Claims
- 1. A method of operating a multi-channel pulsed droplet deposition apparatus having an array of parallel channels, disposed side by side and separated one from the next by side walls extending in the lengthwise direction of the channels;
- a series of nozzles which communicate respectively with said channels for ejection of droplets therefrom;
- connection means for connecting the channels with a source of droplet fluid;
- and electrically actuable means for displacing a portion of a side wall in response to an actuating signal, thereby to eject a droplet from said selected channel,
- the method comprising the steps of
- applying an actuating signal to said electrically actuable means to eject a droplet from a selected channel, the signal being held at a given non-zero level for a period, the length of said period being such that:
- (a) it is greater than the length of that period which would result in the velocity of droplets ejected from said channel being at its maximum; and
- (b) the velocity of a droplet ejected from said selected channel is substantially independent of whether or not channels in the vicinity of said selected channels are similarly actuated to effect droplet ejection simultaneously with droplet ejection from selected channel.
- 2. Method according to claim 1 wherein said selected channel is held in a contracted state for said period.
- 3. Method according to claim 2 wherein said channel is a non-actuated state directly prior to and directly following said period.
- 4. Method according to claim 2 wherein said period during which said channel is held in a contracted state is directly preceded by a further period during which said channel is held in a expanded state.
- 5. Method according to claim 4 wherein said period and said further period having the same duration.
- 6. Method according to claim 1 wherein channels share a common droplet fluid supply manifold.
- 7. Method as claimed in claim 1 wherein the velocity of said droplet ejected from said selected channel is greater than 1 m/s.
- 8. A method according to claim 1 wherein successive channels of the array are regularly assigned to groups such that a channel belonging to any one group is bounded on either side by channels belonging to at least one other group;
- the length of said period being such that:
- (a) it is greater than the length of that period which would result in the velocity of droplets ejected from said channel being at its maximum; and
- (b) the velocity of a droplet ejected from said selected channel is substantially independent of whether or not those channels belonging to the same group as the selected channel and which are located closest to said selected channel in the array are similarly actuated to effect droplet ejection simultaneously with droplet ejection from the selected channel.
- 9. Method according to claim 8 wherein the ratio of the duration of said second period to said period is chosen such that there is generated no pressure wave contribution affecting the velocity of droplet ejection from those channels belonging to the next group of channels to be enabled.
- 10. Method according to claim 9 wherein the ratio of said period to said second period is approximately 3:4.
- 11. Method according to claim 10 wherein successive channels of the array are in turn assigned to each of three groups.
- 12. Method according to claim 1 or claim 8 wherein the length of the period at which the velocity of droplets ejected from said channel is at its maximum is substantially equal to L/c, where c is the effective velocity of pressure waves in the fluid in said channel and L is the length of channel extending between the nozzle and the connection means connecting the channel with a source of droplet fluid.
- 13. Method according to claim 12 wherein said selected channel is held in an expanded state for said period.
- 14. Method according to claim 13 wherein said selected channel is in a non-actuated state directly prior to and following said period.
- 15. Method according to claim 13 wherein the volume of said selected channel is held at a given expanded volume for said period and directly thereafter at a given contracted volume for a second period.
- 16. Method according to claim 15 wherein said second period is longer than said period.
- 17. Method according to claim 15 wherein the ratio of the duration of said second period to said period is chosen such that there is generated no pressure wave contribution affecting the velocity of droplet ejection from the channels belonging to the next group of channels to be enabled.
- 18. Method according to claim 17 wherein the ratio of said period to said second period is approximately 3:4.
- 19. Method according to claim 18 wherein successive channels of the array are in turn assigned to each of three groups.
- 20. Method according to claim 12 wherein said period is greater than that length of the period at which the velocity of droplets ejected from said channel is at its maximum by a factor of approximately 1.7.
- 21. Method of selecting a signal for actuating electrically actuable means for displacing a portion of a side wall extending along a channel of a multi-channel pulsed droplet deposition apparatus, thereby to effect droplet ejection therefrom, said apparatus having an array of parallel channels, disposed side by side and separated one from the next by side walls extending in the lengthwise direction of the channels, a series of nozzles which communicate respectively with said channels for ejection of droplets therefrom and connection means for connecting the channels with a source of droplet fluid, said signal being held at a non-zero level for a period, the method comprising the steps of:
- (a) applying said signal to a selected channel of said array and measuring the velocity of the droplet ejected from the selected channel;
- (b) applying said signal to said selected channel and simultaneously to channels in the vicinity of said selected channel and measuring the velocity of the droplet ejected from the selected channel; and
- (c) choosing the length of period such that there is substantially no variation in velocity between droplets ejected from the selected channel under regime (a) and droplets ejected from the selected channel under regime (b).
- 22. A multi-channel pulsed droplet deposition apparatus having an array of parallel channels, disposed side by side and separated one from the next by side walls extending in the lengthwise direction of the channels:
- a series of nozzles which communicate respectively with said channels for ejection of droplets therefrom;
- connection means for connecting the channels with a source of droplet fluid;
- and electrically actuable means for displacing a portion of a side wall in response to an actuating signal, thereby to eject a droplet from said selected channel,
- and a drive circuit for applying an actuating signal to said electrically actuable means to eject a droplet from a selected channel, the drive circuit being arranged to hold the signal at a given non-zero level for a period, the length of said period being such that:
- (a) it is greater than the length of that period which result in the velocity of droplets ejected from said channel being at its maximum; and
- (b) the velocity of a droplet ejected from said selected channel is substantially independent of whether or not channels in the vicinity of said selected channel are similarly actuated to effect droplet ejection simultaneously with droplet ejection from said selected channel.
- 23. Apparatus according to claim 22 wherein said selected channel is held in a contracted state for said period.
- 24. Apparatus according to claim 23 wherein said channel is in a non-actuated stated directly prior to and directly following said period.
- 25. Apparatus according to claim 23 wherein said period during which said channel is held in a contracted state is directly preceded by a further period which said channel is held in a expanded state.
- 26. Apparatus according to claim 25 wherein said period and said further period have the same duration.
- 27. Apparatus according to claim 22 wherein channels share a common droplet fluid supply manifold.
- 28. Apparatus as claimed in claim 22 wherein the velocity of said droplet ejected from said selected channel is greater than 1 m/s.
- 29. Apparatus according to claim 22 wherein successive channels of the array are regularly assigned to groups such that a channel belonging to any one group is bounded on either side by channels belonging to at least one other group;
- the length of said period being such that:
- (a) it is greater than the length of that period which would result in the velocity of droplets ejected from said channel being at its maximum; and
- (b) the velocity of a droplet ejected from said selected channel is substantially independent of whether or not those channels belonging to the same group as the selected channel and which are located closest to said selected channel in the array are similarly actuated to effect droplet ejection simultaneously with droplet ejection from the selected channel.
- 30. Apparatus according to claim 29 wherein the ratio of the duration of said second period to said period is chosen such that there is generated no pressure wave contribution affecting the velocity of droplet ejection from those channels belonging to the next group of channels to be enabled.
- 31. Apparatus according to claim 30 wherein the ratio of said period to said second period is approximately 3:4.
- 32. Apparatus according to claim 31 wherein successive channels of the array are in turn assigned to each of three groups.
- 33. Apparatus according to claim 22 or claim 29 wherein the length of the period at which the velocity of droplets ejected from said channel is at its maximum is substantially equal to L/c, where c is the effective velocity of pressure waves in the fluid in said channel and L is the length of channel extending between the nozzle and the connection means connecting the channel with a source of droplet fluid.
- 34. Apparatus according to claim 33 wherein said selected channel is held in an expanded state for said period.
- 35. Apparatus according to claim 34 wherein said selected channel is in a non-actuated state directly prior to and following said period.
- 36. Apparatus according to claim 34 wherein the volume of said selected channel is held at a given expanded volume for said period and directly thereafter at a given contracted volume for a second period.
- 37. Apparatus according to claim 36 duration of said second period to said period is chosen such that there is generated no pressure wave contribution affecting the velocity of droplet ejection from those channels belonging to the next group of channels to be enabled.
- 38. Apparatus according to claim 37 wherein the ratio of said period to said second period is approximately 3:4.
- 39. Apparatus according to claim 38 wherein successive channels of the array are in turn assigned to each of three groups.
- 40. Apparatus according to claim 36 wherein said second period is longer than said period.
- 41. Apparatus according to claim 33 wherein said length of said period is greater than that length of the period at which the velocity of droplets ejected from said channel is at its maximum by a factor of approximately 1.7.
Priority Claims (1)
Number |
Date |
Country |
Kind |
9523926 |
Nov 1995 |
GBX |
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Parent Case Info
This application is a continuation of International Application No. PCT/GB96/02900, filed Nov. 22, 1996.
The priority benefit under 35 U.S.C. .sctn.120 of International Application No. PCT/GB96/02900 filed Nov. 22, 1996 is claimed.
US Referenced Citations (3)
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Continuations (1)
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Number |
Date |
Country |
Parent |
PCTGB9602900 |
Nov 1996 |
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