Multiple dose injection pen

Claim 2

The improvement of claim 1 wherein the first means comprises a collar received within the housing adjacent the container second end, the collar having a non-cylindrical opening corresponding generally to the cross-section of the plunger rod for preventing rotation of the plunger rod with respect to the housing.

Claim 3

The improvement of claim 2 wherein the prong means are included within the collar non-cylindrical opening and engage a surface on the plunger rod for restricting movement of the plunger rod toward the housing proximal end.

Claim 4

The improvement of any one of claims 1 to 3 wherein the third means comprises a hollow cap enveloping the plunger rod end opposite the container and extending outward from the housing proximal end, the cap having a threaded interior surface movably engaging a threaded surface of the plunger rod for calibrated adjustment relative thereto.

Claim 5

A syringe having means for adjustment of the dosage of liquid to be injected comprising: a housing receiving a container of liquid, the housing having a proximal end and a distal end, the distal end being adapted to receive a needle assembly for permitting liquid to pass out of a closed first end of the container, a plunger rod received within the housing for exerting a force on a piston closing a second end of the container, the plunger rod having a non-cylindrical cross-section, a first surface including threads, and a second surface, a collar received within the housing adjacent the container second end, the collar having a non-cylindrical opening corresponding generally to the cross-section of the plunger rod for preventing rotation of the plunger rod with respect to the housing and prong means engaging the plunger rod second surface for restricting movement of the plunger rod toward the housing proximal end, and a hollow cap enveloping the plunger rod end opposite the container and extending outward from the housing proximal end, the cap having a threaded interior surface movably engaging the plunger rod first surface portion for calibrated adjustment relative thereto and a distal end facing surface for contacting a stop fixed with respect to the housing upon movement of the cap and plunger rod toward the housing distal end.

Claim 6

The improvement of any one of claims 1 to 4 or the syringe of claim 5 further comprising limit means for limiting the maximum calibrated movement of the third means.

Claim 7

The improvement or syringe of claim 6 wherein the limit means comprises a threaded portion on an outer surface of the hollow cap and a follower adjustibly positioned on the threaded outer surface portion of the cap.

Claim 8

The improvement or syringe of claim 7 wherein the limit means further comprises a barrier element fixed with respect to the housing for limiting the length of movement of the hollow cap relative to the housing by contacting the adjustibly positioned follower.

Claim 9

The improvement of claim 2 or the syringe of claim 5 wherein the collar comprises a radial outside surface frictionally engaging an inside surface of the housing, and a distal end surface contacting the container of liquid for maintaining the container in fixed position with respect to the housing.

Claim 10

The improvement of any one of claims 1 to 4 and 9 or the syringe of claims 5 and 9 wherein the prong means comprises a pair of opposed edges situated on opposite sides of the plunger rod each engaging a surface on the plunger rod so as to prevent movement of the plunger rod toward the housing proximal end.

Claim 11

The improvement of claim 4 or the syringe of claim 5 wherein the hollow cap further comprises a flexible member projecting outward from the cap into engagement with a groved interior surface of the housing, the calibrated relative adjustment causing sensible movement of the flexible member.

Claim 12

In a syringe having a housing for receiving a container of liquid, the housing having a proximal end and a distal end, the distal end being adapted to receive an injection needle assembly for permitting liquid to pass out of a closed first end of the container, an improved means for adjustment of the dosage of liquid to be injected comprising: a plunger rod received within the housing for exerting a force on a piston closing a second end of the container, the plunger rod having a non-cylindrical cross-section, a first surface including threads, and a second surface, a collar received within the housing adjacent the container second end, the collar having a non-cylindrical opening corresponding generally to the cross-section of the plunger rod for preventing rotation of the plunger rod with respect to the housing and prong means engaging the plunger rod second surface for restricting movement of the plunger rod toward the housing proximal end, a hollow cap enveloping the plunger rod end opposite the container and extending outward from the housing proximal end, the cap having a threaded interior surface movably engaging the plunger rod first surface portion for calibrated adjustment relative thereto and a distal end facing surface for contacting a stop fixed with respect to the housing upon movement of the cap and plunger rod toward the housing distal end, and a threaded portion on an outer surface of the hollow cap and a follower adjustibly positioned on the threaded outer surface portion of the cap to permit variation in the limit of the calibrated movement of the cap with respect to the plunger rod.