Improvements relating to lancets

[0001] Lancing devices are used to collect blood samples by quickly and briefly sliding the needle out of the housing in such a way as to puncture the skin of the patient. The device must have some means to cause the needle to return to the housing after the task is completed, and there is usually a drive spring that, when released, moves the needle forward out of its static position. It then returns to its position to insert the needle back into the housing. The object of the invention is to provide for a lancet a spring return assembly that is relatively inexpensive to manufacture and easy to install, and which removes the need to place a return spring against the housing and lancing device. According to the invention, there is provided a lancing device comprising:

a lancet comprising a body which has a drive head at one end and a retractable needle at the other end, the body having integrated bands protruding downwards on both sides towards the location of the tip of the retractable needle, the bands having a corrugated shape and being of flexible material so to act as elastic members, and the lancing device fits inside the housing with a drive spring located between the end of the housing and the driving head of the lancing device.

[0002] By using the corrugated ribbons as elastic members, the ribbons can be shaped in the mold at the same time as the lancing body, thereby saving manufacturing time and assembly time, as there is no separate spring return assembly to be attached.

[0003] The folds of the two ribbons may be mutually incompatible in phase.

[0004] The lancing device ideally has a removable protective cap which is positioned over the exposed end of the needle. The cap can be attached to the free ends of the webs through frangible connecting parts.

[0005] US5324302 discloses a lancing device with a locking sheath in which the distal end of the lancing needle is fixedly mounted in the distal needle element, while the lancing device of the lancing device extends slidably through the proximal needle element. The proximal and distal elements are connected through a pair of opposing and normally bent flexible arms.

[0006] A lancet may be provided with a firing structure in the form of a lancet drive head comprising a flange abutting against a movable housing rib together with a flexible button on the housing, which button is movable to release the rib from the flange to allow the drive spring to move the lancing device to forward.

[0007] The tip of the needle may be covered with a removable protective cap that has a head that is placed around the flanges on the housing but which can be unscrewed from contact with the flanges to allow removal of the cap to reveal the tip of the needle.

[0008] The invention may be implemented in various ways and a preferred example thereof will now be described with reference to the accompanying schematic drawings in which:

Figure 1 is a perspective view of the lancing device holder according to the invention;

Figure 2 illustrates the lancet holder of Figure 1 in an open condition; and

Figure 3 is an illustration of a lancet such as contained within the holder of figures 1 and 2.

[0009] The lancing device holder shown in figure 1 comprises an outer casing 1 from which the operating button 2 protrudes. At the other end, the head 3 of the protective cap protrudes. As can be seen from figure 2, the cap has an elongated shaft 4 that covers and protects the tip of the needle 5 of lancing device 6 (see figure 3). The cap head 3 can be unscrewed to free it from the working contact with the flanges 7 at the end of the housing 1, which allows the cap to be pulled past the needle 5 at the end of the lancing device 6 when the device is to be used.

[0010] The lancing device 6 is prepared for operation by a spring 8, but is held inside the housing 1 by a rib 9 which forms part of the housing 1, which rib holds the collar 10 on the lancing device 6. In use, the strips 11 on the operating button 2 will move further inside the housing 1 when the button 1 is depressed, and the rib 9 (which is elastically attached to the housing 1) will move away from the collar 10, thereby releasing the lancing device 6. The lancing device is now moved forward through the spiral spring 8 to cause the needle 5 to extend through the hole 12 at the end of the housing 1. When the housing 1 is held against the patient's skin (before using button 2), the needle will pierce the skin to allow the small blood samples.

[0011] Typically, in such lancets the needle extends only for a short time and then is automatically retracted into the housing 1. This is usually partly due to the reflection of the spring 8. However, in this device, the spring system 13 strongly pushes the lancing device back into the housing. This elastic arrangement is formed by a pair of corrugated plastic webs 14 integrally formed with lancing device 6. The ribbons 14 are flexible and thereby squeezed into a harmonica when the tops 15 of the ribbons hit the inside of the collar members 7. The energy accumulated inside the compressed ribbon 14 is then released to introduce the lancing device back into the housing 1. As can be seen from figure 3 , the folds of the two webs 14 may not be in phase with each other. This determined return of the lancing device ensures that the needle will withdraw safely into the housing and that it is not dependent on a spring blocked inside the housing or from the lancing device.

[0012] During manufacture, the lancet body 6 is formed around the needle 5, and the webs 14 are integrally formed with the body 6. The tops 15 of the webs 14 can additionally be joined, during the molding process, through thin connecting parts with the shaft 4 of the needle cap. This holds the cap from accidentally unscrewing. However, when deliberate twisting movement of the cap head 3 is applied, the thin connecting portions attached to the web 14 break to allow removal of the cap. As can be seen in particular in figure 2, the guide ribs 16 are shaped inside both housing halves 1 to guide the lancing device when it is moved by the spring 8. The two housing halves 1 are integrally shaped in a mold to include flexible hinges 17. When lancing device 6 and cap 3, together with spring 8, have been loaded into one half of the housing, the two half of the housing may be folded together so that the posts 18 enter tightly fitting holes 19 to hold the two half of the housing together.