The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 24, 1976
Filed:
Jan. 15, 1975
Bengt Eve Hansson, Holden, MA (US);
Edward A Tischlinger, Niantic, CT (US);
Astra Pharmaceutical Products Inc., Worcester, MA (US);
Abstract
A cartridge for a prefilled hypodermic syringe of the type sealed at its forward end with a destructible diaphragm is provided with a piston-piston rod assembly in which the piston of resilient material is molded in the form of a hollow cylinder and has an auxiliary short, cup-shaped member of reduced diameter coaxially enclosed within its forward end, and sealed in yieldable engagement with the inner walls of said hollow cylinder by a transverse, annularly-shaped elastic membrane. The piston rod has a forward portion of lateral cross-section smaller than the inner cross-sectional area of the piston and slidably receivable in the latter, and a following portion having a lateral cross-section dimension greater than the inner cross-sectional area of the piston, the junction of the two rod portions forming a forwardly directed shoulder. When the piston rod is actuated, the forward reduced portion slides forwardly in the piston until it engages the auxiliary member and causes such member to distend forwardly, while the main body of the piston remains stationary. Continued actuation of the piston rod then brings the shoulder formed by the following rod portion into engagement with the main body of the piston to cause the piston to move as a whole within the syringe cartridge.