Injection device which can be cocked only in the zero position

Details Injection device which can be cocked only in the zero position Injection device which can be cocked only in the zero position

1989-11-03

1991-08-27

Yasko, John D.

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

604218, A61M 520

Patent

active

050429779

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The invention relates to an injection device having a mechanism for effecting an injection process by action upon an injection ampule, the mechanism being variable in length and movable into a cocking position by a cocking element counter to the force of a spring.


BACKGROUND

Injection devices with spring-loaded plungers are relatively complicated devices. The patient must therefore be carefully instructed, for instance in a hospital, in their use. Nevertheless, the us of such devices should be made as simple and logical as possible. The present invention seeks an improvement in this respect.


THE INVENTION

Briefly, a blocking device is associated with a rotatable adjustment element, and so coupled thereto that, in dependence on the rotational position of the rotatable adjusting element, displacement of the injection mechanism into a cocking position is prevented when the adjustment element is not in a "zero dose" position, that is, in which an injection dose of zero is displayed. The invention forces the patient to reset the injection does to zero before cocking the injection device, because cocking is completely impossible otherwise. This reminds the patient to reset the injection dose each time and prevents him from injecting too high a dose out of carelessness.
In accordance with a preferred feature of the invention, a second blocking device is provided, controlled by the position of the rotatable adjustment element. The second blocking device prevents tripping of an injection process in a position in which the injection does of zero is displayed on a scale displaying the injection dose, and associated with the adjusting element. The patient cannot make an injection even after cocking the injection device unless he has first set an injection dose that is greater than zero; that is, by this provision also, mistakes on the part of the patient are avoided, and the device reminds him that he must set his injection dose prior to the injection.
In accordance with an especially preferred embodiment, the container which contains the fluid to be injected can be displaced counter the action of a restoring spring up to a stop. Thus, release of the mechanism which causes the injection process must first displace the container up to the stop and thereby cause penetration of the injection needle and only thereafter a displacement of a plunger or piston in the container to effect the actual injection. This has the advantage that the injection dose is still "stored in memory" even after the injection, and even several hours later the patient can still verify what the most recently injected dose was. This is very valuable in practice.


DRAWINGS

Further details and further advantageous features of the invention will become apparent from the exemplary embodiment described below and shown in the drawings, which are understood not to represent any limitation whatever of the invention, and from the dependent claims. Shown are:
FIG. 1, a side view of an injection device according to the invention, seen on an enlarged scale and in the position after an injection has been given, seen from above;
FIG. 2, a view similar to FIG. 1, but rotated by 90.degree. relative to it, in longitudinal section;
FIG. 3, a detail of FIG. 2, on a greatly enlarged scale;
FIG. 4, a longitudinal section through the injection device similar to FIG. 2, but in the cocked state, i.e., before the injection;
FIG. 5, a detail of FIG. 4, on a greatly enlarged scale;
FIG. 6, an exploded three-dimensional view of the so-called B part of the injection device, which is used to hold the cartridge containing the substance to be injected;
FIG. 7, a three-dimensional view of the control portion for controlling the injection quantity;
FIG. 8, a three-dimensional view, on a smaller scale than that of FIG. 7, of the tappet, which is adjustable in length;
FIG. 9, a longitudinal section through an adjusting sleeve used to set the injection quantity, taken along the line IX--IX of FIG. 13;
FIG. 10, a plan view on the adjusting sleeve of FIG.

REFERENCES:
patent: 2565081 (1951-08-01), Maynes
patent: 4194505 (1980-03-01), Schmitz
patent: 4498904 (1985-02-01), Turner et al.
patent: 4717383 (1988-01-01), Phillips
patent: 4722728 (1988-02-01), Dixon
patent: 4820286 (1989-04-01), van der Wal
patent: 4850967 (1989-07-01), Cosmai

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