Droplet deposition apparatus

Droplet deposition apparatus comprising:

• an array of fluid chambers, each chamber communicating with an orifice for droplet ejection, a common fluid inlet manifold and a common fluid outlet manifold;
• and
• means for generating a fluid flow into the inlet manifold, though each chamber in said array and into said outlet manifold, said fluid flow through each chamber being sufficient to prevent foreign bodies in the fluid from lodging in the orifice;
• wherein each chamber is associated with means for effecting droplet ejection from said orifice simultaneously with said fluid flow through the chamber, the resistance to flow of one of said inlet and outlet manifolds being chosen such that the pressure at a fluid inlet to any chamber in the array varies between any two chambers by an amount less than that which would give rise to significant differences in droplet ejection properties between said two chambers in the array.

Droplet deposition apparatus comprising:

• an array of droplet fluid chambers angled to the horizontal, each chamber being supplied with droplet fluid from a common fluid manifold extending parallel to the array;
• and
• means for generating a fluid flow into each chamber of the array;
• wherein properties of said inlet manifold varying in a direction lying parallel to the array in such a way as to substantially match the rate of pressure loss along the manifold due to viscous losses in the manifold to the rate of increase of static pressure along the manifold due to gravity.

Droplet deposition apparatus comprising:

• at least one droplet fluid chamber communicating with a first fluid reservoir located above said at least one chamber and with a second fluid reservoir located below the chamber;
• pump means for conveying fluid from the second fluid reservoir to the first fluid reservoir;
• and
• means for preventing the flow of fluid from the first to the second fluid reservoir when said pump means is not operating.

Droplet deposition apparatus comprising:

• at least one droplet fluid chamber communicating with a first fluid reservoir located above said at least one chamber and with a second fluid reservoir located below the chamber;
• pump means for conveying fluid from the second fluid reservoir to the first fluid reservoir;
• and
• pump control means for controlling said pump in dependence on the fluid level in said first fluid reservoir.

Droplet deposition apparatus comprising:

• at least one droplet fluid chamber communicating with a first fluid reservoir located above said at least one chamber and with a second fluid reservoir located below the chamber;
• means for conveying fluid from the second fluid reservoir to the first fluid reservoir;
• and
• temperature control means for controlling the temperature of fluid conveyed from the second fluid reservoir to the first fluid reservoir.

Droplet deposition apparatus comprising:

• at least one droplet fluid chamber communicating with a first fluid reservoir located above said at least one chamber and with a second fluid reservoir located below the chamber;
• means for conveying fluid from the second fluid reservoir to the first fluid reservoir;
• and
• means for conveying fluid from said first fluid reservoir to said second fluid reservoir when the fluid level in said first fluid reservoir exceeds a given level.

Droplet deposition apparatus comprising:

• at least one droplet fluid chamber communicating with a first fluid reservoir located above said at least one chamber and with a second fluid reservoir located below the chamber;
• means for conveying fluid from the second fluid reservoir to the first fluid reservoir;
• means for supplying fluid to said second fluid reservoir;
• and
• fluid supply control means for controlling the supply of the fluid to said second fluid reservoir depending on the fluid level in said second fluid reservoir.

Droplet deposition apparatus comprising:

• at least one droplet fluid chamber communicating with a first fluid reservoir located above said at least one chamber and with a second fluid reservoir located below the chamber;
• means for conveying fluid from the second fluid reservoir to the first fluid reservoir;
• a third fluid reservoir communicating with said second fluid reservoir;
• and
• means for conveying fluid from said third reservoir to said second reservoir in dependence on the fluid level in said second fluid reservoir.