Methods and apparatus for droplet deposition

A method for depositing droplets of fluid onto a medium utilising a droplet deposition head, the droplet deposition head comprising:

• an array of fluid chambers separated by interspersed walls formed of a piezoelectric material, each fluid chamber communicating with an aperture for the release of droplets of fluid, each of said walls separating two neighbouring fluid chambers, and each fluid chamber being defined by a first wall in a first direction relative to the fluid chamber, and a second wall in a second direction relative to the fluid chamber, the second direction being opposite to the first direction;
• wherein each of said walls has a first electrode on a first side of the wall and a second electrode on a second side of the wall, wherein the second electrode of each of the walls is connected to a common potential, and wherein the first electrode of each of the walls is selectively settable to one of (a) a drive potential that is different from the common potential, and (b) the common potential;
• wherein each of said walls is actuable such that, in response to the application of the drive potential to the respective first electrode, the respective wall will move in the first direction from a neutral position into a deformed position, and in response to the application of the common potential to the respective first electrode, the respective wall will return to, or remains in, the neutral position;
• the method comprising, for an actuation cycle, the steps of:
• receiving input data;
• assigning, based on said input data, all the fluid chambers within said array as either firing chambers or non-firing chambers so as to produce bands of one or more contiguous firing chambers separated by bands of one or more contiguous non-firing chambers;
• and
• applying the common potential to the second electrodes and, based on said input data, selectively applying either the drive potential or the common potential to the first electrodes to actuate the walls of said chambers such that:
• for at least a first firing chamber,
• the first wall of the first firing chamber is repeatedly actuated in the first direction and then returned to the neutral position while the second wall of the first firing chamber is kept in the neutral position;
• and
• at a time in the actuation cycle at which the first firing chamber is to eject a droplet of the fluid therein, the second wall of the first firing chamber is selectively actuated in the first direction substantially concurrently with the returning of the first wall of the first firing chamber to the neutral position, thereby causing the first firing chamber to eject a droplet of the fluid therein, and then the second wall of the first firing chamber is returned to the neutral position;
• said actuations during the actuation cycle resulting in each said firing chamber of the band of one or more contiguous firing chambers releasing at least one droplet, the resulting droplets forming bodies of fluid disposed on a line on said medium, said bodies of fluid being separated on said line by respective gaps for each of said bands of non-firing chambers, the size of each such gap generally corresponding in size to the respective band of non-firing chambers.

A method for depositing droplets of fluid onto a medium utilising a droplet deposition head, the droplet deposition head comprising:

• an array of fluid chambers separated by interspersed walls formed of a piezoelectric material, each fluid chamber communicating with an aperture for the release of droplets of fluid, each of said walls separating two neighbouring fluid chambers, and each fluid chamber being defined by a first wall in a first direction relative to the fluid chamber, and a second wall in a second direction relative to the fluid chamber, the second direction being opposite to the first direction;
• wherein each of said walls has a first electrode on a first side of the wall and a second electrode on a second side of the wall, wherein the second electrode of each of the walls is connected to a common potential, and wherein the first electrode of each of the walls is selectively settable to one of (a) a first drive potential, (b) a second drive potential, and (c) the common potential, the common potential being between the first drive potential and the second drive potential;
• wherein each of said walls is actuable such that, in response to the application of the first drive potential to the respective first electrode, the respective wall will move in the first direction from a neutral position into a deformed position, in response to the application of the second drive potential to the respective first electrode, the respective wall will move in the second direction from the neutral position into a deformed position, and in response to the application of the common potential to the respective first electrode, the respective wall will return to, or will remain in, the neutral position;
• the method comprising, for an actuation cycle, the steps of:
• receiving input data;
• assigning, based on said input data, all the fluid chambers within said array as either firing chambers or non-firing chambers so as to produce bands of one or more contiguous firing chambers separated by bands of one or more contiguous non-firing chambers;
• and
• applying the common potential to the second electrodes and, based on said input data, selectively applying either the first drive potential, the second drive potential or the common potential to the first electrodes to actuate the walls of said chambers such that:
• for at least a first firing chamber,
• the first wall of the first firing chamber is repeatedly actuated in the first direction and then the second direction while the second wall of the first firing chamber is kept in the neutral position;
• and
• at a time in the actuation cycle at which the first firing chamber is to eject a droplet of the fluid therein, the second wall of the first firing chamber is selectively actuated in the first direction substantially concurrently with the actuating of the first wall of the firing chamber in the second direction, thereby causing the first firing chamber to eject a droplet of the fluid therein, and then the second wall of the first firing chamber is returned to the neutral position;
• said actuations during the actuation cycle resulting in each said firing chamber of the band of one or more contiguous firing chambers releasing at least one droplet, the resulting droplets forming bodies of fluid disposed on a line on said medium, said bodies of fluid being separated on said line by respective gaps for each of said bands of non-firing chambers, the size of each such gap generally corresponding in size to the respective band of non-firing chambers.