Safe medical-drug injector and collapsible plunger combination thereof

Abstract

A safe medical-drug injector with a collapsible plunger combination thereof is proposed. The injector includes a hub connected with a needle, a hollow barrel for guiding the needle hub to draw back to the hollow barrel, and the collapsible plunger combination including a hollow cannula and a retractable plunger that are in sleeve joint. A least a stress adjustable notch is formed at the core of the retractable plunger or in an upper edge of the hollow cannula, and at least one raised portion is formed on an outer lateral side of the retractable plunger near the stress adjustable notch to be correspondingly embedded with at least a depression formed on an inner lateral side of the hollow cannula. The connection between the hollow cannula and the retractable plunger is released to make the retractable plunger drawn back to the hollow cannula when a following press is applied on the hollow cannula after the safe medical-drug injector completes an injection, thereby spare space of the hollow barrel for accommodating the needle hub. In this way, the manual operation of single hand and yield of process for the safe medical-drug injector can be achieved.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are cross sectional view of a conventional automatically retractable safe injector with breakable portion.

FIG. 2 is an exploded schematic view of the safe medical-drug injector and the collapsible plunger combination thereof according to the first embodiment of the invention.

FIG. 3 is a cross sectional view with enlarged view of the safe medical-drug injector according to the first embodiment.

FIG. 4 is a schematic view illustrating how the retractable plunger and the hollow cannula of the safe medical-drug injector are connected according to the first embodiment.

FIG. 5 is a schematic view showing the hollow cannula of the safe medical-drug injector according to the first embodiment of the invention.

FIG. 6 is an exploded cross sectional view showing the safe medical-drug injector according to the second embodiment of the invention.

FIG. 7 is a perspective view showing the cross section of the collapsible plunger combination of the safe medical-drug injector according to the third embodiment of the invention.

FIG. 8 is a cross sectional view showing the collapsible plunger combination of the safe medical-drug injector according to the fourth embodiment of the invention.

FIG. 9 is a cross sectional view showing the collapsible plunger combination of the safe medical-drug injector according to the fifth embodiment of the invention.

FIG. 10 is a schematic view showing how the retractable plunger of the safe medical-drug injector is drawn back to the hollow cannula according to the fifth embodiment.

FIG. 11 is a perspective view showing that the retractable plunger of the safe medical-drug injector is provided with rough region according to the sixth embodiment of the invention.

FIG. 12 is an exploded schematic view showing the safe medical-drug injector according to the seventh embodiment of the invention.

FIG. 13 is an exploded schematic view showing the safe medical-drug injector according to the eighth embodiment of the invention.

Claims

1. A safe medical-drug injector comprising: a needle hub connecting a needle;a hollow barrel connected with the needle hub for guiding the needle hub to be drawn back to the hollow barrel after an injection is completed; and a collapsible plunger combination inserted into the hollow barrel, the collapsible plunger combination comprising a hollow cannula and a retractable plunger partly connected with the cannula, there being at least one raised portion formed on outside wall of the retractable plunger near the connection part to be correspondingly embedded in at least one depression formed on the inside wall of the hollow cannula;wherein the hollow cannula is formed with at least one stress adjustable notch on the upper edge and the connection between the hollow cannula and the retractable plunger is released to make the retractable plunger drawn back to the hollow cannula when the stress adjustable notch deforms due to a following press on the hollow cannula after an injection is completed, and thereby spare space of the hollow barrel for accommodating the needle hub.

2. The safe medical-drug injector as set forth in claim 1, wherein the collapsible plunger combination is composed of the hollow cannula and the retractable plunger each formed by injection molding.

3. The safe medical-drug injector as set forth in claim 1, wherein the raised portion comprises outward protruding dots one-piece formed on the outside wall of the retractable plunger.

4. The safe medical-drug injector as set forth in claim 1, wherein the raised portion comprises a plurality of adjacent rows of transversely convex annular ribs.

5. The safe medical-drug injector as set forth in claim 1, wherein the raised portion comprises a plurality of spaced rows of transversely convex annular ribs.

6. The safe medical-drug injector as set forth in claim 1, wherein the lower edge of the retractable plunger is a fillet edge.

7. The safe medical-drug injector as set forth in claim 1, wherein the outside wall of the retractable plunger is formed with rough region above the raised portion.

8. The safe medical-drug injector as set forth in claim 1, wherein the upper edge on the inner side of the hollow cannula has a shape selected from the group consisting of arc, fillet and incline.

9. The safe medical-drug injector as set forth in claim 1, wherein the depression is selected from the group consisting of groove and cavity.

10. The safe medical-drug injector as set forth in claim 1, wherein the depression is selected from the group consisting of a plurality of adjacent rows of transversely concave annular ribs and a plurality of spaced rows of transversely concave annular ribs.

11. The safe medical-drug injector as set forth in claim 1, wherein the hollow cannula is formed with at least one exhausting hole on the sidewall far away from the connection part.

12. The safe medical-drug injector as set forth in claim 1, wherein the hollow cannula is formed with a plurality of blocks near the lower part of the depression on the inside wall.

13. A safe medical-drug injector comprising: a needle hub connecting a needle;a hollow barrel connected with the needle hub for guiding the needle hub to be drawn back to the hollow barrel after an injection is completed; anda collapsible plunger combination inserted into the hollow barrel, the collapsible plunger combination comprising a hollow cannula and a retractable plunger partly connected with the cannula, there being at least one raised portion formed on outside wall of the retractable plunger near the connection part to be correspondingly embedded in at least one depression formed on the inside wall of the hollow cannula;wherein the connection between the hollow cannula and the retractable plunger is released to make the retractable plunger drawn back to the hollow cannula when a following press is applied on the hollow cannula after an injection is completed, and thereby spare space of the hollow barrel for accommodating the needle hub.

14. The safe medical-drug injector as set forth in claim 13, wherein the retractable plunger is formed with at least one stress adjustable notch at the core of the connection part.

15. The safe medical-drug injector as set forth in claim 13, wherein the hollow cannula is formed with at least one stress adjustable notch on the upper edge of the connection part.

16. A collapsible plunger combination for medical-drug injection comprising: a hollow cannula; anda retractable plunger partly connected with the cannula, there being at least one raised portion formed on outside wall of the retractable plunger near the connection part to be correspondingly embedded in at least one depression formed on the inside wall of the hollow cannula;wherein the connection between the hollow cannula and the retractable plunger is released to make at least one part of the retractable plunger drawn back to the hollow cannula when a following press is applied on the hollow cannula after an injection is completed.

17. A safe medical-drug injector comprising: a needle hub connecting a needle;a hollow barrel connected with the needle hub and one-piece formed with a narrow barrel having its diameter smaller than that of the hollow barrel near the needle hub, there being a block set adjacent to the opening of the narrow barrel for preventing the needle hub from escaping and guiding the needle hub to retract after an injection is completed; anda collapsible plunger combination inserted into the hollow barrel, the collapsible plunger combination comprising a hollow cannula and a retractable plunger partly connected with the cannula, there being at least one raised portion formed on outside wall of the retractable plunger near the connection part to be correspondingly embedded in at least one depression formed on the inside wall of the hollow cannula;wherein the connection between the hollow cannula and the retractable plunger is released to make the retractable plunger drawn back to the hollow cannula when a following press is applied on the hollow cannula after an injection is completed, and thereby spare space of the hollow barrel for accommodating the needle hub.

18. The safe medical-drug injector as set forth in claim 17, wherein the block is a movable stopper.

19. The safe medical-drug injector as set forth in claim 17, wherein the block is a neck portion one-piece formed on the hollow barrel.

20. The safe medical-drug injector as set forth in claim 17, wherein the block is formed with through hole.