How are lancets manufactured?

Author: Geym

Jun. 10, 2024

Lancet and method of manufacturing the same - Google Patents

The present invention relates generally to lancets and more particularly to a novel lancet and method of manufacturing the same.

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Diabetes is a disease which typically requires a patient to routinely measure the concentration of glucose in his/her blood. Based upon the results of each blood glucose measurement, the patient may require a particular drug treatment (e.g., an injection of insulin) in order to regulate that the blood glucose level of the patient remains within a specified range. Exceeding the upper limit of said range (hyperglycemia) or dropping beneath the lower limit of said range (hypoglycemia) should be avoided with as much diligence as possible to prevent the patient from experiencing serious medical complications which include, inter alia, retinopathy, nephropathy, and neuropathy.
A two-step process is commonly practiced by diabetes patients to self-monitor the level of glucose present in their blood. In the first step, the patient makes a skin prick (typically in his/her finger) in order to acquire a small sample of blood. In the second step, a blood glucose monitor is used to calculate and, in turn, digitally display the concentration of glucose present in the blood sample.
Blood samples taken from a patient for blood glucose monitoring are typically obtained by piercing the skin of the patient using a lancet. A lancet is designed to penetrate through the epidermis (the outermost layer of the skin) of the patient and into the dermis (the layer of skin directly beneath the epidermis) which is replete with capillary beds. The puncture of one or more capillaries by the lancet generates a sample of blood which exits through the incision in the skin.
Lancets are commonly constructed by cutting a solid, elongated length of cylindrical wire at specified intervals to generate a plurality of shortened wire samples of identical size and shape. The plurality of individual wire samples are mounted parallel to one another within a single cassette. The cassette is then inserted into a grinding machine with the first end of each wire sample directed towards a grinding wheel. In what is typically referred to as a grinding process (or simply a grind), the cassette is positioned in a particular orientation and drawn into contact against the grinding wheel. Subsequent thereto, the cassette is commonly repositioned in different orientations and drawn back into contact against the grinding wheel in additional grinding processes. All in all, three separate grinds are commonly performed on the plurality of individual wire samples to create at the first end of each wire sample a sharpened tip with two separate cutting edges. Upon completion of the grinding processes, the second end of each lancet is often embedded within an enlarged plastic base (e.g., through the process of insert molding) to facilitate its handling.
Lancets of the type as described above are often fired into the skin of a patient to draw a blood sample using a lancing device. A lancing device typically includes a holder into which the lancet may be permanently or removably mounted. A spring-loaded firing mechanism is traditionally coupled to the lancet holder. The firing mechanism commonly includes some type of actuation means, such as an externally-accessible button, which when actuated fires the lancet holder towards the patient such that sharpened tip of the lancet penetrates the skin of the patient.
Conventional lancets typically include a single sharpened tip (with two cutting edges) which is adapted to penetrate into the skin of the patient. However, it has been found that lancets which include a single sharpened tip often suffer from a couple notable drawbacks.
As a first drawback, lancets which include a single sharpened tip often fail to puncture a significant number of capillaries located within the dermis layer of the patient's skin. As a result, multiple firings of the lancet may be required in order to produce an adequate blood sample, the additional lancet firings increasing the overall discomfort experienced by the patient, which is highly undesirable.
As a second drawback, lancets which include a single sharpened tip are often constructed with a sharpened tip of increased diameter to insure that the tip punctures at least one capillary upon insertion into the dermis layer of the skin. However, the utilization of a lancet which includes a sharpened tip of increased diameter causes said lancet to contact a greater number of nerve endings in the skin, thereby increasing patient discomfort, which is highly undesirable.
Accordingly, lancets constructed to include a plurality of reduced diameter tips are known in the art. Lancets which include a plurality of reduced diameter tips have a greater probability of penetrating a capillary upon insertion, thereby increasing the likelihood of producing an adequate blood sample. Furthermore, lancets which include a plurality of reduced diameter tips create relatively small incision wounds in the skin, thereby minimizing patient discomfort, which is highly desirable.
In U.S. Pat. No. 2,801,633 which issued on Aug. 6, in the name of J. C. Ehrlich, there is disclosed, in one embodiment, a lancet comprising two skin-penetrating elements. The lancet is constructed from a blank of flexible sheet metal of a thickness no greater than about 0. inches. The blank is provided with two point members which project from a common edge. The blank is rolled into a tube which has considerable rigidity despite the thinness of the metal stock. With the blank rolled into a tube, the two points project out from the same end of the tube (the two points may be diametrically opposite each other). The pair of points serves to create two puncture sites in the skin of the patient which, in turn, insures a substantial flow of blood from the patient without the necessity for squeezing the area of puncture.
The lancet described in U.S. Pat. No. 2,801,633 to Ehrlich is constructed by first stamping a flat sheet of metal to include a pair of sharpened, generally V-shaped tips, both of said tips protruding out from a first edge of the flat sheet of metal. Upon completion of the stamping step, the flat sheet of metal is rolled into a tubular shape to create a hollow cylindrical needle with the pair of sharpened tips extending out from one end. The flat sheet of material is maintained in its tubular shape by welding together second and third edges of the flat sheet of metal, said welding process creating a longitudinal seam which extends along the majority of the length of the lancet.
The multi-tip lancet described in U.S. Pat. No. 2,801,633 to Ehrlich suffers from a notable shortcoming. Specifically, as noted above, this type of multi-tip lancet is traditionally manufactured using separate stamping, rolling and welding processes. As can be appreciated, the manufacture of a lancet using separate stamping, rolling and welding processes increases the complexity and overall cost of the manufacturing process, which is highly undesirable.
It is an object of the present invention to provide a novel lancet.
It is another object of the present invention to provide a lancet of the type described above which can be used to extract an adequate amount of blood for testing purposes with minimal discomfort to the patient.
It is yet another object of the present invention to provide a simple and inexpensive method of manufacturing the lancet as described above.
Therefore, according to one feature of the present invention, there is provided a lancet comprising a seamless unitary member which is hollowed along at least a portion of its length, said unitary member including a first end, a second end, and a longitudinal axis, wherein the first end of said unitary member is shaped to include first and second sharpened tips.
According to another feature of the present invention, there is provided a lancet comprising a unitary member which is hollowed along at least a portion of its length, said unitary member including a first end and a second end, wherein the first end of said unitary member includes first and second ground surfaces which at least partially define first and second sharpened tips.
According to another feature of the present invention, there is provided a method of manufacturing a lancet, said method comprising the steps of providing a unitary member, said unitary member including a first end and a second end, and performing first and second grinds on the first end of said unitary member so as to yield first and second ground surfaces in the first end of said unitary member, said first and second ground surfaces at least partially defining first and second sharpened tips.
According to another feature of the present invention, there is provided a lancet comprising a unitary member which is hollowed along at least a portion of its length, said unitary member including a first end and a second end, wherein the first end of said unitary member is shaped to include first, second and third sharpened tips.
According to another feature of the present invention, there is provided a method of manufacturing a lancet, said method comprising the steps of providing a unitary member, said unitary member including a first end and a second end, and performing first, second and third grinds on the first end of said unitary member so as to yield first, second and third ground surfaces in the first end of said unitary member, said first, second and third ground surfaces at least partially defining first, second and third sharpened tips in said unitary member.
According to another feature of the present invention, there is provided a lancet comprising a unitary member including a first end, a second end and a longitudinal axis, wherein the first end of said unitary member is shaped to include first, second and third ground surfaces which together at least partially define a single tip and first, second and third cutting edges.
According to another feature of the present invention, there is provided a method of manufacturing a lancet, said method comprising the steps of providing a unitary member which includes a first end, a second end and a longitudinal axis, and performing three separate grinds on the first end of said unitary member to yield first, second and third cutting edges which at least partially define a single sharpened tip.
According to another feature of the present invention, there is provided a lancet comprising a unitary member including a first end, a second end and a longitudinal axis, wherein the first end of said unitary member is shaped to include first, second, third and fourth ground surfaces which together at least partially define a single tip and first, second, third and fourth cutting edges.
According to another feature of the present invention, there is provided a lancet comprising a method of manufacturing a lancet, said method comprising the steps of providing a unitary member which includes a first end, a second end and a longitudinal axis, and performing four separate grinds on the first end of said unitary member to yield first, second, third and fourth cutting edges which at least partially define a single sharpened tip.
Various other features and advantages will appear from the description to follow. In the description, reference is made to the accompanying drawings which form a part thereof, and in which is shown by way of illustration, various embodiments for practicing the invention. The embodiments will be described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the invention. The following detailed description is therefore, not to be taken in a limiting sense, and the scope of the present invention is best defined by the appended claims.
In the drawings wherein like reference numerals represent like parts:
FIGS. 1(a)-(d) represent perspective, top, front and right end views, respectively, of a first embodiment of a lancet constructed according to the teachings of the present invention;
FIG. 2 is perspective view of a unitary member which is subject to series of grinding processes to form the lancet shown in FIGS. 1(a)-(d);
FIGS. 3(a)-(d) represent perspective, top, front and right side views, respectively, of a second embodiment of a lancet constructed according to the teachings of the present invention;
FIGS. 4(a)-(d) represent perspective, top, front and right side views, respectively, of a third embodiment of a lancet constructed according to the teachings of the present invention;
FIGS. 5(a)-(d) represent perspective, top, front and right side views, respectively, of a fourth embodiment of a lancet constructed according to the teachings of the present invention;
FIGS. 6(a)-(d) represent perspective, top, front and right side views, respectively, of a fifth embodiment of a lancet constructed according to the teachings of the present invention;
FIGS. 7(a)-(d) represent perspective, top, front and right side views, respectively, of a sixth embodiment of a lancet constructed according to the teachings of the present invention;
FIGS. 8(a)-(d) represent perspective, top, front and right side views, respectively, of a seventh embodiment of a lancet constructed according to the teachings of the present invention; and
FIGS. 9(a)-(e) represent perspective, front, top, right side and enlarged fragmentary front views, respectively, of an eighth embodiment of a lancet constructed according to the teachings of the present invention.
Referring now to the drawings, there is shown in FIGS. 1(a)-(d), a first embodiment of a lancet which is constructed according to the teachings of the present invention, the lancet being identified generally by reference numeral 11. As can be appreciated, lancet 11 is designed to be fired into the skin of a patient in order to acquire a blood sample for testing purposes.
Referring now to FIG. 2, lancet 11 is preferably formed by subjecting a unitary member 13 to a series of grinding processes which will be described further in detail below. Unitary member 13 is preferably constructed of a 304 gage, full hard, stainless steel material to ensure that lancet 11 will have the necessary rigidity to function properly. Unitary member 13 is also preferably constructed of a stainless steel material which is treated with a bright finish to maximize the sharpness of the skin-penetrable tips which are created through the series of grinding processes.
It should be noted that unitary member 13 is not limited to being manufactured of a rigid stainless steel material. Rather, it is to be understood that unitary member 13 could be manufactured out of any suitable material (e.g., a ceramic material) which has an adequate amount of rigidity and which could be ground to form a plurality of sharpened tips without departing from the spirit of the present invention.
Unitary member 13 is represented herein as being in the form of an elongated, seamless, cylindrical tube which is hollow along its length. As a result, unitary member 13 has a lateral cross-section which is annular and uniform along its length. Unitary member 13 includes a first end 15, a second end 17, a longitudinal bore 18 and a longitudinal axis 19. Due to its uniform lateral cross-section, unitary member 13 can be mass produced by cutting an elongated, hollow cylindrical tube at equidistantly spaced intervals, which is highly desirable.
It should be noted that unitary member 13 is not limited to being in the form of an elongated cylindrical tube which is hollow along its length. Rather, it is to be understood that unitary member 13 could have a different shape (e.g., an oval-shaped lateral cross-section) without departing from the spirit of the present invention. Furthermore, it is to be understood that unitary member 13 need not be hollow along its length. Rather, unitary member 13 could be partially hollowed along its length (i.e., at first end 15 only) or solid along its entire length (and at least partially hollowed out in a subsequent boring, or drilling, process) without departing from the spirit of the present invention.
Referring back to FIG. 1(a), lancet 11 is shown in relation to its longitudinal axis X, its lateral axis Y and its vertical axis Z. Together, longitudinal axis X and lateral axis Y define a horizontal plane XY.
As noted briefly above, lancet 11 is formed by subjecting first end 15 of unitary member 13 to a series of grinding processes. Specifically, as seen most clearly in FIGS. 1(a)-(d), a first grinding process is performed on first end 15 of unitary member 13 so as to create a first ground surface 21. As seen most clearly in FIGS. 1(a) and 1(c), first ground surface 21 is a planar surface which extends from horizontal plane XY at an angle al of approximately 5 degrees relative to longitudinal axis X. First ground surface 21 is referred to in the art as a single angle ground surface because ground surface 21 extends from horizontal plane at a single angle relative thereto (i.e., at an angle relative to a single axis).
As seen most clearly in FIG. 1(d), the first grinding process generates a first ground surface 21 in first end 15 of unitary member 13 which extends approximately 180 degrees about longitudinal axis X. Accordingly, after said first grind, unitary member 13 (with first ground surface 21 formed therein) is rotated 180 degrees about longitudinal axis X and its first end 15 (with first ground surface 21 formed therein) is subjected to a secondary grinding process which is identical in nature to the primary grinding process. As a result of said second grinding process, a second ground surface 23 is formed which mirrors first grinding surface 23 about horizontal plane XY. Completion of the secondary grind results in finished lancet 11.
As can be seen, together the first and second grinding processes create a pair of identically-shaped, sharpened tips, or points, 25 which are spaced 180 degrees apart from one another. As seen most clearly in FIG. 1(b), tips 25 define a gullet 27 therebetween which is generally U-shaped in lateral cross-section.
It should be noted that the angle α1 at which ground surfaces 21 and 23 are formed could be modified without departing from the spirit of the present invention. As can be appreciated, increasing the value of angle α1 would render the resulting lancet tips more robust (i.e., firm and strong) but, at the same time, less sharp. Similarly, decreasing the value of angle α1 would render the resulting lancet tips more sharp but, at the same time, more flimsy (i.e., infirm). As such, the value of angle α1 could be adjusted by the lancet manufacturer to meet specific lancet performance needs.
Upon completion of its manufacturing, the end of lancet 11 opposite tips 25 is preferably embedded into a plastic base (not shown) such as through a process of insert molding. As can be appreciated, a plastic base would serve to improve handling and/or mounting requirements for lancet 11.
In use, lancet 11 can be used to draw a blood sample from a patient in the following manner. Specifically, lancet 11 is orientated such that sharpened tips 25 are directed towards the sample site on the patient. Lancet 11 is then driven (e.g., using a mechanical lancet device) such that both sharpened tips 25 penetrate into the dermis layer of the patient's skin and puncture at least one capillary therein. Preferably, lancet 11 is driven a distance which is less than the length of gullet 27 to minimize the surface area of lancet 11 which penetrates into the patient's skin, thereby minimizing patient discomfort. Lancet 11 is then withdrawn from the patient which causes a blood sample to exit the wound site, said blood sample being available for testing purposes.
The particular design of lancet 11 introduces a notable advantage over conventional lancets which include only a single tip. Specifically, the fact that lancet 11 includes a pair of sharpened tips 25 (as opposed to a single tip as found in most conventional lancets) serves to increase the probability of lancet 11 penetrating a capillary when inserted in the dermis layer of a patient, which is a principal object of the present invention. Furthermore, because two separate tips 25 are formed, the cross-sectional diameter of each tip 25 can be decreased to minimize patient discomfort during lancing, which is another principal object of the present invention.
It should be noted that numerous design modifications could be made to lancet 11 without departing from the spirit of the present invention. In particular, modifications to the quantity and relative sharpness of tips 25 could be made to lancet 11 without departing from the spirit of the present invention, as will be described further below.
Referring now to FIGS. 3(a)-(d), there is shown a second embodiment of a lancet constructed according to the teachings of the present invention, the lancet being identified generally by reference numeral 31. Lancet 31 is similar to lancet 11 in that lancet 31 includes a pair of sharpened tips 33. However, lancet 31 differs from lancet 11 in that lancet tips 33 are generated through a series of four (rather than two) grinding processes. As a result of the two additional grinding processes, lancet 31 is provided with tips 33 which are sharper in construction than tips 25 of lancet 11.
In FIG. 3(a), lancet 31 is shown in relation to its longitudinal axis X&#;, its lateral axis Y&#; and its vertical axis Z&#;. Together longitudinal axis X&#; and lateral axis Y&#; define a horizontal plane XY&#;. In addition, together longitudinal axis X&#; and vertical axis Z&#; define a vertical plane XZ&#;.
Lancet 31 is similar to lancet 11 in that lancet 31 is formed from unitary member 13. In order to manufacture lancet 31, first end 15 of unitary member 13 is subjected to four separate grinding processes. Specifically, a first grinding process is performed on first end 15 of unitary member 13 so as to create a first ground surface 35. As seen most clearly in FIG. 3(a), first ground surface 35 is a substantially planar surface which extends from horizontal plane XY&#; at both an angle α2 of approximately 7 degrees relative to longitudinal axis X&#; and an angle α3 of approximately 15 degrees relative to lateral axis Y&#;. It should be noted that first ground surface 35 is referred to in the art as a compound angle ground surface (or simply as a compound ground surface) because ground surface 35 is a planar surface which extends from horizontal plane XY&#; at multiple angles relative thereto (i.e., at an angle relative to more than one axis).
As seen most clearly in FIG. 3(d), the first grinding process generates a first ground surface 35 in first end 15 of unitary member 13 which extends approximately 90 degrees about longitudinal axis X&#;. Accordingly, after said first grind, unitary member 13 (with first ground surface 35 formed therein) is rotated 90 degrees in the counterclockwise direction about longitudinal axis X and is subjected to a second grinding process. As a result of said second grinding process, a second compound angle ground surface 37 is formed which mirrors first grinding surface 35 about vertical plane XZ&#;. After said second grind, unitary member 13 (with first and second ground surfaces 35 and 37 formed therein) is rotated another 90 degrees in the counterclockwise direction about longitudinal axis X and is subject to a third grinding process. As a result of said third grinding process, a third compound angle ground surface 39 is formed which mirrors second ground surface 37 about horizontal plane XY&#;. After said third grind, unitary member 13 (with first, second and third ground surfaces 35, 37 and 39 formed therein) is rotated another 90 degrees in the counterclockwise direction about longitudinal axis X and is subjected to a fourth grinding process. As a result of said fourth grinding process, a fourth compound angle ground surface 41 is formed which mirrors first ground surface 35 about horizontal plane XY&#;. Completion of the fourth grinding process produces finished lancet 31.
As can be seen, together the first, second, third and fourth grinding processes create a pair of skin-penetrable sharpened tips, or points, 33 which are spaced 180 degrees apart from one another. As seen most clearly in FIG. 3(b), tips 33 define a gullet 43 therebetween which is generally U-shaped in lateral cross-section.
Referring now to FIGS. 4(a)-(d), there is shown a third embodiment of a lancet constructed according to the teachings of the present invention, the lancet being identified by reference numeral 51. Lancet 51 is similar to lancet 11 in that lancet 51 includes a pair of sharpened tips 53. However, lancet 51 differs from lancet 11 in that lancet tips 53 are generated through a series of six (rather than two) grinding processes. As a result of the four additional grinding processes, lancet 51 is provided with tips 53 which are sharper in construction than tips 25 of lancet 11.
In FIG. 4(a), lancet 51 is shown in relation to its longitudinal axis X&#;, its lateral axis Y&#; and its vertical axis Z&#;. Together longitudinal axis X&#; and lateral axis Y&#; define a horizontal plane XY&#;. In addition, together longitudinal axis X&#; and vertical axis Z&#; define a vertical plane XZ&#;.
Lancet 51 is similar to lancet 11 in that lancet 51 is formed from unitary member 13. In fact, lancet 51 is formed by performing four additional grinding operations to lancet 11. Specifically, in order to manufacture lancet 51, a first grinding process is performed on first end 15 of unitary member 13 so as to create a first ground surface 55. As seen most clearly in FIG. 4(a), first ground surface 55 is a planar surface which extends from horizontal plane XY&#; at an angle α4 of approximately 5 degrees relative to longitudinal axis X&#;. As can be appreciated, first grinding process produces a first ground surface 55 in first end 15 of unitary member 13 which extends approximately 180 degrees about longitudinal axis X&#;. Accordingly, after said first grind, unitary member 13 (with first ground surface 55 formed therein) is rotated 180 degrees about longitudinal axis X&#; and its first end 15 (with first ground surface 55 formed therein) is subjected to a secondary grinding process which is identical in nature to the primary grinding process. As a result of said second grinding process, a second ground surface 56 is formed which mirrors first grinding surface 55 about horizontal plane XY&#;. Completion of the second grinding process produces lancet 11.
Lancet 11 is then subjected to four additional grinding processes. Specifically, a third grinding process is performed on one tip 25 of lancet 11 to create a third ground surface 57. Third ground surface 57 is a compound angle ground surface which is planar and which extends from horizontal plane XY&#; at both an angle α5 of approximately 8 degrees relative to longitudinal axis X&#; and an angle α6 of approximately 30 degrees relative to lateral axis Y&#;. The completion of the third grinding process creates a third ground surface 57 which extends approximately 180 degrees about one of said tips 25. Subsequent thereto, a fourth grinding process is performed on the same tip 25 of lancet 11. As a result of said fourth grinding process, a fourth compound angle ground surface 59 is formed on the same tip, said fourth ground surface 59 mirroring third ground surface 57 about horizontal plane XY&#;, as seen most clearly in FIGS. 4(c) and (d).
A fifth grinding process is performed on the other tip 25 of lancet 11 to create a fifth ground surface 61. As seen most clearly in FIGS. 4(b) and (d), fifth ground surface 61 is a compound angle ground surface which mirrors third ground surface about vertical plane XZ&#;. After the fifth grinding process, a sixth grinding process is performed. As a result of the sixth grinding process, a sixth compound angle ground surface 63 is formed which mirrors fifth compound angle ground surface 61 about horizontal plane XY&#;.
As can be seen, together the six grinding processes create a pair of sharpened tips 53-1 and 53-2 which are spaced 180 degrees apart from one another about longitudinal axis X&#;. As seen most clearly in FIG. 4(b), tips 53 define a gullet 65 therebetween which is generally U-shaped in lateral cross-section.
Referring now to FIGS. 5(a)-(d), there is shown a fourth embodiment of a lancet constructed according to the teachings of the present invention, the lancet being identified generally by reference numeral 71. Lancet 71 differs from lancet 11 primarily in that lancet 71 comprises three sharpened tips 73 (whereas lancet 11 includes only a pair of sharpened tips 25) which are created from three separate grinding processes (whereas lancet 11 is created from only a pair of grinding processes). It should be noted that the fact that lancet 71 includes three (rather than two) sharpened tips 73 improves the probability that lancet 71 will puncture a capillary when fired, which is a principal object of the present invention.
In FIG. 5(a), lancet 71 is shown in relation to its longitudinal axis X&#;&#;, its lateral axis Y&#;&#; and its vertical axis Z&#;&#;. Together longitudinal axis X&#;&#; and lateral axis Y&#;&#; define a horizontal plane XY&#;&#;. In addition, together longitudinal axis X&#;&#; and vertical axis Z&#;&#; define a vertical plane XZ&#;&#;.
Lancet 71 is similar to lancet 11 in that lancet 71 is formed from unitary member 13. To manufacture lancet 71, first end 15 of unitary member 13 is subjected to three separate grinding processes. Specifically, a first grinding process is performed on first end 15 of unitary member 13 so as to create a first single angle ground surface 75. As seen most clearly in FIGS. 5(a) and 5(b), first ground surface 75 is a planar surface which extends from horizontal plane XY&#;&#; at an angle α7 of approximately 7 degrees relative to longitudinal axis X&#;&#;.
As seen most clearly in FIG. 5(d), the first grinding process generates a first ground surface 75 in first end 15 of unitary member 13 which extends approximately 120 degrees about longitudinal axis X&#;&#;. Accordingly, after said first grind, first end 15 of unitary member 13 (with first ground surface 75 formed therein) is rotated 120 degrees in the counterclockwise direction about longitudinal axis X&#;&#; and is subjected to a second grinding process which is identical in nature to the first grinding process. As a result of the second grinding process, a second single angle ground surface 77 is formed. Furthermore, after said second grind, first end 15 of unitary member 13 (with first and second ground surfaces 75 and 77 formed therein) is rotated an additional 120 degrees in the counterclockwise direction about longitudinal axis X&#;&#; and is subjected to a third grinding process which is identical in nature to the first and second grinding processes. As a result of the third grinding process, a third single angle ground surface 79 is formed which mirrors second ground surface 77 about vertical plane XZ&#;&#;. Together, the three grinding processes create three sharpened tips 73-1, 73-2 and 73-3 which are spaced 120 degrees apart from one another about longitudinal axis X&#;&#;, adjacent tips 73 defining a gullet 80 therebetween which is generally U-shaped in lateral cross-section.
Referring now to FIGS. 6(a)-(d), there is shown a fifth embodiment of a lancet constructed according to the teachings of the present invention, the lancet being identified generally by reference numeral 91. Lancet 91 is similar to lancet 71 in that lancet 91 includes three sharpened tips 93. However, lancet 91 differs from lancet 71 in that lancet 91 is created by subjecting unitary member 13 to six separate grinding processes (whereas lancet 71 is created by subjecting unitary member 13 to three separate grinding processes). It should be noted that the fact that lancet 91 is created by subjecting unitary member 13 to three more grinding processes than lancet 71 results in tips 93 of lancet 91 being stronger (i.e., robust) than tips 73 of lancet 71, as will be described further below.
In FIG. 6(a), lancet 91 is shown in relation to its longitudinal axis X&#;&#;, its lateral axis Y&#;&#; and its vertical axis Z&#;&#;. Together longitudinal axis X&#;&#; and lateral axis Y&#;&#; define a horizontal plane XY&#;&#;. In addition, together longitudinal axis X&#;&#; and vertical axis Z&#;&#; define a vertical plane XZ&#;&#;.
The first three grinding processes in manufacturing lancet 91 are identical to the first three grinding processes in manufacturing lancet 71 with the exception of the particular grinding angle performed. Specifically, a first grinding process is performed on first end 15 of unitary member 13 so as to create a first single angle ground surface 95. As seen most clearly in FIGS. 6(a) and 6(b), first ground surface 95 is a planar surface which extends from horizontal plane XY&#;&#; at an angle α8 of approximately 3 degrees relative to longitudinal axis X&#;&#;.
As seen most clearly in FIG. 6(d), the first grinding process generates a first ground surface 95 in first end 15 of unitary member 13 which extends approximately 120 degrees about longitudinal axis X&#;&#;. Accordingly, after said first grind, first end 15 of unitary member 13 (with first ground surface 95 formed therein) is rotated 120 degrees in the counterclockwise direction about longitudinal axis X&#;&#; and is subjected to a second grinding process which is identical in nature to the first grinding process. As a result of the second grinding process, a second single angle ground surface 97 is formed. Furthermore, after said second grind, first end 15 of unitary member 13 (with first and second ground surfaces 95 and 97 formed therein) is rotated an additional 120 degrees in the counterclockwise direction about longitudinal axis X&#;&#; and is subjected to a third grinding process which is identical in nature to the first and second grinding processes. As a result of the third grinding process, a third single angle ground surface 99 is formed which mirrors second ground surface 97 about vertical plane XZ&#;&#;. Together, the three grinding processes create three sharpened tips 93-1, 93-2 and 93-3 which are spaced 120 degrees apart from one another about longitudinal axis X&#;&#;, adjacent tips 93 defining a gullet 100 therebetween which is generally U-shaped in lateral cross-section.
Upon completion of the first three grinding processes, three additional grinding processes are performed which serve to shorten the length of each tip 93 and thereby increase its strength, which is highly desirable. Specifically, a fourth grinding process is performed with the unitary member disposed in the same orientation in which the first grinding process is performed. The fourth grinding process creates a pair of single angle ground surfaces 101-1 and 101-2 on tips 93-1 and 93-2, repsectively. As seen most clearly in FIG. 6(a) and 6(b), single angle ground surfaces 101-1 and 101-2 are planar surfaces which extend from horizontal plane XY&#;&#; at an angle α9 of approximately 5 degrees relative to longitudinal axis X&#;&#;.
After said fourth grind, a fifth grinding process is performed with the unitary member disposed in the same orientation in which the second grinding process is performed. The fifth grinding process creates a pair of single angle ground surfaces 101-3 and on tips 93-2 and 93-3, respectively. Similarly, after said fifth grind, a sixth grinding process is performed with the unitary member disposed in the same orientation in which the third grinding process is performed. The sixth grinding process creates a pair of single angle ground surfaces 101-5 and 101-6 on tips 93-3 and 93-1, respectively. As can be appreciated, the fourth, fifth and sixth grinding processes serve to decrease the length of tips 93 (thereby rendering them more robust) while maintaining their sharpness, which is highly desirable.
The various grinding processes described above in conjunction with the multi-tip lancets of the present invention could be used to create a single tip lancet with an increased number of cutting edges as compared to conventional prior art lancets (which typically include two cutting edges). A single tip lancet which includes a greater number of cutting edges than a conventional lancet would be more likely to draw a blood sample when fired into the skin of a patient, which is highly desirable.
As an example, referring now to FIGS. 7(a)-(d), there is shown a sixth embodiment of a lancet constructed according to the teachings of the present invention, the lancet being identified generally by reference numeral 111. Lancet 111 is preferably formed by subjecting a solid (i.e., non-hollow) cylindrical tube which has a uniform circular cross-section along its length to three grinding processes.
Specifically, the three grinding processes are performed at approximately 120 degrees apart from one another about the longitudinal axis for lancet 111, each grind being performed at a planar angle of 7 degrees relative to the horizontal plane. The three grinding processes serve to create three adjacent single angle ground surfaces 113-1,113-2, 113-3 which together define a single sharpened tip 115.
It should be noted that adjacent ground surfaces 113 define an elongated cutting surface 117 therebetween. Accordingly, ground surfaces 113 serve to define first, second and third cutting surfaces 117-1, 117-2 and 117-3 which are spaced approximately 120 degrees apart from one another about the longitudinal axis for lancet 111. As can be appreciated, the formation of three separate cutting surfaces (as opposed to conventional lancets which only include two separate cutting surfaces) increases the likelihood that lancet 111 will puncture a capillary when fired into the skin of a patient, which is highly desirable.
It should also be noted that three additional grinding processes could be performed to lancet 111 to shorten the length of its sharpened tip, thereby rendering it more robust (i.e., strong). Specifically, fourth, fifth and sixth grinding processes can be performed with the unitary member disposed in the same orientation in which the first, second and third grinding processes are performed, wherein each of the three additional grinding processes is performed at an angle greater than the grinding angle of the three primary grinding processes.
Referring now to FIGS. 8(a)-(d), there is shown a seventh embodiment of a lancet constructed according to the teachings of the present invention, the lancet being identified generally by reference numeral 121. Lancet 121 is preferably formed by subjecting a solid cylindrical tube which has a uniform circular cross-section along its length to four grinding processes.
Specifically, the four grinding processes are performed approximately 90 degrees apart from one another about the longitudinal axis for lancet 121, each grind being performed at a planar angle of 9 degrees relative to the horizontal plane. The four grinding processes serve to create four adjacent single angle ground surfaces 123-1, 123-2, 123-3 and 123-4 which together define a single sharpened tip 125.
It should be noted that adjacent ground surfaces 123 define an elongated cutting surface 127 therebetween. Accordingly, ground surfaces 123 serve to define first, second, third and fourth cutting surfaces 127-1, 127-2, 127-3 and 127-4 which are spaced approximately 90 degrees apart from one another about the longitudinal axis for lancet 121. As can be appreciated, the formation of four separate cutting surfaces (as opposed to conventional lancets which only include two separate cutting surfaces) increases the likelihood that lancet 121 will puncture a capillary when fired into the skin of a patient, which is highly desirable.
Referring now to FIGS. 9(a)-(e), there is shown an eighth embodiment of a lancet constructed according to the teachings of the present invention, the lancet being identified generally by reference numeral 131. Lancet 131 is preferably formed by subjecting a solid cylindrical tube which has a uniform circular cross-section along its length to four grinding processes.
Specifically, the first three grinding processes are performed at approximately 120 degrees apart from one another about the longitudinal axis for lancet 131, each grind being performed at a planar angle of 4 degrees relative to the horizontal plane. The first three grinding processes serve to create three adjacent single angle ground surfaces 133-1,133-2 and 133-3 which together define a single sharpened tip.
It should be noted that adjacent ground surfaces 133 define an elongated cutting surface 135 therebetween. Accordingly, ground surfaces 133 serve to define first, second and third cutting surfaces 135-1, 135-2 and 135-3 which are spaced approximately 120 degrees apart from one another about the longitudinal axis for lancet 131. As can be appreciated, the formation of three separate cutting surfaces (as opposed to conventional lancets which only include two separate cutting surfaces) increases the likelihood that lancet 131 will puncture a capillary when fired into the skin of a patient, which is highly desirable.
The fourth (and final) grinding process is performed on the sharpened tip. Specifically, a 32 degree cone-shaped grinding process is performed on the sharpened tip to create a shortened, rounded, ground-off tip 137, as seen most clearly in FIG. 9(e). As can be appreciated, the fourth grinding process serves to minimize the length of tip 137 to improve its strength. It should be noted that a cone-shaped grinding process is accomplished by drawing the lancet tip into contact against a grinding wheel with the longitudinal axis of the lancet disposed at a non-orthogonal angle relative to the grinding surface of said wheel and, at the same time, continuously rotating the lancet 360 degrees about its longitudinal axis.

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The embodiments shown in the present invention are intended to be merely exemplary and those skilled in the art shall be able to make numerous variations and modifications to it without departing from the spirit of the present invention. All such variations and modifications are intended to be within the scope of the present invention as defined in the appended claims.

Lancet, method for manufacturing the lancet, and mold for the ...

The present invention relates to a production (or manufacturing) process of a lancet as well as a lancet produced by such a process and a mold for that process. In the present description, the lancet means a device which comprises a pricking member having a sharp front end portion which injures a predetermined portion of a body and which is constructed such that the device is launched or ejected toward the predetermined portion so that the front end portion pricks the predetermined portion. Such device includes various lancets which are widely used for collecting a body fluid, particularly blood from the predetermined potion.
When blood is collected from a predetermined position of a body for the purpose of various tests, it sometimes happens that such position is injured by a member having a sharp front end portion so as to exudate the blood from that position. A device called a lancet is used for such injuring. For example, in order to measure a glucose concentration in blood, a fingertip, an ear lobe or a palm is injured so as to collect blood.
The lancet used for the blood collection generally comprises a lancet cap and a lancet body, which are formed integrally by means of a weakened portion between them, so that a pricking member (such as a needle) extends through that portion while straddling them.
Upon blood collecting, a rear end portion of the lancet body is inserted into an injector which ejects the lancet toward a predetermined position, so that the lancet is loaded on the injector. Then, the weakened portion is broken so as to remove the lancet cap from the lancet body, so that an front end portion of the pricking member is exposed from a front end portion of the lancet body. When such lancet body is ejected thereafter, such exposed front end portion instantaneously moves toward and sticks the predetermined position, that it pricks the predetermined position, and then returns back immediately.
Pricking as mentioned above is an operation to injure a body by means of a sharp member. Before carrying out pricking, people whose blood is collected have a kind of tension in that they would feel some pain, and just upon pricking, they feel some pain. It is desirable that such tension and pain are depressurized as much as possible. For such depressurizing, it is conceived that a finer needle is used as the pricking member. The finer needle is desirable from a viewpoint of depressurizing, but there comes up a problem in that such needle is readily bent due to its less rigidity.
The lancet as mentioned above is produced by an injection molding process wherein a molten resin is injected into a mold in which a pricking member is inserted beforehand followed by solidifying the injected resin. When the pricking member is finer, a force generated by means of inertia of the injected molten resin is applied to the pricking member supported in the mold, so that molding may be carried out while the pricking member is in its curved (or flexed) state. For example, it is possible that a front end portion of the pricking member is curved (or flexed).
In the case wherein the front end portion of the pricking member is curved (or flexed), it is possible that said portion is not in the condition wherein it is exposed straight from the end surface of a front end portion of the lancet body when the lancet cap is removed from the lancet body upon pricking. When an injector ejects such lancet body toward a predetermined position, the front end portion of the pricking member is to stick in the predetermined position obliquely as to such portion (in spite of an intention that it essentially pricks at a right angle or an angle close thereto). In this case, the direction along which the lancet body moves is not corresponding to the direction along which the front end portion of the pricking member pricks the predetermined position.
As a result, since the front end portion of the pricking member tries to move obliquely in the skin, smoothly moving of that portion in the skin becomes more difficult compared with a case in which the pricking member is not curved (or flexed), so that pain which is felt upon pricking is increased. Therefore, it is desirable that curving (flexing) of the pricking member, particularly an area around the front end portion thereof is suppressed.
In order to suppress the above mentioned curving (or flexing) of the pricking member, a production process of a lancet is proposed in which an outer peripheral portion of a lancet cap is thicker while a portion of the lancet cap close to a front end portion of the pricking member is thinner (see Patent Document 1 below).
As to the lancet produced by the above mentioned process, a portion between the front end portion of the pricking member and the outer peripheral portion is thin. Thus, in a mold with which such lancet is formed, its passage for a molten resin to be injected through a point corresponding to a leading end of the lancet cap is narrow in an area corresponding to such thin portion. It is said that as a result, a velocity of the molten resin which passes through such narrow area is tentatively lowered, so that the inertia of the injected resin is equalized, whereby a force which intends to curve the front end portion of the pricking member is relaxed.
However, in order to produce the same number of the lancet as conventional according to the above mentioned process, an injection pressure of the molten resin should be increased because the passage for the molten resin is narrow. In this case, the inertia of the injected molten resin becomes larger, so that there comes a problem in that the effect of curving suppression may be insufficient. On the other hand, when the injection pressure of the molten resin is reduced, it takes a longer time to fill the mold with the molten resin, so that there comes a problem in that the same number of the lancet cannot be produced.
Patent Document 1:
Japanese Patent Kohyo Publication No. -
Therefore, it is desired that the above mentioned problems are suppressed as much as possible, so that a process of producing a lancet is provided wherein curving (or flexing) of the front end portion of the pricking member is further suppressed.
The inventor studied the above mentioned problem extensively, and finally has found that the problem is solved by a process of producing a lancet by injection molding of a resin with a pricking member inserted in a mold as a forming tool (i.e. insert molding) wherein upon forming at least a portion of a lancet cap in which portion the molten resin supplied to the mold surrounds a front end portion of a pricking member (that is, a front end portion surrounding portion), a mold is configured such that at least a portion of the molten resin which forms said portion of the lancet cap &#;flows along the front end portion of the pricking member toward its leading end&#;. It is noted that &#;at least a portion of the molten resin&#; is intended to mean that a whole of the molten resin which &#;flows along the front end portion of the pricking member toward its leading end&#; may form the front end portion surrounding portion or a portion of such molten resin may form the front end portion surrounding portion.
More specifically, the above mentioned &#;flows along the front end portion of the pricking member toward its leading end&#; is carried out by providing the mold which is configured such that said &#;at least a portion of the molten resin&#; flows from a lateral position beside any point of the front end portion of the pricking member (i.e. side position) toward the pricking member while a gas (usually air) present in a cavity of the mold which is to be filled with said &#;at least a portion of the molten resin&#; is pushed out of the mold through an opening located through a mold wall positioned in front of the leading end of the inserted pricking member. Therefore, in the process for the production of the lancet according to the present invention, said &#;at least a portion of the molten resin&#; flows along at least a portion of the front end portion which includes the leading end of the pricking member toward the leading end.
The above mentioned &#;any point of the front end portion of the pricking member&#; is not particularly limited as long as such point is located at somewhere of the front end portion of the pricking member. Such point may be the tail end of the front end portion, or it may be the front-most end of the front end portion (therefore, the front-most end of the pricking member). Such point is preferably between the leading end and the rear-most end of the front end portion (that is, any point which is located behind the front-most end of the front end portion and in front of the tailing end of the front end portion), and more preferably located at any point which is located on the front side of the middle point between the leading end and the rear-most end of the front end portion. Such &#;any point&#; may be any point located on an outer periphery around the pricking member, or may be in a ling form as a portion of the outer periphery or a whole of the outer periphery (usually a circle). Alternatively, it may be in a plane form wherein such line is extended along a longitudinal direction of the pricking member by a predetermined length. In a further embodiment, it may be in a line-like form wherein the above mentioned points are located along the longitudinal direction of the pricking member over a predetermined length.
The lateral position of the above mentioned &#;any point&#; is any point located on an outside from the outer periphery of the pricking member (for example, a point on a circle of which center corresponds to the pricking member so as to encompass the pricking member) which outside is laterally separated from said any point of the pricking member by a space. When such any point is in a dot form, the &#;lateral position&#; may also be in a dot form. When such any point is in a line form, the &#;lateral position&#; is also in a line form. When such any point is in a plane form, the &#;lateral position&#; is also in a plane form.
It is preferable that a plurality of the above mentioned &#;any point of the front end portion of the pricking member&#; are present. It is preferable that each stream of the molten resin goes from the lateral position toward the front end portion of the pricking member, and then goes as a stream that &#;flows along the front end portion of the pricking member toward a leading end of the front end portion&#; wherein those streams are in a symmetric condition as to the pricing member. That is, assuming a cross section of the pricking member perpendicular to the longitudinal direction of the pricking member as a point or a very small circle, the streams are in a point symmetry condition as to such point or vary small circle and/or in a line symmetry condition as to a straight line which passes such a point or very small circle. It is noted that as to &#;the streams are in the symmetric condition&#;, the directions and amounts of the streams are particularly to be considered. Also, it is more preferable that each of the streams is equalized at any position around the pricking member. For example, the streams of the molten resin toward the leading end of the pricking member flow ahead evenly around the pricking member. In the most preferable embodiment, the resin which flows around the pricking member is equivalent along a circumferential direction of the pricking member at any point along the longitudinal direction of the pricking member.
In order to achieve the above mentioned symmetrical flow, for example, it is preferable that above mentioned &#;any point of the front end portion of the pricking member&#; is located in a symmetric condition around the pricking member. For example, the above mentioned &#;any point of the front end portion of the pricking member&#; is provided so as to face each other through the pricking member (that is, at an angle of every 180° around the pricking member), or provided at an even angle (for example, every 120°, every 90° or every 60°) around the pricking member. In a particularly preferable embodiment, the above mentioned &#;any point of the front end portion of the pricking member&#; is present around a whole periphery of the pricking member. That is, &#;any point of the front end portion of the pricking member&#; is continuously (therefore, infinitely) present.
In the first aspect, the present invention provides a process for the production of a lancet by injecting a molten resin into a mold including a pricking member inserted therein beforehand followed by solidifying the resin, which process is characterized in that
the lancet comprises a lancet body and a lancet cap which are integrated with a weakened portion, the pricking member which extends in the lancet body and the lancet cap,
the pricking member comprises, as its portion, a front end portion which extends in the lancet cap (which portion protrudes from a front end of the lancet body upon using the lancet),
the front end portion of the pricking member comprises, at its front end portion, a sharp leading end which sticks a predetermined portion, and
the mold to be used comprises a cavity forming a resin passage which is formed so as to make a portion of the molten resin supplied to the mold flow along the front end portion toward its leading end (therefore, so as to substantially prevent said portion of the molten resin from flowing from the leading end backward and toward a rear of the front end portion),
(in consequence, said portion of the molten resin forms at least a portion of a front end portion surrounding portion of the lancet cap which encloses the front end portion of the pricking member).
It is noted in the present description that as to the lancet having the pricking member which extends in the lancet cap and the lancet body which are connected integrally together through the weakened portion, the &#;front end portion of the pricking member&#; is intended to mean a portion of the pricking member which portion protrudes from a front end surface of the lancet body when the weakened portion is broken and the lancet body is separated from the lancet body for the purpose of pricking. Also, the &#;leading end of the front end portion&#; is intended to mean a front-most end (which can substantially be regarded as a point) of the front end portion which is a portion of the pricking member
In a preferable embodiment of the process according to the present invention, the mold to be used includes a molten resin passage which is configured such that the molten resin flows toward a lateral position beside the front end portion of the pricking member, and then changes its flowing direction so as to flow forward along the front end portion of the pricking member. In one embodiment, the mold is configured such that the molten resin flows from a lateral position beside the pricking member toward the pricking member substantially perpendicular to the front end portion, and then changes its flowing direction so as to flow forward along the front end portion of the pricking member. In other embodiment, the mold is configured such that the molten resin flows from a lateral position beside the pricking member obliquely toward the front end portion of the pricking member, and then changes its flowing direction so as to flow forward along the front end portion of the pricking member. A further embodiment may employ a combination of the above mentioned embodiments. It is noted that the change of the flowing direction happens not like in a polygonal line, but like a curved line wherein the flowing direction in fact gradually changes. It should be understood that the first flow direction of the molten resin changes to the final flow direction of the molten resin as described in the above.
In the second aspect, the present invention provides a lancet which is produced by the process for the production of the lancet according to the present invention as described above. This lancet is characterized in that a portion of the lancet cap which portion surrounds the front end portion of the pricking member (i.e. the front end portion surrounding portion) includes a convex portion which protrudes forward so as to define cavities on the both sides and in front of the front end portion surrounding portion and encloses at least the leading end of the front end portion of the pricking member. The cavities may pass through vertically as to the lancet, or the cavities may have a wall, preferably a thin wall, for example a layered or film potion as bottoms of the cavities.
In the third aspect, the present invention provides a mold which is used in the process for the production of the lancet according to the present invention as described above. The mold has a wall as a blocking member which is located between a gate and the leading end of the pricking member on a line connecting them, so that the mold is configured such that the molten resin which is supplied through the gate into a mold cavity is prevented from flowing directly toward the leading end of the pricking member. It is noted that the above and below explanations as to the process for the production of the lancet according to the present invention are applicable when relevant.
In the production process according to the present invention, a portion of the molten resin supplied to the mold flows from a lateral position beside the front end portion toward the front end portion, and then flows along the front end portion and substantially passes the leading end finally up to its front. That is, such molten resin flows first near the leading end of the front end portion from its near side and then flows in the vicinity of the leading end. In the mold, since the pricking member is generally supported at two points (points from the both ends of the pricking member inside by 1/3 to 1/4 of the length of the pricking member) so that a length between a fulcrum point and an operation point is large, a large moment is acted on the leading end of the pricking member even though a small force is applied to the leading end. (It is noted that in the drawings referred to below, holes 52 and 54 are shown which are formed by the presence of support pins which function to support the pricking member.)
Therefore, when the leading end of the pricking member is located as downstream as possible as to the molten resin flow, the molten resin has already surrounded a portion of the front end portion near the leading end before the molten resin reaches the leading end of the pricking member, so that the fulcrum point at which the pricking member is supported is shifted forward to the leading end side, whereby a moment acted to the leading end is greatly reduced. In addition, the inertia of the molten resin flow becomes smaller in its more downstream, i.e. nearer the leading end. As a result of those, the moment acted on the leading end of the pricking member and the inertia of the molten resin become smaller in the present invention, so that the occurrence of curving or flexing of the front end portion of the pricking member is suppressed. Considering such effect, the present invention is particularly effective for the production of a lancet wherein a diameter of the pricking member is small. For example, when a stainless steel needle is used as the pricking member, the production process according to the present invention is advantageous in the case wherein the diameter of the needle is 0.4 mm or smaller, for example 0.32 mm or smaller, and particularly advantageous in the case wherein the diameter of the needle is 0.3 mm or smaller, especially 0.2 mm or smaller.
FIG. 1 schematically shows a perspective view of a lancet according to the present invention when viewing it from its above obliquely.
FIG. 2 schematically shows a perspective view of the lancet of FIG. 1 while it is turned upside down.
FIG. 3 schematically shows the lancet of FIG. 1 according to the present invention while its near side half is cut away (except that a whole of the pricking member is shown).
FIG. 4 schematically shows the lancet of FIG. 1 according to the present invention while its near half is cut away when the lancet is cut along a plane including the pricking member (which plane is perpendicular to the cut away plane in FIG. 3) (except that a whole of the pricking member is shown).
FIG. 5 schematically shows a perspective view of a mold in its open state which is used when the lancet according to the present invention is formed.
FIG. 6 schematically shows a perspective view of the mold of FIG. 5 in its closed state, namely in the state wherein an upper mold half and a lower mold half are fastened (except that a near half of the mold is cut away).
FIG. 7 schematically shows a lancet in a perspective view which is taken out of a lower mold half after injection molding of the lancet with using the mold shown in FIG. 5 and opening the mold (except that a near halves of the lancet and the mold are cut away).
10: lancet, 12: lancet body, 14: lancet cap,
16: weakened portion, 18: concave portion,
20: pricking member, 22: front end portion,
24: leading end, 26: rear end portion,
30: leading end of lancet, 30&#;: gate of mold,
32: front portion, 34: rear portion,
36: front end portion surrounding portion,
38: connection portion, 44: front cavity,
46: side cavity, 48: side cavity,
50: convex portion, 60: mold,
62: sliding back stopping pin, 64: pushing out pin,
66: pushing out pin, 68: pushing out pin,
70: upper mold half, 72: support pin, 74: support pin,
80: lower mold half, 82: pin, 84: pin,
86: ejection opening
The lancet of the present invention which is produced by the production process according to the present invention is shown in its perspective view in FIG. 1 when it is viewed from its oblique above and also in FIG. 2 when it is turned upside down. The lancet 10 comprises a lancet body 12 and a lancet cap 14, which are connected integrally by means of a weakened portion 16 which is located between them. The pricking member strides the lancet body 12 and the lancet cap 14, and a portion of the pricking member which extends in front of the weakened portion corresponds to the front end portion.
The shown lancet comprises a concave portion 18 in a front portion of the lancet cap, and a front end portion of the lancet body 12 with the leading end of the front end portion of the pricking member protruding from its end surface is adapted to fit into the concave portion 18. By means of the front end portion of the lancet body thus fitting into the concave potion, the protruding front end portion of the pricking member is substantially insulated, so that the spent lancet is can be disposed without carelessly touching the front end portion of the pricking member.
In FIG. 3, the lancet according to the present invention shown in FIG. 1 is schematically shown in a perspective view with its near side half cut away except that the pricking member is shown in whole. In FIG. 4, the lancet according to the present invention shown in FIG. 1 is schematically shown in a perspective view with its upper side half cut away when the lancet is cut along a plane which includes the pricking member (and which is perpendicular to the cut away plane in FIG. 3) except that the pricking member is shown in whole.
As readily seen, a portion of the pricking member 20 protruding forward from the front end surface 21 of the lancet body 12 in which the pricking member extends while striding the lancet body 12 and the lancet cap 14 corresponds to the front end portion 22 of the pricking member 20. Upon pricking, when the lancet cap 14 is removed by breaking the weakened portion 16 by means of twisting-off, the portion which protrudes from the front end surface of the lancet body corresponds to the front end portion 22. The leading end 24 of the front end portion 22 corresponds to the front-most end of the pricking member.
The mold which is used in the process for the production of the lancet according to the present invention will be explained below with reference to the lancet which is to be produced. It is noted that the produced lancet corresponds to the cavity of the mold, and the exposed surfaces of the produced lancet correspond to the walls of the cavity of the mold. Since the basic concept of the present invention resides in the flow of the molten resin, it is convenient to refer to the lancet to be produced.
In order to explain the present invention in detail, one example of the mold for the production of the lancet is shown FIGS. 5 and 6. FIG. 5 schematically shows the mold in its perspective view while it is opened wherein the mold is composed of an upper mold half 70 and a lower mold half 80. The pricking member 20 is inserted between these mold halves as shown in FIG. 5, and a molten resin is injected in the condition wherein these mold halves are fastened while the upper surfaces of them are joined together, so that the lancet is injection-molded. In FIG. 6, the mold which is formed together by fastening the halves is schematically shown in a perspective view while a near half of the mold is cut away.
When the shown mold is used, the pricking member 20 is supported by support pins 72 and 74 on the upper mold half side as well as support pins 82 and 84 on the lower mold halve side, and a pin 62 supports the rear end 23 of the pricking member which functions as a backward movement stopper of the pricking member. The pin 62 has a surface which the end surface 23 abuts. As a result, in the condition wherein the rear end 23 of the pricking member abuts the pin 62, the backward movement of the pricking member is prevented even when a backward force is applied to the pricking member 20.
Upon carrying out the production process of the lancet according to the present invention, the molten resin is supplied into the cavity of the mold as shown with the arrows (in which the pricking member is supported beforehand as mentioned above) through a point 30&#; of the mold which corresponds to a leading end 30 of the lancet (see FIGS. 4 and 6). That is, that point 30&#; functions as a gate. A cavity which corresponds to a portion which defines the front portion 32 of the lancet cap 14, particularly the concave portion 18 (see FIG. 2) is first filled, and then a cavity which corresponds to a portion which defines the rear portion 34 of the lancet cap is filled.
By means of the latter cavity filling as mentioned above, the front end portion of the pricking member is enclosed by the resin, so that the front end portion surrounding portion 36 and the connection portions 38 bridging the portion 36 and the front portion 32 are formed (see FIG. 4, borders between the front end portion surrounding portion 36 and the connection portion 38 are shown with broken lines 39). As shown with arrows in FIG. 4, the resin fills the cavity 32&#; which forms the front portion 32, and then fills the cavity 38&#; which forms the connection portions 38. Thereafter, a portion of the resin fills the cavity 36&#; which forms the front end portion surrounding portion 36, and the other portion of the resin fills the cavity 12&#; which forms the lancet body 12. The flows of the resin as mentioned above are schematically shown in the arrows in FIG. 4.
What is particularly noted is in that the molten resin flows from a lateral position beside the pricking member toward the front end portion thereof (see arrows &#;a&#;), and then a portion of the molten resin flows along the front end portion 22 of the pricking member toward its leading end.24 (see arrows &#;b&#;) while the balance of the molten resin flows toward the rear end 26 of the pricking member so as to form the lancet body (see arrows &#;c&#;). The present invention resides in the flows of the molten resin shown with arrows &#;a&#; and &#;b&#;.
As readily seen from FIG. 4, the molten resin supplied to the mold flows through cavities which form the connection portions 38, and then a portion of the resin flows along the pricking member toward its leading end 24 and the other portion of the molten resin flows along the pricking member toward its rear end 26. That is, the molten resin is divided into a portion flowing forward and a portion flowing backward. The portion flowing backward fills the cavity which forms a portion of the rear portions of the front end portion surrounding portion 36 and then fills the cavities which form the weakened portion 16 and the lancet body 12.
It is noted that gas which has been present in the cavities before the injection is discharged out by the molten resin from the mold through a gap (not shown because it is narrow) between a push-out pin 64 located in front of the leading end of the pricking member and a peripheral hole wall around the pin 64 (which is used for the removal of the lancet after molding), gaps (not shown because they are narrow) between the support pins (72, 74, 82 and 84) and peripheral hole walls around the pins, a gap (not shown because it is narrow) between the pin 62 and a peripheral hole wall around the pin, a gap (not shown because it is narrow) between a push-out pin 66 (which is used for the removal of the lancet after molding) and a peripheral hole wall around the pin, and an exhaust opening 86 which is provided in the rear end portion 26 in the mold.
As readily seen, the gap between the push-out pin 64 (which is used for the removal of the lancet after molding) and the peripheral hole wall around the pin functions an opening provided in the wall of the mold which is located in front of the leading end of the pricking member, so that the gas (usually, air) present in the cavity of the mold is pushed out through the gap which cavity is to be filled by the above mentioned &#;at least a portion of the molten resin&#;.
It is noted that the gas in the cavity which corresponds to the front portion 32 of the lancet cap is pushed out through the gap (not shown) between push-put pins 68 (which is used for the removal of the lancet after molding) and peripheral hole walls around the pins. Also, it is noted that the lancet is schematically shown in FIG. 7 which is pushed out from the lower mold half by the push-out pins while opening the mold after molding.
In the production process according to the present invention, the molten resin flow from any lateral position beside the front end portion toward the front end portion after filling the cavity which form the connection portion. In the embodiment shown in FIG. 4, referring to the arrows, the molten resin flows from a near side and a far side of the front end portion 22 of the pricking member toward the pricking member over a relatively long length, so that such flowing corresponds to &#;any point of the front end portion of the pricking member&#; in the form of a line on the either side over some length of the pricking member. A portion of the resin which has flowed as described above flows along the front end portion toward its leading end to form the front portion of the front end portion surrounding portion 36 while the other portion flows along the front end portion toward its rear end 26 to form the rear portion of the front end portion surrounding portion 36 as well as the weakened portion and the lancet body 12.
As readily seen, the arrows are shown in FIG. 4 such that the molten resin flows from the near side lateral position and the far side lateral position (that is, from two points) toward the front end portion, and the flow of the molten resin is not limited to the embodiment shown with the arrows as long as the molten resin flows from the lateral position(s) around the front end portion of the pricking member equiangularly toward the front end portion. For example, in place of flowing toward the front end portion from every 180° lateral position (that is, from two points), the molten resin may flow from every 90° lateral position (that is, from four points) or from every any other equal degree lateral position. More preferably, the &#;lateral position beside any point of the front end portion of the pricking member&#; is not in the form of a dot, but in the form of a line. For example, such line may be in the form of an arc having a certain length provided equiangularly around the front end portion. Most preferably, the molten resin flows toward the front end portion from a whole periphery laterally spaced from the outside of the front end portion.
Further, the &#;lateral position beside any point of the front end portion of the pricking member&#; preferably extends over a certain length along the longitudinal direction of the front end portion. In such case, such position is in the form of a line or plane. In a particularly preferred embodiment, such position is in an annular form which is laterally spaced from and over a certain length along the front end portion.
In one embodiment, the mold which is used in the production process according to the present invention has a blocking member in a front portion of the cavity which forms a resin portion surrounding the front end portion of the pricking member (that is, the front end portion surrounding portion) and the blocking member is adapted to prevent the molten resin injected through an inlet, that is, the gate into the cavity of the mold from flowing directly toward the leading end of the pricking member. Specifically, such blocking member is provided as described below.
When the lancet is produced, a gate is generally provided at a point which corresponds to a center of a leading end of the lancet cap to be formed, and the molten resin is injected through the gate 30&#;. The pricking member inserted in the cavity of the mold is supported in the center of the cavity along the longitudinal direction of the cavity, so that the leading end 24 of the front end portion 22 of the supported pricking member is facing to the gate through a space. Therefore, it is sufficient that the blocking member is a partition which is positioned between the gate 30&#; and the leading end 24 of the front end portion. That is, the blocking member should be present on a straight line which connects the gate 30&#; and the leading end 24. Therefore, in one embodiment, the mold of the present invention has a wall as the blocking member which is provided on a line connecting the gate and the leading end of the pricking member.
Since the gate and the leading end can substantially be regarded to be like points, the partition is in principle able to block the molten resin injected through the gate so as to prevent the resin from directly flowing toward the leading end of the pricking member even though a width of the partition, that is, a length of the partition along a direction perpendicular to the longitudinal direction of the pricking member is not so long. However, since there is a resin stream which bypasses the partition toward the leading end, it is preferable that the partition has a certain length of the width.
When the lancet shown in FIG. 4 is produced, the mold to be used is adapted to form the cavity 44 in front of the front end portion surrounding portion 36 by providing a blocking member 44&#; in front of the cavity which forms the front end portion surrounding portion 36. In order to minimize an amount of the molten resin which flows around the blocking member and flows directly toward the leading end of the pricking member, the mold is adapted to further form the cavities 44 and 46 beside the front end portion surrounding portion 36. That is, blocking members 46&#; and 48&#; are provided in the mold so as to form the cavities 46 and 48. Namely, in the shown embodiment, a mold is used in which the blocking member is provided so as to define a cavity of which front and both sides are closed around a portion of the front end portion of the pricking member which portion includes the leading end thereof. Only a rear portion and its both side portions are opened in such cavity, so that the molten resin gets into the cavity through its rear portion and/or the sides thereof and then flows along a portion of the front end portion of the pricking member toward its leading end.
By providing the blocking member as mentioned above, a portion of the lancet cap which encloses the front end portion of the pricing member (that is, the front end portion surrounding portion) defines the cavities 46 and 48 on the both sides of such front end portion surrounding portion as well as the cavity 44 in front of such portion, and the front end portion surrounding portion is characterized by comprising the convex portion 50 which protrudes forward and encloses at least the leading end of the front end portion of the pricking member. It is noted that those cavities may be those which penetrates vertically through the lancet as shown in the drawings.
In other embodiment, the cavities may have thin walls as their bottoms, that is, they may have thin films which close openings of such penetrating cavities at their ends. When the connection portions and the front end portion surrounding portions are connected with such walls, the positional relationship between the connection portions and the front end portion surrounding portion becomes firmer, so that the shape of the lancet cap becomes stable and careless breakage of the weakened portion is prevented. It is of course that the walls may be used for indicating product numbers thereon.
As to the lancet production process according to the present invention and the lancet produced by such process, known matters as to the known lancet production process and the lancet produced by the process can be applied except the above mentioned matters (that is, the concept according to the present invention in which the molten resin flows along the front end portion of the pricking member toward its leading end as well as the matters related such concept), and therefore explanations as to such known matters are omitted. For example, the known matters can be applied as to the materials used for the lancet, the known matters as to the pricking members, the general production process of the lancet and the like can be applied.
Therefore, when the technical matters according to the present invention is combined with the known matters as to the lancet, a lancet is produced with further less occurrence of bending in the front end portion. It is noted that the present invention can be applied not only to the shown lancet, but also it can be applied to various lancets in which the front end portion of the pricking member is enclosed with a resin.
It is noted that as to the terms &#;front&#; and &#;rear&#; which indicate directions, the direction along which the lancet moves for pricking is indicated with the term &#;front&#; and its opposite direction is indicated with the term &#;rear&#;. Also, the term &#;upper&#; indicates the direction from the shown lancet toward its above in FIG. 1 (the direction of arrow A), and its opposite direction is indicated with the term &#;lower&#; (the direction of arrow B).
The present application claims a priority under Paris Convention or other relevant priority under a law in the state where the present application is filed based on Japanese Patent Application No. - filed on Oct. 7, (Title of Invention: Production Process of Lancet), ant all of the contents of the Japanese Application form a portion of the present description.

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