Latch mechanism for preventing lancet oscillation in a lancing device

A device for lancing skin, comprising:

• a lancet having a sharp tip for puncturing the skin during a lancing stroke;
• a carrier holding the lancet and movable through the lancing stroke from a retracted position, through a forward portion of the lancing stroke, to an advanced position puncturing the skin, and through a return portion of the lancing stroke;
• and
• a latch mechanism operable to permit the lancet carrier to travel through the lancing stroke but prevent excess oscillation of the lancet carrier, wherein the latch mechanism includes a latch member and a pressed surface and a latch-engaging element of the lancet carrier, wherein the latch member includes a pressing surface and a drive-stop surface, and wherein the latch member pivots between a blocking position, an intermediate non-blocking position, and a press non-blocking position, and is spring-biased from the press non-blocking position to the blocking position,
• wherein as the lancet carrier travels along the forward portion of the lancing stroke the latch member pivots from the intermediate non-blocking position to the press non-blocking position with the pressed surface of the lancet carrier interfering with the pressing surface of the latch member to prevent pivoting of the latch member to the blocking position,
• wherein as the lancet carrier travels along the return portion of the lancing stroke the pressed surface of the lancet carrier clears interference with the pressing surface of the latch member and the spring-biased latch member pivots from the press non-blocking position to the blocking position, and
• wherein, with the latch member in the blocking position, if the lancet carrier is driven along the forward portion of the lancing stroke a second time the drive-stop surface of the latch member engages and blocks the latch-engaging element of the lancet carrier to prevent excess lancet-carrier oscillation.

A method of lancing skin, comprising:

• charging a lancing device having a lancet with a sharp tip for puncturing the skin during a lancing stroke, a carrier holding the lancet and movable through the lancing stroke, and a latch mechanism with a pivotal latch member;
• pivoting the latch member from a blocking position to an intermediate non-blocking position, wherein in the blocking position a drive-stop surface of the latch is positioned in a travel path of a latch-engaging surface of the lancet carrier, and wherein in the intermediate non-blocking position the drive-stop surface is removed from the travel path of the latch-engaging surface;
• retaining the latch member in the intermediate non-blocking position;
• releasing the lancet carrier to travel along a forward portion of a lancing stroke;
• after the lancet carrier has begun traveling along the forward portion of the lancing stroke, releasing the latch member so that it reverse-pivots from the intermediate non-blocking position to a press non-blocking position, wherein in the press non-blocking position the drive-stop surface of the latch is not positioned in the travel path of the latch-engaging surface of the lancet carrier and a pressed surface of the lancet carrier interferes with and is biased against by a pressing surface of the latch member;
• after the lancet carrier has reached an advanced position lancing the skin and then traveled along a rearward portion of the lancing stroke far enough that the pressed surface of the lancet carrier has cleared interference with the pressing surface of the latch member, reverse-pivoting the latch member from the press non-blocking position to the blocking position, wherein if the lancing device re-charges sufficient to initiate a second lancing stroke the drive-stop surface of the latch in the blocking position interferes with and blocks the latch-engaging surface of the lancet carrier traveling past it to the advanced lancing position to prevent excess lancet-carrier oscillations.