Retractable dental syringe

• US 5,997,512 A
• Filed: 03/04/1998
• Issued: 12/07/1999
• Est. Priority Date: 03/04/1998
• Status: Expired due to Term

• Current Assignee: Retractable Technologies Incorporated
• Original Assignee: Retractable Technologies Incorporated
• Inventors: Shaw, Thomas J.
• Primary Examiner(s): YASKO JR, JOHN D
• Application Number:
  US09/034,411
• Time in Patent Office: 643 Days
• Field of Search: 604/110, 604/187, 604/195, 604/198, 604/263, 604/232
• US Class Current: 604/195
• CPC Class Codes: A61M 2005/3117 Means preventing contamination of the medicament compartment of a syringe
• CPC Class Codes: A61M 2005/3121 via the proximal end of a syringe, i.e. syringe end opposite to needle cannula mounting end
• CPC Class Codes: A61M 5/24 Ampoule syringes, i.e. syringes with needle for use in combination with replaceable ampoules or carpules, e.g. automatic ampoules or carpules A61J1/06
• CPC Class Codes: A61M 5/3137 Specially designed finger grip means, e.g. for easy manipulation of the syringe rod
• CPC Class Codes: A61M 5/3232 Semi-automatic needle retraction, i.e. in which triggering of the needle retraction requires a deliberate action by the user, e.g. manual release of spring-biased retraction means
• CPC Class Codes: A61M 5/3234 Fully automatic needle retraction, i.e. in which triggering of the needle does not require a deliberate action by the user
• CPC Class Codes: A61M 5/502 for blocking the piston
• CPC Class Codes: A61M 5/508 Means for preventing re-use by disrupting the piston seal, e.g. by puncturing

Abstract

A single use retractable medical device dispenses fluids from a separable carpule. A retraction mechanism having a spring loaded needle holder with a double ended needle is mounted the in front of a housing by means of a push ring slidingly mounted on a widened portion of the needle holder. An outer edge of the push ring grips or is restrained by the inner wall surface of the housing to hold the needle holder in place. A carpule positioned through an opening in back of the housing is progressively received by a plunger which drives a separable two-part piston to unload medicine from the carpule through the needle. At the end of an injection, the plunger is depressed further to remove the push ring in cooperation with the carpule thereby freeing the needle holder for retraction through the front opening of the carpule. As the needle is retracted into the housing from one end, the edge of the thumb cap of the plunger disappears into an opening at the opposite end of the housing. An alternative embodiment has a thumb ring instead of a thumb cap. The alternate version has a dish shaped push ring with forwardly angled edges which tend to bind against the housing when pushed from the center by the front of the carpule. The edge of the push ring is easily released by an outer wall portion of the plunger which unlocks the dished edges from a stop structure on the inner wall of the housing as the plunger is moved forward to retract after an injection is made.

Claims

1. A retractable medical device for dispensing fluid from a carpule, comprising:

a tubular housing having a front portion, an inner wall surface and an open back end;

a carpule to fit in the housing, the carpule having a front with an opening having a slidable front seal and a wall extending rearwardly with an opening in back having sliding two part piston seal with a releasable core member;

a plunger having an outer wall and an inner wall wherein said outer wall is adapted to progressively receive the carpule while entering the housing and said inner wall is adapted to move the piston seal forward to the front of the carpule;

a retraction mechanism mounted in the front portion of the housing comprising a needle holder body with a widened part and a separable member grippingly holding the widened part of the needle holder and being restrained by the inner wall surface of the housing, the needle holder including the needle portion extending forwardly and rearwardly from the needle holder body and biasing means applying a retraction force to the needle holder;

the carpule being installable in the housing with the front opening facing the separable member and the front seal being punctured by the rearwardly extending needle portion; and

retraction being triggered by depression of the plunger to cause relative movement of the separable member and carpule relative to the needle holder whereby a passage for retraction of the needle holder is opened into the carpule upon removal of the separable member to free the needle holder for retraction into the carpule in response to the retraction force.

2. The medical device of claim 1 wherein the two part sliding piston seal comprises a rim member of a suitable length circumscribing the releasable core member wherein the rim member and core member contact each other along a longitudinal distance which is less than said length.

3. The medical device of claim 2 wherein the outer wall of the plunger extends forwardly beyond the plunger inner wall to partially receive the back of the carpule and help position it in the housing.

4. The medical device of claim 1 wherein the plunger is depressed to empty the carpule, the relative length of the inner and outer wall of the plunger is such that the piston seal bottoms out in the carpule at about the same time as the outer wall of the plunger reaches the separable member thereby causing movement of the carpule as well as the plunger relative to the housing during further depression of the plunger to remove the separable member from the needle holder.

5. The medical device of claim 4 wherein the needle holder, front seal and core member are adapted to contact each other when the plunger is depressed to bottom out the piston seal in the carpule so that further depression of the plunger to remove the separable member moves the carpule and separable member relative to the front seal and core member, in preparation for retraction.

6. The medical device of claim 1 wherein the inner wall surface of the housing has a small stop structure positioned under the separable member, said structure being adapted to provide overcomable resistance to movement of the separable member.

7. The medical device of claim 6 wherein the separable member has a center body portion and a forwardly angled outer rim positioned behind the stop structure whereby force imposed on the separable member by the carpule during an injection tends to jam the outer rim against the housing without removing the separable member until the outer wall of the plunger releases the outer rim of the separable member from the stop structure.

8. The medical device of claim 7 wherein the angled outer rim comprises a plurality of forwardly angled segments that interact with the stop structure on the inner wall surface of the housing to hold the separable member in place until it is released by the plunger.

9. The medical device of claim 6 wherein the plunger is depressed to empty the carpule, the relative length of the inner and outer wall of the plunger is such that the piston seal bottoms out in the carpule at about the same time as the outer wall of the plunger reaches the separable member thereby causing movement of the carpule as well as the plunger relative to the housing during further depression of the plunger to remove the separable member from the needle holder.

10. The medical device of claim 9 wherein the needle holder, front seal and core member are adapted to contact each other when the plunger is depressed to bottom out the piston seal in the carpule so that further depression of the plunger to remove the separable member moves the carpule and separable member relative to the front seal and core member, in preparation for retraction.

11. The medical device of claim 10 wherein the two part sliding piston seal comprises a rim member of a suitable length circumscribing the releasable core member wherein the rim member and core member contact each other along a longitudinal distance which is less than said length.

12. The medical device of claim 1 wherein the needle holder has a projection and the front of the carpule has a socket to receive said projection when the carpule is inserted in the housing thereby facilitating alignment of the carpule and needle holder.

13. The medical device of claim 12 wherein the front seal is a cup shaped member with an open side that serves as said socket.

37. The improvement of claim 1 wherein the removable core member and front seal move together after the carpule is emptied by depression of the plunger.

38. The improvement of claim 37 wherein an extension of the removable core member or the front seal causes contact between them to cause them to move together.

14. A retractable medical device for dispensing fluid from a carpule, comprising:

a tubular housing having a wall defining a front end portion, a main body portion and an open back end, the wall having an inner surface defining a hollow interior;

a retraction mechanism mounted in the front end portion of the housing, comprising;

a needle holder having an elongated body with a front, a back and a widened part of the body spaced behind the front

needle portions extending from the front and back of the needle holder

a spring mounted under the widened part of the needle holder body to apply a retraction force thereto,

a releasable member grippingly mounted around the widened part of the needle holder and extending outwardly in sliding gripping contact with the inner wall of the housing to hold the needle holder in place against the retraction force provided by the spring;

a carpule for fluid to be dispensed, the carpule having a front end with an opening and slidable puncturable front seal, a body comprising a wall extending rearwardly and an opening in back with a two part slidable piston seal, the carpule being adapted to slide into the housing whereby the front seal is punctured by the needle;

a plunger adapted to progressively receive the carpule while entering the housing and pressing the slidable piston forward to dispense fluid through the needle until depression of the plunger reaches an end of injection position wherein substantially all fluid is dispensed and part of the plunger reaches the releasable member; and

the plunger being further depressible along with said carpule beyond the end of injection position to trigger retraction by moving the releasable member from the widened part of the needle holder while dislodging the front seal and part of the piston seal whereby the retraction force drives the needle holder and needle through the front opening into the carpule where they are safe.

15. The medical device of claim 14 wherein the inner wall surface of the housing has a small stop structure positioned under the releasable member, said structure being adapted to provide overcomable resistance to movement of the releasable member.

16. The medical device of claim 15 wherein the releasable member has a center body portion and a forwardly angled outer rim positioned behind the stop structure whereby force imposed on the releasable member by the carpule during an injection tends to jam the outer rim against the housing without removing the releasable member until the outer wall of the plunger releases the outer rim of the releasable member from the stop structure.

17. The medical device of claim 16 wherein the angled outer rim comprises a plurality of forwardly angled segments that interact with the stop structure on the inner wall surface of the housing to hold the releasable member in place until it is released by the plunger.

18. A carpule for a retractable medical device comprising:

a cylindrical wall defining a fluid chamber, said wall having a front end with an opening into the fluid chamber and an open back end;

a slidable front seal lodged in the opening of the front end;

a sliding piston seal lodged in the open back end wherein the piston seal has an outer rim portion in sliding sealing contact with the wall of the fluid chamber and a forcibly removable core;

wherein the sliding piston seal can be driven forward to displace fluid from the fluid chamber when a fluid path is provided by a needle portion traversing the front seal;

the sliding piston seal having a position at the front of the fluid chamber that corresponds to the end of injection position whereby substantially all fluid has been dispensed from the fluid chamber; and

the front seal and forcibly removable core of the sliding plunger seal can be driven back into the fluid chamber to clear the way for retractable parts to enter the fluid chamber through said opening.

19. The carpule of claim 18 wherein the inner surface of the outer rim portion and the outer surface of the forcibly removable core are in contact over only a portion of their extent to reduce the amount of movement required to disengage the core from the rim.

20. The carpule of claim 18 wherein the removable core part of the piston seal and the slidable front seal are configured to come together at the end of injection position so they can be moved together.

21. The carpule of claim 20 wherein the inner surface of the outer rim portion and the outer surface of the forcibly removable core are in contact over only a portion of their extent to reduce the amount of movement required to disengage the core from the rim.

22. The carpule of claim 20 wherein the front of the carpule is shaped like a socket to receive the end of a needle holder.

23. The carpule of claim 22 wherein the front seal is a cup shaped member with an open side which serves as said socket.

24. The carpule of claim 23 wherein the inner surface of the outer rim portion and the outer surface of the forcibly removable core are in contact over only a portion of their extent to reduce the amount of movement required to disengage the core from the rim.

25. In a retractable medical device having a tubular housing having an inner wall surface and an open back end, a retraction mechanism mounted in the front of the housing, the retraction mechanism including a spring loaded needle holder and double ended needle, a carpule designed to fit in the housing, the carpule having a front end with sealed front opening which is punctured by the needle and a back end having a piston plug which is moved by a plunger which pushes the piston forward to empty the contents of the carpule through the double ended needle, the improvement comprising:

the carpule has a slidable front seal in the front opening and a slidably removable core member in the center of the piston plug, wherein the slidable core member is brought adjacent to the front seal in response to depression of the plunger to expel substantially all the contents of the carpule;

an opening for the needle holder to retract into the carpule is created by sliding removal of the slidable front seal from the front opening and sliding removal of the slidable core member from the piston;

the needle holder is positioned and held with the needle extended by means of a removable push ring circumscribing the needle holder, wherein the push ring is in forcible movable contact with a portion of the inner wall surface of the housing; and

depression of the plunger after empty the contents of the carpule through the needle causes relative movement of the carpule and push ring relative to the needle holder thereby opening a passage into the carpule for retraction of the needle holder as it is being released by removal of the push ring.

26. The improvement of claim 25 wherein the front end of the carpule is supported against forward movement by the needle holder and/or push ring in response to depression of the plunger while an injection is being given.

27. The improvement of claim 26 wherein there is a wall of material which extends between the front seal and the core member when the piston has moved forward to expel the contents of the carpule.

28. The improvement of claim 27 wherein a portion of the core member extends into the front opening of the carpule when the carpule has been emptied by depression of the plunger.

29. The improvement of claim 28 wherein the carpule has a body portion in which the piston operates, said body portion having a larger inner diameter than the diameter of the front opening whereby a lateral stop surface is created at the back of said opening which provides a stop for the piston at the bottom of its forward travel.

30. A retractable medical device for dispensing fluid from a carpule, comprising:

a tubular housing with a longitudinally extending wall having an inner wall surface and an open back end;

a retraction mechanism mounted in the front of the housing, the retraction mechanism comprising a needle holder grounded in the housing, the needle holder having an elongate body, a widened portion and a demountable member grippingly mounted on the widened portion of the needle holder, the member having an outer portion slidingly gripping the inner wall of the housing in opposition to a biasing element applying a retraction force to the needle holder, the needle holder including forwardly and rearwardly extending needle portions with a fluid passage therethrough;

a removable carpule having an elongate wall comprising an opening in front sized to pass the needle holder and an opening in back, the carpule having a seal slidably lodged in the front opening and a piston seal slidably lodged in the back opening, the interior of the carpule defining a fluid chamber;

the carpule being installable into the housing behind the demountable member with the rearwardly extending needle portion extending through the front seal in fluid communication with the chamber;

the piston seal including an outer rim portion and a forcibly removable core, the piston seal being movable in sliding contact with the elongate wall of the carpule to a front position in the carpule to dispense substantially all fluid from the chamber;

a plunger having an inner wall adapted to move the piston seal to the front position in the carpule by pushing on the outer rim of the piston seal;

wherein further depression of the plunger moves the demountable member forward to demount it from the needle holder while freeing the front seal from its opening and freeing the core of the piston seal from the outer rim whereby the biasing element can drive the needle holder into the chamber thereby retracting the needle.

31. A retractable medical device for dispensing fluid from a carpule comprising:

a tubular housing having a front portion, an inner wall surface and an open back end;

a retraction mechanism mounted in the front portion of the housing comprising a needle holder including needle portions extending forwardly and rearwardly from the needle holder, a biasing element applying a retraction force to the needle holder and a separable member which cooperates with the inner wall surface of the housing to hold the needle holder and needle in a position for use;

a carpule to fit in the housing having a front opening sealed with a slidable front seal and a medicament chamber behind;

whereby the separable member is released from the needle holder and at least part of the needle enters the medicament chamber in response to depression of the plunger thereby safely retracting the needle.

32. In a retractable medical device having a tubular housing having an inner wall surface and an open back end, a retraction mechanism mounted in the front of the housing, the retraction mechanism including a retractable spring loaded needle holder and double ended needle, a carpule designed to fit in the housing, the carpule having a front end with sealed front opening which is punctured by the needle and a back end having a piston plug which is moved by a plunger which pushes the piston forward to empty the contents of the carpule through the double ended needle, the improvement comprising:

the carpule has a seal in front and a removable core member in the center of the piston, wherein the core member comes adjacent to the seal in response to depression of the plunger to expel the contents of the carpule;

removal of the seal from the front opening and the core member from the piston leaves an opening for the needle holder to retract into the carpule;

the needle holder is positioned and held with the needle extended by means of a separable member circumscribing the needle holder, which is restrained by the inner wall surface of the housing; and

depression of the plunger to empty the contents of the carpule releases the needle holder by removal of the separable member from the needle holder whereby the needle holder and the needle enter the carpule through said front opening.

33. In a retractable medical device having a tubular housing having an inner wall surface and an open back end, a retraction mechanism comprising a spring loaded needle holder and double ended needle mounted in the front portion of the housing, a carpule designed to fit in the housing, the carpule having a front end with a front opening having a seal which is punctured by the needle and a back end having a piston plug which is moved by the plunger during an injection, the interior of the carpule behind the front opening comprising a chamber for fluid contents, whereby the piston is pushed forward to empty the contents of the carpule through the double ended needle, the improvement comprising:

releasable structure extending between the needle holder and the housing releasably holding the retraction mechanism in the housing;

the carpule has a slidable front seal in the front opening, a chamber behind the front opening and a removable core member in the piston plug;

depression of the plunger after emptying the contents of the carpule through the needle is accompanied by release of the releasable structure, sliding removal of the front seal from the front opening of the carpule and release of said core member from the piston plug to create an opening for the needle holder into said chamber of the carpule, caused by depression of the plunger;

whereby the needle holder is automatically retracted into the carpule by depressing the plunger after the carpule is emptied.

34. The improvement of claim 33 wherein the plunger has an outer wall that progressively receives the carpule and an inner wall which progressively pushes the piston plug forward within the carpule as the plunger is depressed.

35. The improvement of claim 34 wherein the releasable structure for holding the retraction mechanism in the housing is released in response to forward movement of the carpule relative to the tubular housing caused by depression of the plunger after the carpule is emptied.

36. The improvement of claim 35 wherein the needle holder serves as a stop for the slidable front seal as the carpule moves forward thereby removing the front seal of the carpule to create an opening for entry of the needle holder.

39. A retractable medical device for dispensing fluid from a carpule, comprising:

a tubular housing having a front end portion and a retractable needle for dispensing the fluid contents of a carpule;

a sealed carpule having a fluid chamber in fluid communication with the retractable needle;

a depressible plunger which at the end of an injection can be depressed further causing the retractable needle to automatically enter the fluid chamber.