JP7574611B2 - Needles and Syringes - Google Patents

Description

The present invention relates to medical injection needles and syringes.

Conventionally, medical injection needles are used by being inserted into a blood vessel through a patient's skin. When an injection needle is inserted into a blood vessel through a patient's skin, it incises the skin as it penetrates, so the injection needle generates a breaking force when it breaks the skin and a frictional force when it penetrates the skin. If the breaking force or frictional force generated in the injection needle is large, the patient will feel strong pain.

In response to this, medical injection needles are known that have a blade surface that is formed with a downward incline from the base end to the tip end (see, for example, Patent Document 1). The injection needle of Patent Document 1 is a lancet point type injection needle that has a blade surface formed by a first blade surface located on the base end side and a second blade surface located on the tip end side. The medical injection needle described in Patent Document 1 is said to be able to easily pierce the skin and reduce pain to the patient when piercing by forming a notch surface on the radially opposite side of the blade surface at the tip side in the axial direction.

JP 2008-154843 A

In the technology described in Patent Document 1, the shape of the injection needle is designed to reduce pain felt by the patient when the needle is inserted through the patient's skin into a blood vessel. Further improvements in injection needles to reduce pain felt by patients are required.

The present invention aims to provide an injection needle that can reduce pain for patients.

The present invention relates to a cylindrical injection needle comprising a blade surface portion formed with a downward inclination from the base end side to the tip end side in the axial direction of the injection needle, and a recess formed in a bottom surface located on the opposite side of the blade surface portion in the radial direction of the injection needle, the blade surface portion having a first blade surface disposed on the base end side in the axial direction of the injection needle, a second blade surface formed continuous with the tip side of the first blade surface, a heel formed at the base end of the first blade surface, a point formed at the tip of the second blade surface, and a junction disposed between the heel and the point and formed at the transition portion between the first blade surface and the second blade surface, the recess has a tip side inclined bottom surface portion formed with an upward inclination approaching the blade surface portion from the tip side to the base end side in the axial direction of the injection needle, and the inclination change rate of the upward inclination of the tip side inclined bottom surface portion is in the range of 0.2 to 0.4.

It is also preferable that the recess is formed continuously from the tip end to the base end of the injection needle in the axial direction of the injection needle, sandwiching the position where the junction is formed.

In addition, the first blade surface has a first blade surface inclined portion that is inclined downward from the base end to the tip end in the axial direction of the injection needle, and it is preferable that the first blade surface inclined portion and the tip side inclined bottom surface portion are formed approximately parallel to each other.

It is preferable that the recess has a base end side inclined bottom surface portion that is formed continuously with the base end side of the tip end side inclined bottom surface portion and that slopes downward away from the blade surface portion as it moves from the tip end side to the base end side in the axial direction of the injection needle.

The present invention relates to a syringe that includes the injection needle, a syringe to the tip of which the injection needle is attached, and a plunger that is provided on the syringe so as to be movable forward and backward.

The present invention provides an injection needle that can reduce pain for patients.

1 is a perspective view of an injection needle according to an embodiment of the present invention, seen obliquely from above. FIG. FIG. 2 is a perspective view of an injection needle according to an embodiment, as viewed obliquely from below. FIG. 2 is a plan view of an injection needle according to one embodiment. FIG. 2 is a side view of an injection needle according to one embodiment. FIG. 2 is a bottom view of an injection needle according to one embodiment. FIG. 1 is a perspective view of a conventional injection needle, seen obliquely from above. FIG. 1 is a side view of a conventional injection needle. 1 is a graph showing the puncture resistance versus puncture distance of a conventional injection needle. 1 is a table of test results showing the first peak, second peak, and third peak puncture resistance for samples of a conventional injection needle and an injection needle of the present invention.

One embodiment of the injection needle 1 of the present invention will be described below with reference to the drawings. The injection needle 1 of the present invention is a medical injection needle. The injection needle 1 is used, for example, as an injection needle for use in a disposable syringe. The syringe includes the injection needle 1, a syringe (syringe barrel) to the tip of which the injection needle 1 is attached, and a plunger (push rod) provided on the syringe so as to be movable forward and backward.

As shown in Figures 1 to 5, the injection needle 1 is formed in a cylindrical shape with a blade surface portion 2 provided on the tip side. The cylindrical portion of the injection needle 1 is formed in a cylindrical shape with a predetermined thickness and extends in the axial direction. The injection needle 1 has a blade surface portion 2 formed with a downward inclination from the base end side to the tip side in the axial direction, and a recessed portion 5 formed on the opposite side to the blade surface portion 2 in the radial direction.

As shown in Figs. 1 and 2, the blade surface portion 2 has a first blade surface 3 arranged on the base end side and a second blade surface 4 arranged on the tip end side in the axial direction of the injection needle 1, and the first blade surface 3 and the second blade surface 4 are formed continuously. The injection needle 1 is a lancet point type injection needle that has a blade surface portion 2 in which the first blade surface 3 arranged on the base end side and the second blade surface 4 arranged on the tip end side are formed continuously.

As shown in FIG. 3, the first blade surface 3 is disposed on the base end side of the blade surface portion 2. In a plan view, the first blade surface 3 is formed in a U-shape that is open at the tip end and has a certain width. A heel 21 (described later) is formed on the end portion on the base end side of the first blade surface 3. As shown in FIG. 3 and FIG. 4, the first blade surface 3 has a pair of first blade surface inclined portions 31 that are formed on the open side of the U-shape on the tip side in the axial direction of the injection needle 1, sloping downward from the base end to the tip.

As shown in Figures 3 to 5, the second blade surface 4 is formed on the tip side of the first blade surface 3. In a plan view, the second blade surface 4 is formed in a V-shape with a pointed tip and an open base end. The second blade surface 4 has a pair of second blade surface inclined portions 41. The base ends of the pair of second blade surface inclined portions 41 are each connected to the open end on the tip side of the first blade surface inclined portion 31 of the first blade surface 3 at a junction 23 (described later). The tips of the pair of second blade surface inclined portions 41 are connected to each other to form the pointed tip of the V-shape of the second blade surface 4.

The pair of second inclined blade surfaces 41 are each formed with a width, and are curved in the axial direction of the injection needle 1, sloping downward from the top to the bottom as they move from the base end to the tip end as shown in FIG. 4, and are formed in a downward inclination from the inside to the outside in the thickness portion of the injection needle 1 as shown in FIG. 3. The connection portion of the tip of the pair of second inclined blade surfaces 41 is formed to extend in the axial direction of the injection needle 1 as shown in FIG. 3, and is formed in a downward inclination as it moves toward a point (described later) formed at the tip as shown in FIG. 4.

In the blade surface portion 2 configured as described above, the first blade surface 3 and the second blade surface 4 are formed continuously, and as described above, a heel 21, a point 22, and a junction 23 are formed as shown in Figures 3 and 4.

The heel 21 is formed at the most proximal end of the closed U-shaped portion of the first blade surface 3 in the axial direction of the injection needle 1 .
The point 22 is formed at the most tip of the second blade surface 4 in the axial direction of the injection needle 1. The point 22 is the most tip part of the connecting part of the tips of the pair of second blade surface inclined portions 41, and is the apex part of the V-shaped tip of the second blade surface 4.
The junction 23 is disposed between the heel 21 and the point 22 in the axial direction of the injection needle 1. The junction 23 is formed at a transition portion between the first blade surface 3 and the second blade surface 4.

As shown in Figures 3 and 4, the junction 23 is formed at the connection between the first inclined blade surface 31 of the first blade surface 3 and the second inclined blade surface 41 of the second blade surface 4 at the tip of the first inclined blade surface 3. As shown in Figure 4, the junction 23 extends downward toward the tip side at the same inclination angle as the first inclined blade surface 31 of the first blade surface 3 in side view, and as shown in Figure 3, it is formed in a line shape that inclines from the outside to the inside in the radial direction of the injection needle 1 as it moves from the base end side to the tip side in plan view.

As shown in FIG. 4, the recess 5 is formed on the opposite side of the blade surface 2 in the radial direction of the injection needle 1, and is recessed in a substantially triangular shape from the bottom surface 1a of the injection needle 1 toward the blade surface 2 in side view. The recess 5 is formed continuously from the tip side to the base end side of the injection needle 1 in the axial direction of the injection needle 1, sandwiching the position where the junction 23 is formed. The recess 5 has a through hole 6 formed in the bottom surface 1a of the injection needle 1. As shown in FIG. 3, the through hole 6 opens in a plan view in an egg shape with a rounded tip side and a pointed base end side. The through hole 6 is also called a back eye, for example.

As shown in FIG. 4, the recess 5 has a tip end inclined bottom surface portion 51 and a base end inclined bottom surface portion 52 in side view.

The tip side inclined bottom surface portion 51 is formed with an upward inclination so as to approach the blade surface portion 2 from the tip side to the base end side in the axial direction of the injection needle 1. The tip side inclined bottom surface portion 51 extends from the cutting start point 53 of the recess 5 to the cutting maximum point 54, and is formed in a substantially straight line that inclines upward from the tip side to the base end side. The tip side inclined bottom surface portion 51 is formed substantially parallel to the first blade surface inclined portion 31 of the first blade surface 3. The tip side inclined bottom surface portion 51 is formed with a slight curve near the cutting maximum point 54 in the axial direction of the injection needle 1, and is connected to the base side inclined bottom surface portion 52.

The cutting start point 53 is the point where cutting starts when cutting the recess 5 into the injection needle 1, and is the most distal part of the recess 5. The cutting start point 53 is located in the axial direction of the injection needle 1, approximately in the center of the range where the second blade surface 4 is formed.

When the recess 5 is cut into the injection needle 1, the maximum cutting point 54 is the portion of the recess 5 that is most deeply recessed from the bottom surface 1a of the injection needle 1. The maximum cutting point 54 is located at the same position as the junction 23 in the axial direction of the injection needle 1, or slightly closer to the heel 21 than the junction 23.

The base end inclined bottom surface portion 52 is formed continuously with the base end side of the tip end inclined bottom surface portion 51. The base end inclined bottom surface portion 52 inclines downward away from the blade surface portion 2 from the tip end side to the base end side in the axial direction of the injection needle 1. The base end inclined bottom surface portion 52 extends from the maximum cutting point 54 to the cutting end point 55 of the recess 5, and is formed in a substantially straight line that inclines downward from the tip end side to the base end side. The base end inclined bottom surface portion 52 is formed to be slightly curved near the maximum cutting point 54 in the axial direction of the injection needle 1, and is connected to the tip end inclined bottom surface portion 51.

The cutting end point 55 is the point where cutting ends when cutting the recess 5 into the injection needle 1, and is the most proximal part of the recess 5. The cutting end point 55 is located at approximately the same position as the heel 21 in the axial direction of the injection needle 1.

In this embodiment, as shown in FIG. 4, a distance L1 from the point 22 to the cutting start point 53 in the axial direction of the injection needle 1 is, for example, 1.0 mm.
The distance L2 from the cutting start point 53 to the cutting maximum point 54 is, for example, 1.0 mm.
A distance L3 from the maximum cutting point 54 to the cutting end point 55 is, for example, 2.0 mm.
The height H1 from the bottom surface 1a of the injection needle 1 to the maximum cutting point 54 is, for example, 0.3 mm.
The shortest distance L4 between the tip side inclined bottom surface portion 51 and the parallel portion of the first blade surface inclined portion 31 of the first blade surface 3 is, for example, 0.37 mm.
In the present embodiment, the values of the distance L1, the distance L2, the distance L3, the height H1, and the shortest distance L4 are merely examples and are not limited to these values. In addition, the tip-side inclined bottom surface portion 51 is not limited to a straight line, and may be formed in a curved line.

The rate of change in slope R of the upward slope of the tip-side inclined bottom surface portion 51 is in the range of 0.2 to 0.4. In this embodiment, the rate of change in slope R of the upward slope of the tip-side inclined bottom surface portion 51 means the ratio of the change in height H1 from the bottom surface 1a of the injection needle 1 to the maximum cutting point 54 to the distance L2 from the cutting start point 53 to the maximum cutting point 54 in the axial direction of the injection needle 1 in a side view of the tip-side inclined bottom surface portion 51 as shown in FIG. 4 (R=H1/L2).

In this embodiment, for example, the distance L2 is set to 1.0 mm and the height H1 is set to 0.3 mm, so that the slope change rate R of the tip-side sloped bottom surface portion 51 in the upward slope is set to, for example, 0.3. However, the distance L2 and the height H1 are not limited to this. For example, the distance L2 may be set to 1.0 mm and the height H1 to 0.2, so that the slope change rate R of the tip-side sloped bottom surface portion 51 in the upward slope may be set to, for example, 0.2, or the distance L2 may be set to 1.0 mm and the height H1 to 0.4, so that the slope change rate R of the tip-side sloped bottom surface portion 51 in the upward slope may be set to, for example, 0.4. In this embodiment, the slope change rate R is set to a constant value all along the axial direction of the injection needle 1 by forming the slope of the tip-side sloped bottom surface portion 51 in a linear shape. However, this is not limited to this, and for example, the slope change rate R of the tip-side sloped bottom surface portion 51 may be formed in a curved shape, so that the value changes with the axial position.

A method for producing the injection needle 1 of this embodiment will be briefly described.
First, the tip end of a cylindrical tube is cut or cut in a bamboo split shape with a plane that slopes downward toward the tip end to form a U-shaped first blade surface 3 that is open toward the tip end.
Next, the tip side of the U-shape of the first blade surface 3 is cut or milled to form a pair of second blade surface inclined portions 41, thereby forming a second blade surface 4 that has a V-shape with a pointed tip when viewed in a plane.
Then, on the bottom surface 1a located on the radially opposite side of the blade surface portion 2 of the injection needle 1, as shown in Figure 4, a tip-side inclined bottom surface portion 51 and a base-side inclined bottom surface portion 52 are cut in the range from the cutting start point 53, via the cutting maximum point 54, to the cutting end point 55, thereby forming a recess 5 that is recessed in a substantially triangular shape from the bottom surface 1a of the injection needle 1.

In the above-described injection needle 1, the puncture resistance of the injection needle 1 is reduced by forming a recess 5 having a tip-side inclined bottom surface portion 51 with an inclination change rate R in the range of 0.2 to 0.4. This reduces the pain felt by the patient when the injection needle 1 is inserted.

The reason why the puncture resistance of the injection needle 1 can be reduced by forming a recess 5 having a tip-side inclined bottom surface portion 51 with an inclination change rate R in the range of 0.2 to 0.4 in the injection needle 1 of the present invention will be explained by comparing a conventional injection needle 10 with the injection needle 1 of the present invention. First, the configuration of the conventional injection needle 10 will be explained. Note that in the explanation of the conventional injection needle 10, the same reference numerals may be used to designate the same configuration as the injection needle 1 of the present invention described above, and explanations thereof may be omitted.

As shown in Figures 6 and 7, the conventional injection needle 10 has a through hole 14 on the radially opposite side of the blade surface 11, so that the radially opposite side of the blade surface 11 is slightly recessed. Note that the conventional injection needle 10 does not have the recess 5 formed in the injection needle 1 of the present invention, which has a slope with a slope change rate R in the range of 0.2 to 0.4.

As shown in Figs. 6 and 7, the conventional injection needle 10 has a blade surface portion 11 and a through hole 14 (back eye). The blade surface portion 11 has a first blade surface 12 and a second blade surface 13. The blade surface portion 11 has a heel 111, a point 112, and a junction 113. The conventional injection needle 10 is a lancet point type injection needle with a two-stage blade surface, similar to the injection needle 1 of the present invention.

The blade surface 11, through hole 14, heel 111, point 112 and junction 113 of the conventional injection needle 10 and the injection needle 1 of the present invention are configured similarly to the blade surface 2, through hole 6, heel 21, point 22 and junction 23 of the injection needle 1 of the present invention, so a description thereof will be omitted. The conventional injection needle 10 is provided with a through hole 14 (back eye), but is not provided with a recess 5 having a slope with a slope change rate R in the range of 0.2 to 0.4, as is formed in the injection needle 1 of the present invention.

The resistance when a conventional injection needle 10 is inserted is due to the force generated when the injection needle 10 penetrates the skin while cutting it. The force of cutting the skin becomes the skin breaking force, and the force of penetrating the skin becomes a friction force. Therefore, if the distance the skin is cut is increased, the friction force when penetrating the skin can be reduced. However, in order to reduce the pain when the skin is punctured, it is necessary to reduce the distance the skin is cut. Therefore, there is a demand to minimize the distance the skin is cut to allow the injection needle to penetrate the skin, and to suppress the friction force when penetrating the skin.

For example, when the injection needle 10 is inserted into a film, the puncture resistance of the injection needle 10 is the sum of the film's breaking force and the film's frictional force. The film's breaking force is related to the opening distance at which the film is cut. The film's frictional force is related to the cross-sectional area of the injection needle penetrating the film relative to the film's opening distance. Increasing the film's opening distance reduces the frictional force when the injection needle 10 penetrates, and decreasing the film's opening distance increases the frictional force when the injection needle 10 penetrates.

Here, as shown in Figure 8, there is a graph that measures the puncture resistance versus the puncture distance of a conventional injection needle 10.

First, the test conditions for measuring the puncture resistance of the injection needle 10 will be described.
The test method involved attaching a film to an opening with a diameter of 56 mm, and measuring the puncture resistance of the injection needle 10 when the film was punctured by the injection needle. A polyethylene (PE) film with a thickness of 0.05 mm was used as the film.
A Tensilon tester was used as the tester. In the Tensilon tester, the load cell was set to 50 N, the puncture speed was 24 mm/s, the puncture angle was 90°, and the puncture distance was 10 mm.
The injection needle used had a gauge of 18G (outer diameter 1.2 mm).
The test environment temperature was about 23° C. The test environment humidity was about 30%.

Under these test conditions, the puncture resistance was measured when a conventional injection needle 10 was punctured into a film. Considering the graph shown in Figure 8, it was found that there were mainly five points (first resistance slope S1, second resistance slope S2, third resistance slope S3, fourth resistance slope S4, and fifth resistance slope S5) where the slope of the puncture resistance changed with respect to the puncture distance of the injection needle 10. It was also found that there were mainly three peaks (first peak P1, second peak P2, and third peak P3) in the puncture resistance of the injection needle 1.

The first resistance gradient S1 is the puncture resistance when the tip of the injection needle 1 breaks the film and the injection needle 10 penetrates the film. The maximum peak of the first resistance gradient S1 is the first peak P1. After reaching the first peak P1, the puncture resistance drops significantly due to the stick-slip phenomenon (a phenomenon in which friction of the injection needle 1 drops discontinuously when friction changes from static to kinetic friction).

The second resistance gradient S2 is the puncture resistance when the tip side of the second blade surface 13 of the injection needle 1 breaks the film so that the opening becomes larger in the radial direction due to the second blade surface 13 of the injection needle 1.

The third resistance gradient S3 is the puncture resistance when the injection needle 1 moves to the junction 113 at the boundary between the first blade surface 12 and the second blade surface 13 at the second blade surface 13, causing the film to break so that the opening becomes larger in the radial direction by the second blade surface 13 of the injection needle 1, and the frictional force caused by the axial movement of the second blade surface 13 of the injection needle 10 increases. The maximum peak of the third resistance gradient S3 is the second peak P2 that occurs near the junction 113. After reaching the second peak P2, the puncture resistance is significantly reduced due to the stick-slip phenomenon (a phenomenon in which friction of the injection needle 1 decreases discontinuously when friction changes from static friction to kinetic friction).

The fourth resistance gradient S4 and the fifth resistance gradient S5 are resistances only due to the frictional force between the injection needle 10 and the film, without the injection needle 10 breaking the film, as the injection needle 1 moves from the junction 113 to the heel 111 on the first blade surface 12. The film breaks in the injection needle 10 up to the point where the diameter of the blade surface of the injection needle 10 is at its maximum, and thereafter, the film is not broken and only frictional force occurs. The maximum peak of the fifth resistance gradient S5 is the third peak P3. After reaching the third peak P3, the puncture resistance is greatly reduced due to the stick-slip phenomenon (a phenomenon in which friction of the injection needle 1 decreases discontinuously when friction changes from static friction to kinetic friction).

Further considering the puncture resistance of the injection needle 10, as shown in FIG. 8, the second peak P2 and the third peak P3 are greater than the first peak P1. In order to reduce the puncture resistance of the conventional injection needle 10, it is preferable to reduce the second peak P2 and the third peak P3.

Therefore, in the injection needle 1 of the present invention, the shape is changed from that of the conventional injection needle 10 so as to reduce the influence of the breaking force out of the breaking force and the frictional force occurring in the third resistance gradient S3, thereby reducing the second peak P2, thereby reducing the puncture resistance. Since the frictional force of the injection needle is related to the cross-sectional area where the injection needle penetrates the film, it is preferable to reduce the cross-sectional area of the injection needle in order to reduce the frictional force of the injection needle. Therefore, in the injection needle 1 of the present invention, the cross-sectional area of the injection needle 1 is reduced by forming recesses 5 in the parts before and after the occurrence of the second peak P2.

More specifically, in the injection needle 1 of the present invention, as shown in FIG. 4, a recess 5 having a tip-side inclined bottom surface portion 51 with a slope change rate R in the range of 0.2 to 0.4 is formed on the radially opposite side of the blade surface portion 2 in the axial direction before and after the junction 23 where the second peak P2 occurs. This reduces the distance from the blade surface portion 2 of the injection needle 1 to the radially opposite side of the blade surface portion 2, thereby reducing the cross-sectional area of the injection needle 1, thereby reducing the second peak P2 of the puncture resistance of the injection needle 1.

Here, multiple samples of the conventional injection needle 10 and the injection needle 1 of the present invention were prepared, and the puncture resistance when the injection needle penetrates the film was compared, as shown in Figure 9. The injection needle 1 of the present invention differs from the conventional injection needle 10 only in that it is provided with a recess 5 having a tip-side inclined bottom surface portion 51 with a slope change rate R in the range of 0.2 to 0.4.

Referring to FIG. 9, the second peak P2 of the puncture resistance of the injection needle 1 of the present invention (average value: 0.11 N) is smaller than the second peak P2 of the puncture resistance of the conventional injection needle 10 (average value: 0.15 N). In detail, as shown in FIG. 9, the second peak P2 of the puncture resistance of the conventional injection needle 10 is 0.15 N (average value of five samples), whereas the second peak P2 of the puncture resistance of the injection needle 1 of the present invention is 0.11 N (average value of three samples). As a result, the second peak P2 of the puncture resistance of the injection needle 1 of the present invention (average value: 0.11 N) is approximately 27% ((0.15-0.11)/0.15=approximately 0.27) smaller than the second peak P2 of the puncture resistance of the conventional injection needle 10 (average value: 0.15 N). Therefore, in the present invention, the puncture resistance of the injection needle 1 can be reduced, thereby reducing the pain of the patient.

Also, referring to the test results in FIG. 9, the third peak P3 (0.13 N) of samples No. 1 to 3, which is the maximum peak of the puncture resistance of the injection needle 1 of the present invention, was smaller than the second peak P2 (0.15 N) of samples No. 3 to 5, which is the maximum peak of the puncture resistance of the conventional injection needle 10. In detail, as shown in FIG. 9, the second peak P2 of samples No. 3 to 5, which is the maximum peak of the puncture resistance of the conventional injection needle 10, was 0.15 N, whereas the third peak P3 of samples No. 1 to 3, which is the maximum peak of the puncture resistance of the injection needle 1 of the present invention, was 0.13 N. As a result, the third peak P3 (0.13 N), which is the maximum peak of the puncture resistance of the injection needle 1 of the present invention, was smaller than the second peak P2 of samples No. 3 to 5, which is the maximum peak of the puncture resistance of the conventional injection needle 10. It was possible to reduce the second peak P2 (0.15 N) of 3 to 5 by approximately 13% ((0.15-0.13)/0.15 = approximately 0.13). Therefore, in the present invention, the puncture resistance of the injection needle 1 can be reduced, thereby reducing the pain felt by the patient.

The injection needle 1 of the present embodiment described above provides the following advantages.
The injection needle 1 is configured with a blade surface portion 2 formed with a downward incline from the base end side to the tip end side in the axial direction, and a recessed portion 5 formed in a bottom surface 1a located on the opposite side to the blade surface portion 2 in the radial direction of the injection needle 1, by being recessed from the bottom surface 1a to approach the blade surface portion 2 side. The blade surface portion 2 is configured with a first blade surface 3, a second blade surface 4 formed continuously with the first blade surface 3, a heel 21 formed at the base end of the first blade surface 3, a point 22 formed at the tip of the second blade surface 4, and a junction 23 disposed between the heel 21 and the point 22 and formed at a transition portion between the first blade surface 3 and the second blade surface 4. The recessed portion 5 is configured with a tip-side inclined bottom surface portion 51 formed with an upward incline from the tip side to the base end side in the axial direction of the injection needle 1 to approach the blade surface portion 2 side. The inclination change rate R of the upward inclination of the tip-side inclined bottom surface portion 51 is in the range of 0.2 to 0.4. This makes it possible to reduce the puncture resistance of the injection needle 1 and, for example, lower the second peak P2 and the maximum peak. Therefore, by reducing the puncture resistance of the injection needle 1, the pain felt by the patient can be alleviated.

The recesses 5 are formed continuously from the tip to the base end of the injection needle 1 in the axial direction of the injection needle 1, sandwiching the position where the junction 23 is formed. By forming the recesses 5 continuously on either side of the position where the junction 23 is formed, the puncture resistance of the injection needle 1 can be continuously reduced before and after the junction 23. This reduces the pain felt by the patient.

The first blade surface 3 is configured to have a first blade surface inclined portion 31 that is formed with a downward inclination from the base end to the tip in the axial direction of the injection needle 1, and the first blade surface inclined portion 31 and the tip side inclined bottom surface portion 51 are formed approximately parallel to each other. As a result, even if a recess 5 is formed on the opposite side of the blade surface portion 2 in the radial direction of the injection needle 1, the circumferential length of the injection needle 1 in the part where the first blade surface inclined portion 31 and the tip side inclined bottom surface portion 51 are parallel can be secured, so bending at the recess 5 can be suppressed and the strength of the injection needle 1 can be secured.

The recess 5 is also configured to have a base end side inclined bottom surface portion 52 that is formed continuously with the base end side of the tip end side inclined bottom surface portion 51 and that slopes downward away from the blade surface portion 2 as it moves from the tip end side to the base end side in the axial direction of the injection needle 1. By forming the base end side inclined bottom surface portion 52, the diameter of the injection needle 1 can be gradually increased as it moves toward the base end side of the blade surface portion 2, thereby ensuring the strength of the injection needle 1.

Although the preferred embodiment of the injection needle 1 of the present invention has been described above, the present invention is not limited to the above-described embodiment and can be modified as appropriate.
In the above embodiment, the recess 5 is provided with the through hole 6 (back eye) penetrating the portion of the injection needle 1 opposite to the blade surface portion 2, but is not limited thereto. The recess 5 does not necessarily have to be provided with a through hole.

REFERENCE SIGNS LIST 1 injection needle 1a bottom surface 2 blade surface portion 3 first blade surface 4 second blade surface 5 recess 21 heel 22 point 23 junction 31 first blade surface inclined portion 51 distal end side inclined bottom surface portion 52 proximal end side inclined bottom surface portion R inclination change rate

Claims (4)

A cylindrical injection needle,
a blade surface portion that is formed so as to slope downward from the base end side to the tip end side in the axial direction of the injection needle, and a recessed portion that is recessed from the bottom surface toward the blade surface portion , the recessed portion being disposed in a range in the axial direction of the injection needle where the blade surface portion is provided, on a bottom surface located on the opposite side to the blade surface portion in the radial direction of the injection needle ,
the blade surface portion has: a first blade surface disposed on the base end side in the axial direction of the injection needle; a second blade surface formed continuously with the tip end side of the first blade surface; a heel formed on the base end of the first blade surface; a point formed on the tip end of the second blade surface; and a junction disposed between the heel and the point and formed at a transition portion between the first blade surface and the second blade surface,
the recess has a tip-side inclined bottom surface portion that is inclined upward so as to approach the blade surface portion from the tip side toward the base end side in the axial direction of the injection needle,
The rate of change in the inclination of the tip-side inclined bottom surface portion is in the range of 0.2 to 0.4,
The recess is formed continuously from the tip end side to the base end side of the injection needle in an axial direction of the injection needle, on either side of a position where the junction is formed . the first blade surface has a first blade surface inclined portion formed to be inclined downward from the base end to the tip end in the axial direction of the injection needle,
The injection needle according to claim 1 , wherein the first blade surface inclined portion and the tip side inclined bottom surface portion are formed substantially parallel to each other. 3. The injection needle according to claim 1, wherein the recess has a base-end-side inclined bottom surface portion that is formed contiguous with the base-end-side inclined bottom surface portion and that slopes downward away from the blade surface portion from the tip side to the base end side in the axial direction of the injection needle. An injection needle according to any one of claims 1 to 3 ;
a syringe to which the injection needle is attached at its tip;
a plunger provided on the syringe so as to be movable forward and backward.

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