HK1144242B - Puncture instrument - Google Patents

Abstract

A puncture instrument (10) includes a needle assembly (44), a hub passage (16) for axially guiding a hub (42), a needle passage (18) communicating with the hub passage (16) and having a distal end opening (18a) for allowing the tip end of a needle (40) to project instantaneously therethrough, two arms (46) having first junctions (52) connected to the hub (42) and inclined rearward in a direction away from the hub (42) in an initial state, two push rods (48) connected to second junctions (54) of the arms (46) and extending rearward, a button (50) for pushing the push rods (48) forwardly, and fulcrum members (24) disposed more closely to the distal end than the arms (46) for abutment against portions of the arms (46) when the arms (46) are moved. When the push rods (48) are pushed forwardly by the button (50), the arms (46) push the needle assembly (44) forwardly, thereafter have portions thereof brought into abutment against the fulcrum members (24), and turn to pull the needle assembly (44) rearward.

Description

Puncture outfit

Technical Field

The present invention relates to a puncture instrument including a needle for momentarily extending the needle to puncture a person's skin with the needle.

Background

Diabetic patients are generally recommended to perform daily diabetes self-management by measuring blood glucose levels themselves. The blood glucose level may be measured with a blood component measuring device. According to a blood component measuring apparatus equipped with a test paper impregnated with a reagent that changes color depending on the amount of glucose contained in a blood sample brought into contact with the test paper. In operation, a blood sample is applied to the test strip and the degree of color change of the reagent is optically measured to determine the blood glucose level in the blood sample. The determined blood glucose level is then displayed. Another blood component measuring device employs an electrochemical sensor to measure the blood glucose level of a blood sample.

In order for a diabetic to sample his or her blood, the diabetic uses a puncture instrument equipped with a puncture needle having a needle that can move in an axial direction. The puncture needle head is removably mounted on the puncture instrument, and a pushing force from the elastic body is applied to the needle inside, causing the needle to momentarily protrude and puncture the skin (e.g., finger, palm, arm, etc.) of the patient, thereby serving to allow a small amount of blood to flow out. After the puncture, the needle is retracted by the return mechanism.

Generally, a puncture instrument is used with a puncture needle mounted thereon, and the puncture needle is discarded after use. Although hospitals and clinics have a large number of puncture needles to spare, depending on the number of patients and the frequency of blood glucose measurements, a relatively small number of puncture instruments can be used. Therefore, if many patients need to measure blood glucose levels at the same time, all patients may take longer to measure blood glucose levels than usual because there are not enough puncture instruments available. There is a need for a simpler puncture device, since the puncture needle head is mounted on and removed from the puncture device during each measurement.

Japanese patent No. 3795511 discloses a simple lancet assembly which is integrally combined with a puncture needle. The disclosed lancet assembly eliminates the need to mount and remove the lancet needle each time a blood sample is to be taken.

Disclosure of Invention

An object of the present invention is to provide a puncture instrument which can be operated stably and has a simple structure.

The puncture instrument according to the present invention comprises: a housing; a needle assembly movably disposed within the housing and including a needle and a hub holding the needle; a hub passage for guiding the hub in an axial direction, the hub passage being provided in the housing; a needle channel disposed in the housing and in communication with the hub channel, the needle channel having a distal end opening for allowing a tip of the needle to extend therethrough; at least one arm having a first connection part connected to the hub at one end thereof and a second connection part at the other end thereof, the arm being inclined from the first connection part toward the proximal end of the housing in an initial state; a push rod coupled to the second connection portion and extending toward the proximal end; a pusher for pushing the push rod toward the distal end of the housing; and a fulcrum member for abutting against a portion of the arm when the arm is moved, wherein, when the push rod is pushed toward the distal end by the pusher, the arm pushes the needle assembly toward the distal end with the portion thereof abutting against the fulcrum member and rotating about the fulcrum member, so that the arm is inclined from the first connection toward the distal end, thereby pulling the needle assembly back toward the proximal end.

With the puncture instrument described above, the needle assembly is directly pushed by the push rod without intermediating an elastic body for biasing the needle assembly in the axial direction, the skin can be stably punctured, and the structure is simple. After the needle pierces the skin, the arm rotates about the fulcrum member to reliably withdraw the needle from the skin. The term "housing" as referred to above is used in a broad sense to denote a component that serves as the base of the penetrator.

The push rod may include a leaf spring capable of elastically deforming under the force exerted by the arm when the pusher pushes the push rod toward the distal end. If the push rod includes a leaf spring, it does not interfere with the rotation of the arm, thus allowing the arm to operate more stably. After the needle assembly finishes its movement, the needle assembly is elastically biased to move backward by the elastic force of the push rod.

In an initial state, the arm may be inclined toward the proximal end in a direction away from the hub, and when the push rod is pushed toward the distal end as the pusher is pushed, the arm may rotate about the fulcrum member and be inclined toward the distal end in a direction away from the hub.

At least one of the first and second connection portions may be narrower than the arm and may be plastically deformed when the arm is rotated and changes its inclination direction. The pusher is stably held at the end-of-stroke position without moving back toward the initial position if at least one of the first connecting portion and the second connecting portion is plastically deformed. Thus, the puncture instrument can be prevented from being reused.

The hub may include a base at a proximal end portion thereof, the base having a flat surface parallel to the arm rotation plane, the first connecting portion being rotatably connected to the base at a position on the plane spaced a predetermined distance from a longitudinal axis of the hub.

The pusher may include a male or female engagement portion, and the housing includes a first engageable portion that engages the engagement portion when the pusher is in an initial position and a second engageable portion that engages the engagement portion when the pusher is in an end-of-stroke position.

In the initial position, the engagement portion of the pusher engages the first engageable portion and is therefore not accidentally moved. When the pusher is forcibly pushed toward the distal end, the engaging portion is disengaged from the first engageable portion, allowing the pusher and the needle assembly to be forcibly moved toward the distal end. The needle is thus able to penetrate the skin at a certain speed. Thereafter, the engaging portion engages the second engageable portion to hold the pusher stably in place.

The pusher may be movably disposed in an internal cavity formed in the housing and have a proximal end that extends from the housing a distance ranging from 5mm to 30mm when the pusher is in an initial position and extends from the housing a distance less than 5mm when the pusher is in an end-of-stroke position. With this arrangement, the user of the puncture instrument can easily recognize whether or not the puncture instrument has been used by confirming the distance by which the pusher protrudes from the housing. After the puncture instrument has been used, the pusher is almost entirely inserted into the housing and prevented from being accidentally pulled back out of the housing.

The needle channel may be narrower than the hub channel and a step is provided between the needle channel and the hub channel for abutment of a distal end surface of the hub against the step to limit movement of the needle assembly. The step reliably and effectively limits the movement of the needle assembly, thereby achieving a suitable depth of penetration of the needle into the skin.

The arm may comprise two arms and the push rod may comprise two push rods, the two arms and the two push rods being symmetrical with respect to the longitudinal axis of the hub. The two arms and the two push rods provide a relatively simple structure with few parts, are structurally symmetrical and are well balanced.

The puncture instrument may further include a biasing means for biasing the pusher toward the distal end and a stopper for restricting movement of the pusher toward the distal end biased by the biasing means and releasing the pusher in response to operation of the trigger. The biasing means allows the user to operate the trigger with less force to cause the needle to penetrate the skin.

The housing may be hollow cylindrical and the puncture instrument may further comprise a protective cap removably mounted at the distal end of the housing for holding and sealing the needle in the needle passage. When the protective cap is mounted, the hollow cylindrical housing can be highly sealed, thereby keeping the needle sterile.

The puncture instrument according to the present invention provides the following advantages.

The needle assembly is directly pushed by the push rod, and an elastic component for biasing the needle assembly along the axial direction is not arranged in the middle, so that the skin can be stably punctured, and the structure is simple. After the needle has penetrated the skin, the arm pivots about the fulcrum member to reliably pull the needle back from the skin.

Further, the lancet assembly disclosed in japanese patent No. 3795511 appears to be capable of performing lancing with a single operation. However, inside the lancet assembly, a spring needs to be compressed just before puncturing, and then the puncturing is fired. If the spring is compressed in advance, the spring performance tends to deteriorate. Although such a two-step operation can avoid the deterioration of elasticity, the internal structure of the lancet assembly becomes complicated. In contrast, since the puncture instrument of the present invention does not require a spring, the deterioration of elasticity does not affect and a simple structure is realized.

The above and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings. In the drawings, preferred embodiments of the invention are shown by way of illustrative examples.

Drawings

Fig. 1 is an external perspective view of a puncture instrument according to a first embodiment of the present invention;

FIG. 2 is a cross-sectional view of the puncture instrument shown in FIG. 1, showing an initial state thereof;

FIG. 3A is a perspective view of the housing according to the first example when deployed;

fig. 3B is a perspective view of a housing according to a second example;

FIG. 4 is a perspective view of the movable member of the puncture instrument;

FIG. 5 is a schematic view showing the manner in which the penetrator may be placed against the skin;

FIG. 6 is a cross-sectional view of the hub against the step of the penetrator;

FIG. 7 is a cross-sectional view of the penetrator with the arm abutting the fulcrum member;

FIG. 8 is a cross-sectional view of the penetrator with the arm pivoted about the fulcrum member;

FIG. 9 is a cross-sectional view of the puncture instrument when the movable member has reached the end of its stroke;

fig. 10 is a perspective view of a puncture instrument according to a second embodiment of the present invention;

FIG. 11 is a cross-sectional view of the puncture instrument shown in FIG. 10, showing an initial state thereof;

FIG. 12 is a cross-sectional side view of the puncture instrument shown in FIG. 11;

fig. 13 is a perspective view of a puncture instrument according to a third embodiment of the present invention, showing an initial state thereof;

fig. 14A is a sectional view showing an arm according to a first modification in its initial state;

fig. 14B is a sectional view showing the arm according to the first modification when it reaches the end of its stroke;

fig. 15 is a sectional view showing an arm according to a second modification;

FIG. 16 is an enlarged cross-sectional view of a distal end portion of a modified penetrator incorporating a nut for adjusting needle extension;

fig. 17 is a perspective view of a puncture instrument according to a fourth embodiment of the present invention;

FIG. 18 is an exploded perspective view, partially in section, of the puncture instrument of FIG. 17;

FIG. 19 is a cross-sectional view of the puncture instrument of FIG. 17, showing the puncture instrument in a state ready for puncture;

FIG. 20 is a cross-sectional view of the puncture instrument shown in FIG. 17, showing the manner in which the needle punctures the skin of the patient after the protective cap is removed from the puncture instrument;

FIG. 21 is a cross-sectional view of the puncture instrument shown in FIG. 17, with the arm abutting the fulcrum member and rotating;

FIG. 22 is a cross-sectional view of the penetrator of FIG. 17 after the pusher has reached the end of its travel;

fig. 23 is a perspective view of a puncture instrument according to a fifth embodiment of the present invention;

FIG. 24 is an exploded perspective view, partially in section, of the puncture instrument shown in FIG. 23;

FIG. 25 is a cross-sectional view of the puncture instrument of FIG. 23, showing the puncture instrument in a state ready for puncture;

FIG. 26 is a cross-sectional view of the puncture instrument shown in FIG. 23, showing the manner in which the needle punctures the skin of the patient after the protective cap is removed from the puncture instrument;

FIG. 27 is a cross-sectional view of the puncture instrument shown in FIG. 23, with the arm abutting the fulcrum member and rotating; and

FIG. 28 is a cross-sectional view of the puncture instrument of FIG. 23 when the movable member has reached the end of its stroke.

Detailed Description

A puncture device according to a preferred embodiment of the present invention will be described below with reference to fig. 1 to 28 of the drawings. The direction indicated by the arrow X1 in fig. 1 is directed to the front (distal end) of the puncture instrument, and the direction indicated by the arrow X2 in fig. 1 is directed to the rear (proximal end) of the puncture instrument.

As shown in fig. 1 to 9, a puncture instrument 10 according to a first embodiment of the present invention includes a housing 12, a movable member 14 movably provided in the housing 12, and a protective cap 15. The housing 12 serves as a base of the puncture instrument 10, and has a thin pentagonal-shaped body including a substantially square rear portion 12a and a tapered front portion 12 b. The puncture instrument 10 may be made of resin (e.g., polypropylene or polyethylene) or metal, except for the needle 40 described later. The housing 12 has a distal end face 12c, the distal end face 12c having a suitable area for abutting against the skin of a patient.

As shown in FIG. 2, the front portion 12b has a hub passage 16 and a needle passage 18 formed axially therethrough. The needle channel 18 has a distal end opening 18a that opens at the distal end face 12c and a rear end that communicates with the hub channel 16. The needle passage 18 is smaller in diameter than the hub passage 16, and a step 20 is provided between the needle passage 18 and the hub passage 16.

The rear portion 12a has an inner cavity 22 formed by walls enclosed in four directions. The inner cavity 22 has a forward central end in communication with the hub passage 16 and a rearward open rear end. The rear portion 12a has a front wall defining the front end of the cavity 22 and including two fulcrum members 24 projecting slightly rearwardly from respective portions of the front wall on opposite sides of the hub passage 16. Each fulcrum member 24 has a rear end portion that is semicircular in cross-sectional shape in plan view.

The side walls 22a of the inner cavity 22 each include a first recess (first engageable portion) 26 formed therein near the open rear end of the inner cavity 22 and a second recess (second engageable portion) 28 formed therein at a substantially axially central position. The side wall 22a has a smooth surface except for the first recess 26 and the second recess 28.

As shown in fig. 3A, according to a first example, the housing 12 comprises two symmetrical members 30 joined to each other by a short bendable member 32. The symmetrical members 30 can be brought together around the bendable members 32. As shown in FIG. 3B, according to a second example, the housing 12 includes a body 34 including the hub passage 16, the needle passage 18, and the internal cavity 22, and a cover 36 placed over the body 34. The body 34 and the cover 36 may be joined to one another by a member similar to the bendable member 32 shown in fig. 3A.

As shown in fig. 2 and 4, the movable member 14 includes a needle assembly 44 including a needle 40 and a hub 42 holding the needle 40, a pair of arms 46 and a pair of push rods 48 having a symmetrical shape with respect to the longitudinal axis C of the hub 42, and a push button (pusher) 50 for pushing the push rods 48 forward. Since the movable member 14 has two arms 46 and two pushers 48, the number of arms 46 and pushers 48 is small, the structure is simple, and they are well balanced due to their symmetrical shapes. However, the movable member 14 may have a single arm 46 and a single pushrod 48, or more than three arms 46 and more than three pushrods 48. If the movable member 14 has more than three arms 46 and more than three pushrods 48, the arms 46 and pushrods 48 may be equiangularly spaced from one another about the longitudinal axis C of the hub 42.

The needle 40 includes a hollow needle or a solid needle, and may be made of metal such as stainless steel, aluminum, or titanium, or hard resin such as polyphenylene sulfide. The push rod 48 has sufficient mechanical strength for the push arm 46 and the needle assembly 44, and has sufficient elasticity to bend outward. Thus, the push rod 48 has a function as a leaf spring. When the push rod 48 is in the initial state shown in fig. 2, even in the storage state before use, the push rod 48 is not elastically strained, and therefore, the elastic force is not reduced even if the push rod 48 is kept stored for a long time.

The needle 40, which is used to pierce the skin of the patient, is disposed in the forward portion of the needle assembly 44. In the initial state shown in fig. 2, the tip of the needle 40 is inserted into the needle passage 18.

Each arm 46 includes a first connection 52 at one end connected to the hub 42 and a second connection 54 at the other end connected to the distal end of the push rod 48. In the initial state, the arms 46 extend outwardly in a rearward direction and are rearwardly inclined in a corresponding direction away from the longitudinal axis C of the hub 42. The angle θ 1 at which the arm 46 is inclined with respect to the longitudinal axis C of the hub 42 is, for example, approximately 50 °.

The arms 46 have respective recesses 56 formed on their rear surfaces at the first connection 52 and respective recesses 58 formed on their front surfaces at the second connection 54. Thus, the first and second connections 52, 54 are narrower than the rest of the arm 46.

The distal ends of the push rods 48 are linked to the respective arms 46. The push rods 48 extend rearwardly substantially parallel to the longitudinal axis C of the hub 42, and respective rear ends are joined to a front surface of a push button 50. The push rod 48 is suitably spaced from the side wall 22 a.

The push button 50 substantially closes the rear opening of the interior cavity 22. In the initial state, only the front end portion of the push button 50 is inserted into the inner cavity 22. The front end portion of the push button 50 inserted into the cavity 22 has a pair of projections (engaging portions) 60 on opposite outer sides thereof, and the pair of projections 60 are engaged in the respective first recesses 26 in the initial state. The push button 50 has a rear end portion protruding from the housing 12 by a certain distance and having rounded corners, allowing the push button 50 to be easily operated by a human hand. The rear end portion of the push button 50 protrudes from the housing 12 by a distance in the range of 5mm to 30mm for allowing the push button 50 to be easily operated by a human hand.

The movable member 14 has a space 61 defined therein surrounded by the hub 42, the arm 46, the push rod 48, and the push button 50.

The protective cap 15 comprises a tubular member 62 inserted into the hub passage 16 and the needle passage 18 and covering the needle 40, and a projection 64 connected to the front end of the tubular member 62. The tubular member 62 has a tapered rear end portion, which is fixed to the front end face of the hub 42 by fusion, adhesion, or the like. The needle 40 has a needle portion sealed in the tubular member 62 by insert molding. The hub 42 and the protective cap 15 may be integrally molded. The protective cap 15 is irradiated with gamma rays, electron beams, or the like to sterilize the needle 40 in the tubular member 62.

The operation of the puncture instrument 10 thus constructed will be described below.

The tubular member 62 is first twisted off the hub 42 by twisting the protrusion 64, whereupon the protective cap 15 is removed from the housing 12.

Next, as shown in FIG. 5, the housing 12 is held in place, the distal end face 12c is placed against the patient's skin 70, and the push button 50 is then pushed into the lumen 22. At this time, the push button 50 can be pushed in with the thumb while the front portion 12b is held between the index finger and the middle finger. The housing 12 may have projections that act as finger stops.

When the push button 50 is pushed in, the movable member 14 is initially motionless because the protrusion 60 is engaged in the first recess 26. When the push button 50 is pushed with a greater force, the protrusion 60 is forced out of the first recess 26. Since the push button 50 is pushed with a larger force and the wall 22a does not have something to hinder the movement of the protrusion 60, the movable member 14 moves forward quickly. Accordingly, the movable member 14 ensures a certain penetration speed of the needle 40 required.

As shown in fig. 6, when the movable member 14 moves forward, the tip of the needle 40 protrudes out of the distal end face 12c of the housing 12 and pierces the skin. Specifically, the needle assembly 44 is not biased axially by the elastomer, but is pushed directly by the push rod 48 to allow the needle 40 to stably penetrate the skin. When the hub 42 engages the step 20 and stops thereby, the distance that the needle 40 projects beyond the distal end face 12c is limited. Thus, the needle 40 penetrates the skin 70 to a suitable depth.

As shown in fig. 7, when the hub 42 engages the step 20, the needle assembly 44 stops moving forward with the movable member 14. As the push button 50 is pushed in continuously, the arm 46 and the push rod 48 are moved further forward, bringing the front surface of the arm 46 into abutment with the fulcrum member 24. The fulcrum member 24 engages the front surface of the arm 46 near the first connection 52 on the side opposite the recess 56.

As the push button 50 is pushed in further, the push rod 48 and the push button 50 move forward further, and the arm 46 rotates about the fulcrum member 24, as shown in fig. 8. At this time, the arm 46 smoothly rotates about the fulcrum member 24 because the rear end portion of the fulcrum member 24 is a semicircular cross-sectional shape.

Because the fulcrum member 24 engages the arm 46 near the hub 42, the arm 46 generally rotates about the first connection 52, causing the second connection 54 to move in an arc about the first connection 52. The distal end of the push rod 48 is pushed outward. At this time, the push rod 48 acts as a leaf spring, elastically bending outward around the rear end portion of the push rod 48. Since the pushers 48 act as leaf springs, they do not hinder the rotation of the arm 46, but rather stabilize the movement of the arm 46.

When the arm 46 rotates, stress concentrates on the narrow first and second connection portions 52 and 54, so that the first and second connection portions 52 and 54 are plastically deformed beyond the elastic range.

The fulcrum members 24 located next to the hubs 42 are spaced apart from the hubs 42 by a distance L, respectively (see fig. 7). When the second connecting portion 54 moves forward, the first connecting portion 52 moves rearward because the arm 46 pivots about the fulcrum member 24. The needle assembly 44 now begins to move rearwardly.

As shown in fig. 9, as the push rod 48 and the push button 50 move further rearward with the movable member 14, the arm 46 pivots further about the fulcrum member 24. When the projection 60 engages in the second recess 28, the push button 50 is pushed to the end of its travel and stops moving.

At this point, the arms 46 are tilted forward in respective directions away from the longitudinal axis C of the hub 42. The needle assembly 44 is retracted sufficiently to pull the needle 40 out of the skin 70 into the needle channel 18. Since the arm 46 is rotated about the fulcrum member 24 to pull back the needle assembly 44, the needle 40 is reliably pulled out of the skin 70. The arm 46 is inclined at an angle θ 2 of, for example, about 60 ° relative to the longitudinal axis C of the hub 42. When the needle assembly 44 is fully retracted, the hub 42 enters a space 61 sufficient to accommodate the hub 42 and the push button 50. Therefore, the needle assembly 44 does not interfere with the push button 50.

As the arm 46 rotates about the fulcrum member 24, the second connecting portion 54 moves slightly toward the longitudinal axis C of the hub 42, and the push rod 48 also moves slightly rearward toward the longitudinal axis C of the hub 42. Although the spring force applied to the arms 46 from the push rod 48 is reduced, this force is of sufficient magnitude to keep the needle assembly 44 pushed rearward.

At this time, the first connection portion 52 and the second connection portion 54 have been plastically deformed, and some cracks may even occur. Therefore, their elastic force is significantly reduced to such an extent that the arms 46 can no longer restore their original posture, i.e., the needle assembly 44 can no longer be pushed back, so that the arms 46 and the needle assembly 44 are stably maintained retracted. Since the first and second connections 52, 54 are not completely broken, they continue to retain the needle assembly 44 within the housing 12. The push button 50 is prevented from being pulled out to use the puncture instrument 10 again.

The push button 50 is almost entirely or completely inserted into the cavity 22 and therefore is not inadvertently operated thereafter. When the push button 50 has reached the end of its travel, it is either fully inserted in the lumen 22 or its rear end portion protrudes out of the lumen 22 by a distance of less than 5mm, so that the push button 50 cannot be pulled back out of the lumen 22. The user can easily identify whether the puncture instrument 10 is in the pre-use state or the post-use state simply by looking at how much the push button 50 protrudes from the housing 12.

Since the recess 56 is formed on the rear surface at the first connecting portion 52 of the arm 46, when the arm 46 rotates about the fulcrum member 24, the end 56a of the recess 56 moves away from the hub 42 and is held without interfering with the hub 42. Since the recess 58 is formed on the front surface of the arm 46 at the second connecting portion 54, when the arm 46 rotates about the fulcrum member 24, the end 58a of the recess 58 moves away from the push rod 48 and is held without interfering with the push rod 48.

The puncturing action shown in fig. 2, 6, 7, 8, 9 is completed in a very short time, and therefore, the tip of the needle 40 momentarily protrudes from the distal end opening 18a of the needle passage 18.

When the skin 70 is punctured by the needle 40, a small amount of blood flows out of the skin 70 and is sampled. The sample blood is analyzed with a blood glucose meter, not shown, or the like, and the blood components are measured. The puncture instrument 10 is discarded after use. Since the needle 40 is fully retracted within the needle channel 18, there is no danger of being hit by anyone when the puncture instrument 10 is thrown away.

The puncture instrument 10 according to the first embodiment provides the following advantages. The puncture instrument 10 does not contain an elastomer for biasing the needle assembly 44 for axial movement. Instead, the needle assembly 44 is pushed directly outward by the push rod 48 and the arm 46, causing the needle 40 to stably penetrate the skin 70. Since the needle assembly 44 is pushed directly outward by the push rod 48 and the arms 46, no mechanism is required within the penetrator 10 to axially compress the elastomer and then fire the resilient member to release its energy to push the needle assembly 44. Therefore, the puncture instrument 10 is relatively simple in structure. After the needle 40 penetrates the skin 70, the arm 46 is rotated about the fulcrum member 24, pulling back the needle assembly 44 to thereby reliably pull the needle 40 out of the skin 70.

Since the puncture instrument 10 having a simple structure can be mass-produced, it is inexpensive and suitable for use as a disposable product. The puncture instrument 10 is basically constituted by two parts, i.e., a combined assembly of the movable member 14 and the protective cap 15, and the housing 12. Therefore, the puncture instrument 10 is constituted by a small number of parts, and is simple in structure and easy to assemble.

The push button 50 may have a recess instead of the projection 60, and the housing 12 may have a projection instead of the first and second recesses 26, 28. The housing 12 may have a vent hole to allow the movable member 14 to move smoothly therein.

A puncture instrument 100 according to a second embodiment of the present invention will be described with reference to fig. 10 to 12. Those parts of the puncture instrument 100 which are the same as those of the puncture instrument 10 according to the first embodiment are denoted by the same reference numerals and will not be described in detail below.

As shown in fig. 10 to 12, the puncture instrument 100 according to the second embodiment includes a pusher 102, a capsule (biasing means) 104 for biasing the pusher 102 to be pushed forward, a trigger switch (trigger) 106, and a stopper 108 for holding the pusher 102 against forward movement and releasing the pusher 102 to move forward when the trigger switch 106 is pressed. The pusher 102, the capsule 104, the firing switch 106, and the stopper 108 are used to perform the function of the push button 50 of the puncture instrument 10 according to the first embodiment. Other details of the puncture instrument 100 according to the second embodiment are substantially the same as those of the puncture instrument 10 according to the first embodiment.

The housing 12 includes a rear end wall 12d covering the rear end of the inner cavity therein. The capsule 104 is disposed in the enclosed space between the pusher 102 and the rear end wall 12 d. The pusher 102 is the same in configuration as the front end portion of the push button 50 of the puncture instrument 10 according to the first embodiment. Two push rods 48 are connected to the pusher 102. The rear end wall 12d has a central hole defined therein that retains the gas supply port 104a of the bladder 104 therein. A compressed air supply tube 110 in the hospital is removably connected to the air supply port 104 a.

The stopper 108 has a rear end portion connected to the pusher 102 and extending forward from the pusher 102. The stopper 108 has a front end portion that gently engages an end surface of the first upper hole 12e formed in the upper wall of the housing 12. The firing switch 106 has a rear end connected to the rear end wall 12d of the housing 12 and extending forward from the rear end wall 12 d. The cocking switch 106 substantially covers the first upper aperture 12 e. The firing switch 106 is disposed above the stop 108 and extends along the stop 108.

The housing 12 also has a second upper aperture 12f formed in the upper wall of the housing, closer to the distal end than the first upper aperture 12 e. The user of the puncture instrument 100 can confirm the position of the movable member 14 through the second upper hole 12f to see whether the puncture instrument 100 is in the pre-use state or the post-use state. The puncture instrument 100 does not have the protrusion 60, the first recess 26, and the second recess 28 of the puncture instrument 10 according to the first embodiment.

The operation of the puncture instrument 100 is as follows: first, the protective cap 15 is removed, and then a compressed air supply tube 110 is connected to the air supply port 104a to introduce compressed air into the bladder 104, thereby pressurizing the bladder 104. When the bladder 104 is pressurized, it biases the pusher 102 forward. However, since the stopper 108 engages the end face of the first upper hole 12e, the pusher 102 remains stationary.

Next, the user holds the housing 12, abuts the distal end face 12c against the skin 70, and then presses the trigger switch 106. The trigger switch 106 is resiliently depressed to disengage the stopper 108 from the end surface of the first upper hole 12 e. The movable member 14 is released and pushed rapidly forward by the inflated balloon 104, causing the needle 40 to pierce the skin 70. Thereafter, the arm 46 is rotated about the fulcrum member 24, pulling the needle 40 back from the skin 70 into the needle channel 18.

The puncture instrument 100 provides the same advantages as the puncture instrument 10 according to the first embodiment. Further, the pusher 102 is pushed by the balloon 104 and the firing switch 106 can be operated with a very light force.

In the case of using air pressure to push the pusher 102, the bladder 104 may be replaced with a diaphragm or a pneumatic actuator (bellophragm). The seal may be fitted around the pusher 102 and slidably held in contact with the inner wall surface of the housing 12 such that the pusher 102 and the housing 12 operate together as a piston-cylinder mechanism.

A puncture instrument 200 according to a third embodiment of the present invention will be described with reference to fig. 13. Those parts of the puncture instrument 200 which are the same as those of the puncture instruments 10, 100 according to the first and second embodiments are denoted by the same reference numerals, and will not be described in detail below.

As shown in fig. 13, the puncture instrument 200 includes a pusher 202, a main magnet (biasing means) 204 provided in the pusher 202, and a pair of auxiliary magnets (biasing means) 206 symmetrically provided in the front portion 12b of the housing 12. The two push rods 48 are connected to the pusher 202 like the push buttons 50 of the puncture instrument 10. The puncture instrument 200 includes a firing switch 106, a stopper 108, a rear end wall 12d, a first upper hole 12e, and a second upper hole 12f, like the puncture instrument 100.

The main magnet 204 and the auxiliary magnet 206 are oriented such that their N-and S-poles are opposite to each other, attracted to each other by magnetic force, and thus serve to bias the pusher 202 to be pushed forward.

The operation of the puncture instrument 200 is as follows: the actuator 202 is biased to move forward under the magnetic force from the main magnet 204 and the auxiliary magnet 206 in a normal case. But the pusher 202 is held stationary because the stopper 108 engages the end face of the first upper hole 12 e. When the user holds the housing 12, abuts the distal end face 12c against the skin 70, and then presses the trigger switch 106, the stopper 108 is released from engagement with the end face of the first upper hole 12e, and thus the movable member 14 is released and pushed forward, so that the needle 40 pierces the skin 70. Thereafter, the arm 46 is rotated about the fulcrum member 24, pulling the needle 40 back from the skin 70 into the needle channel 18.

The puncture instrument 200 provides the same advantages as the puncture instrument 100 according to the second embodiment. Moreover, the puncture instrument 200 does not require an external power source such as a compressed air source, because the pusher 202 is normally biased forward by the magnetic force from the main magnet 204 and the auxiliary magnet 206.

The housing 12 of the penetrator 200 may have an aperture for removing the auxiliary magnet 206 and the main magnet 204 therethrough after the main magnet 204 reaches the end of its travel.

Next, modifications of the puncture instrument 10, 100, 200 will be described.

According to a first variant shown in fig. 14A, the first connection portion 52 of the arm 46 is rotatably supported on the hub 42. When the arm 46 rotates about the first connecting portion 52, the second connecting portion 54 is plastically deformed as shown in fig. 14B.

Alternatively, the second connecting portion 54 may be rotatably supported on the push rod 48, and the first connecting portion 52 may be plastically deformed. In other words, as long as at least the first connecting portion 52 or the second connecting portion 54 can be plastically deformed, the movable member 14 can be stably held at the stroke end thereof.

According to a second modification, as shown in fig. 15, the first connecting portion 52 of the arm 46 is rotatably supported on the hub 42, and the second connecting portion 54 is rotatably supported on the push rod 48.

Fig. 16 shows a further modified puncture instrument, wherein the distal end face 12c is provided with a nut 250 screwed onto the distal end of the front face portion 12 b. As the nut 250 is rotated about its own axis, the distance between the distal end face 12c and the step 20 is changed to adjust the distance that the needle 40 protrudes from the distal end face 12 c. The nut 250 may have an indexing mechanism for setting itself to a number of angular positions about its own axis. Any of a variety of other mechanisms may be employed to adjust the distance that the needle 40 extends beyond the distal end face 12 c.

A puncture instrument 300 according to a fourth embodiment of the present invention will be described with reference to fig. 17 to 22. Those parts of the puncture instrument 300 which are the same as those of the puncture instruments 10, 100, 200 according to the first, second, and third embodiments are denoted by the same reference numerals, and will not be described in detail below.

As shown in fig. 17 to 22, the puncture instrument 300 includes a body 302, a hub holder 304 movably disposed in the body 302, a hub 306 held at one end of the hub holder 304 and supporting the needle 40, a pusher 308 for pushing the hub holder 304 forward, a link mechanism 310 for transmitting a pressure applied to the pusher 308 to the hub holder 304, and a protective cap 312 mounted on the body 302.

The body 302 is a hollow, substantially cylindrical structure having a tapered front end portion 302a in which the needle 40 is inserted and a rear end portion 302b having a larger diameter than the front end portion 302 a. The pusher 308 is partially exposed from the rear end portion 302 b.

Body 302 has a hub passage 314 and a needle passage 316 formed in nose portion 302a and extending axially through nose portion 302 a. The needle passage 316 has one end opening at the front end portion 302a of the body 302 and an opposite end communicating with the hub passage 314. The needle passage 316 has a smaller diameter than the hub passage 314, and a first step 318 is disposed between the needle passage 316 and the hub passage 314.

The rear end portion 302b of the body 302 has an inner cavity 320 formed therein, and the pusher 308 is inserted in the inner cavity 320. The internal cavity 320 communicates with the hub passage 314 through a retainer bore 322 formed centrally in the body 302. The cavity 320 is circular in cross-sectional shape and opens at the rear end portion 302 b. The holder hole 322 is substantially rectangular in cross-sectional shape, and the hub holder 304 is movably disposed in the holder hole 322. Second step 324 is disposed between retainer bore 322 and hub passage 314.

The rear end portion 302b of the body 302 has a plurality of guide grooves 326 formed therein at angular intervals equally spaced in the circumferential direction. The pusher 308 has a plurality of protrusions 328 to be described later, and the protrusions 328 are respectively inserted into the guide grooves 326. The guide groove 326 has a predetermined length in the axial direction of the body 302 indicated by arrows X1, X2. The interior cavity 320 of the body 302 communicates with the exterior of the body 302 via the guide channel 326.

A pair of fulcrum members 330a, 330b are provided on the inner wall surface of the holder hole 322 in alignment with the axis of the body 302. The fulcrum members 330a, 330b extend rearward from the inner wall on the hub passage 314 side by a predetermined distance, and have ends of a semicircular cross-sectional shape. The fulcrum members 330a, 330b are disposed in opposing relation to each other on either side of the hub holder 304 disposed within the holder hole 322.

A pair of guide grooves 332 are formed in the other inner wall surface of the holder hole 322 at respective positions angularly spaced apart by 90 ° from the fulcrum members 330a, 330 b. The guide groove 332 extends in the axial direction of the body 302.

The hub holder 304 includes a base 334 having a substantially rectangular shape and a hollow cylindrical hub support 336 projecting axially forward from the base 334. The base 334 has rails 338 disposed on respective opposite side surfaces thereof and projecting laterally therefrom. The guide rails 338 are slidably engaged in the guide grooves 332, respectively, to axially guide the hub holder 304 in the directions indicated by the arrows X1, X2 without allowing the hub holder 304 to rotate about its own axis in the body 302.

The base 334 has a pair of arm holes 340 formed therethrough at respective positions laterally spaced apart from each other by a predetermined distance on both sides of the axis of the base 334. The linkage 310 includes two arms 350a, 350b that are disposed on upper and lower surfaces of the base 334, respectively, and have respective ends (described later) pivotally supported in the arm holes 340.

A hub support 336 extends from the forward end of the base 334. The hub 306 has a rear end that fits into the front end of the hub support 336, and is thus supported by the hub support 336.

The pusher 308 includes a cylindrical button 342 and a pair of push rods 344a, 344b extending from a front end of the button 342. The button 342 is partially housed within the interior cavity 320 of the body 302. A plurality of protrusions 328 are provided on the outer circumferential surface of the button 342 and are respectively inserted into the guide grooves 326 of the body 302. Since the guide groove 326 extends in the axial direction of the body 302, the pusher 308 is movably guided in the axial direction indicated by the arrows X1, X2.

The push rods 344a, 344b are offset with respect to the center of the button 342 and extend axially straight a predetermined distance from the button 342. Specifically, as shown in fig. 18, the push rods 344a, 344B are vertically spaced apart from each other by a predetermined distance on both sides of the center of the button 342 in the direction indicated by the arrow a, and are also laterally spaced apart from each other by a predetermined distance on both sides of the center of the button 342 in the direction indicated by the arrow B.

The push rods 344a, 344b have respective wide supports 346 on their distal ends. The other ends of the arms 350a, 350b are pivotally supported on respective supports 346. As shown in fig. 18, the support member 346 has respective link holes 348 formed therein that extend vertically through the support member 346 perpendicular to the push rods 344a, 344b and parallel to each other.

The arms 350a, 350b of the linkage 310 have respective first pins 352 at their ends and respective second pins 354 at their other ends.

First and second pins 352, 354 extend perpendicular to the axis of the arms 350a, 350 b. The first pin 352 extends in one direction and the second pin 354 extends in the opposite direction. The first pins 352 are inserted in the arm holes 340 of the hub holder 304, respectively, and the second pins 354 are inserted in the link holes 348 of the push rods 344a, 344b, respectively. The first pin 352 functions as a first connection to the hub holder 304 and the second pin 254 functions as a second connection to the push rods 344a, 344 b.

When the puncture instrument 300 is in a state ready for puncture, i.e., before puncturing the skin 70 with the puncture instrument 300, as shown in fig. 19, the arms 350a, 350b are disposed one by one in a crossing relationship with each other on the side of the hub holder 304.

The protective cap 312 protects a tubular member 356 inserted in the needle passage 316 and covering the needle 40 and a projection 358 connected to the front end of the tubular member 356. The tubular member 356 is inserted and fitted in the needle passage 316. The tubular member 356 may be secured to the needle passage 316 by fusing, bonding, or the like. The protective cap 312 is irradiated with gamma rays, electron beams, or the like to sterilize the needle 40 in the tubular member 356.

The operation of the puncture instrument 300 is as follows: in the ready-to-puncture state shown in fig. 19, the projection 358 of the protective cap 312 is twisted to release the tubular member 356 from engagement with the body 302, thereby removing the protective cap 312.

Next, the body 302 is held by hand with the leading end portion 302a thereof being abutted against the skin (not shown), and then the button 342 of the pusher 308 is pushed toward the body 302 in the direction indicated by the arrow X1. At this time, the button 342 is pushed in with the thumb while the area of the body 302 near the front end portion 302a is held between the index finger and the middle finger.

When the pusher 308 is pushed, the movement of the pusher 308 is initially limited to some extent because the protrusion 328 engages the inner wall surface of the inner cavity 320. As the pushing force applied to the pusher 308 increases, the protrusion 328 moves out of engagement with the inner wall surface of the inner cavity 320 and is inserted into the guide groove 326 (see fig. 20). At this time, the pusher 308 is guided to move toward the front end portion 302a of the body 302 along the axial direction of the body 302 in the direction indicated by the arrow X1.

When the pusher 308 is moved toward the front end portion 302a as shown in fig. 20, the arms 350a, 350b are pivotally supported by the push rods 344a, 344b, and the hub holder 304 is moved toward the front end portion 302a, moving the hub 306 held by the hub holder 304 along the hub passage 314 and the needle passage 316. At this point, the arms 350a, 350b do not rotate, but move in unison with the pusher 308 and the hub holder 304. Also illustrated, the arms 350a, 350b remain as struts between the hub holder 304 and the pusher 308.

The hub holder 304 only moves axially and does not rotate about its own axis, as it is guided by the guide rails 338 engaged in the respective guide slots 332.

The tip of the needle 40 protrudes out of the front end portion 302a of the body 302 and pierces the skin. Specifically, needle 40 is not axially biased by the elastomer, but is pushed directly by push rods 344a, 344b and hub holder 304 as pusher 308 is pushed. When the hub 306 engages the first step 318, axial movement of the needle 40 is limited, thus controlling the distance the needle 40 extends beyond the forward end 302a of the body 302. Therefore, the needle 40 penetrates the skin to a suitable depth.

As the pusher 308 is pushed in further, the arms 350a, 350b are gradually rotated about the second pins 354 by the push rods 344a, 344b, as shown in fig. 21. Rotation of the arms 350a, 350b pulls the hub holder 304 toward the pusher 308 in the direction indicated by arrow X2 as the substantially central regions of the arms 350a, 350b abut against the ends of the fulcrum members 330a, 330b and rotate about the abutment regions relative to the hub holder 304 and the pusher 308 from the initial angular position of the arms 350a, 350 b. Hub 306, held by hub holder 304, moves in a direction into body 302 to withdraw needle 40 into needle passage 316.

When the arms 350a, 350b are rotated, since the arms 350a, 350b are restricted from moving in the axial direction of the body 302 by the fulcrum members 330a, 330b, the push rods 344a, 344b holding the ends of the arms 350a, 350b are elastically deformed so that their supports 346 move toward the opposite side wall surfaces of the holder hole 322.

When the pusher 308 is further pushed into the inner cavity 320 as shown in fig. 22, the supports 346 of the push rods 344a, 344b are further pushed into the holder holes 322, and the arms 350a, 350b held against the fulcrum members 330a, 330b are further rotated about the second pins 354, pulling the hub holder 304 further toward the pusher 308 in the direction indicated by the arrow X2. When the end of the pusher 308 abuts the step at the boundary between the inner cavity 320 and the holder hole 322, the pusher 308 reaches the end of its stroke. At this point, the puncturing process is ended.

The body 302 of the puncture instrument 300 has a hollow cylindrical shape. Before use of the puncture instrument 300, the front end portion 302a of the body 302 on which the protective cap 312 is mounted is highly sealed. Specifically, the needle passage 316, in which the needle 40 is housed, is highly hermetically sealed to maintain the sterility of the needle 40 after sterilization of the needle 40.

In the illustrated embodiment, the hub 306 and the hub holder 304 are separate from each other. However, the hub 306 and the hub holder 304 may be integrally combined with each other.

A puncture instrument 400 according to a fifth embodiment of the present invention will be described with reference to fig. 23 to 28. Those parts of the puncture instrument 400 which are the same as those of the puncture instruments 10, 100, 200, 400 according to the first, second, third, and fourth embodiments are denoted by the same reference numerals, and will not be described in detail below.

As shown in fig. 23 to 28, the puncture instrument 400 includes a body 402, a movable member (pusher) 404 movably provided in the body 402, an adjustment dial 406 that adjusts the depth to which the needle 40 on the movable member 404 punctures the skin, and a protective cap 408 mounted on the front end portion of the body 402.

The body 402 is of a hollow, substantially cylindrical configuration and has a small diameter portion 410 at its front end into which the pin 40 is inserted and a large diameter portion 412 at its rear end that is larger in diameter than the small diameter portion 410. The movable member 404 is partially exposed at the rear end of the body 402. The diameters of the small diameter portion 410 and the large diameter portion 412 are substantially constant. The small diameter portion 410 has an externally threaded outer peripheral surface 414.

The body 402 has a needle passage 416 axially centered through the small diameter portion 410 and an internal cavity 418 formed in the large diameter portion 412, the moveable element 404 being disposed in the internal cavity 418. The body 402 also has a retainer bore 420 (hub passage) formed axially in the body between the needle passage 416 and the internal cavity 418. The movable member 404 has a base 432 retained in the retainer hole 420. The small diameter portion 410 has a cap hole 422 formed therein at the end of the needle passage 416. The protective cap 408 is partially installed in the cap hole 422. The cap hole 422 opens outward at the distal end of the small-diameter portion 410, and has a diameter larger than the needle passage 416.

The large diameter portion 412 includes an annular ridge 424, the annular ridge 424 being disposed at a proximal end of the inner lumen 418 and projecting slightly radially inward. The movable member 404 has an outer circumferential surface that slidably engages the annular ridge 424.

The retainer bore 420 is substantially rectangular in cross-sectional shape. A pair of fulcrum members 426a, 426b are provided on the inner wall surface of the holder hole 420 in alignment with the axis of the body 402. The fulcrum members 426a, 426b extend rearward from the inner wall surface on the needle passage 416 side by a predetermined distance, and have ends of a semicircular cross-sectional shape. A pair of guide grooves 428 are formed on the inner wall surface of the holder hole 420 at respective positions angularly spaced apart from the fulcrum members 426a, 426b by 90 °. The guide groove 428 extends in the axial direction of the body 402 in the directions indicated by the arrows X1, X2.

The movable member 404 includes a needle assembly 430 including a needle 40 and a hub 429 that holds the needle 40, a base 432 on which the needle assembly 430 is mounted, a pair of arms 434a, 434b integrally coupled to the base 432, a pair of push rods 436a, 436b integrally coupled to the respective arms 434a, 434b, and a push button 438 for pushing the push rods 436a, 436b forward.

The arms 434a, 434b include respective first connections 440 joined at one end to the base 432 and respective second connections 442 joined at the other end to the distal ends of the push rods 436a, 436 b. In a state ready for piercing, the arms 434a, 434b are inclined at an angle relative to the axis of the movable member 404 and are disposed in an interdigitating relationship with the base 432 between the arms 434a, 434b, as shown in fig. 25.

The arms 434a, 434b have respective recesses 444 formed in the rear surfaces thereof at the first junctions 440 and respective recesses 446 formed in the front surfaces thereof at the second junctions 442. Therefore, the first and second junctions 440, 442 are narrower than the rest of the arms 434a, 434 b.

The push rods 436a, 436b project from the end surface of the push button 438 and extend in the axial direction of the movable member 404. The second junctions 442 of the arms 434a, 434b are connected to the distal ends of the push rods 436a, 436b, respectively.

The button 438 is disposed near an opening of the inner cavity 418, and has an end portion protruding out of the inner cavity 418 when the puncture instrument 400 is in a state ready for puncture (see fig. 25). The other end of the button 438 that is connected to the push rods 436a, 436b has an annular ridge 448 on its outer peripheral surface. When the annular ridge 448 is fitted against the annular ridge 424 formed in the inner cavity 418, the movable member 404 including the button 438 is restricted from axial movement and the interior space containing the needle 40 remains sterile prior to use.

The adjustment dial 406 is annular in shape and includes an internally threaded inner circumferential surface 450 that is threaded onto the small diameter portion 410 of the body 402. The adjustment dial 406 has graduation marks 452 on its outer circumferential surface. When the adjustment dial 406 is turned, it moves axially on the small diameter portion 410 in the directions indicated by the arrows X1, X2. Since the front end portion of the adjustment dial 406 is movable by a predetermined distance toward the distal end with respect to the front end portion of the body 402, the distance by which the needle 40 projects from the front end portion of the adjustment dial 406 can be adjusted.

The protective cap 408 includes a tubular member 454 fitted in the cap hole 422 of the body 402 and a grip 456 joined to the tubular member 454 for gripping when the protective cap 408 is to be removed. The tubular member 454 is in the form of a hollow bottomed cylinder, and when the protective cap 408 is mounted on the body 402, a portion of the needle 40 is fitted in the tubular member 454. In a state where the protective cap 408 is mounted on the body 402, the puncture instrument 400 is irradiated with gamma rays, electron beams, or the like to sterilize the needle 40 in the tubular member 454.

The operation of the puncture instrument 400 is as follows: in the state ready for puncture shown in fig. 25, the grip 456 of the protective cap 408 is twisted to release the tubular member 454 from engagement with the body 402, thereby removing the protective cap 408.

Next, the body 402 is held by hand, the leading end portion is abutted against the skin (not shown), and then the button 438 of the movable member 404 is pushed toward the body 402 in the direction indicated by the arrow X1. The annular ridge 448 of the button 438 is disengaged from the annular ridge 424 of the body 402 and inserted into the internal cavity 418. At this time, the movable member 404 is guided toward the front end portion of the body 402 along the axial direction thereof indicated by the arrow X1 (refer to fig. 26).

As shown in fig. 26, as the movable member 404 moves toward the front end portion of the body 402 in the direction indicated by the arrow X1, the hub 429 mounted on the base 432 moves in and along the needle passage 416 and the cap hole 432. At this time, the movable member 404 moves only in the axial direction and does not rotate about its own axis because it is guided by the guide rails 338 engaged in the respective guide grooves 428.

The tip of the needle 40 protrudes from the front end portion of the body 402 and penetrates the skin. Specifically, needle 40 is not axially biased by the elastomer, but rather is directly pushed by pushrods 436a, 436b and arms 434a, 434b as movable member 404 is pushed. By abutting against the base 432, the wall surface of the holder bore 420 limits axial movement of the needle 40.

As shown in fig. 27, when the pusher 404 is further pushed in, substantially central regions of the arms 434a, 434b abut against the fulcrum members 426a, 426b, and the arms 434a, 434b gradually rotate about the abutting regions, thereby moving the first junctions 440 toward the proximal end of the body 402 and the second junctions 442 toward the distal end of the body 402. As the arms 434a, 434b are rotated, the base 432 is pulled toward the button 438 in the direction indicated by arrow X2, moving the hub 429 held by the base 432 into the body 402, thereby retracting the needle 40 into the needle passage 416 of the body 402. At this time, the distal ends of the push rods 436a, 436b elastically bend outward away from each other.

When the movable member 404 is further pushed into the internal cavity 418 as shown in fig. 28, because the arms 434a, 434b abut against the fulcrum members 426a, 426b, the second junctions 442 of the arms 434a, 434b are pushed in toward the front end portion of the body 402 by the push rods 436a, 436b, and the first junctions 440 of the arms 434a, 434b are pulled toward the push buttons 438 in the direction of the arrow X2, which is opposite to the direction in which the second junctions 442 are pushed. Further movement of the base 432 toward the button 438 in the direction indicated by arrow X2 moves the hub 429 and needle 40 toward the button 438 along the needle passage 416.

When the end of the button 438 abuts the step at the boundary between the inner cavity 418 and the holder bore 420, the button 438 reaches the end of its travel. At this point, the puncturing process is ended.

Because the annular ridge 448 of the button 438 is fully inserted into the interior cavity 418, the button 438 cannot be accidentally removed from the interior cavity 418 beyond the annular ridge 424 after the puncture is completed. The button 438 is more effectively prevented from being removed from the inner cavity 418 if a second annular ridge is provided on the inner peripheral surface of the inner cavity 418 near the holder hole 420 for engagement with the annular ridge 448.

When the body 402 is a hollow substantially cylindrical structure, the front end portion of the body 402 on which the protective cap 408 is mounted and the rear end portion of the body 402 inside which the button 438 is fitted are highly sealed before the puncture instrument 400 is used. As a result, the needle 40 remains sterile after sterilization.

Unlike the arms of the puncture instrument 300 according to the fourth embodiment, the arms 434a, 434b are constructed as integral parts of the movable member 404. Therefore, the puncture instrument 400 is manufactured from a small number of parts, and thus can be assembled in a small number of assembly steps.

Although certain preferred embodiments of the present invention have been shown and described in detail, it should be understood that various changes and modifications may be made herein without departing from the scope of the appended claims.

Claims (11)

1. A puncture instrument, comprising:

a housing (12);

a needle assembly (44), the needle assembly (44) movably disposed within the housing (12) and including a needle (40) and a hub (42) holding the needle (40);

a hub passage (16) for guiding the hub (42) in an axial direction, the hub passage (16) being provided in the housing (12);

a needle channel (18), said needle channel (18) being disposed in said housing (12) and communicating with said hub channel (16), said needle channel (18) having a distal end opening for allowing a tip of said needle (40) to protrude therethrough;

at least one arm (46), the arm (46) having a first connection (52) at one end thereof connected to the hub (42) and a second connection (54) at the other end thereof, the arm (46) being inclined from the first connection (52) towards the proximal end of the housing (12) in an initial state;

a push rod (48), the push rod (48) coupled to the second connection (54) and extending toward the proximal end;

a pusher (50), the pusher (50) for pushing the push rod (48) towards the distal end of the housing (12); and

a fulcrum member (24), the fulcrum member (24) for abutting a portion of the arm (46) when the arm (46) is moved;

wherein when the push rod (48) is pushed toward the distal end by the pusher (50), the arm (46) pushes the needle assembly (44) toward the distal end, causing the portion of the arm to abut against the fulcrum member (24) and rotate about the fulcrum member (24) such that the arm (46) is inclined from the first connection portion (52) toward the distal end, thereby pulling the needle assembly (44) back toward the proximal end.

2. A puncture instrument according to claim 1, wherein the push rod (48) includes a leaf spring that is elastically deformable under the force exerted by the arm (46) when the pusher (50) pushes the push rod (48) towards the distal end.

3. A puncture instrument according to claim 1, wherein in the initial state, the arm (46) is inclined toward the proximal end in a direction away from the hub (42), and when the push rod (48) is pushed toward the distal end as the pusher (50) is pushed, the arm (46) rotates about the fulcrum member (24) and is inclined toward the distal end in a direction away from the hub (42).

4. A puncture instrument according to claim 1, wherein at least one of the first connecting portion (52) and the second connecting portion (54) is narrower than the arm (46) and is plastically deformable when the arm (46) is rotated and changes its inclination direction.

5. A puncture instrument according to claim 1, wherein the hub (306) comprises a base (334) at its proximal end portion, the base (334) having a flat surface parallel to the plane in which the arms (350a, 350b) rotate, the first connection portion (352) being rotatably connected to the base (334) at a position spaced apart from the longitudinal axis of the hub (306) by a predetermined distance.

6. A puncture instrument according to claim 1, wherein the pusher (50) includes a male or female engaging portion (60), and the housing (12) includes a first engageable portion (26) that engages the engaging portion (60) when the pusher (50) is in the initial position and a second engageable portion (28) that engages the engaging portion (60) when the pusher (50) is in the end-of-stroke position.

7. A puncture instrument according to claim 6, wherein the pusher (50) is movably disposed in an inner cavity formed in the housing (12) and has a proximal end, the proximal end of the pusher (50) protruding from the housing (12) by a distance ranging from 5mm to 30mm when the pusher (50) is in an initial position, and the proximal end of the pusher (50) protruding from the housing (12) by a distance smaller than 5mm when the pusher (50) is in a stroke end position.

8. A puncture instrument according to claim 1, wherein the needle passage (18) is narrower than the hub passage (16), and a step (20) is provided between the needle passage (18) and the hub passage (16) for abutting a distal end surface of the hub (42) against the step (20) to limit the movement of the needle assembly (44).

9. A puncture instrument according to claim 1, wherein the arm (46) comprises two arms (46), the push rod (48) comprises two push rods (48), and the two arms (46) and the two push rods (48) are symmetrical with respect to the longitudinal axis of the hub (42).

10. The puncture instrument according to claim 1, further comprising:

a biasing means (104), said biasing means (104) for biasing said pusher (102) towards said distal end; and

a stopper (108), the stopper (108) for limiting movement of the pusher (102) biased by the biasing device (104) toward the distal end and releasing the pusher (102) in response to operation of a trigger (106).

11. The puncture instrument according to claim 1, wherein the housing (302, 402) is a hollow cylinder, the puncture instrument further comprising:

a protective cap (312, 408), said protective cap (312, 408) being removably mounted at a distal end of said housing (302, 402) for retaining and sealing said needle (40) in said needle channel (316, 416).