This is a National Phase Application filed under 35 U.S.C. 371 as a national stage of PCT/JP2018/009691, filed Mar. 13, 2018, an application claiming the benefit of Japanese Application No. 2017-071731, filed Mar. 31, 2017, the content of each of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a syringe.

BACKGROUND ART

Patent Document 1 discloses a syringe. This syringe includes a cylinder having a needle mount and a bypass structure, a finger grip, and a plunger rod. The needle mount is attached to the distal end of the cylinder. A plug accommodating chamber is formed inside the needle mount. A communication groove in the form of a recess is formed in an inner wall of this plug accommodating chamber. A syringe needle is attached to the needle mount at the opposite end from the side connected to the cylinder. At the distal end inside the cylinder is mounted a front plug, and successively from there a middle plug and an end plug. The finger grip is attached at the rear end of the cylinder such as to surround part of the circumference of the cylinder. Further, the plunger rod is attached to the rear end of the cylinder.

PRIOR ART DOCUMENTS

Patent Documents

Patent Document 1: WO 2004/073774

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

The syringe disclosed in Patent Document 1 has a problem that the sense of feel when in use with fingers rested on the finger grip is not favorable. The interior of the syringe of Patent Document 1 is divided to a first chamber and a second chamber by the bypass structure and the stoppers. When the plunger rod of this syringe is pushed forward, the stoppers of the syringe move, so that the first chamber and the second chamber connect to each other via the bypass. As the plunger rod is further pushed forward, the inner space of the cylinder connects to the syringe needle via the communication groove of the needle mount. Not just the syringe of Patent Document 1, but in general, when the plunger rod of the syringe is pushed forward, fingers are rested on the finger grip to stabilize the syringe. The finger grip not having a favorable feel when in use means that the finger grip causes a pain in the finger, the finger grip lacks stability, or the finger grip hardly allows smooth transmission of force to the plunger rod, when the plunger rod is pushed forward with fingers rested on the finger grip. For medical workers, the finger grip not having a favorable feel when in use may cause an increased sense of tiredness in repeated administration, or an increase in time required for preparation of drugs.

The present invention was made to solve these problems. An object of the present invention is to provide a syringe with an improved sense of feel when in use with fingers rested on the finger grip.

Solutions to the Problems

Through intensive investigation of the problems described above, the inventors found out that the shape of finger hook portions of the finger grip has a large impact on the sense of feel when in use with fingers rested thereon, which led to the completion of the present invention. Namely, the present invention is as follows:

The first aspect of the invention is a syringe including:

a cylinder;

a syringe needle connected to one end of the cylinder;

a finger grip connected to the other end of the cylinder; and

a plunger rod passing through the finger grip and entering into the cylinder,

the finger grip including

a cylindrical portion having one end and the other end, the cylinder being inserted from the one end, and the plunger rod extending through from the other end of the cylindrical portion, and

a pair of finger hook portions protruding from an outer circumferential surface of the cylindrical portion to opposite directions,

the finger hook portion including

an inclined curved surface located on one side surface of the finger hook portion facing the one end of the cylindrical portion and having an area on a proximal side of the side surface and an area on a distal side of the side surface, the area on the distal side of the side surface being closer to the other end of the cylindrical portion than the area on the proximal side of the side surface, and the area on the proximal side having a shallower slope with respect to a center axis of the cylindrical portion than the area on the distal side, and

an end-side curved surface disposed in a boundary between a tip of the finger hook portion and the inclined curved surface and extending along the boundary.

The second aspect of the invention is characterized in that, in addition to the configuration according to the first aspect of the invention,

the end-side curved surface extends as far as to the tip of the finger hook portion, and

a length obtained by subtracting twice a radius of curvature of the end-side curved surface and an outside diameter of the cylindrical portion from a length between the tip of one finger hook portion and the tip of the other finger hook portion is 19.2 mm or more.

The third aspect of the invention is characterized in that, in addition to the configuration according to the second aspect of the invention,

the length obtained by subtracting twice a radius of curvature of the end-side curved surface and an outside diameter of the cylindrical portion from a length between the tip of one finger hook portion and the tip of the other finger hook portion is 22.2 mm or less.

The fourth aspect of the invention is characterized in that, in addition to the configuration according to the second aspect of the invention,

the length obtained by subtracting twice a radius of curvature of the end-side curved surface and an outside diameter of the cylindrical portion from a length between the tip of one finger hook portion and the tip of the other finger hook portion is 20 mm or less.

The fifth aspect of the invention is characterized in that, in addition to the configuration according to the fourth aspect of the invention,

the inclined curved surface has a radius of curvature of 15.8 mm or more.

The sixth aspect of the invention is characterized in that, in addition to the configuration according to the first to fifth aspects of the invention, the plunger rod includes

a plate-like plate part, and

a rod part continuous with the plate part and receiving a force from the plate part,

the plate part being provided with a recess on one surface opposite from a surface continuous with the rod part.

Effects of the Invention

The present invention allows the sense of feel when in use with fingers rested on the finger grip to be improved.

