syringe

Abstract

To provide a syringe capable of further improvement of precision.SOLUTION: A syringe 1 includes: an external cylinder 10; a pusher 20 freely slidably inserted into the external cylinder 10 from a rear end of the external cylinder 10; and a sealing member 30 preventing content in the external cylinder 10 from the rear end of the external cylinder 10 through between the external cylinder 10 and the pusher 20 from leaking. The sealing member 30 is provided on an inner periphery on the rear end side of the external cylinder 10. The external cylinder 10 is provided with: a glass cylindrical body 11; and a tubule 12 made of stainless steel inserted in and fixed to the end of the cylindrical body 11. The pusher 20 is made of stainless steel and is provided with a small diameter part (an end of a small diameter member 22) insertible into the tubule 12 at the end so that at least a part of the content in the tubule 12 can be pushed out.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a syringe.

Background Art

[0002] Conventionally, a syringe is known that includes a glass outer barrel, a stainless steel plunger slidably inserted into the outer barrel from the rear end thereof, and a sealing member provided at the distal end of the plunger to prevent the content inside the outer barrel from leaking out between the outer barrel and the plunger (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] The outer barrel of a syringe is required to have transparency so that the amount of content pushed out by the plunger can be visually recognized. However, outer barrels made of transparent materials such as glass have relatively large machining tolerances. For example, in the case of syringes for handling relatively small amounts of content for ophthalmic use, the accuracy of the amount of content pushed out from the outer barrel by the plunger becomes a concern, but there is a limit to further improvement in accuracy.

[0005] In view of the above points, the present invention aims to provide a syringe that can achieve further improvement in accuracy.

Means for Solving the Problem

[0006] [1] To achieve the above object, the present invention provides: an outer barrel, a plunger slidably inserted into the outer barrel from the rear end of the outer barrel, a sealing member that prevents the content inside the outer barrel from leaking from the rear end of the outer barrel through the gap between the outer barrel and the plunger, A syringe equipped with, The sealing member is provided on the inner circumference of the rear end side of the outer cylinder, The outer cylinder comprises a cylindrical body made of glass and a thin stainless steel tube inserted into and fixed at the tip of the cylindrical body. The plunger is made of stainless steel, and its tip is provided with a small diameter portion that can be inserted into the tube so as to push out at least a portion of the contents inside the tube. Occasionally, The plunger is configured such that its outer diameter is smaller than the inner diameter of the cylindrical body. A gap exists between the plunger and the cylindrical body. The sealing member is located at the rear end of the gap. It is characterized by the following:

[0007] According to the present invention, the sealing member is provided on the inner circumference of the rear end of the outer cylinder, rather than at the tip of the plunger. Furthermore, since the plunger does not need to be transparent, there is greater freedom in material selection compared to the outer cylinder. Therefore, by making the plunger out of stainless steel, which has smaller processing tolerances than glass, the contents can be extruded with high precision by the product of the cross-sectional area of ​​the plunger and the amount of the plunger's pushing stroke. This makes it possible to provide a syringe with higher precision in the amount of extrusion and easier dimensional control than conventional syringes.

[0008] Furthermore, by configuring the outer cylinder to include a glass cylindrical body and a stainless steel tubing, even when a tapered member is attached to the tip of the outer cylinder to connect a connector, it is possible to prevent the contents from coming into contact with the tapered member by passing the tubing through the tapered member, thereby improving the biological safety and chemical resistance of the syringe.

[0009] [2] In addition, in the present invention, The outer cylinder has a frustoconical shape, gradually decreasing in diameter towards the tip, and has a tapered surface 13a on its outer circumference, and includes a tapered member connected to the tip of the cylindrical body. The tapered member and the thin tube may be made of stainless steel and may be integrally molded.

[0010] With this configuration, since the tapered member and the thin tube are integrally molded from stainless steel, the number of parts in the syringe is reduced, and the syringe can be easily assembled.

[0011] [3] Furthermore, in the present invention, the syringe can be used for ophthalmic purposes. Syringes used for ophthalmic purposes often dispense a small amount of contents, and the syringe of the present invention can be used effectively in such cases.

[0012] [4] In addition, in the present invention, it is preferable that silicone is applied between the sealing member and the plunger. With this configuration, the sliding resistance of the plunger's movement by the sealing member is reduced, and the plunger can move smoothly back and forth relative to the outer cylinder.

[0013] [5] In addition, in the present invention, it is preferable that the inner diameter of the cylindrical body is 1.2 mm or less, and that the cylindrical body and the plunger are configured such that the difference between the outer diameter of the portion of the plunger located inside the cylindrical body and the inner diameter of the cylindrical body is 0.1 mm or less. With this configuration, the time lag from the pressing operation of the plunger 20 until the contents are actually discharged can be reduced compared to the case where the difference exceeds 0.1 mm. [Brief explanation of the drawing]

[0014] [Figure 1] An explanatory diagram showing a syringe according to the first embodiment of the invention. [Figure 2] A cross-sectional view showing an enlarged view of the tip of the syringe according to the first embodiment. [Figure 3] A cross-sectional view showing an enlarged view of the rear end of the syringe of the first embodiment. [Figure 4] A cross-sectional view showing an enlarged view of the tip of a syringe according to the second embodiment of the invention. [Modes for carrying out the invention]

[0015] With reference to the drawings, the syringe according to the first embodiment of the invention will be described. Referring to Figure 1, the syringe 1 of the first embodiment is a small-capacity syringe of 20 μl to 25 μl for ophthalmic use. Figure 2 is an enlarged cross-sectional view showing the distal end portion of the syringe 1, and Figure 3 is an enlarged cross-sectional view showing the proximal end portion of the syringe 1.

[0016] Referring to Figures 1 to 3, the syringe 1 includes a cylindrical outer barrel 10, a pusher 20 slidably inserted into the outer barrel 10 from the proximal end of the outer barrel 10, and a sealing member 30 composed of a packing made of PTFE or FEP that hermetically seals the space between the outer barrel 10 and the pusher 20.

[0017] The outer barrel 10 includes a transparent glass cylindrical main body 11 having graduations 11a, a thin stainless steel tube 12 inserted into the distal end of the cylindrical main body 11 and fixed with an adhesive, a tapered member 13 made of metal or resin that is fixed and attached to the distal end of the cylindrical main body 11 with an adhesive so as to cover the thin tube 12, and a flange portion 14 made of metal or resin having a larger diameter than the outer diameter of the cylindrical main body 11, which is fixed and attached to the proximal end of the cylindrical main body 11 with an adhesive.

[0018] The tapered member 13 is provided with an inclined frustoconical tapered surface 13a that gradually decreases in diameter toward the distal end, so that it can be connected to a connector (not shown) at the proximal end of a tube (not shown) provided with a cannula (not shown) at the distal end. In addition, the tapered member 13 is provided with a through hole 13b for discharging the content inside the outer barrel 10. The tapered member 13 is also provided with a tapered-side recess 13c that fits into the distal end portion of the cylindrical main body 11, and the distal end of the cylindrical main body 11 is fitted into the tapered-side recess 13c. The flange portion 14 is provided with a through hole 14a through which the pusher 20 is inserted. A large-diameter recess 14c is formed on the inner peripheral surface of the distal end side of the flange portion 14, and the proximal end portion of the cylindrical main body 11 is fitted into this large-diameter recess 14c.

[0019] The plunger 20 is composed of a stainless steel inner cylinder member 21, a stainless steel small-diameter member 22 inserted into the inner cylinder member 21 with its tip protruding from the tip of the inner cylinder member 21, and a metal or resin head 23 provided at the rear end of the inner cylinder member 21. The amount of the small-diameter member 22 protruding from the tip of the inner cylinder member 21 is set to be the same as the length of the thin tube 12. This allows the contents of the cylindrical body 11 to be pushed out relatively large by setting the inner cylinder member 21 to be larger than the inner diameter of the thin tube 12, and furthermore, the contents of the thin tube 12 can be pushed out relatively large by the small-diameter member 22 from the outer cylinder 10. The scale 11a displayed on the cylindrical body 11 can be read at the step portion between the inner cylinder member 21 and the small-diameter member 22, that is, at the tip of the inner cylinder member 21. In this embodiment, the portion of the small-diameter member 22 protruding from the tip of the inner cylinder member 21 corresponds to the small-diameter portion of the present invention.

[0020] It is preferable to configure the cylindrical body 11 and the inner cylindrical member 21 such that the inner diameter of the cylindrical body 11 is 1.2 mm or less, and the difference between the inner diameter of the cylindrical body 11 and the outer diameter of the inner cylindrical member 21 is 0.1 mm or less. In this embodiment, the inner diameter of the cylindrical body 11 is set to 0.800 mm, and the outer diameter of the inner cylindrical member 21 is set to 0.715 mm. This made it possible to reduce the time lag from the pressing operation of the plunger 20 until the liquid (contents) is actually discharged. This is thought to be because by making the difference between the inner diameter of the cylindrical body 11 and the outer diameter of the inner cylindrical member 21 0.1 mm or less, the amount of air inside the cylindrical body 11 can be reduced, and in situations such as when pressure is generated in the opposite direction to the injection direction due to the influence of intraocular pressure, the counteracting force of air compression inside the cylindrical body 11 can be reduced.

[0021] As a comparative example, a syringe 1 was created with a cylindrical body 11 having an inner diameter of 1,200 mm and an inner cylinder member 21 having an outer diameter of 0.715 mm, while all other components were identical. When this was tested, it was found that the comparative syringe 1 had a greater time lag between pressing the plunger 20 and the actual discharge of the liquid (contents) compared to the syringe 1 of this embodiment. However, even the comparative syringe 1 possesses the other effects of the present invention besides the "time lag reduction effect."

[0022] The sealing member 30 is press-fitted into a fitting recess 14b provided on the inner circumferential surface of the flange portion 14 of the outer cylinder 10. By airtightly sealing the space between the outer cylinder 10 and the plunger 20 with the sealing member 30, the contents can be sucked into the outer cylinder 10 or discharged from the tip of the outer cylinder 10 by moving the plunger 20 forward and backward.

[0023] The sealing member 30 is cylindrical in shape, and silicone is applied to its inner circumferential surface. Applying silicone to the inner circumferential surface of the sealing member 30 reduces the sliding resistance of the plunger 20's movement by the sealing member 30, allowing the plunger 20 to move smoothly against the outer cylinder 10. However, if the sliding resistance of the plunger 20 by the sealing member 30 is low even without applying silicone, it is not necessary to apply silicone to the inner circumferential surface of the sealing member 30.

[0024] Next, the method of using the syringe 1 of the first embodiment will be described. First, the connector (not shown) at the base end of the tube (not shown) equipped with a cannula (not shown) is connected to the tapered member 13. Then, the plunger 20 is retracted to quantitatively aspirate the liquid (contents). Finally, the plunger 20 is pushed in to quantitatively discharge the aspirated liquid (contents) through the cannula (not shown).

[0025] In the syringe 1 of the first embodiment, the amount of contents dispensed is the difference in volume between when the contents are drawn up and when the contents are dispensed, which is the difference in volume of the plunger 20 that was inside the syringe 1 (cross-sectional area of ​​the inner cylinder member 21 of the plunger 20 (including the internal space) × the amount of the pushing stroke).

[0026] The outer diameter of the inner cylinder member 21 of the plunger 20 is smaller than the inner diameter of the cylindrical body 11 of the outer cylinder 10, and a gap exists between the inner cylinder member 21 and the cylindrical body 11. Therefore, the retraction length of the plunger 20 is not equal to the length of the liquid (contents) inside the outer cylinder 10 that is being sucked in. In other words, the length of the liquid (contents) sucked into the cylindrical body 11 is smaller than the retraction amount of the plunger 20 due to the difference in cross-sectional area. Therefore, a space is created between the plunger 20 and the sucked liquid (contents) during suction. This prevents the sucked liquid (contents) and the sealing member 30 from coming into direct contact.

[0027] According to the syringe 1 of the first embodiment, the part that comes into contact with the contents is made of glass or stainless steel, and a rubber or PTFE packing is not used at the tip of the plunger, thus providing excellent biological safety and chemical resistance.

[0028] Furthermore, the stainless steel plunger 20 has smaller machining tolerances compared to glass, which improves the accuracy of the dispensing volume of the syringe 1. In addition, the dimensional control accuracy of the glass cylindrical body 11 can be reduced, and dimensional control becomes easier as only the dimensions of the stainless steel plunger 20, which has relatively small machining tolerances, need to be controlled. Generally, the machining tolerance of stainless steel is said to be ± a few micrometers, while the machining tolerance of glass is said to be ± tens to hundreds of micrometers.

[0029] Furthermore, the syringe of the present invention may be used for purposes other than ophthalmology. Also, the capacity of the syringe of the present invention is not limited to 20 μl to 25 μl, but may be other capacities. Additionally, the sealing member is not limited to PTFE or FEP, but may be made of other materials.

[0030] Furthermore, although the first embodiment described an assembly of a thin tube 12 and a tapered member 13, the thin tube 12 and the tapered member 13 may be integrally constructed from stainless steel, as shown in the syringe 1 in Figure 4, which is the second embodiment of the invention, by integrally molding the stainless steel tapered member 13, which is made of the same material as the thin tube 12, around the stainless steel thin tube 12. By integrally molding the thin tube 12 and the tapered member 13 from stainless steel, the number of parts of the syringe 1 can be reduced, and the syringe 1 can be easily assembled. [Explanation of symbols]

[0031] 1 syringe 10 Outer cylinder 11. Cylindrical body 11a scale 12 Capillary 13 Tapered member 13a Tapered surface 13b Through hole 13c Tapered side recess 14 Flange section 14a Through hole 14b Fitting recess 14c Large diameter recess 20 plungers 21 Inner cylinder member 22 Small diameter member 23 Head 30 Sealing member

Claims

1. Outer cylinder and A plunger is slidably inserted into the outer cylinder from the rear end of the outer cylinder, A sealing member that prevents the contents inside the outer cylinder from leaking out from the rear end of the outer cylinder through the space between the outer cylinder and the plunger, A syringe equipped with, The sealing member is provided on the inner circumference of the rear end side of the outer cylinder, The outer cylinder comprises a cylindrical body made of glass and a thin stainless steel tube inserted into and fixed at the tip of the cylindrical body. The plunger is made of stainless steel, and its tip is provided with a small diameter portion that can be inserted into the tube so as to push out at least a portion of the contents inside the tube. The plunger is configured such that its outer diameter is smaller than the inner diameter of the cylindrical body. A gap exists between the plunger and the cylindrical body. A syringe characterized in that the sealing member is located on the rear end side of the gap.

2. A syringe according to claim 1, The outer cylinder has a frustoconical shape, gradually decreasing in diameter towards the tip, and has a tapered surface 13a on its outer circumference, and includes a tapered member connected to the tip of the cylindrical body. A syringe characterized in that the tapered member and the thin tube are made of stainless steel and are integrally molded.

3. A syringe according to claim 1 or claim 2, The syringe is characterized in that it is for ophthalmic use.

4. A syringe according to claim 3, A syringe characterized in that silicone is applied between the sealing member and the plunger.

5. A syringe according to claim 4, A syringe characterized in that the inner diameter of the cylindrical body is 1.2 mm or less, and the cylindrical body and the plunger are configured such that the difference between the outer diameter of the portion of the plunger located inside the cylindrical body and the inner diameter of the cylindrical body is 0.1 mm or less.

6. A syringe according to claim 1, A syringe characterized in that silicone is applied between the sealing member and the plunger.

7. A syringe according to claim 1, A syringe characterized in that the inner diameter of the cylindrical body is 1.2 mm or less, and the cylindrical body and the plunger are configured such that the difference between the outer diameter of the portion of the plunger located inside the cylindrical body and the inner diameter of the cylindrical body is 0.1 mm or less.

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