Abstract:
An improved safe and convenient disposable automatic lancet, comprising a housing ( 1 ), a needle core ( 2 ), a spring ( 3 ) and a protective rod ( 4 ), wherein, a pressing arm of a trigger button ( 10 ) is divided into a first pressing leg ( 11 ) and a second pressing leg ( 19 ), and the first pressing leg ( 11 ) is used for triggering an elastic arm in a locking structure to form a press-type trigger structure, and the second pressing leg ( 19 ) fits with a safety sleeve ( 20 ) and a press-down channel ( 17 ) to achieve a safety function of the trigger button ( 10 ); a barb ( 12 ) on the second pressing leg ( 19 ) fits with a self-locking hook ( 13 ) on the housing ( 1 ) so as to achieve a self-locking function after one press. In order to shorten the exposed needle length of a needle body on the needle core ( 2 ), in the automatic lancet, the distance between the second pressing leg ( 19 ) and the needle tip ( 7 ) is designed to be less than the distance between the first pressing leg ( 11 ) and the needle tip ( 7 ). Since the exposed needle length depends on the position of the safety sleeve ( 20 ), the exposed needle length is shortened, therefore the puncture performance increases, which enables the design of the lancet to be more reasonable and practical.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to the field of medical device, particularly relates to a disposable automatic lancet. Based on the previous safe and convenient design, the lancet has an improved puncture performance of a needle body, which makes the design of the lancet more reasonable and practical. 
       BACKGROUND OF THE INVENTION 
       [0002]    Disposable automatic lancet is the main trend of today&#39;s lancet device, which has been improved and developed over years. The Chinese patent office authorized an invention patent on Apr. 7, 2010 with the title of “SAFE AND CONVENIENT DISPOSABLE AUTOMATIC LANCET”, the patent number of 200810136675.3, and the authorized publication number of CN101444428B. This patent utilizes the fit of a protective rod and the internal space of an ejection chamber to allow a needle core to be set in a locked state of to-be-launched, and before use, due to the blocking effect of an end of the protective rod, the button cannot be pressed down and then the needle core is set in a safety state. When in use, the needle core can immediately enter a launching state once the protective rod is removed by screwing, and after launching, it automatically enters the locked state by locking the button through the fit of the button and housing, and cannot be used again. Compared with other disposable automatic lancets, this patent has advantages of advanced technology, easy to operate and safe to use. However, in the specific solution given in Example 2 of this patent (see its  FIGS. 12 to 15 ), after the protective rod is removed, 11.5 mm length of the needle body of the needle core is exposed, which has a problem that the exposed length of needle is too long. Too long exposed length of needle not only increases the force of screwing the protective rod, but also results in a biggest defect that the needle is easily to bending deflected during puncture. Particularly, with the development of medical device technology, the required blood volume of the existing blood testing equipments becomes smaller and smaller, and in order to reduce algesia, the diameter of the lancet is made finer and finer, i.e. changing from the former 23 G (Φ0.6 mm) and 26 G (Φ0.45 mm) to the present 28 G (Φ0.36 mm) and 30 G (Φ0.30 mm). Such a fine lancet, if it has too long exposed length of needle, is prone to bending and deflecting during puncture, which greatly reduces the puncture performance of the needle tip. Accordingly, the object of the present invention is how to solve the problem of too-long-exposed-length of needle, and on the other hand, retain the existing safe and convenient design. 
       SUMMARY OF THE INVENTION 
       [0003]    The invention provides an improved safe and convenient disposable automatic lancet, and the objective of the invention is to solve the problem of too-long-exposed-length of needle after a protective rod is removed. 
         [0004]    In order to achieve the above-mentioned objective, the present invention provides the following technical solution: an improved safe and convenient disposable automatic lancet, comprising a housing, a needle core and a spring, wherein 
         [0005]    the needle core is provided with a needle body having a needle tip; 
         [0006]    the housing defines an ejection chamber in which the needle core is located, wherein the needle core has one end provided with a protective rod and another end on which the spring is fixed, 
         [0007]    the protective rod has one end protruding from a needle ejecting hole and another end detachably connected to the needle core; 
         [0008]    the housing has an elastic arm extending toward the inside of the ejection chamber for locking the needle core, a bayonet is provided on the needle core, corresponding to an end of the elastic arm, the end of the elastic arm snaps fit with the bayonet, characterized in that the housing is provided with a trigger button which has a first pressing leg and a second pressing leg, both legs are inserted into the ejection chamber, wherein in a state of to-be-launched, the distance between the second pressing leg and the needle tip is less than the distance between the first pressing leg and the needle tip; the first pressing leg is close to or contacts with the end of the elastic arm; and the second pressing leg is provided with a barb, corresponding to which a self-locking hook is provided on the housing; the self-locking hook is positioned in the press-down route of the barb when the second pressing leg, together with the barb provided thereon, is pressed downward, the barb and the self-locking hook forms a self-locking fit; 
         [0009]    a press-down channel is left in the ejection chamber along the press-down route of the second pressing leg, the protective rod is provided with a safety sleeve, and when the protective rod is assembled, the safety sleeve covers the needle tip and occupies the space of the press-down channel to prevent the second pressing leg from pressing downward; when the protective rod is removed, the safety sleeve is withdrawn from the press-down channel to allow the second pressing leg to be pressed downward, so as to bring the barb and the self-locking hook into a self-locking fit. 
         [0010]    The design concept and working principle of the present invention is that: based on the structure provided in the Chinese Patent CN101444428B, the present invention divides the previously designed pressing arm of the trigger button into the first and second pressing legs, wherein the first pressing leg is used for triggering the elastic arm in a locking structure to form a trigger structure of press-type, and the second pressing leg fits with the safety sleeve and the press-down channel to achieve a safety function of the trigger button, the barb on the second pressing leg fits with the self-locking hook on the housing, so as to achieve a self-locking function after one press. In order to shorten the exposed length of the needle body on the needle core, the present invention designs the distance between the second pressing leg and the needle tip to be less than the distance between the first pressing leg and the needle tip. Since the exposed length of needle depends on the position of the safety sleeve, the objective of shortening the exposed length of needle could be achieved by setting the distance between the second pressing leg and the needle tip be less than the distance between the first pressing leg and the needle tip. 
         [0011]    With the above technical solution, the invention has the following advantages and effects compared with the prior art: 
         [0012]    1. The exposed length of the needle body on the needle core according to the present invention is shortened, and the exposed length can be shortened for at least 4 mm compared with the prior art. 
         [0013]    2. Since the exposed length of the needle body on the needle core is shortened, and by contrast the puncture strength of the needle tip is increased, this is advantageous to use a finer needle body. Now proved by experiments, the finest diameter of the needle body can be 33 G (0.2 mm). 
         [0014]    3. It is possible to use finer needle body, which makes the protective rod is easier to be pulled out, and facilitate a user&#39;s use. 
     
    
     
       BRIEF DESCRIPTION THE DRAWINGS 
         [0015]      FIG. 1  shows a front view of the first embodiment of the invention; 
           [0016]      FIG. 2  shows a first perspective view of the first embodiment of the invention; 
           [0017]      FIG. 3  shows a second perspective view of the first embodiment of the invention; 
           [0018]      FIG. 4  shows a first exploded perspective view of the first embodiment of the invention; 
           [0019]      FIG. 5  shows a second exploded perspective view of the first embodiment of the invention; 
           [0020]      FIG. 6  shows a first perspective view of an upper cover of the housing according to the first embodiment of the invention; 
           [0021]      FIG. 7  shows a second perspective view of the upper cover of the housing according to the first embodiment of the invention; 
           [0022]      FIG. 8  shows a front view of the upper cover of the housing according to the first embodiment of the invention; 
           [0023]      FIG. 9  shows a first perspective view of a lower cover of the housing according to the first embodiment of the invention; 
           [0024]      FIG. 10  shows a second perspective view of the lower cover of the housing according to the first embodiment of the invention; 
           [0025]      FIG. 11  show a front view of the lower cover of the housing according to the first embodiment of the invention; 
           [0026]      FIG. 12  shows a perspective view of the needle core and the protective rod according to the first embodiment of the invention; 
           [0027]      FIG. 13  shows a front view of the needle core and the protective rod according to the first embodiment of the invention; 
           [0028]      FIG. 14  shows a structure diagram of closest prior art; 
           [0029]      FIG. 15  shows a sectional view along a line A-A of  FIG. 14 ; 
           [0030]      FIG. 16  shows a structure diagram of the first embodiment of the invention; 
           [0031]      FIG. 17  shows a sectional view along a line B-B of  FIG. 16 ; 
           [0032]      FIG. 18  shows a sectional view along a line C-C of  FIG. 16 ; 
           [0033]      FIG. 19  shows a comparison view of the exposed needle length before use; 
           [0034]      FIG. 20  shows a comparison view of the exposed needle length after use; 
           [0035]      FIG. 21  shows a sectional view of safety structure of the trigger button according to the second embodiment of the invention. 
       
    
    
       [0036]    Reference signs in the figures mentioned above: 
         [0037]      1 —housing 
         [0038]      2 —needle core 
         [0039]      3 —spring 
         [0040]      4 —protective rod 
         [0041]      5 —ejection chamber 
         [0042]      6 —needle ejecting hole 
         [0043]      7 —needle tip 
         [0044]      8 —elastic arm 
         [0045]      9 —bayonet 
         [0046]      10 —trigger button 
         [0047]      11 —first pressing leg 
         [0048]      12 —barb 
         [0049]      13 —self-locking hook 
         [0050]      14 —needle body 
         [0051]      15 —upper cover 
         [0052]      16 —lower cover 
         [0053]      17 —press-down channel 
         [0054]      18 —thin neck 
         [0055]      19 —second pressing leg 
         [0056]      20 —safety sleeve 
         [0057]      21 —pressing leg 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0058]    The invention will be further described with reference to the drawings and embodiments: 
       Embodiment 1 
     An Improved Safe and Convenient Disposable Automatic Lancet 
       [0059]    The above-mentioned technical solution is explained as follows: 
         [0060]    As illustrated in  FIGS. 1-13  and  16 - 18 , a lancet consists of a housing  1 , a needle core  2 , a spring  3  and a protective rod  4 . The housing  1  is composed of an upper cover  15  and a lower cover  16 , which are connected into an integral structure through a hole and a pin provided in contact surfaces thereof. The housing  1  defines an ejection chamber  5  provided with a needle ejecting hole  6  in one end thereof, the needle core  2  is located in the ejection chamber  5 , and one end of the needle core  2  is provided with the protective rod  4  which has one end protruding from the needle ejecting hole  6  of the housing  1 , a needle body  14  is provided in the needle core  2 , a needle tip  7  of the needle body  14  is positioned in the protective rod  4  and facing toward the needle ejecting hole  6 , the protective rod  4  is detachably connected to the needle core  2  by virtue of a socket joint or a thin neck  18  which can be twist off, the spring  3  is arranged on the other end of the needle core  2  to form an ejection structure where the spring  3  pushes the needle core  2  to move. 
         [0061]    An elastic arm  8  for locking the needle core  2  is extending from the bottom wall of the lower cover  16  of the housing  1  to the ejection chamber  5 , and the elastic arm  8  is inclined to the ejection chamber  5 . A bayonet  9  is provided on the needle core  2 , corresponding to an end of the elastic arm  8 , and the end of the elastic arm  8  snaps fit with the bayonet  9 , to constitute a locking structure of to-be-launched after the spring  3  is compressed by the needle core  2 . 
         [0062]    The upper cover  15  of the housing  1  is provided with a trigger button  10  formed by a extended body on the housing  1  (or formed by a separate member mounted on the housing  1 ). The trigger button  10  is provided with a first pressing leg  11  and a second pressing leg  19 , both of them are inserted into the ejection chamber  5 , and in the state of to-be-launched, the distance between the second pressing leg  19  and the needle tip  7  is less than the distance between the first pressing leg  11  and the needle tip  7 . The first pressing leg  11  and the second pressing leg  19  both forms a “U” shaped branch structure in the cross section perpendicular to the axis of the needle body  14 , wherein, two arms of the “U” shaped branch structure of the first pressing leg  11  respectively are close to or contact with the end of the elastic arm  8  from two sides of the needle core  2  across the ejection chamber  5 , to form a press-type trigger structure. Barbs  12  are respectively provided on one side, which faces toward the housing  1 , of the two arms of the “U” shaped branch structure of the second pressing leg  19 , one self-locking hook  13  is provided on each side of the housing  1  corresponding to each barb  12 , the self-locking hook  13  is located in a press-down route of the barb  12  when the second pressing leg  19 , together with the barb  12  provided thereon, is pressed downward, and the barb  12  fits with the self-locking hook  13  to form a self-locking structure after one press of the trigger button  10 . 
         [0063]    For the second pressing leg  19 , two press-down channels  17  are provided in the ejection chamber  5  to allow the “U” shaped branch structure of the second pressing leg  19  to press downward (see the circle area  17  enclosed by double-dotted line in  FIG. 18 ). In order to clearly indicate the direction, Z direction of the press-down channel  17  is defined as the press-down direction of the second pressing leg  19 , X direction is defined as the direction parallel to the axis of the needle body  14 , and Y direction is defined as the direction perpendicular to the X direction and Z direction. It can be understand with reference to coordinate directions as illustrated in  FIG. 18 . An end of the protective rod  4 , which locates in the ejection chamber  5 , is provided with a safety sleeve  20 , and when the protective rod  4  is assembled, the safety sleeve  20  covers the needle tip  7  and occupies part of the space of the press-down channel  17  in Y direction, to make the width of the press-down channel  17  in Y direction be less than the allowable insertion width of the second pressing leg  19 , so as to prevent the second pressing leg  19  from pressing downward. When the protective rod  4  is removed, the safety sleeve  20  is withdrawn from the press-down channel  17 , to make the width of the press-down channel  17  in Y direction be larger than or equal to the allowable insertion width of the second pressing leg  19 , thereby allowing the second pressing leg  19  to press downward to bring the barb  12  and the self-locking hook  13  into a self-locking fit, so as to form the safety structure of the trigger button. 
         [0064]      FIGS. 6-13  separately give a configuration diagram of the upper cover  15 , the lower cover  16 , the needle core  2  and the protective rod  4  according to the present embodiment, and  FIGS. 16-18  give assembly drawings of the embodiment. From the figures, details in all parts and the connection relationship under assembly state of the housing  1 , the needle core  2  and the protective rod  4  can be clearly seen. 
         [0065]    The invention allows the needle core to be assembled into the locking state of to-be-launched during manufacture of the lancet (it also may be not assembled into the locking state of to-be-launched, but one action of pushing the protective rod  4  should be added in use). As shown in  FIGS. 16-18 , in such state, due to the protective rod  4  is not removed, the trigger button  10  is under protective status, phenomenon of erroneous emission will not occur. When in use, as long as the protective rod  4  is twist off by the health care workers, the lancet will be entered into the state of to-be-launched (after the protective rod  4  is twist off, the protective rod  4  and the needle core  2  is cracked on the thin neck  18 , and after the protective rod  4  is removed, the safety sleeve  20  is withdrawn from the press-down channel  17 ). At this time when the trigger button  10  is pressed, the second pressing leg  19  is allowed to be pressed downward, and the first pressing leg  11  is pressed the elastic arm  8  to make the needle core  2  and the housing  1  unhooked, thereby the needle core  2  is pushed by the spring  3  to inject. At the same time, the second pressing leg  19  is beyond the self-locking hook  13  during press-down movement. Accordingly during rebound process, the barb  12  is locked in a position of the self-locking hook  13  and form self-locking, which cannot return to its original state, so that locking-ejection structure is failed and it cannot be used again. 
         [0066]    In the present embodiment, the elastic arm  8  is designed to lock the needle core  2 , and it can be designed into many forms which fall into the protection scope of the invention as long as the objective of locking and unlocking the needle core  2  is achieved by utilizing the elasticity of the elastic arm  8  to fit with the bayonet  9  of the needle core  2 . Wherein, the elastic arm  8  is best to be set inclined, and the inclined direction can be shown in  FIG. 18 , and the elastic arm  8  can also be set in the opposite direction, and then a hook is used to hook the bayonet  9 . 
         [0067]      FIGS. 14 and 15  are the schematic structure of the closest prior art (Example 2 of Chinese Patent CN101444428B). As can be seen from  FIGS. 14 and 15 , the prior art is characterized in that: a pressing leg  21  with only one pair of “U” shaped branch structure is provided on the trigger button  10  of the upper cover  15 . When the trigger button  10  is pressed after the protective rod  4  is removed, the pressing leg  21  pushes the elastic arm  8  on the lower cover  16 , and after the needle core  2  is separated and injected from the elastic arm  8 , the pressing leg  21  makes the bard  12  and the self-locking hook  13  on the lower cover  16  be locked with each other during the press-down process, and the product can no longer be used after injection. However, after the protective rod  4  on the needle core  2  is twist off, front portion of the needle body  14  on the needle core  2  is exposed too long, which is prone to bending deformation during puncturing skin, reducing the puncture performance of the needle body. 
         [0068]      FIGS. 16-18  shows assembly diagram of the present embodiment of the invention, as can be seen from the figures, the invention is characterized in that: pressing legs with two pairs of “U” shaped branch structure i.e. the first pressing leg  11  and the second pressing leg  19 , are provided on the front and rear of the trigger button  10  of the upper cover  15 , and in the state of to-be-launched as shown in  FIG. 16 , the distance between the second pressing leg  19  and the needle tip  7  is less than that between the first pressing leg  11  and the needle tip  7 . When the trigger button  10  is pressed after the protective rod  4  is removed, the first pressing leg  11  on the left pushes arm  8  on the lower cover  16 , and after the needle core  2  is separated and ejected from the elastic arm  8 , during the press-down process the second pressing leg  19  makes the bard  12  and the self-locking hook  13  on the lower cover  16  be locked with each other, and the product can no longer be used after ejection. The key of the invention is that the pressing leg is divided into two pairs from the original one pair, with maintaining the formal functions (that is, firstly the connection between the safety sleeve  20  and the press-down channel  17  provides safety before use, secondly the fit between the bard  12  on the second pressing leg  19  and the self-locking hook  13  on the lower cover  16  provides safety after use, and thirdly the needle core  2  is assembled to be entered into the locking state of to-be-launched to provide convenience of use), and the effect of shortening the exposed length of needle is achieved. 
         [0069]      FIGS. 19 and 20  respectively show a comparison diagram of the exposed needle length before use and after use, wherein the word “D” indicates the length of the needle body  14 , and the word “E” indicates a shorten value of the exposed needle length. The upper part of  FIG. 19  shows the state of the needle core  2  and the protective rod  4  of the prior art before use, and the lower part of  FIG. 19  show the state of needle core  2  and the protective rod  4  of the invention before use. The upper part of  FIG. 20  shows the state of the needle core  2  and the protective rod  4  of the prior art after use, and the lower part of  FIG. 20  shows the state of the needle core  2  and the protective  4  of the invention after use. Comparing the two figures, it can be seen clearly that the exposed needle of the prior art is longer than that of the invention, and the difference therebetween is E. 
       Embodiment 2 
     An Improved Safe and Convenient Disposable Automatic Lancet 
       [0070]    As shown in  FIG. 21 , the difference between this embodiment and the first embodiment is that: the safety sleeve  20  covers the front part of the needle body  14 , the safety sleeve  20  occupies the two press-down channels  17  (with reference to the circle area enclosed by double-dotted line, indicated by reference number  17  in  FIG. 21 ) in Z direction (as illustrated in the coordinate of  FIG. 21 ), to block the press-down channels  17  in Z direction, thereby preventing the second pressing leg  19  from pressing downward. When the protective rod  4  is removed, the safety sleeve  20  is withdrawn from the two pressing channels  17 , to make the two pressing channels  17  be opened in direction Z, thereby allowing the barb  12  and the self-locking hook  13  to be self-locking fit when the second pressing leg  19  pressing downward, so as to form the safety structure of the trigger button. Other structure and principles are the same as that of the first embodiment, and which is not repeated here. 
         [0071]    As can be seen from the above two embodiments that, “the safety sleeve  20  simultaneously occupies the press-down channels  17  from the Y direction and Z direction” means that, the width of the Y direction is less than the allowable insertion width of the second pressing pin  19 , while Z direction is clogged. This is easy to be understood by the person skilled in the art. 
         [0072]    The above described embodiment are to illustrate the technical concept and character of the invention, the purpose of which is to make the person skilled in the art to be able to understand the content of the invention and to carry out the invention, without limiting the protection scope of the invention. The equivalent changes or modifications according to the script of the invention should be fallen into the protection scope the invention.