Safety needle assembly

1. A safety needle assembly comprising:

a hub having a proximal end and a distal end;

a needle fixed to the hub, the needle having a distal end, formed for insertion into a patient, and a proximal end;

a first shield having a tubular body at least partially encircling a portion of the needle, wherein, in an initial state, the first shield extends from the distal end of the hub;

a second shield having a tubular body at least partially encircling a portion of the needle;

biasing means disposed to urge the second shield distally towards the distal end of the needle; and,

releasable retaining means for releasably retaining the second shield in a first state; wherein

upon a predetermined extent of proximal movement of the first shield relative to the hub and the second shield, the retaining means releases the second shield thereby allowing the biasing means to urge the second shield to a second state, the second shield covering the distal end of the needle in the second state; and

the second shield is located further radially outward from the needle than the first shield.

2. An assembly as in claim 1 , wherein the second shield does not cover the distal end of the needle in the first state.

3. A safety needle assembly comprising:

a hub having a proximal end and a distal end;

a needle fixed to the hub, the needle having a distal end, formed for insertion into a patient, and a proximal end;

a first shield having a tubular body at least partially encircling a portion of the needle, wherein, in an initial state, the first shield extends from the distal end of the hub;

a second shield having a tubular body at least partially encircling a portion of the needle;

first biasing means disposed to urge the second shield distally towards the distal end of the needle;

releasable retaining means for releasably retaining the second shield in a first state; and

second biasing means disposed between the first and second shields;

wherein upon a predetermined extent of proximal movement of the first shield relative to the hub, the retaining means releases the second shield thereby allowing at least the second biasing means to urge the second shield to a second state, the first and second shields covering the distal end of the needle in the second state.

4. An assembly as in claim 3 , wherein the second shield does not cover the distal end of the needle in the first state.

5. A safety needle assembly comprising:

a hub having a proximal end and a distal end;

a needle fixed to the hub, the needle having a distal end, formed for insertion into a patient, and a proximal end;

a first shield having a tubular body at least partially encircling a portion of the needle, wherein, in an initial state, the first shield extends from the distal end of the hub;

a second shield having a tubular body at least partially encircling a portion of the needle;

first biasing means disposed to urge the second shield distally towards the distal end of the needle; and,

releasable retaining means for releasably retaining the second shield in a first state; and

second biasing means disposed between the first and second shields, wherein the first biasing means provides a greater biasing force than the second biasing means;

wherein:

upon a predetermined extent of proximal movement of the first shield relative to the hub, the retaining means releases the second shield thereby allowing at least the second biasing means to urge the second shield to a second state, the second shield covering the distal end of the needle in the second state; and

the second shield is located further radially outward from the needle than the first shield.

6. An assembly as in claim 5 , wherein the second shield does not cover the distal end of the needle in the first state.