Air shot mechanism for electronic injection devices

An electronic injection device, comprising:

• a housing containing an electronic circuit into which the size of a set dose can be read by operation of dose setting means, an injection button which can be operated to inject a set dose, an ampule from which a medicine can be pressed out through a needle mounted at the distal end of the ampule when the injection button is operated, a display driven by the electronic circuit to show the dose set by operation of the dose setting means, wherein the electronic circuit is designed to work in two alternative modes:
• an air shot mode in which it controls an automatic pre-setting of a small air shot dose to be pressed out from the ampule when the injection button is actuated, and a dose injection mode in which a dose set by operation of the dose setting means is injected by operation of the injection button, the circuit normally working in the air shot mode but shifting to work in the dose injection mode when it receives a signal indicating that the dose setting means has been operated, wherein the circuit is so designed that it cannot receive a signal from the dose setting means until at least one air shot dose has been administered.

An electronic injection device, comprising:

• a housing containing an electronic circuit into which the size of a set dose can be read by operation of dose setting means, an injection button which can be operated to inject a set dose, an ampule from which a medicine can be pressed out through a needle mounted at the distal end of the ampule when the injection button is operated, a display driven by the electronic circuit to show the dose set by operation of the dose setting means, wherein the electronic circuit is designed to work in two alternative modes:
• an air shot mode in which it controls an automatic pre-setting of a small air shot dose to be pressed out from the ampule when the injection button is actuated, and a dose injection mode in which a dose set by operation of the dose setting means is injected by operation of the injection button, the circuit normally working in the air shot mode but shifting to work in the dose injection mode when it receives a signal indicating that the dose setting means has been operated, wherein the circuit returns to its air shot mode when receiving a signal indicating that a set dose has been injected, wherein the circuit comprises a memory wherein historical information of injected doses and the time for their injection are stored.