively induce the latch  102  to pivot to the blocking position. Thus, a latch spring biasing the latch  102  from the press non-blocking position to the blocking position is provided by the resilient finger  130  interacting with the front portion  191  of the ramp  190 . That is, the deflected resilient finger  130  is biased to resiliently return to its neutral position, and as it so discharges it biases against the front ramped portion  191 . In turn, this biases the latch member  102  (to which the finger  130  is attached) to pivot to the blocking position. So the discharging force exerted by the bias of the deflected finger  130  that is in contact with the front ramped portion  191  overcomes any frictional forces between these components. Similarly, the ramp  190  also includes a rear ramped portion  192  that is engaged by the deflected resilient finger  130  when the charging actuator  31  is axially retracted to cooperatively induce the latch  102  to pivot to and be retained in the intermediate non-blocking position. Thus, the spring-biased latch retainer  130  is provided by the resilient finger interacting with the rear portion  192  of the ramp  190 . In this way, the ramp  190  urges the latch  102  to remain in either the blocked or intermediate non-blocked position when the latch is not in contact with the latch-engaging element  181  or the latch-pivoting element  135 . In typical embodiments such as that depicted, the ramp  190  is arcuate and elongated, and it includes a tipping point  193  between the front and rear ramped portions  191  and  192 . 
     In alternative embodiments, the ramp  190  is outwardly extending/facing from/on an extension (e.g., extending from the housing  12 ) such that it contacts the inner face  134  of the resilient finger  130  and deflects outwardly (away from the latch member) from its neutral state to its charged state, as depicted in  FIGS.  6 A- 6 B , respectively. In such embodiments, the pivot point  107  can be located on the extension defining the ramp  190 . In still other embodiments, friction between a feature on the housing  12  or other portion of device  10  and the resilient finger  130  may be used to hold the latch member  102  in the blocking or intermediate non-blocking position, or the ramp  190  is eliminated and the latch member is urged to the blocking and intermediate non-blocking positions by gravity or other spring-biased latch retaining mechanisms or elements. 
     Having described details of the structure of the latch mechanism  100 , details of its operation will now be described with respect to  FIGS.  1 A- 1 F . In a normal (e.g., neutral) state ( FIG.  1 A , see also  FIGS.  3 A- 3 E ), the latch member  102  is in the blocking (leg-down/foot-up) position with the leg  110  lowered and generally aligned with the axis of translation of the lancet carrier  18 , the blocking foot  120  raised and generally upright relative to the leg, and the finger  130  (and/or the leg) resting on a rib or shelf  194  of the housing  12 . As the charging actuator  31  is retracted (as indicated by the linear-motion arrow in  FIG.  1 B ) or otherwise actuated, the latch-pivoting element  135  of the charging mechanism  30  slides rearwardly against the charge-pivot face  122  of the foot  120  of the latch member  102 , pivoting it (e.g., counter-clockwise as indicated by the angular-motion arrow in  FIG.  1 B ) about the pivot pin  107  (see also  FIG.  4   ). Retraction of the charging actuator  31  also retracts the lancet carrier  18  and the drive mechanism  15  by contact between the charging element or shoulder  33  (of the internal component  37  of the charging mechanism  30 ) and lancet carrier (e.g., the spring retainer  80  mounted at the distal end of the lancet carrier). As the latch member  102  pivots further, the foot  120  is lowered into a substantially horizontal orientation and the leg  110  is raised to a substantially upright orientation until the latch member is in the intermediate non-blocking (foot-down/leg-up) position ( FIG.  1 C ). Thus, the lancing device  10  is now in the charged state with the latch mechanism  100  in the intermediate non-blocking position. 
     As the latch member  102  pivots from the blocking position of  FIG.  1 A  (see also  FIGS.  3 A- 3 E ), through the pivoting motion of  FIG.  1 B , to the intermediate non-blocking position of  FIG.  1 C , the outer face  132  of the finger  130  is pivoted into contact with the front ramped portion  191  of the ramp  190  (e.g., extending inward from the housing  12 ) to deflect the finger inward (toward the leg  110 ). As the latch member  102  pivots further, the outer face  132  of the finger  130  moves past the tipping point  193  and onto the rear ramped portion  192  of the ramp  190 . In typical embodiments such as that depicted, the biasing force of the deflected finger  130  against the rear ramped portion  192  urges the latch member  102  all the way to the intermediate non-blocking position even if it has not been pivoted all the way there by the engagement of the latch-pivoting element  135  and the foot  120 . By the time the latch member  102  has pivoted to the intermediate non-blocking position of  FIG.  1 C , the finger  130  has cleared the ramp  190  and resiliently deflected back out to retain the latch member in place. 
     As shown in  FIG.  1 D , when the lancing device  10  is actuated by operation of the release mechanism  40 , for example by depressing the release actuator  41  (as indicated by the vertical-motion arrow), the discharging of the drive spring  14  drives the lancet carrier  18  and the attached spring retainer  80  forward to propel the lancet carrier through the drive/forward portion of the lancing stroke (as indicated by the horizontal-motion arrow). As the spring retainer  80  translates forward, it passes over the lowered foot  120  of the latch member  102  until its latch-engaging surface  181  contacts and pushes drive-pivot face  111  of the leg  110 , which causes the latch member to reverse rotate (e.g., clockwise as indicated by the angular-motion arrow in  FIG.  1 D ), thereby lowering the leg  110  and raising the blocking foot  120 . In this way, the latch member  102  is pivoted from the intermediate non-blocking position back toward the blocking position. 
     In typical embodiments, the lancet carrier  18  and lancet  20  come to their fully extended/forward lancing position before the spring retainer  80  has pivoted the latch member  102  all the way back to the blocking position to avoid imparting vibrations to the lancet while puncturing the skin, as shown in  FIG.  1 D . In the depicted embodiment, at this point the finger  130  remains deflected and engaged on the front ramped portion  191  of the ramp  190 , biasing the latch member  102  toward the blocking position (see also  FIG.  5   ). But the latch member  102  is restrained from completing its full pivotal movement and held in this press non-blocking position (between the intermediate non-blocking and blocking positions) because the pressed surface  282  of the lancet carrier (e.g., of the spring retainer  80  or another element of the lancet carrier or drive mechanism  15 ) interferes with pressing surface  125  of the foot  120  (e.g., the latch chamfered face). Thus, the spring retainer  80  has a length such that it does not clear the space above the foot  120  when the lancet carrier  18  and the lancet  20  come to their fully extended/forward lancing position (see  FIG.  1 D ). 
     The return spring  16  then returns the lancet carrier  18  from the extended/forward position back through the return/reverse portion of the lancing stroke (as indicated by the linear-motion arrow of  FIG.  1 E ) toward the normal (e.g., neutral) position, with the spring retainer  80  retracting over the blocking foot  120  in its press non-blocking position ( FIG.  1 E ). Because the charging mechanism  30  is not again being actuated, its latch-pivoting element  135  is not retracted to push the latch member  102  back to the intermediate non-blocking position. So upon the spring retainer  80  clearing the foot  120 , the latch member  102  is now free to pivot to the blocking position, and the charged finger  130  discharges against the front ramp surface  191  to return the latch member to its blocking (leg-down/foot-up) position of  FIG.  1 F  (see also  FIGS.  1 A and  3 A- 3 E ). The upright-positioned foot  120  then blocks the spring retainer  80  from passing forward again under the force of the drive spring  14 , thereby arresting any further/excess/secondary oscillation of the drive mechanism  15  and preventing the lancet tip  22  from subsequent advancement and potential re-contact with the lancing site. 
     In the depicted embodiment, there is also provided a lancet-ejection mechanism  60 . When the endcap  50  of the lancing device  10  is installed on the housing  12 , abutment of an extension  62  of the ejection mechanism  60  against the cap prevents actuation of the ejection mechanism. To eject the lancet, the cap  50  is removed to allow the ejection mechanism  60  to advance. When the extension  62  of the ejection mechanism  60  is advanced, an ejection finger  64  of the ejection mechanism contacts the lancet  20  through a slot in the lancet carrier  18  to eject the lancet from the lancet carrier in a forward direction (see  FIG.  1 F ). Contact by the foot  120  of the latch member  102  against the spring retainer  80  prevents forward motion of the lancet carrier  18  during ejection of the lancet, enabling a shorter ejection stroke. In other embodiments, the ejection mechanism is eliminated (i.e., for disposable lancing devices) or provided in another conventional form. 
       FIGS.  7 A- 11 C  show the lancing device  10  as substantially described above, except including a latch mechanism  200  according to a second example embodiment of the present invention. The latch mechanism  200  includes a latch member  202 , a spring-biased latch retainer  290 , a latch-pivoting element  235  of the charging mechanism  30 , and a latch-engaging element  281 , a pressed surface  282 , and a blocking surface  283  of the lancet carrier  18 , that cooperatively function to produce a substantially similar result to that of the first embodiment. That is, a first forward and rearward oscillation of the lancet  20  is permitted when the latch member  202  is in intermediate and press non-blocking positions, and subsequent/excess/secondary oscillations are prevented when the latch mechanism is in a blocking position. The latch member  202  pivots (rotates) between the blocking and non-blocking positions about an axis B ( FIG.  7 C ) that is parallel (e.g., coaxial) with the linear advancement and retraction motion of the lancet carrier  18  during the lancing stroke. 
       FIGS.  7 A- 7 C  show details of the sleeve latch member  202 . The latch member  202  is typically in the form of a cylindrical or tubular sleeve that pivots (rotates) about an axis, though it can be in the form of a curved wall section that does not define a complete circle/cylinder. The latch member  202  includes a sleeve body  210  extending from a first end  204  to a second end  205  and defining a retainer-biasing surface  223 , an anti-pivot surface  224 , a pressing surface  225 , a drive-stop surface  228 , and a charge-pivot cam surface  222 . In addition, the latch member  202  includes a spring  244  that pivotally (i.e., rotationally) biases it in an angular direction. 
     The anti-pivot surface  224  is formed on an axial/radial side of the sleeve body  210  and engages the spring-biased latch retainer  290 . In the depicted embodiment, for example, the sleeve body  210  includes a tooth (e.g., a tab, wedge, post, or other projection)  212  that is integrally formed with or attached to it and that has at least a portion extending generally axially therefrom, with the anti-pivot surface  224  formed on an axial/radial side of the tooth. The anti-pivot surface  224  of the tooth  212  is angled (with respect to a radius line) or otherwise formed to accommodate interaction with the spring-biased latch retainer  290 . Thus, the anti-pivot surface  224  can be angled so that when the sleeve body  210  is pivoted into the non-blocking position, it is flush with the catch surface  295  of the spring biased latch retainer  290 . 
     The retainer-biasing surface  223  is formed on the sleeve body  210  and engages the spring-biased latch retainer  290 . In the depicted embodiment, for example, the sleeve body  210  includes the tooth  212 , and the retainer-biasing surface  223  is formed on the outer surface of the tooth of the sleeve body. The spring-biased latch retainer  290  contacts the retainer-biasing surface  223  when the latch member  202  is in the blocking position and the spring-biased latch retainer is in the charged position, with this contact retaining the latch retainer in the charged position (see  FIGS.  9 A,  10 A, and  11 A ). 
     The pressing surface  225  is formed on an axial/radial side of the sleeve body  210  and engages the pressed surface  282  of the lancet carrier  18 . And the drive-stop surface  228  is formed on the rear side (transverse to the axial/radial side) of the sleeve body  210  and engages the latch-engaging surface  281  of the lancet carrier  18 . In the depicted embodiment, for example, the sleeve body  210  includes a foot (e.g., a tooth, tab, post, wedge, or other projection)  220  that is integrally formed with or attached to it and that extends generally transversely and radially inward therefrom (e.g., from the tooth  212  or adjacent the tooth), with the pressing surface  225  formed on an axial/radial side of the foot and the drive-stop surface  228  is formed on the rear side of the foot. The pressing surface  225  provides a sufficient contact surface for interference engagement with the pressed surface  282  of the lancet carrier  18  when the latch member  202  is in the press non-blocking angular position (see  FIGS.  7 C,  9 C,  10 C , and  11 C). 
     The charge-pivot surface  222  is formed on an axial/radial surface (transverse to the front and rear sides) of the sleeve body  210  and engages the latch-pivoting element  235  of the charging mechanism  30 . In the depicted embodiment, for example, the sleeve body  210  includes a void  250  formed near the first end  204  of the latch member  202 , with the charge-pivot surface  222  defining a portion of the void. The charge-pivot surface  222  is angled with respect to the axis of the sleeve body  210  so that when the latch-pivoting element  235  of the charging mechanism  30  is moved longitudinally along it the latch member  212  pivots in an angular direction from the blocking position to the intermediate non-blocking position. In alternative embodiments, the charge-pivot surface  222  is formed on a wedge extending radially outward from the sleeve body  210 , is non-linear to provide for a non-constant pivoting rate, is non-angled (or less angled) with the latch-pivoting element  235  being angled, or is provided in other configurations for providing the functionality described herein. 
     The latch spring  244  biases the latch member  202  to pivot from the intermediate and press non-blocking positions toward the blocking position. In the depicted embodiment, the latch spring  244  is a torsion spring that is positioned around the sleeve body  210  and mounted to it by a retaining bracket  240  at the second end  205  of the latch member  202 . For example, a first arm  245  of the torsion spring can be retained by the retaining bracket  240  and a second arm  246  can engage the housing  12  or another part of the lancing device  10 . In other embodiments, the latch spring is a compression or tension coil spring, a leaf spring, a resiliently deformable member, or another type of spring element that biases the latch member  202  as described herein. 
     The latch-pivoting element  235  of the charging mechanism  30  engages the charge-pivot cam surface  222  and thereby pivots the latch member from the blocking position to the intermediate non-blocking position when the charging actuator  31  is operated to charge the drive mechanism  15 . In the depicted embodiment, for example, the latch-pivoting element  235  is a pin that extends radially inward from an internal component of the charging mechanism  30  and slides along the charge-pivot surface  222 . In other embodiments, the latch-pivoting element is a post, bar, rod, shaft, panel, finger, boss, or another element that engages the charge-pivot cam surface to pivot the latch member  202  as described herein. 
     The latch-engaging element  281  and the blocking surface  283  of the lancet carrier  18  engage the spring-biased latch retainer  290 , and the pressed surface  282  of the lancet carrier  18  is engaged by the pressing surface  225  of the latch  202 . In the depicted embodiment, for example, the latch-engaging element  281 , the pressed surface  282 , and the blocking surface  283  are contact surfaces formed on forward, lateral, and bottom faces of a spring retainer  80  of the lancet carrier  18 , with the spring retainer retaining the return spring  16  in place on the lancet carrier for charging and discharging. In other embodiments, these surfaces are defined by one, two, or three other elements of the lancet carrier  18 , whether dedicated element for use only in the latch mechanism or for shared use in other functions of the lancing device. 
       FIGS.  8 A- 8 B  show details of the spring-biased latch retainer  290  of the depicted embodiment, which is in the form of a resilient finger that is biased from a charged non-latch-retaining position to a discharged latch-retaining position. The resilient finger  290  extends from a stationary element of the lancing device  10  and includes contact surfaces that selectively engage the latch member  202  and the lancet carrier (or an element coupled thereto)  18  to provide for permitting a first lancet oscillation and preventing subsequent oscillations. In the depicted embodiment, for example, the resilient finger  290  is a cantilevered arm with a head at its free end, the arm projecting inwardly from the housing  12  and the head defining the contact surfaces for engaging the latch member  202  and the lancet carrier  18 . The contact surfaces of the resilient finger  290  include a first surface  292 , second surface  293 , third surface  294 , and fourth surface  295 . 
     The first surface  292  contacts the latch member  202 , for example the retainer-biasing surface  223  of the tooth  212  of the sleeve body  210 , when the latch member is in the blocking position and the resilient finger  290  is in the charged non-latch-retaining position, with this contact retaining the resilient finger in position (see  FIGS.  9 A,  10 A, and  11 A ). The first surface  292  can also contact the lancet carrier  18 , for example the blocking surface  283  of the spring retainer  80 , when the latch member is in the press non-blocking position and the resilient finger  290  is in the partially charged (e.g., deflected) non-latch-retaining position, with this contact retaining the resilient finger in position (see  FIGS.  9 C,  10 C, and  11 C ). 
     The fourth surface  295  contacts the latch member  202 , for example the anti-pivot surface  224 , when the latch member is in the intermediate non-blocking position and the resilient finger  290  is in the discharged latch-retaining position, with this contact retaining the latch member in the intermediate non-blocking position (see  FIGS.  9 B,  10 B, and  11 B ). 
     The third surface  294  extends between the first and fourth surfaces  292  and  295  and is ramped (e.g., chamfered or beveled) to facilitate smooth movement across the anti-pivot surface  224  (or portions thereof) when the resilient finger  290  is in partially charged positions moving between the charged non-latch-retaining and discharged latch-retaining positions (see  FIGS.  9 C,  10 C, and  11 C ). 
     And the second surface  293  contacts the lancet carrier  18 , for example the latch-engaging surface  281 , and is ramped (e.g., chamfered or beveled) so that when the lancet carrier is being propelled forward through the lancing stroke the latch-engaging surface  281  of the lancet carrier rides along the ramped second surface  293  to deflect the resilient finger  290  and thereby withdraw it from the discharged latch-retaining position toward the charged non-latch-retaining position (in positions between the positions of  FIGS.  11 B and  11 C ). 
     Typically, but not necessary in all commercial embodiments, the resilient finger  290  is fully discharged in the discharged position (that is, in some embodiments the resilient finger can still have a small charge when in the “discharged” position). In other embodiments, instead of the cantilevered resilient finger, the spring-biased latch retainer includes a compression or tension coil spring, a torsion spring, a leaf spring, a resiliently deformable member, or another type of spring element, and still includes the contact surfaces that biasingly engage the lancet carrier  18  and the latch member  202  to provide the functionality described herein. In still other embodiments, the latch retainer is not spring-biased and instead is moved between the non-latch-engaging and latch-engaging positions by an additional mechanism or element. And in yet still other embodiments, the latch retainer is eliminated or formed by an element of the charging mechanism  30  so that the charging mechanism temporarily retains the latch  202  in the intermediate position until the lancet carrier  18  moves far-enough forward that the latch member can be released to reverse-pivot to the press non-blocking position. 
       FIGS.  9 A- 9 C,  10 A- 10 C, and  11 A- 11 C  show the operational use of the latch mechanism  200 . In a normal (e.g., neutral) state ( FIGS.  9 A,  10 A, and  11 A ), the latch member  202  is in the blocking position with the foot  220  inserted into the lancing stroke path of the lancet carrier  18  (and/or the lancet  20 ). In use, as the charging actuator  31  is retracted (as indicated by the linear-motion arrow in  FIGS.  9 B and  10 B ) or otherwise actuated, the latch-pivoting element  235  of the charging mechanism  30  slides rearwardly against the ramped charge-pivot cam face  222  of the latch member  202 , pivoting the latch member (e.g., as indicated by the angular-motion arrow in  FIGS.  9 B and  10 B ) about its axis (e.g., the lancing path axis) from its blocking position to its non-blocking position of  FIGS.  9 B,  10 B, and  11 B . Retraction of the charging actuator  31  also retracts the lancet carrier  18  and the drive mechanism  15  by contact between the charging element or rib  33  (of an internal component  37  of the charging mechanism  30 ) and the lancet carrier (e.g., the spring retainer  80  mounted at the distal end of the lancet carrier). As the latch member  202  pivots from its blocking position to its intermediate non-blocking position, the spring  244  begins to transition from a normal (neutral/uncharged or only slightly charged) state to a charged state to bias the latch member  202  back towards the blocking position. In the depicted embodiment, for example, as the latch member  202  rotates, the retaining bracket  240  follows along the spring first arm  245 , and as a result the spring second arm  246  is engaged with an inner portion (e.g., an inner wall surface) of the housing  12  (or another element of the lancing device  10 ), thus charging the torsional spring to bias the latch member  202  towards the blocking position. The lancing device  10  is now in the charged state with the latch mechanism  200  retained in the intermediate non-blocking position. 
     The pivotal movement of the latch mechanism  202  from the blocking position to intermediate non-blocking position frees the spring-biased latch retainer  290  (e.g., the resilient finger) to move from the charged non-latch-retaining position to the discharged latch-retaining position. For example, when the latch member  202  is in the blocking position, the resilient finger  290  can be deflected outward with the first finger surface  292  biased against the retainer-biasing surface  223  of the latch body  210 . In the particular case of the depicted embodiment, when the latch member  202  is in the blocking position, the first finger surface  292  is positioned below the tooth  212  and the finger-blocking surface  223  is defined by the outer wall of the tooth of the latch body  210  ( FIGS.  9 A,  10 A, and  11 A ). And when the latch member  202  is pivoted to the intermediate non-blocking position, the retainer-biasing surface  223  of the latch  202  is pivoted out of contact with the resilient finger  290  ( FIGS.  9 B,  10 B, and  11 B ). So the charged resilient finger  290 , now free of the interference with the latch member  202 , discharges and thereby deflects inward from the charged position to the discharged position. 
     In the discharged latch-retaining position, the resilient finger  290  prevents the latch member  200  in the intermediate non-blocking position from reverse pivoting back toward the blocking position. In the depicted embodiment, for example, the fourth finger surface  295  (or adjacent surfaces/edges) aligns with the anti-pivot surface  224  of the tooth  212  of the latch member  202  in an interference position to prevent such reverse pivoting ( FIGS.  9 B,  10 B, and  11 B ). 
     To initiate the lancing stroke, the release mechanism  40  is actuated to release the lancet carrier  18  to be propelled through the lancing stroke by the drive mechanism  15 . In the depicted embodiment, for example, the release actuator  41  is depressed (as indicated by the downward linear arrow of  FIGS.  9 C and  10 C ) to disengage mating elements of the release mechanism  40  and the lancet carrier  18 . The released lancet carrier  18  is then propelled along the forward portion of the lancing stroke by the discharging drive spring  14 . 
     As the lancet carrier  18  moves forward, a portion of it engages the resilient finger  290  and displaces it out of the way. In the depicted embodiment, the blocking surface  283  of the lancet carrier  18  (e.g., formed on the lancet carrier&#39;s spring retainer  80 ) comes into contact with the second finger surface  293 . The second finger surface  293  is ramped (and/or the blocking surface  283  can be ramped) so that this engagement deflects the resilient finger  290  from the discharged latch-retaining position to a partially charged non-latch-retaining position ( FIGS.  9 C,  10 C, and  11 C ). So now the fourth finger surface  295  has been removed from interference/alignment with the anti-pivot surface  224  of the latch member  202 , and the latch member reverse-pivots (in the second/reverse angular direction) slightly under the biasing force of the charged spring  244  to the press non-blocking position. But because the lancet carrier  18  has moved forward, its pressed surface  282  (e.g., of the spring retainer  80 ) is now in an interfering position with (and is thus pressed upon by) the pressing surface  225  (e.g., of the foot  220 ) of the spring-biased latch member  202  to block the latch member from further reverse-pivoting ( FIGS.  9 C,  10 C, and  11 C ). 
     The lancet carrier  18  continues blocking the latch member  202  from further reverse-pivoting as it travels forward to the fully extended position to lance the subject&#39;s skin and then begins retracting on the reverse portion of the lancing stroke. Thus, the pressed surface  282  of the lancet carrier  18  has a length sufficient to maintain this interference with the pressing surface  225  of the latch member  202  during these segments of the forward and reverse portions of the lancing stroke. Friction caused by contact between the pressed surface  282  (e.g., of the spring retainer  80 ) and the pressing surface  225  (e.g., of the foot  220 ) is substantially small so that the lancing movement is smooth and easy. 
     Once the lancet carrier  18  retracts to where its pressed surface  282  has cleared blocking interference with the pressing surface  225  of the latch member  202 , the latch member then further reverse-pivots (in the second/reverse angular direction), under the biasing force of the charged spring  244 , back to the blocking position of  FIGS.  9 A,  10 A, and  11 A . This in turn causes the anti-pivot surface  224  of the latch member  202  to drive against the ramped third surface  294  of the resilient finger  290  to return/deflect the finger to the charged non-latch-retaining position. 
     After this first lancet oscillation (i.e., the lancing stroke), the drive spring  14  may be sufficiently re-charged to initiate a subsequent lancet oscillation. But with the latch member  202  in the blocking position of  FIGS.  9 A,  10 A, and  11 A , the blocking drive-stop surface  228  of the latch member  202  (e.g., of its tooth  220 ) is now in an interference position (inserted into the path of the lancet carrier  18  and/or the lancet  20 ) so that it will contact the latch-engaging surface  281  of the lancet carrier (e.g., of its spring retainer  80 ) and block it from further forward travel. In this way, excess oscillations of the lancet  20  are prevented, thereby minimizing the pain associated with repeated sticks by the lancet tip  22 . 
     In alternative embodiments, the latch mechanism does not include the spring finger  290  (or the surfaces of the latch and other mechanisms of the lancing device that it engages) and instead includes other types of spring-biased latch retainers that retain the latch member in the intermediate non-blocking position but only until the portion of the lancet carrier that the latch presses against moves into an interference position during the forward portion of the lancing stroke. In some such embodiments, the spring-biased latch retainer is a spring-biased plunger (e.g., a spring-biased pin or projection) extending from the latch member (or the housing) for operating similarly to the resilient finger  290 . In one embodiment, for example, the plunger extends axially from the second end of the latch where it is biased against a portion of the housing. During charging, the spring-biased plunger rides along the housing as the latch member pivots until it aligns with an anti-pivot pocket (e.g., formed with the housing) in the intermediate non-blocking position, and then the plunger is extended into the pocket under the biasing influence of its spring force, thereby retaining the latch member in the intermediate non-blocking position. As the lancet carrier travels forward after operation of the actuation mechanism, a plunger-retraction member (e.g., of the lancet carrier) is engaged to retract the plunger from the anti-pivot pocket and the latch member reverse-pivots slightly (in the second angular direction) under the biasing force of the charged spring to the press non-blocking position. From there, the operation of the latch mechanism is the same as described above. It will be understood that included within the scope of the invention are other forms of spring or biasing latch-retaining elements that operate to retain the latch member in the intermediate non-blocking position and then release the latch member to reverse-pivot to the press non-blocking position as a part of the overall operation to permit the first forward and rearward oscillation of the lancet and to then prevent subsequent/excess oscillations after the latch member returns to the blocking position. 
     In the depicted embodiment, the latch member  202  pivots in a first angular direction (counter-clockwise when viewed from behind) and a second opposite angular direction (clockwise when viewed from behind) when functioning to permit the first oscillation of the lancet  20  and prevent subsequent oscillations. In other embodiments, the latch mechanism is configured so that the latch member pivots in opposite directions or pivots in only one angular direction (whether clockwise or counter-clockwise) when functioning to permit the first oscillation of the lancet and prevent subsequent oscillations. 
     While the invention has been described with reference to preferred and example embodiments, it will be understood by those skilled in the art that a variety of modifications, additions and deletions are within the scope of the invention, as defined by the following claims.