Title of Invention

A NON RE-USABLE HYPODERMIC SYRINGE

Abstract

A non re-usable hypodermic syringe comprising a cylinder and a plunger reciprooatingly mounted within the cylinder; a first circumferential ridge on the inner wall, of the cylinder and a second circumferential ridge on the outer wall of the plunger the second ridge having a larger circumference than that of the first ridge, the stem of the plunger being made of an elastic material provided with a slot, such that when the plunger is pushed in the cylinder, the ridges on the cylinder and on the lunger butt against each other while simulta eonsl)" the slotted portion of the stem gets resiliently compressed to allow the ridges to ride over each other and thus allow the stem to pass through into the top portion of the cylinder fo~ administering the injection the stem however being restrained from retracting by reason of the ridges fouling with each oilier such that the stem breaks off on forcible withdrawal from the cylinder.

Full Text

This invention relates to a non-reusable hypodermic syringe. It is known that unscrupulous persons attempt to reuse hypodermic syringes after administering one injection, in order to save cost and thereby give room for spreading disease and create unhygienic conditions. This situation exists despite disposable syringes being put on the market for providing adequate health care. It is therefore an object of this invention to propose a hypodermic syringe which, once used, is incapable of being used again, because if an attempt is made to reuse it, it destroys itself rendering it incapable of any reuse. The non re-usable hypodermic syringe according to this invention comprises a cylinder and a plunger reciprocating mounted within the cylinder, a first circumferential ridge on the inner wall of the cylinder and a second circumferential ridge on the outer wall of the plunger, the second ridge having a larger circumference than that of the first ridge, the stem of the plunger being made of an elastic material provided with a slot, such that when the plunger is pushed in the cylinder, the ridges on the cylinder and On the plunger butt against each other while simultaneously the slotted portion of the stem gets resiliently compressed to allow the ridges to ride over each other and thus allow the stem to pass through into the top portion of the cylinder for administering the injection, the stem however being restrained from retracting by reason of the ridges fouling with each other such that the stem breaks off on forcible withdrawal from the cylinder. This invention will now be described with reference to the accompanying drawings which illustrate by way of example and not by way of limitation one of possible embodiments of the hypodermic syringe proposed herein Figs. 1A and 1B illustrating a view of the plunger and cylinder of the syringe, with the top end of the plunger just entering the top end portion of the cylinder Fig. 2 illustrating the ridge on the outer wall of the plunger riding over the ridge on the inner wall of the cylinder Fig.3 illustrating the top end of the plunger completing its full traverse and Fig. 4 illustrating the plunger breaking off as an attempt is made to retract the plunger for refilling the syringe The non-reusable hypodermic syringe comprises a cylinder G and a plunger P reciprocating mounted within the cylinder. The inner wall of the cylinder is provided with a first circumferential ridge R1 and the outer wall of the plunger is provided with a second circumferential ridge R2 near the top of the plunger, the ridge R2 having a larger circumference than that of the ridge R2. The stem of the plunger is made of an elastic material and i$ provided with a slot T, such that when the plunger is pushed in the cylinder, the ridges R1 R2 on the cylinder and on the plunger butt against each other. Consequently, the ridge R2 rides over the ridge R1 by compressing the stem at the slot to allow the ridge s to ride over each other and thus allow the stem to pass through into the upper portion of the cylinder to administer the injection. However, any subsequent attempt to withdraw (that is, retract) the plunger will be resisted by the ridges R1 and R2 fouling with each other, thus preventing such withdrawal. If the plunger is sought to be forcibly withdrawn, the stem breaks off at G wher0 two adjacent portions of the stem are connected by a strut S which ruptures on such force being applied. Consequently, the syringe is incapable of being reused. To facilitate riding of the ridges over each other the ridge R2 is tapered at E to ride over the ridge R1, but not When the ridge R2 is retracted because, in such a case, the very taper at E which enabled passage of the stem past the ridge R1 restrains the passage of the stem in the reverse direction. Besides, in the reverse direction, the stem at its slotted portion is not under compression. The bottom end of the plunger is attached to a knob by a strut F which breaks away on forcible withdrawal of the plunger from the cylinder thus rendering the syringe incapable of being refilled for fresh use. It will be appreciated that various other embodiments are possible without departing from the scope and ambit of this invention. I Claim: 1. A non re-usable hypodermic syringe comprising a cylinder and a plunger reciprocatingly mounted within the cylinder; a first circumferential ridge on the inner wall of the cylinder and a second circumfererntial ridge on second ridge the outer wall of the plunger, the having a larger circumference that that of the first ridge, the stem of the plunger being made of an elastic material provided with a slot, such that when the plunger is pushed in the cylinder, the ridges on the cylinder and on the plunger butt against each other while simultaneously the slotted portion of the stem gets re siliently compressed to allow the ridges to ride over each other and thus allow the stem to pass through into the top portion of the cylinder for administering the injection, the stem however being restrained from retracting by reason of the ridges fouling with each other such that the stem breaks off on forcible withdrawal from the cylinder. to facilitate riding over the first ridge, except when the plunger is sought to be retracted when the ridges foul with each other preventing such retraction. 3. A non re-usable hypodermic syringe substantially as herein described and illustrated in the accompanying drawings.

Documents:

407-CHE-2008 AMENDED PAGES OF SPECIFICATION 04-01-2012.pdf

407-CHE-2008 AMENDED CLAIMS 04-01-2012.pdf

407-CHE-2008 EXAMINATION REPORT REPLY RECEIVED 04-01-2012.pdf

407-CHE-2008 POWER OF ATTORNEY 04-01-2012.pdf

407-che-2008-claims.pdf

407-che-2008-correspondnece-others.pdf

407-che-2008-description(complete).pdf

407-che-2008-drawings.pdf

407-che-2008-form 1.pdf

407-che-2008-form 18.pdf